1 L Aboratory- 9 Directed Evelopment°$

LA-13278-PR Progress Report 1 L ABORATORY- 9 DIRECTED

EVELOPMENT°$

Los Alamos NATIONAL LABORATORY Los Alamos Laboratory is operated the Unive States Department of Energy unde ontract W- ABSTRACT

This report summarizes the FY 1996 goals and accomplishments of Laboratory-Directed Research and Development (LDRD) projects. It gives an overview of the LDRD program, summarizes work done on individual research projects, and provides an index to the projects' principal investigators. Projects are grouped by their LDRD component: Indi- vidual Projects, Competency Development, and Program Development. Within each component, they are further divided into nine technical disciplines: (1) materials science, (2) engineering and base technologies, (3) plasmas, fluids, and particle beams, (4) chemistry, (5) mathematics and computational sciences, (6) atomic and molecular physics, (7) geoscience, space science, and astrophysics, (8) nuclear and particle physics, and (9) biosciences.

FRONT COVER

The background graphic is an atomic force microscope image of the slip bonds on a stressed iron- silicon-boron magnetic ribbon (M. Haw ley, "Scanning Probe Microscopy Competency Develop- ment"). The superimposed upper- left image shows the trajectory of a single deuterium-tritium fusion alpha particle through a magnetized target plasma (R. Kirkpatrick, "Generation and Compression of a Target Plasma for Magnetized Target Fusion"). To the right are two scattered-light images showing the effect of a low-density plasma on a high-intensity laser probe (J. Cobble, "High-Intensity Matter Interaction Physics"). The equation describes the transport of vorticity in turbulent fluid flow in two-dimensional Cartesian space. UC-900 Issued: May 1997

1 L ABORATORY- 9 D IRECTED 9 R ESEARCH AND 6 D EVELOPMENT

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FY1996 PROGRESS REPORT

COMPILED BY JOHN VIGIL AND JUDY PRONO

DISCLAIMER

This report was prepared as an account of work sponsored by an agency of the United States Government. Neither the United States Government nor any agency thereof, nor any of their employees, makes any warranty, express or implied, or assumes any legal liability or responsibility for the accuracy, completeness, or usefulness of any information, apparatus, product, or process disclosed, or represents that its use would not infringe privately owned rights. Refer- ence herein to any specific commercial product, process, or service by trade name, trademark, MASTER manufacturer, or otherwise does not necessarily constitute or imply its endorsement, recommendation, or favoring by the United States Government or any agency thereof. The views and opinions of authors expressed herein do not necessarily state or reflect those of the United States Government or any agency thereof.

DISTRIBUTION OF THIS DOCUMENT IS UNLIMITED

Los Alamos

Los Alamos, New Mexico 87545 Published by Los Alamos National Laboratory

Laboratory Director: Sig Hecker

Director for Science and Technology Base Programs: Al Sattelberger

Office Leader for Laboratory-Directed Research and Development: Ed Heighway

Scientific Editor: John Vigil

LDRD Office Team: Shelly Cross, Jo McCarthy, and Leonard Salazar

Managing Editor: Judy Prono (CIC-I)

Editors: Deborah Bacon, lleana Buican, Marty DeLanoy, Anne Garnett, Jennifer Graham, Sheila Molony, Kathleen Park, Amy Reeves, and James Russell (CIC-I)

Editorial Support: Eileen Patterson (CIC-I)

Cover Design:Susan Carlson (CIC-I)

Layout, Composition,and Production: Wendy Burditt (CIC-I)

Printing Coordination: CIC-I 7 Printing Team

The previous reports in this unclassified series are LA-12680-PR, LA-12880-PR, and LA-131 10-PR.

This report was prepared as an account of work sponsored by an agency of the United States Government. Neither The Regents of the University of California, the United States Government nor any agency thereof, nor any of their employees, makes any warranty, express or implied, or assumes any legal liability or responsibility for the accuracy, completeness, or usefulness of any information, apparatus, product, or process disclosed, or represents that its use would not infringe privately owned rights. Reference herein to any specific commercial product, process, or service by trade name, trademark, manufacturer, or otherwise, does not necessarily constitute or imply its endorsement, recommendation, or favoring by The Regents of the University of California, the United States Government, or any agency thereof. The views and opinions of authors expressed herein do not necessarily state or reflect those of The Regents of the University of California, the United States Government, or any agency thereof. Los Alamos National Laboratory strongly supports academic freedom and a researcher's right to publish; as an institution, however, the Laboratory does not endorse the viewpoint of a publication or guarantee its technical correctness. iv Los Alamos FY1996 LDRD Progress Report DISCLAIMER Portions of this document may be illegible in electronic image products. Images are produced from the best available original document* Contents

LDRD Program Overview—FY 1996 Individual Projects

Materials Science

9 Origin of Radiation Damage in Potassium Titanyl 16 Innovative Composites through Reinforcement Phosphate Morphology Design—A Bone-Shaped Short-Fiber Composite 10 Development of a Fundamental Understanding of Chemical Bonding and Electronic Structure in 18 New Deposition Processes for the Growth of Oxide Spinel Compounds and Nitride Thin Films

11 Phase Stability of Transition Metals and Alloys 18 Texture Characterization for HE Design

12 Theoretical and Experimental Investigation on the 19 Interfacial Charge Transport in Organic Electronic

Low-Temperature Properties of the NbCr2 Laves Materials: The Key to a New Electronics Phase Technology

14 Nanostructured Materials: Growth and Patterning 19 Thermodynamic and Electrodynamic Studies of Using Hyperthermal Materials Chemistry Unusual Narrow-Gap Semiconductors

14 Inorganic-Organic Composite Nanoengineered Films 20 A Molecular Architectural Approach to Novel Using Self-Assembled Monolayers for Directed Electrooptical Materials Zeolite Film Growth 21 Characterization and Manipulation of Broken- 15 Rigid Molecular Foams Symmetry Materials at Phase Boundaries

15 Materials Research for Optical Refrigeration

Engineering and Base Technologies

23 Development of New and Efficient Hard-Rock 25 The Development of Fullerene-Based Hydrogen Mining Methods Using Pulsed-Laser Excavation Storage Systems

23 Virtual Reality and Telepresence Control of Robots 25 Optical Imaging through Turbid Media Using a Used in Hazardous Environments Degenerate, Four-Wave, Mixing Correlation Time Gate 24 Nuclear Magnetic Resonance Imaging with Hyperpolarized Noble Gases 26 High-Average-Power, Intense Ion Beam for Materials Modification and Other Applications

Contents Individual Projects (cont.)

Engineering and Base Technologies (cont.)

27 Multichip Module Technology Development 32 Application of Intense Surface Discharge VUV Light Sources to Photoresist Ashing in 27 Magnetic Resonance Force Microscope Semiconductor Manufacturing Development 33 All-Solid-State Four-Color Laser 28 Femtosecond Scanning Tunneling Microscope 34 Material Processing for Self-Assembling Machine 29 Exploration of Technologies for Improving Civil Systems Security 34 Diode Laser Development for Quantum 30 Fiber-Optic Communications Using Solitons Computation (FOCUS) 35 Designing a Micromechanical Transistor 30 New Applications for Zeeman Interferometry 35 High-Sensitivity, Solid-State Carbon Monoxide 31 A Comprehensive Monitoring System for Damage Sensor Development Identification and Location in Large Structural and Mechanical Systems 35 Acoustic Resonance Spectroscopy

31 Quantum Cryptography for Secure 36 Liquid-Metal, Focused-Ion-Beam Etch Communications to Low-Earth-Orbit Satellites Sensitization and Related Data Transmission Processes

36 Experimental Validation of Superconducting Quantum Interference Device Sensors

Plasmas, Fluids, and Particle Beams

37 High-Power, High-Frequency, Annular-Beam Free- 41 Turbulence and Turbulence Spectra in Complex Electron Maser Fluid Flows

38 Determination of Optical Field-Ionization 41 A Water-Filled, Radio-Frequency Accelerating Dynamics in Plasmas through Direct Measurement Cavity of the Optical-Phase Change 42 A Target Plasma Experiment for Magnetized Target 39 Delta-f and Hydrodynamic Methods for Fusion Semiconductor Transport 43 Developing Electron-Beam Bunching Technology 40 A Compact Compton-Backscattering X-Ray at Subpicosecond Pulse Lengths for Improving Source for Mammography and Coronary Photon Sources Angiography 44 High-Intensity Laser-Matter Interaction Physics 40 Equation of State of Dense Plasmas

vi Los Alamos FY1996 LDRD Progress Report Individual Projects (cont.) Chemistry

45 New Fullerene-Based Mixed Materials: Synthesis 54 Binding of Hydrocarbons and Other Extremely and Characterization Weak Ligands to Transition-Metal Complexes that Coordinate Hydrogen: Investigation of Cis- 46 Uses of Novel Selenium-Containing Chiral Interactions and Delocalized Bonding Involving Derivatizing Agents: Potential Catalysis for the Sigma Bonds Chiral Oxidation of Simple Alkenes and Chiral- Promoted Aldol Reactions 55 Asymmetric Catalysis in Organic Synthesis

47 Metal-Ligand "Multiple" Bonding: Revelations in 56 Temperatures and Vibrational Frequencies of

the Electronic Structure of Complexes of High- Liquid N2/O2 and CO/O2 Mixtures Shock- Valent f-Elements Compressed to 10 GPa and 2000 K

48 Chemistry and Catalysis in Supercritical Media 57 Catalysts for Hydrocarbon Oxidation

50 Decay of Surface Nanostructures Via Long-Time- 57 Fundamental Studies of Polymer Filtration Scale Dynamics 58 Modification of Heterogeneous Chemistry by 51 Solvation and Ionic Transport in Polymer Realistic Substrate Complexity Electrolyte Membranes 59 Ionically Conducting Polymers for High-Energy- 51 Heterogenization of Homogeneous Catalysts: Density Batteries The Effect of the Support 59 Advanced Polymer Chemistry of Organometallic 52 Photoredox Reactions: Energy Storage and Anions Halocarbon Degradation 60 Reaction Kinetics Relevant to the Recycle 52 Reactivity at Metal Centers Bound to Water- Hydride-Dehydride Process for Plutonium Soluble Catalysts Recovery

53 Cyclodextrin-Based Chemical Microsensors for 60 Ultrafast Laser Studies of Solution Reactivity Volatile Organic Compounds (VOCs)

Mathematics and Computational Sciences

61 Parallel Three-Dimensional Spherical-Harmonics 63 Dispersive Water Waves in One and Two Transport Methods Dimensions

61 Adaptive, Composite, Overlapping Mesh 64 Mimetic Difference Approximations of Partial Algorithms on Message-Passing Architectures Differential Equations

62 A Self-Consistent Multiscale Theory of Internal- 64 Wavelet Transforms as Solutions of Partial Wave, Mean-Flow Interactions in the Ocean Differential Equations

62 Geometry in the Large and Hyperbolic Chaos 65 Dispersive, Internal, Long-Wave Models

63 Industrial Processing of Complex Fluids: 65 Solution-Adaptive Methods for Low-Speed and Formulation and Modeling All-Speed Flows

Contents VII Individual Projects (cont.)

Mathematics and Computational Sciences (cont.)

66 Combinatorics, Geometry, and Mathematical 68 Computational Three-Dimensional Inversion for Physics Seismic Exploration

66 The Fundamental Role of Solitons in Nonlinear 68 Super-Speed Computer Interfaces and Networks Partial Differential Equations 69 Particles and Patterns in Cellular Automata 67 Elliptic Solvers for Adaptive Mesh Refinement 69 High-Quality Finite-Difference Schemes for Partial Grids Differential Equations and Discrete Vector and 67 Studies of Structure of Turbulence by High- Tensor Analysis Resolution Simulation and Theory 70 Modeling Mesoscopic Phenomena in Extended Dynamical Systems

Atomic and Molecular Physics

71 State-to-State Photodetachment in the Two- 73 Optical Wave Packets (Optical Bullets): A New, Electron Hydrogen Ion Diffraction-Free Form of Light Travel

71 Transient Quantum Mechanical Processes 74 Nonlinear Atom Optics

72 Calculation of Satellite Line Structures in Highly 74 Dynamics of Quantum Wave Packets Stripped Plasmas

Geoscience, Space Science, and Astrophysics

75 Low-Energy Neutral Atom Imager 81 Theoretical Research on Dwarf and Classical Novae 76 Nonlinear Processes in Earthquakes 81 Micro/Macroscale Coupling in Magnetospheric 78 Lead Immobilization in Thermally Remediated Plasmas Soils and Igneous Rocks 82 Numerical Simulations of Convection Experiments 78 Experimental Studies of Auroral-Arc Generators and Earth's Interior 79 Fundamentals of Laser Ablation in the Analysis of 83 High-Velocity Neutron Stars Geological Materials 83 Sedimentary Basin Response to Strong Motion in 80 Integrating Chemistry into Three-Dimensional Populous Regions Climate Models: Detailed Kinetics in the Troposphere and Stratosphere of a Global Climate 84 Heterogeneous Processing of Bromine Compounds Model by Atmospheric Aerosols: Relation to the Ozone Budget 80 Using Microspheres as Tracers for Flow in Geologic Media

viii Los Alamos FYI996 LDRD Progress Report Individual Projects (cont.)

Geoscience, Space Science, and Astrophysics (cont.)

85 Coronal Mass Ejections in the Solar Wind 95 Close Encounters of Asteroids and Comets to Planets 85 Modeling Core-Collapse Supernovae in Three Dimensions 95 Isotopic Prediction of Eruption Volume at Continental Volcanoes 86 Deriving the Structure of Presupernovae and Delta Scuti Stars Using Nonradial Oscillations 96 Experimental Cosmology: The Early Universe

88 Magmatic Tritium 98 Cosmology with Massive Neutrinos

90 Minerals of Earth's Deep Interior 98 Global Climate Effects of the Emerging Chinese Transportation System 91 Striation-Image Monitoring of Plasmaspheric, L-Resolved Electrodynamics (SIMPLE) 99 Regge Geometrodynamics in Support of Gravity Wave Astronomy 91 Coupled Ocean-Atmosphere Model System for Studies of Interannual-to-Decadal Climate 99 Remote Sensing of Thundercloud Electric-Field Variability over the North Pacific Basin Airglow

92 Particle Acceleration from Reconnection in the 100 Accretion onto Black Holes: The Power- Geomagnetic Tail Generating Mechanism

93 Fluxes of Water and Energy in Physically 102 Thermal Rocketing and the Laser Geodynamic Heterogeneous Environments Satellite (LAGEOS-1)

94 Hare Star Monitoring with a New Single-Photon- 102 Plasmasphere Refilling: New Numerical and Counting Imaging Detector Observational Tools

Nuclear and Particle Physics

103 Time-Reversal Tests in Polarized Neutron Reactions 109 Antiquark Distributions in the Proton

104 Exploring and Testing the Standard Model and Beyond 109 Nucleon-Nucleon Data Analysis

104 L3 Physics at the Z Resonance and a Search for the 110 Solar Neutrino Physics Higgs Particle 111 Chiral Symmetry in Finite Nuclei 105 Neutrinos and Theory of Weak Interactions 111 Simulating the Decays of Bottom and Charm 106 Weak Interaction Measurements with Optically Mesons Trapped Radioactive Atoms 112 Nonequilibrium Dynamics of the Quark-Gluon 108 Neutrino Physics at Fermilab Plasma in Heavy-Ion Collisions

108 A Continuous Watch of the Northern Sky above 113 Determination and Study of Cosmic-Ray 40 TeV with the CYGNUS Array Composition above 100 TeV

108 Neutron Measurements to Optimize Treatment of 114 Nonperturbative Estimates of the Standard Model Cancer Patients with Fast Neutrons Parameters

Contents IX Individual Projects (cont.)

Biosciences

115 Biotechnology Approaches to Stable-Isotope 121 Engineering Sequence-Specific RNA and Single- Labeling for Biomolecular Structure/Function Stranded-DNA Binding Proteins Studies 122 Theoretical Studies of Allosteric Changes and 116 Preparation and Utilization of 13C- and 15N-Labeled DNA Binding of a cAMP-Dependent Transcription DNAs for the Determination of Unusual DNA Activation Protein Structures Relevant to the Human Genome Project by Nuclear Magnetic Resonance Spectroscopy 122 Engineering the Specificity of xylR: A Bacterial Protein that Detects Chemicals in the Environment 116 Applications of Strand-Specific In Situ 123 Optimization and Monitoring of Hollow-Fiber Hybridization Bioreactors 117 Computer Simulation of Protein Solvation, Hydrophobic Mapping, and the Oxygen Effect in 124 Optimal Screening Designs for Biomedical Radiation Biology Technology 126 Nuclear Magnetic Resonance (NMR) Spectroscopy 117 Electromagnetic Inverse Applications for of Unusual DNA Structures and Functions Functional Brain Imaging Associated with Human Disease 118 Gene Shuffling Using Flow Cytometry 127 Emerging Pathogens: Dynamics, Mutation, and 118 Identification and Characterization of a Human Drug Resistance DNA Double-Strand Break Repair Complex 127 Optical Measurement of Drug Concentrations in 119 Determining the Role of the Telomere on the Tissue Severity of Birth Defects 128 Stable-Isotope Labeling of Oligosaccharide Cell- 119 Development of an Ultrasensitive and Rapid DNA Surface Antigens for Structural Studies Repair Assay 129 Protein Motions that Determine the Efficiency of 120 Structure and Thermodynamics of Surface Photosynthesis Recognition 129 Studying Properties of Cell Suspensions with 120 Neutron Structural Biology Elastic Scattering

121 Sum-Frequency Generation Studies of Membrane 130 Numerical Simulations of Biochemical Self- Transport Phenomena Organization: Calcium Wave Propagation and Microtubule Growth

Los Alamos FYI996 LDRD Progress Report Competency Development Projects Materials Science

135 Actinide Crystal Structures with an Emphasis on 148 Characterization of Active Sites in Zeolite Catalysts Plutonium Alloys 149 New Initiatives in Materials Characterization, 136 The Implications of Diffraction In Situ Loading Modeling, and Synthesis Macrostrain Measurements in Composites and Finite-Element Interpretations 149 Dynamics of Polymers at Interfaces

137 Chemical and Physicochemical Properties of 150 Understanding and Controlling Self-Assembly Submicron Aerosol Agglomerates 151 Role of Charge Localization in the Basic High- 137 Characterization of Bioactive Materials Using Temperature Superconductivity Mechanism Neutron Reflectivity and Atomic Force Microscopy 152 Measurement by Neutron Diffraction of Strains in 138 Bulk Amorphous Materials Advanced Engineering Structural Materials including AlSiC and AlTiC 139 Characterization of Advanced Electronic Materials 153 Chemistry and Microstructure of High-Temperature 140 Neutron Scattering Studies on Shear-Induced Superconductor Interfaces Structure in Polymers 154 Texture Science and Technology 140 Structural and Magnetic Characterization of Actinide Materials 154 Microstructures of Transition Metal Oxides Characterized by Neutron and X-Ray Scattering 142 Equation-of-State, Thermodynamic, and Structural- Mechanical Properties of Intermetallic Compounds 155 A Thermodynamically Consistent, Damage- Dependent, Interface Debonding Model for 142 Neutron Scattering from Correlated-Electron Composites Systems 155 Zircon as a Host Phase for Plutonium Disposition 143 Advanced Deformation Process Modeling 156 Many-Body Theory Research 144 Scanning Probe Microscopy Competency Development 157 Alloy Design and Phase Stability of the Ternary Alloy Ti-Al-Nb 145 Design and Implementation of an X-Ray Strain Measurement Capability Using a Rotating Anode 158 Synthesis and Characterization of Correlated- Machine Electron Materials

146 Computational Modeling of Materials Processing 159 Tailoring the Interfacial Electronic Structure of and Processes Organic Electronic Materials and Devices

146 Nanometer-Scale Materials 159 Controlling Function of Polar Organic Multilayers

147 Science and Technology of Reduced-Dimensional 160 Pinning Vortices and Enhancing High-Temperature Magnetic Materials Superconductor (HTS) Critical Currents

147 Complementary Neutron Diffraction and 161 Nonlinearity in Structural and Electronic Materials Computational Micromechanics Studies of 163 High-Resolution Electron Microscopy of Advanced Polycrystalline Deformation in Advanced Materials Materials

Contents Competency Development Projects (cont.)

Engineering and Base Technologies

167 Molten Salt and Molten Lead Systems Studies 172 Development of Inexpensive Continuous-Emission Monitors for Feedback Control of Combustion 168 Advanced Measurements and Techniques in High Devices to Minimize Greenhouse Gases, Toxic Magnetic Fields Emissions, and Ozone-Damaging Products 168 Dynamic High-Strain Deformation of Materials: 173 Distortion, Residual Stress, and Thermal Gradient Experiments, Advanced Constitutive Modeling, Issues for Plutonium Gravity Casting in Ambient- and Computational Implementation Temperature Molds 169 Ultrasensitive Sensors for Weak Electromagnetic 174 Radiation Resistance Measurements of Rare-Earth Fields Using HTS SQUIDs for Biomagnetism, Permanent Magnet Material for High-Intensity NDE, and Corrosion Currents Linac Applications 170 Short-Pulsed Electric-Discharge Degradation 174 Molten Salt and Separations Technologies of Toxic and Sludge Wastes Evaluation 171 Laser-Sheet Imaging of HE-Driven Interfaces 175 Neutron Metrology for Stockpile Stewardship at 171 A Neural-Network-Based System for Damage LANSCE Identification and Location in Structural and Mechanical Systems

Plasmas, Fluids, and Particle Beams

177 High-Energy Test of Proton Radiography Concepts 179 Development of Ion-Beam Techniques for the Study of Special-Nuclear-Materials-Related 177 Comparison of Cyclotrons and Linacs for High- Problems Intensity-Beam Applications 180 Generation and Compression of a Target Plasma 178 A 1-kW-Power Demonstration from the Advanced for Magnetized Target Fusion Free-Electron Laser 182 Advanced Modeling of High-Intensity Accelerators 179 Advanced Techniques for Producing, Polarizing, and Storing Ultracold Neutrons

Chemistry

183 Binding Carbon Dioxide in Mineral Form: A Critical 185 Kinetic Studies of Competitive Adsorption Step toward a Zero-Emission Coal Power Plant Processes Related to Automobile Catalytic Converters 183 Foreign Nuclear Test Radiochemical Diagnostics 185 Investigations of Biomimetic Light-Energy- 184 The Characterization of Atmospheric Aerosols: Harvesting Pigments Applications to Heterogeneous Gas-Particle Reactions

xii Los Alamos FYI996 LDRD Progress Report Competency Development Projects (cont.) Mathematics and Computational Sciences

187 Nuclear Futures Analysis and Scenario Building 195 Theoretical Foundation for Adaptive Monte Carlo

188 New Numerical Models for Global Ocean 196 Advanced Three-Dimensional Eulerian Modeling Hydrodynamic Algorithm Development

188 Lie Group Applications to the Solution of 198 Phase Transitions, Nonequilibrium Dynamics, and Differential Equations Critical Behavior of Strongly Interacting Systems

189 Lithospheric Processes 198 Numerical Simulations of Disordered Superconductors 189 Geometrically Compatible 3-D Monte Carlo and Discrete-Ordinates Methods 199 Transactional Memories: A New Abstraction for Parallel Programming 190 Adaptive Monte Carlo Methods for Radiation Transport 199 Development of an Integrated System for Estimating Human Error Probabilities and 191 High-Perf ormance Computing of Electron Modeling Their Effects Microstructures 200 Novel Monte Carlo Algorithms for Statistical 192 Modeling Complex Phenomena: Multiple Length Mechanics and Time Scales in Extended Dynamical Systems 200 Advanced Computational Science 192 Continuing Benchmarking of Ocean-Circulation Models 201 Development of an Automated Core Model for Nuclear Reactors 193 Simulation Methods for Advanced Scientific Computing 201 Density Function Estimation for Monte Carlo Simulations 193 Adaptive Mesh Refinement Algorithm Development and Dissemination 202 Self-Organization and Pattern Formation

194 Neutron Transport Methods for 3-D Cartesian 203 Application of Discrete Mathematics Adaptive Meshes 204 Theory and Modeling of Correlated-Electron 194 Applications of Nonlinear and Stochastic Materials Dynamics

Geoscience, Space Science, and Astrophysics

207 Modeling the Heat Flow and Resulting Dynamics 210 Analysis and Visualization of Global in Earth's Interior Magnetospheric Processes

208 Remote Sensing Science Thrust: New Concepts 211 Neutron Star Evolution and Emission

209 Subsurface Noble Gas Transport at the Nevada 212 Remote Sensing Science Thrust: Laser Remote Test Site Sensing

Contents XIII Competency Development Projects (cont.)

Geoscience, Space Science, and Astrophysics (cont.)

213 Development of the First Nonhydrostatic, Nested- 216 Studies of Dynamical Processes Affecting Global Grid, Grid-Point Global Atmospheric Modeling Climate System on Parallel Machines 218 Transport Processes in Space Plasmas 213 Production and Application of High-Specific- 220 Physical Properties and Mantle Dynamics Activity Si-32

214 Remote Sensing Science Thrust: Hyperspectral Sensing

Nuclear and Particle Physics

223 Advanced Research Capabilities for Neutron Science and Technology—Neutron Polarizers

Biosciences

225 Solution Structure of the cAMP-Dependent Protein 230 Microbial Acquisition of Iron from Iron-Bearing Kinase Minerals

225 Development of Biosensors and Bioprobes Based 230 The Biology of Novel Animal Genes: Mouse on Spectroscopic Monitoring of Enzymes and APEX Gene Knockout Other Proteins Encapsulated in Sol-Gel Glasses 231 Competency Development in Antibody Production 226 Molecular Characterization of Flow-Sorted for Cancer Cell Biology Mammalian Centromeres 232 Covariation of Mutations: A Computational 226 Advanced Biomolecular Materials Based on Approach for Determination of Function and Membrane-Protein/Polymer Complexation Structure from Sequence

227 Similarity Landscapes: An Improved Method for 233 Structure, Dynamics, and Function of Biomolecules Scientific Visualization of Information from Protein and DNA Database Searches 234 Advanced NMR Technology for Bioscience and Biotechnology 227 Formation of Drug-Bearing Vesicles in Mixed Colloids of Bile Salts and Phosphatidylcholine 234 Nonlinear Analysis of Biological Sequences 235 Indigenous Bacteria as Hosts for Proteins for 228 Structural Biology of Disease-Associated DNA Repeats and Protein-DNA Complexes Involved in Bioremediation the Repair of DNA Damage 236 Landscapes and Dynamics of Proteins

229 Applications of Optical Trapping to 237 Engineering Haloalkane Dehalogenase Single-Molecule DNA Sequencing for Bioremediation

xiv Los Alamos FYI996 LDRD Progress Report Program Development Projects

Materials Science

241 Fundamental and Applied Studies of Helium 243 Giant Magnetoresistance Materials for Magnetic Ingrowth in Plutonium Recording Technology

241 Cost-Effective Development of Thin Films for 243 Characterizing Mechanical Effects of Aging Hat-Panel Displays Damage

242 Development of High Magnetic Fields for Energy 244 High-Magnetic-Field Research Collaborations Research 244 Ceramic/Polymer, Functionally Graded Material 242 Advancing the Technology Base for High- (FGM), Lightweight Armor System Temperature Membranes 245 New Anion-Exchange Polymers for Improved Separations in Nuclear and Industrial Applications

Engineering and Base Technologies

247 Detection of Underground Structures and Tunnels 251 Modeling and Assessment of Concrete and the Energy Infrastructure 247 Active Noise and Vibration Control for Vehicular Applications 251 Global Nuclear Material Monitoring

248 Study of Possible Detector Geometries for 252 Frequency-Resolved Optical Gating: A Diagnostic Detection of Radioactivity in Moving Vehicles for the Characterization of Optoelectronic Materials and Devices 248 Environmentally Conscious Coal Combustion: Development of Process Monitors and Improved 253 Neutron-Based, Land-Mine Detection System Numerical Models Development

249 Establishing the Operational Durability of Polymer 254 Development of the Transient-Reactor Analysis Light-Emitting Diodes Code (TRAC) for Real-Time Applications

249 Helium-3 Targets for Tritium Production in Fission 254 Rapid Prototyping of Hazardous Materials Using Systems the Directed-Light Fabrication Process

250 Explosives Detector Using the Optical Signature of 255 Reactor-Based Tritium Production Deflagrating Explosive Particulates 255 Methods for the Rapid On-Line Detection of 250 Directed-Light Fabrication—A Laser Metal- Biological and Chemical Weapons Deposition Process for Fabrication of Near-Net- 256 Night-Vision Device Technology Development Shape Components 256 Integrated Approach to Advanced Machining

Contents xv Program Development Projects (cont.)

Plasmas, Fluids, and Particle Beams

259 Subsurface, Directed-Energy Methods for 261 Advanced Ignition of Jet Turbine Engines Groundwater Treatment 262 Removal of Transuranic Materials from 260 Plasma Source Ion Implantation for Advanced Contaminated Equipment Using Plasma Manufacturing Decontamination

260 Magnet Design Concepts for the 100-MeV 262 Supporting Technologies for a Long-Pulse Isotope-Production Facility Spallation Source

Chemistry

265 Advanced Oxidation Technologies for Chemical 268 Integration of Advanced, Nuclear Materials Demilitarization Separations Processes

266 Advanced Nuclear Fuel Processing 269 Catalysis for Alternative Feedstocks

267 Chemical-Biological Treatment of Heterogeneous 270 Separation Science and Technology: Membrane- Wastes Based Separations and Destruction Processes

267 Radionuclide Separations Using Pillared Layered 271 Microwave Processing Improvements for Methane Materials Conversion to Ethylene

Mathematics and Computational Science

273 Data Resources and Sample Applications for 275 Low-Speed Flow Hydrodynamics Information Analysis in Chemical and Biological Warfare Defense 276 A New Model to Estimate Regional Emissions Inventories 273 Information-Handling/Data-Fusion Technologies to Extract and Analyze Export Information Improving Industrial Performance through 278 Integrated Process Simulation, Control, and 274 Intelligent Controllers for Battlefield Simulations Optimization: Modeling Atoms to Enterprise

274 Visualization Capability for Nonproliferation and National Environmental/Economic Infrastructure Emergency Training: A "Poor Man's" Virtual- 278 System Model Reality System 279 Global Nuclear Material Flow Model 275 Modeling for Environmentally Conscious Manufacturing

Atomic and Molecular Physics

281 Measurement Criteria Analysis for Krypton, Xenon, and Hydrogen (Hydrogen/Deuterium/Tritium) Isotopes and Concentration Variability at Distance

xvi Los Alamos FYI996 LDRD Progress Report Program Development Projects (cont.)

Geoscience, Space Science, and Astrophysics

283 The Carpinteria Reservoir Redevelopment Project 285 Improved Atmospheric Transport for Risk Assessment in Complex Terrain 284 Satellite-Based Laser Windsounder 285 Reservoir Enhancement on the Impermeable 284 Conditioning Geological Reservoir Realizations Margins of Productive Geothermal Fields: with Time-Dependent Data Integrated Resource Development and Management

Nuclear and Particle Physics

287 Disposition of Plutonium as Nonfertile Fuel for 288 Measurement of Fissile Material in Spent Fuel and Water Reactors Alternate Nuclear Materials

288 An Ultracold Neutron Facility at the Manual Lujan Jr. Neutron Scattering Center

Biosciences

289 A Consortium for Biomedical Applications of 293 Distributed Telemedicine for the National Single-Molecule Detection Information Infrastructure Testbed

290 Cancer Risk Assessment 293 Deformable Human Body Model Development

290 Human Brain Mapping: Experimental and 294 Detection and Characterization of Biological- Computational Approaches Weapons Agents by Matrix-Assisted Laser Desorption/Ionization Mass Spectrometry 291 Universal Biological-Agent Point-Sensor Program Development 294 Novel Gene Complex Structure Determination by Neutron and X-Ray Scattering 291 Sensors for Point Detection of Chemical and Biological Warfare Agents 295 In Situ Bioremediation of Trichloroethylene- Contaminated Groundwater 292 Molecular Medicine for the 21 st Century: A Computational Basis for Design and Critique of Vaccines and Therapeutics

299 Index of Principal Investigators

Contents xvii Overview

developing technology to help LDRD Program Overview—FY 1996 eliminate proliferation of nuclear materials and weapons. To show how these activities are supported at Los Ed Heighway and John Vigil Alamos, a breakdown of the Laboratory's FY 1996 funding by The Laboratory-Directed Research All three types of research are major programs is shown in Fig. 1. and Development (LDRD) Program is represented in the Los Alamos LDRD authorized by Congress to fund program. Projects are chosen based on internally proposed research and their innovation and scientific merit in Program Structure development that extends the a mission context, and as a result the LDRD is a formally managed Laboratory's science and technology work leads to a large number of program that imposes accountability capabilities in support of its mission. publications, patents, and external in the processes of selecting, conduct- There are three ways in which LDRD awards. These in turn result in greater ing, and documenting projects. All helps extend these capabilities. First, visibility for the Laboratory's science projects are selected competitively the research explores new ways of and technology, and LDRD becomes through review by peers or scientific tackling mission problems, thereby a vehicle for attracting the best managers. Innovation and scientific identifying opportunities to execute scientists and engineers. excellence are key selection criteria. the Laboratory's mission in a cheaper, The primary mission of Los Alamos All projects must be in science and faster, or better way. Second, the National Laboratory is "to reduce the technology areas that support the research invests in new core capabili- nuclear danger," and there are four Laboratory's mission. ties needed to fulfill the mission, major pieces of that mission: ensuring The LDRD program at Los Alamos perhaps adding a multidisciplinary that the nation's nuclear stockpile is has three components—Individual approach that provides new insight. reliable and safe, managing the Projects (IP), Competency Develop- And third, but by no means least, production and use of nuclear ment (CD), and Program Develop- LDRD invests in the fundamental materials, ensuring that the environment (PD)—each with slightly science and technology base that ment is both restored from past differing goals. The IP component is underpins the Laboratory's ability to nuclear activities and is minimally intended to fund the most far-reaching execute its mission. impacted by future activities, and

WFO-Federal Agencies Other WFO WFO-DOD WFO-DOE 5% 6% Other DOE 4%

Nonproliferation & International Security 9%

Energy Research 6% Environmental Restoration & Waste Management 15%

Fig. 1. Funding for major programs at Los Alamos National Laboratory during FY 1996.

Overview and fundamental research proposed selected for funding. These projects establishes a technical path to by technical staff members to extend are generally funded for three years. In advanced solutions of existing the Laboratory's core science and FY 1996, 166 projects were funded. problems. PD projects are generally technology base. The CD component Competency Development. This of shorter duration than those in the invests in large multidisciplinary other two components, typically being activities that tackle significant component funds the key science and technology competencies that support funded for only one or two years. problems from several approaches, Proposals are solicited, reviewed, and often combining theory and experi- the Laboratory's missions and enable it to respond to new Department of selected by scientific managers and ment. The PD component is intended technical staff within the Laboratory's to invest in nearer-term research for a Energy (DOE) and national issues. CD projects are intended to be cross- eight program offices. In FY 1996, specific sponsor that requires some 73 PD projects were funded. exploration of feasibility or other cutting: that is, they draw on the resources of several Laboratory The high quality of science sup- confidence-building demonstration. In ported by all three LDRD components FY 1996, the LDRD program funded divisions and have clear institutional value beyond the strategic interest of is attested by the number of related 356 projects at a total expenditure of scientific publications, patents, and $54.9 million. The funding distribu- any single division. CD projects are proposed by the scientific staff awards. In 1996, LDRD projects tion among the three components is generated 27% of all Laboratory shown in Fig. 2. through their technical division and program offices, are reviewed both for publications, 39% of its patent Individual Projects. This compo- technical content and strategic value, awards, and half of the Laboratory's nent funds basic research whose and are ultimately selected by the R&D 100 Awards—with only 5.5% of potential is high but whose payoff Laboratory Director. In FY 1996, the budget. In addition, the LDRD may be distant. Often mapping 117 CD projects were funded. program is a significant testing uncharted territory, these projects are ground for the talent attracted to the more exploratory than those of the Program Development. This Laboratory through its postdoctoral other two components. Proposals are component funds research that allows program. In 1996,150 postdoctoral evaluated and ranked by peer-review the Laboratory to examine novel ways staff members worked on LDRD teams (one team for each of nine of meeting extended or future needs of projects. Of these, many will go on to technical disciplines), and the most program sponsors. Generally explor- become permanent Laboratory highly ranked and relevant ones are atory or demonstrational, this research employees and contribute to core assesses the feasibility of new scien- scientific missions. tific approaches or technologies and

Program Development Competency Development

Individual Projects

Fig. 2. Distribution of FY 1996 LDRD funding among the three program components.

1 Los Alamos FY 1996 LDRD Progress Report Highlights of LDRD Support of "snapshots" of the evolving instabil- properties, and are shaped to within a National Security ity, leading to more accurate simula- few thousandths of an inch of final tion models and improved tolerance without the use of a mold, LDRD projects tend to be cutting- calculations. pattern, or forming die. The process is edge research and contribute broadly Understanding the effects of aging ideal for low-volume production of to the science and technology base on nuclear weapon components, precision parts for both defense and that supports the Laboratory's particularly plutonium and polymers, civilian applications. mission. They contribute to nuclear is an important aspect of science- LDRD researchers have also weapons science and technology, to based stockpile stewardship. LDRD developed and benchmarked com- nonproliferation, counterproliferation, researchers are making major puter simulations that predict distor- and arms control, and to nuclear contributions to this understanding tion, residual stress, and thermal materials characterization and defense through theoretical, computational, management in cast plutonium parts. waste disposal, as well as to other and experimental analyses. Using Advances in these areas will benefit national security areas such as transmission electron microscopy, two DOE initiatiatives—Advanced materials, detectors, and computa- small-angle neutron scattering, and Design and Production Technology tional tools for military applications. other advanced techniques, LDRD (ADaPT) and the Accelerated In this year's summary, we have researchers are investigating alpha- Strategic Computing Initiative chosen to highlight just a few LDRD decay-generated helium bubbles that (ASCI). contributions related to national form in aged plutonium metal. They security. Advanced Computational are also developing computer simula- Capability and Nuclear Weapons Nuclear Weapons Science and tion tools to evaluate the effects of Simulation. In the absence of nuclear Technology. Without nuclear testing, this and other aging phenomena on testing, the ability to predict the a fundamental understanding of properties that are germane to nuclear performance of nuclear weapons nuclear weapons performance weapons safety and performance. based on computer simulations is one becomes paramount. LDRD research- Degradation of polymers as they of the key requirements for maintain- ers are developing new ways to make age is probably the most important ing a safe, secure, and reliable the measurements needed for stock- factor limiting the lifetimes of stockpile. Computer simulations of pile certification and for improving stockpiled weapons. LDRD research- the complex phenomena that occur in the modeling capability of nuclear ers are using both experiment and a nuclear explosion continue to tax weapons codes. theory to link the large span of scales available state-of-the-art capabilities. Recently, LDRD researchers needed to accurately predict how Past LDRD work has produced the identified a promising new approach changes in chemical structure, discrete ordinates method for radia- for using high-energy protons to make physical structure, and stress affect tion transport, the particle-in-cell high-resolution radiographs of very the mechanical properties of materi- method for hydrodynamics, and other rapid events in high-density materials. als. Although aspects of each of the computational tools that are now used Proton radiography's advantages are size scales (atomic, molecular, micro-, widely in both military and civilian high spatial resolution, sensitivity to meso-, and macroscales) have been applications. Today, LDRD research- density variations, and the ability to studied in the past, this LDRD work is ers are providing the technology to capture the time history of an implo- one of the first attempts to link such a implement these tools on the new sion. The LDRD program funded a wide range of scales into a coherent generation of massively parallel proof-of-principle test that produced picture that can be used to understand supercomputers. They are also ex- proton radiographs of a dense, static the behavior of polymeric elastomers. tending the capability of these tools test object. Researchers are now through such developments as a developing the capability to make Advanced Manufacturing complex geometric representation dynamic radiographs of dense objects Processes for the Weapons Program, common to both Monte Carlo and under explosive compression. LDRD researchers have developed a new fabrication process called discrete ordinate codes. The tendency of adjacent but dis- directed-light fabrication (DLF), and Computer simulations of nuclear similar liquid layers to mix (interface they are exploring its application to weapons require not only the most instability) is a problem of central nuclear weapons fabrication (beryl- powerful computers available, but importance to nuclear weapons lium, uranium, and plutonium also the ability to transfer huge performance and simulation. In components). DLF is an automated, amounts of computational data and particular, the interfacial instability of rapid, one-step method of making display the data in forms that can be a thin fluid layer driven by shock complex metal parts by fusing metal easily digested and analyzed. LDRD compression is a fundamental issue in powder in the focal zone of a laser researchers have advanced the state of turbulent mixing in nuclear weapons. beam. The resulting parts are fully the art in fast data-transfer networks LDRD researchers are developing a dense, have excellent structural by inventing the high-performance new measurement technique to obtain

Overview parallel interface (HIPPI), which dimethyl sulfoxide and have been weapons. The hydride-dehydride supports local networks at data- detected at approximately 100 ppb by recycle process eliminates the transfer rates of 800 megabits/s volume in air. environmental hazards associated (equivalent to transmitting one Global proliferation of weapons- with other plutonium recovery hundred 250-page books per second). grade plutonium and highly enriched methods. It takes advantage of Adopted as a standard by the uranium has become one of the plutonium's strong affinity for American National Standards foremost threats to the security of the hydrogen gas. In the hydriding step, Institute, HIPPI has been imple- United States and the entire world. hydrogen reacts with the plutonium to mented by many vendors and is LDRD researchers are characterizing form plutonium hydride powder, currently the high-speed interface of and modeling, from a global perspec- which is collected and then reheated choice for supercomputers. Building tive, the management, control, and to release the hydrogen (the on this LDRD work, researchers have flow of weapons-grade nuclear dehydriding reaction), forming a developed a synchronous optical materials. The objective of this metal powder. This metal powder is network (SONET) gateway that can research is to provide a computer- then melted to form storage-ready link supercomputers at HIPPI speeds based tool capable of (1) capturing ingots. over very large distances. Work is and enumerating data concerning the LDRD researchers have developed now under way to extend the network global inventory of nuclear weapons and evaluated water-soluble chelating bandwidth to the 5 to 10 gigabits/s materials, (2) providing a global view polymers for recovering actinide and range. of the management and control of toxic metals from a variety of process nuclear materials, (3) undertaking streams, as well as polymer filtration Nonproliferation, Counter- macrosystem simulations of safe- for recovering precious metals from proliferation, and Arms Control. guards accounting surety and resource industrial process streams. The high LDRD researchers are advancing the estimation, and (4) visually represent- cost associated with the long-term technology required to verify and ing the nuclear materials information, storage of radioactive and toxic monitor arms control treaties and to including both inter- and intracountry wastes mandates separating these detect clandestine production of flows. nuclear, chemical, or biological components in a process waste stream before the waste is packaged and weapons. Nuclear Materials. LDRD-funded stored. A portable polymer filtration Earth-orbiting satellites have activities at Los Alamos have con- system that recovers zinc and nickel detected transionospheric pulse pairs tributed significantly to advanced ions from electroplating rinse waters that are similar to the signature of a methods for processing and recover- won an R&D 100 Award in 1995. nuclear explosion. LDRD researchers ing plutonium, to recovery of acti- have shown that these pulses can be nides and toxic metals from a variety LDRD researchers are now investi- explained by a runaway electron of process streams, and to develop- gating membrane-based separation mechanism near thunderstorms that ment of sensors for monitoring technologies for removing plutonium causes upward-propagating dis- special nuclear materials. and americium from nuclear-materials-processing waste water, fission- charges called "sprites." Their new LDRD researchers are exploring product separations using cobalt theory agrees with measurements of actinide crystal chemistry to learn dicarbolide for solvent extraction, radio-frequency "chirp" pairs, as well why the ideosyncratic structures of hollow-fiber membrane modules for as with optical and x-ray emissions plutonium metal occur. They are separating gases and nuclear materi- associated with this phenomenon. doing this by examining the crystal This understanding will allow structures of several actinide alloys: als, and selective waste remediation scientists to more accurately identify neptunium-uranium, plutonium- using in situ photocatalytic reactors. signals from clandestine nuclear thorium, and plutonium-zirconium. explosions. Such additional structural data may LDRD researchers are developing very well lead to a solution of the technology for detecting (with plutonium structure problem. surrogates) chemical and biological LDRD researchers are performing warfare agents. The detection technol- a series of laboratory-scale experi- ogy is based on the combination of ments to enhance the operation and membrane introduction and ion-trap safety of a new process for recovering mass spectrometry, and preliminary metallic plutonium from nuclear methods for continuous surrogate detection have been successfully developed. The surrogates include chlorobenzene, cyclohexanol, dimethyl methyl phosphonate, and

Los Alamos FYI996 LDRD Progress Report Other National Security Research. fections. The technique was further LDRD Project Summaries LDRD contributions to other national applied to detect cracks and other In the following sections, we have security research include development flaws in commercial and military grouped project summaries by LDRD of materials, detectors, and computa- hardware. RUS is now being used for component—IP, CD, and PD—and tional tools for conventional military nondestructively testing military then subdivided them into nine applications, as well as sensors for components (aircraft landing assem- technical disciplines: environmental monitoring. blies, turbine disks, helicopter rotor Intelligent computer-generated parts, and ball bearings) and for Materials Science forces are an area of growing model- identifying the contents of chemical Engineering and Base Technologies ing importance within the Department munitions. Exploratory work is under of Defense (DoD). LDRD researchers way for using RUS to study the Plasmas, Fluids, and Particle Beams are successfully using intelligent effects of aging on hemispherically Chemistry control and adaptive systems technol- shaped explosive charges as part of ogy as well as advanced simulation the Laboratory's stockpile steward- Mathematics and Computational software to develop, test, and demon- ship mission. Sciences strate new intelligent actor capability Using molecular self-assembly Atomic and Molecular Physics in warfare simulations. techniques, LDRD researchers have Resonant ultrasound spectroscopy developed a compact, robust, surface- Geoscience, Space Science, and (RUS) was originally used as a acoustic-wave-based chemical Astrophysics diagnostic tool in an LDRD project microsensor for remote, real-time Nuclear and Particle Physics that studied the properties of high- sensing of volatile organic com- temperature superconducting crystals. pounds. The microsensor is reversible Biosciences It was quickly determined that RUS and can be used to monitor continu- A list of related publications written could be used for nondestractively ously changing concentrations of a by project team members is included testing crystals for structural imper- contaminant over an extended period with the summaries. An index to the of time. This capability is relevant to projects' principal investigators is environmental monitoring of defense provided at the end of this report. wastes and to detecting environmental indicators of weapons production.

Overview

Individual Projects

Individual Projects (IPs) are staff-initiated R&D aimed at strengthening the Laboratory's science and technology base and fostering a stimulating research environment. These projects play a key role in maintaining the expertise and state- of-the-art technologies that underpin the Laboratory's scientific and engineering excellence. IPs accounted for 38% of this year's LDRD budget and 46% of all projects, and they supported research in all nine technical disciplines.

Examples of subjects investigated by IPs include nonlinear atom optics, dynamics of quantum wave packets, chemistry and catalysis in supercritical media, microsensors for volatile organic compounds, quantum cryptography, optical imaging through turbid media, nonlinear processes in earthquakes, three-dimensional climate models, nanoengineered films, phase stability of transition metals and alloys, particles and patterns in cellular automata, high-speed computer interfaces and networks, antiquark distributions in the proton, weak interaction measurements using optically trapped radioactive atoms, high-intensity laser-matter interactions, turbulence in complex fluid flows, the structure and dynamics of surface recognition, and the role of the telomere in birth defects.

Materials Science

Origin of Radiation Damage in Potassium electric fields of approximately 30 kV/cm. These results agree with Titanyl Phosphate what we expected based on pyroelectricity in KTP; the surface field D. Wayne Cooke should be proportional to dPsldt or, equivalent^, to (dPs/dT)(dT/dt), Potassium titanyl phosphate (KTP) electrons via ionization as a result of where Ps is spontaneous polarization, is the most widely used material for the pyroelectric effect in KTP. We T is temperature, and t is time. From the second factor, dTldt, we see that nonlinear optical applications such as excited the KTP sample with CO2 optical parametric oscillators and laser radiation and, with an optical fields evolve from a large rate of laser frequency-doublers. However, multichannel analyzer, measured change in temperature, as induced by its use is limited to low-power bursts of light coincident with the the laser on-off pulse. Observation of applications because of laser-induced laser pulse. By attaching electrodes to pyroelectricity in KTP provides an damage incurred at high power. The two surfaces of the crystal, we also important new insight into the origin of this damage is presently measured current pulses. possible origin of optical damage in unknown. Shown in the accompanying figure these materials. Recent investigations of radiation is the current generated in KTP at damage in KTP showed that the 295 K by a CO2 laser pulse. The Publications material emits bursts of light upon maximum current occurs during the heating or cooling over a broad on-off cycle of the laser, which Cooke, D.W., B.L. Bennett, R.E. temperature range (4-675 K). This corresponds to the maximum change Muenchausen, et al., "Pyroelectricity emission is believed to result from the in the crystal's spontaneous polariza- and its Role in Radiation Damage of development of a large surface tion. Simultaneous with this peak Potassium Titanyl Phosphate electric field that discharges into the current is the occurrence of optical Crystals," in Proceedings of the SPIE (SPIE, Bellingham, Wash., in press). ambient environment. The field bursts of light, implying surface evolves from a change in spontaneous polarization as a function of temperature, a phenomenon called pyroelec- 200 tricity. This observation implies that cn o if T - 295 *f laser excitation of KTP may cause a P ~ 0.1 K,Is change in its temperature, thereby 100 A ^ inducing large electric fields that might contribute to the optical- \ damage threshold in KTP. The r o _- consensus is that reduction of Ti4+to -• 3+ o Ti ions in KTP is responsible for the -100 \( damage and that two-photon absorption or other electronic mechanisms 22 are involved. I -200 We believe that laser-induced '5 thermal mechanisms may be relevant. Specifically, our objective was to -300 1 demonstrate that electrons could be produced in KTP by thermal rather -400 10 20 30 40 50 60 70 80 90 than optical excitation. That is, Time (s) excitation with a CO2 laser, which has a wavelength 10 times that of a neodymium-based laser and therefore Current generated in KTP at 295 Kby a CO2 laser pulse. The continuous-wave cannot excite electrons across the laser is turned onatt = 10 s and off at t = 30 s, as shown by the dashed profile. band gap, may in fact produce The approximate crystal heating rate during this time interval is 0.1 K/s.

Individual Projects—Materials Science 9 Development of a Fundamental Understanding of Chemical Bonding and Electronic Structure in Spinel Compounds

Kurt E. Sickafus

Our objective is to investigate the the composition field MgOAl203 accommodating deviations from the role of chemical bonding and point through MgOCr203 from magne- equimolar spinel composition reside defects (both extrinsic point defects sium, aluminum, and chromium on both tetrahedral and octahedral and cation-disorder antisite defects) nitrate precursors. We are using these cation sites. on structural stability and electronic samples to measure electron-loss We completed total-energy elec- structure in compounds with the near-edge structure (ELNES) by the tronic-structure calculations for spinel crystal structure. Experimen- EELS technique (see plot of energy MgOAl203 and MgO»Ga2O3 in both tally, we assess structural and elec- loss vs electron intensity). ELNES is normal and inverse structures (see tronic properties of spinel samples proportional to the density of states at plots of E - EF vs D(E) for using electron energy-loss spectros- the bottom of the conduction band of MgOAl203). We demonstrated copy (EELS) and electron, x-ray, and the material being examined. excellent agreement between theory neutron diffraction techniques. We We performed neutron diffraction and experiment in basic structural perform total-energy electronic- experiments on single crystals of parameters. By analyzing the band structure calculations to determine stoichiometric (equimolar) spinel structure, we have identified alumi- structural stability, band structure, (MgOAl203) and nonstoichiometric num-related sp bands pulled down out density of states, and electron (nonequimolar) single crystals of of the valence band in the inverse distribution. spinel (Mg03Al203). Crystal- structure as the source of the extra This year we prepared, by sol-gel structure refinements of the diffrac- peak observed in the EELS/ELNES synthesis routes, oxide compounds in tion data revealed that point defects spectra.

2000

1600 lit s rar y u r 1200 bit i

800 itensit ) ro n I r 400

LU Al -1-2,3 edge MgAI2O4 spinel

I I I ! 77 7J 79 80 81 82 83 84 85 Energy Loss (eV)

Aluminum in octahedrally coordinated sites Aluminum in tetrahedrally coordinated sites EELS spectra obtained using a dedicated scanning transmission electron microscope. In these spectra we examine the ELNES in magnesio-aluminate spinel, MgO*Al2O3. The peak just below 80 eV is at the onset of the aluminum L23 absorption edge and reflects the aluminum contribution to the density of states of the conduction band from octahedrally coordinated aluminum ions. Following neutron irradiation to a high dose, a substantial fraction of aluminum atoms in the lattice relocate from octahedral to tetrahedral sites. This relocation is manifested in EELS analyses by an enhancement of the ELNES peak at 78 eV. In a perfectly ordered, "normal" spinel crystal, this additional ELNES peak would not exist. Quantitatively, the occupation of tetrahedral sites by aluminum atoms increases from about 20% to greater than 50% following neutron irradiation.

10 Los Alamos FY1996 LDRD Progress Report 0.0 10 15 10 15 E-EF(eV) E - EF (eV)

Calculated valence site, E - EF, vs projected density of Calculated valence site, E - EF, vs projected density, states, D(E), for the normal structure ofMgO*Al2O3, D(E), of states for the inverse structure of wherein all of the aluminum cations reside on MgO*Al2O3. In this case the aluminum cations are octahedrally coordinated lattice sites. Contributions to distributed equally between octahedral and the density of states from the different lattice sites are tetrahedral lattice sites. A prominent new feature in indicated by the different shadings. the density of states for inverse spinel appears near 8 eV. This structure is absent in the density of states for normal spinel. It is probable that this new band of states arises primarily from tetrahedral aluminum and is responsible for the additional peak that we observe in the ELNES spectra at 78 eV.

Phase Stability of Transition Metals The Mo-Re (40%) buttons shattered upon rolling as a result of the pres- and Alloys ence of sigma-phase material. Samples of Hf-Nb (1%), HF-Nb (3%), and pure hafnium were pro- Robert Hixson duced. Experimental. Our work has Our objectives were to study the structural stability of pure titanium continued on defining the alpha-to- phase transitions in transition metals and its alloys. The results confirm the omega transition pressure in pure and to attempt to move the transition first year's results that the omega titanium, which has turned out to be pressure by alloying with d-electron phase occurs as a result of one- more difficult than anticipated. Pure donor metals. Such a study will lead to electron band filling. As compared titanium and the Ti-V material studied a better understanding of the phase with Ti-V alloys, tantalum and in previous years have very close to diagrams of both pure transition metals tungsten decrease the structural the same free energy, and our experi- and alloys. Furthermore, this study is transition pressure. mental work shows a very similar essential for a complete understanding Metallurgy. We have prepared alpha-omega transition pressure. of the physical properties of materials samples of hafnium and molybdenum Because this result was surprising, we under varying conditions. We also alloys. In addition, we prepared have spent the last year perfecting our made progress in the areas of theory, samples of Mo-Re (10%), Mo-Re technique for growing single crystals metallurgy, and experiment. (30%), and Mo-Re (40%) with in the DAC. This work shows a Theory. We have calculated the sufficiently fine grain structure to be transition pressure close to 90 kbar for virtual crystal approximation of the used in the diamond anvil cell (DAC). both pure metal and Ti-V alloy.

Individual Projects—Materials Science I I Theoretical and Experimental Investigation on the Low-Temperature Properties of the NbCr2 Laves Phase

Dan Thoma

Laves phases are the most abundant ments include (1) preparing materials (2) measuring physical properties yet least utilized intermetallic phases. for single-crystal growth and me- such as elastic parameters (see Because of some unique properties chanical testing (see photograph), accompanying spectrum), (including superconductivity, magnetic properties, hydrogen-storage characteristics, high melting temperatures, high strength, reasonable NbCr, oxidation resistance, and excellent creep properties), they have unusually high potential for a wide variety of NbCr, applications that are directly related to energy sciences. For example, in addition to high-temperature structural applications (heat exchangers for Nb45Cr55 coal conversion and gas turbine engine materials), Laves phases also have significant nonstructural applications: (Tb,Dy)Fe2 is used as a magnetoelastic transducer because of I Ill I its giant magnetorestriction, 0 1 in 2 in (Hf,Zr)V2 has been used for special superconductivity requirements, Arc-melted buttons and rods ofNbCr2 and NbCr2-based composites. Zr(Cr,Fe)2 has been utilized for hydrogen-storage applications, and the Mo(Co,Si)2 Laves phase contributes to the wear-resistance of "Tribaloy" materials. Unfortunately, the overall potential of Laves phases has not been exploited, largely because of their tendency for low- temperature brittleness. We are focusing on experimental and theoretical alloy design methodologies in order to elucidate and optimize deformation mechanisms as a function of defect structure for the C15 Laves phase NbCr2 (C15 refers to the crystal structure). Our results should provide a scientific methodology—from atomic to bulk scale—that will improve the low- temperature ductility and toughness of Laves phases. As a result, an increased application of the largest class of materials will be available for a 1000 1050 1100 1150 1200 variety of energy-related technologi- FREQUENCY (kHz) cal fields. We have made substantial progress A portion of a resonant ultrasound spectrum ofC15 NbCr2 taken at room in the past year to achieve these temperature. This spectrum is used to determine the elastic parameters ofC15 project objectives. Our accomplish- NbCr2. The units of amplitude are arbitrary.

12 Los Alamos FY1996 LDRD Progress Report (3) establishing ternary phase total-energy and electronic-structure Publications diagrams for Nb-Cr-M (M = Ti, V, calculations for the C15 NbCr2 Laves Chu, E, Y. He, et al., "Elastic and Be), such as the two diagrams phase, and (6) developing an alloy Constants of the C15 Laves Phase shown, (4) determining the defect design scheme for the C15 NbCr2 Compound NbCr ," Sen Metal. Mater. structures/mechanisms and alloying Laves phase based on the combined 2 33, 1295 (1995). behavior in C15 NbCr2-based Laves experimental and theoretical investi- phases, (5) performing first-principles gations. Chu, E, A. Ormeci, T. Mitchell, et al., "Stacking Fault Energy of the NbCr2 Laves Phase," Philos. Mag. Lett. 72, Cr 147 (1995). Chu, E, DJ. Thoma, Y. He, et al., "Resonant Ultrasound Spectroscopy: Elastic Properties of Some Intermetallic Compounds," in Nondestructive Evaluation (NDE) and Materials Properties (III), P.K. Liaw et al., Eds. (The Materials Society, Warrendale, Pa., in press). Kotula, P.G., I.M. Anderson, E Chu, et al., "ALCHMEI of NbCr/V CIS- Structured Laves Phase," Proc. of Microscopy and Microanalysis 1996 1996, 554 (1996). Ormeci, A., E Chu, J. Wills, et al., "Electronic Structures and Mechanical Properties of C15 Laves Nb Phase Compounds: NbCr2 and HfV2," Ti Phys. Rev. B 54,12753 (1996). Thoma, D.J., E Chu, et al., "Alloying Effect in NbCr2 and Nb(Cr,V)2 C15 Laves Phases" (to be published in Mater. Sci. Eng.). Thoma, D.J., E Chu, et al., "Comparison of NbCr2 and HfV2 C15 Laves Phases," in High Temperature Ordered Intermetallic Alloy•s-VII, MRS Symposium Proceedings, C.C. Koch et al., Eds. (Materials Research Society, Boston, Mass., in press).

Nb 90 80 70 60 50 40 30 20 10

Ternary phase diagrams ofNb-Cr-Ti and Nb-Cr-V, indicating the phase field of

the ternary Laves phase based on NbCr2-

Individual Projects—Materials Science 13 incorporation into the surfaces in spite Nanostructured Materials: Growth and of the thick oxide layers already Patterning Using Hyperthermal Materials present on some of the surfaces. For example, thick nitride films grow on Chemistry indium and aluminum surfaces, and silicon forms silicon nitride and Mark Hoffbauer silicon oxynitride. Detailed analysis of the quality of these nitride films In the next century, high-density be easily produced at low surface will enable us to further optimize the compact disks, large and bright flat- temperatures, avoiding common growth process. Analysis of the panel displays, fast computers, and problems such as thermal degradation, diamond surfaces indicates that we many other microelectronic devices defect formation, and chemical have incorporated significant amounts will rely on our ability to produce impurities that are associated with of nitrogen into the surface. If further nanostructured thin-film materials. existing high-temperature processes. analysis demonstrates that we have These thin-film materials are pro- We are using hyperthermal materi- formed a crystalline carbon nitride duced atom-by-atom for the purpose als chemistry to grow wide-band-gap, film, we will be the first to have of controlling their atomic-layer thin-film nitride materials (such as synthesized this substance, which is properties. Our research goal is to gallium, indium, aluminum, and theoretically predicted to be harder produce nanostructured thin-film carbon nitrides). Using a beam of than diamond. materials that will make electronic high-kinetic-energy nitrogen atoms, We have achieved significant and optical products run longer, faster, we have grown gallium nitride films progress toward improving nitride and more efficiently than those on GaAs. Analysis of these films thin-film growth using hyperthermal presently available. using x-ray photoelectron spectros- atoms. The next step will be to At the Laboratory, we have recently copy has shown that nitrogen com- process selected areas of materials developed a facility for producing pletely replaces the arsenic. Early using direct patterned thin-film nanostructured thin-film materials indications are that we have synthe- growth and etching. These processes using hyperthermal materials chemis- sized thick gallium nitride films are necessary for electronic device try, in which we selectively activate (>20 nm) of very high quality at low production. Our goal is to use desired chemical reactions using the surface temperatures. hyperthermal atom beam sources to kinetic energy of one or more key We have also grown nitride films at perform carefully controlled process- atomic species incident upon a thin- low surface temperatures on indium, ing on length scales of < 100 nm. We film surface. The advantage of aluminum, silicon, diamond, and will then be able to create hyperthermal materials chemistry is sapphire surfaces. Our preliminary nanostructured devices of unprec- that coveted electronic materials can analysis indicates significant nitrogen edented quality.

Inorganic-Organic Composite dimer, trimer, tetramer, and their isomers. We prepared the ethyl carboxy- Nanoengineered Films Using Self-Assembled late as the precursor to further chemical reactions which should produce the Monolayers for Directed Zeolite Film Growth targeted quaternary ammonium salt. Several attempts at producing the free Robert Dye carboxylic acid failed. Our last try was only moderately successful. The objective of the project is to ammonium group which could Deposition of LB films using attempt the directed growth of a nucleate the crystallization of ZSM-5 equipment at the Advanced Materials zeolite (aluminosilicate) cage crystal zeolite, and preparation of LB films of Laboratory in Albuquerque resulted in from an organic template deposited as selected model compounds onto a high-quality films that could be used for a Langmuir-Blodgett (LB) film on a treated silicon wafer. our purposes. Under appropriate silicon wafer substrate. This work We took the organic synthesis of a reaction conditions, we used one of supports fundamental research on monosubstituted norbornadiene trimer these model films to produce what materials synthesis of an inorganic to the ethyl carboxylate stage. Then appeared to be ZSM-34 zeolite on the material from a tailored organic we developed a large-scale synthetic surface. Making the experiment safer by precursor film (biomimetic synthesis). method to make the norbornadiene using a high-pressure bomb instead of a We ran two phases of this project trimer in good yield, using selective sealed glass jar resulted in our not being concurrently: synthesis of the target sublimation and recrystallizations to able to reproduce the first success. amphiphile containing a quaternary obtain pure trimer from a mixture of

14 Los Alamos FY1996 LDRD Progress Report Rigid Molecular Foams experiments. Pore size distributions ranged from 5 to 1000 A, depending on starting materials. Warren P. Steckle Publications Carbon foams have been finding and porosity to temperatures greater many applications in recent years. than l,000°C in nonoxidizing Steckle, WP. Jr., "Carbon Foams Applications include fuel-cell atmospheres. We also investigated the Prepared from Hypercrosslinked electrocatalysts, general catalyst hypercrosslinked foams and the Polymer Foams" (submitted to Recent supports, porous adsorbents, and foam carbonization of these materials for Advances in Polymeric Foam and electrodes for use in batteries and their ability to chelate metals. Technology, Am. Chem. Soc. Books). capacitors for energy efficiency and We prepared polymeric crown Steckle, W.P. Jr., "Carbon Foams conservation. We prepared a series of ethers by the polycondensation of Prepared from Hypercrosslinked rigid hypercrosslinked foams, using dibenzo-18-crown-6. Crown ethers Polymeric Foams," Polymer Preprints simple, rigid polyaromatic hydrocar- can chelate certain metals within their 37 (2), 777 (1996). bons such as benzene, biphenyl, ring. Supported crown ethers have m-terphenyl, diphenylmethane, and been of interest for the past several Steckle, W.P. Jr., M.A. Mitchell, and polystyrene, with p-dichloroxylene as years in environmental clean-up and P.G. Apen, "Hypercrosslinked the crosslinking agent. After drying remediation. We also prepared other Polmeric Foams Prepared by Friedel- the gels, we found the resulting foams potential candidates for metal uptake Crafts Polycondensation," Polymeric robust and rigid. Their densities range by the sulfonation of other aromatic Mater. Sci. Eng. 74, 344 (1996). from 0.3 to 0.5 g/cm3. Upon carbon- hypercrosslinked foams. To elucidate Steckle, W.P. Jr., M.A. Mitchell, and ization the densities of these foams the structure of these hypercross- P.G. Apen, "Tailoring the Pore Size of increased to a range from 0.6 to linked materials, we used nitrogen- Hypercrosslinked Polymer Foams" (to 1.0 g/cm3. adsorption, surface-area analysis, be published in Mater. Res. Soc. As catalyst supports, these carbon- transmission electron microscopy, and Symp. Proc: Microporous and ized foams can retain their integrity solid-state, nuclear magnetic resonance Macroporous Mater.).

very promising absorption and Materials Research for Optical fluorescent spectra. The initial Refrigeration calorimetric measurements, however, showed that the particular sample we were studying does not cool at room Richard Epstein temperature because of impurity contamination. We will be working to Our objective is to characterize and 100 K. This was the first demonstra- correct that problem by using purer test a variety of crystals and glasses for tion of a solid-state cooling process BaYYbF crystals in our experiments. their usefulness as optical refrigerants. that works below 150 K, and it laid Depending on the operating conditions the groundwork for developing a to which they are subjected, numerous practical cryogenic device. Addition- Publications materials can be useful optical ally, we have created a list of candi- Fajardo, J.C., G.H. Sigel Jr., B.C. refrigerants. In particular, the optimal date cooling materials that may be Edwards, et al., "Electrochemical refrigerant material will depend upon superior to ytterbium-doped fluoride Purification of Heavy Metal Fluoride operating temperatures and type of glasses. In particular, we are looking Glasses" (to be published in /. Non- diode lasers used. Our research is for materials that will cool at lower Cry st. Solids). significant because of its great temperatures and have better thermal potential for allowing the development and mechanical properties than Mungan, C.E., M.I. Buchwald, B.C. of cryocoolers that operate efficiently ytterbium-doped fluoride glasses. We Edwards, et al., "Laser Cooling of a between a few tens of kelvins up to have characterized the spectral Solid by 16 K Starting from Room food-freezer temperatures. properties of seven materials (five Temperature" (to be published in This year, we confirmed theoretical ytterbium-doped crystals, an ytter- Phys. Rev. Lett.). predictions that some ytterbium-doped bium-doped glass, and ruby). We fluoride glasses may effectively cool at found that one material, BaYYbF, has

Individual Projects—Materials Science 15 Innovative Composites through Zhu, Y.T., WR. Blumenthal, and T.C. Lowe, "Determination of Non- Reinforcement Morphology Design—A Symmetric 3-D Fiber Orientation and Average Fiber Length in Short-Fiber Bone-Shaped Short-Fiber Composite Composites" (to be published in J. Composite Mater.). Yuntian T. Zhu Zhu, Y.T., WR. Blumenthal, and T.C. Lowe, "On the Tensile Strength of The objective of this project is to different load-transfer functions as Short-Fiber Reinforced Composites" improve the strength and toughness of determined by FEM. (to be published in J. Mater. ScL). conventional short-fiber composites by using innovative "bone-shaped," short Zhu, Y.T., W. R. Blumenthal, et al., fibers as reinforcement. We have made Publications "Modeling of Statistical Tensile Strength of Short-Fiber Composites," significant progress in the fabrication Taylor, S.T.,Y.T. Zhu, etal., in Modeling of Composites: and characterization of a prototype "Characterization of Nicalon Fibers Processing and Properties, S.P. Chen, composite and in the understanding of with Varying Diameters. Part I: and M.P. Anderson, Eds. (TMS, the toughening mechanisms through Strength and Fracture Studies" Anaheim, Calif., 1996), pp. 11-21. numerical modeling. Our accomplish- (submitted to /. Am. Ceram. Soc). ments on the experimental front Zhu, Y.T., W. R. Blumenthal, et al., Taylor, S.T., Y.T. Zhu, et al, "Some include the following: (1) We have "Modeling of Young's Modulus of New Perspectives on the Strength and demonstrated that the strength and Composites Reinforced with 3-D Fracture of Nicalon Fibers," Third Int. toughness of a bone-shaped, short- Oriented Short Fibers" (TMS Annual fiber composite improve by 34% and Conf. on Composite Engin. Proc, 837 Meeting, Anaheim, Calif., February 200%, respectively, over that of a (1996). 4-8, 1996). conventional short-fiber composite (as shown in the first figure). (2) We have automated the fabrication of bone- shaped fibers with a fiber production rate of 2400/h. (3) We have established a procedure to form nodules along Nicalon fibers (see second figure). When chopped, these nodular Nicalon fibers play a similar role as the bone- shaped fibers. (4) We have established a facility and procedure to make composite samples with short fibers randomly distributed and aligned as in the third figure. Reinforced with straight fibers Using the finite-element method Reinforced with straight fibers (FEM), we are studying the load- Reinforced with bone-shaped fibers transfer mechanism of bone-shaped Reinforced with bone-shaped fibers Reinforced with bone-shaped fibers fibers and searching for better fiber geometrical design. We have found that there is a critical fiber length above which bone-shaped fibers are superior in strength as compared with straight-fiber composites. 10 15 20 On the modeling front, we have strain% tailored the composite lattice spring failure-analysis model (CLASFAM) to Stress-strain curves of composite samples, which are made of polyester matrix facilitate both chopped, straight, and reinforced with straight nickel fibers (bottom two dotted lines) or bone-shaped bone-shaped fibers randomly distrib- nickel fibers (upper three solid lines). Nickel fiber length = 2.5 mm, diameter = uted in an elasto-plastic matrix with 76.2 mm, and fiber volume fraction = 3.3%. The average strength and fiber failure strength following the toughness (area under the stress-strain curve) of the bone-shaped, short-fiber Weibull distribution. We accounted for composite samples improve by 34% and 200%, respectively, over that of the fiber shape in the model by using conventional short-fiber composite samples.

16 Los Alamos FY1996 LDRD Progress Report A Nicalon fiber with nodules obtained by high-temperature oxidation of commercial Nicalon fibers.

J'H, = 1

Fibers are aligned and randomly distributed in a glass-fiber-reinforced, polyester-composite sample.

Individual Projects—Materials Science 17 New Deposition Processes for the Growth This year we successfully completed a low-pressure CVD reactor for of Oxide and Nitride Thin Films the deposition of pure and doped GaN thin films and synthesized homoleptic amido precursors for the Ga and for Kevin Hubbard the Zn dopant. We also successfully deposited pure and Zn-doped GaN The general goal of this effort is to Control of the fundamental chemistry films at low temperatures (250°C- apply an integrated approach to of a deposition process is the key to 550°C) and developed synthesis develop and understand the details of advancement of the OMCVD routes for homoleptic amido precur- the deposition process for metal technique. sors for the deposition of A1N, InN, oxides and nitrides from homoleptic Recently, the efficient transamina- and In2O3, as well as their alloys. TiN metal amido precursors. This under- tion of homoleptic metal amides and Zr3N4 were deposited using standing will lead to new routes for [M(NR2)X] with ammonia to yield plasma-enhanced CVD. We deposited the production of high-quality highly reactive metal amido/imido the TiN on Kevlar fibers to improve materials that have wide application. intermediates has been used to their performance under compressive Organometallic chemical vapor develop low-temperature, high- stress and studied Zr3N4 for its deposition (OMCVD) has been slow growth-rate processes for the deposi- dielectric properties. in gaining acceptance for coatings tion of high-purity metal nitrides and applications despite the possibilities oxides. The purpose of this project is for significant advantages over metal- to improve our understanding of the Publications halide-based CVD processes. The deposition mechanisms for these Atagi, L.M., J.A. Samuels, et al., major underlying limitation is the lack precursors and to expand the list of "Plasma Enhanced Chemical Vapor of understanding of the chemistry technologically important materials Deposition of Zirconium Nitride Thin important to the deposition process. that can be deposited from them. Films," Mat. Res. Soc. Symp. Proc. 410, 289 (1996).

Texture Characterization for HE Design We can adapt these techniques to anisotropic elasticity by averaging elastic constants over the grains. We Sheila Schiferl incorporated a texture-based model of anisotropic strength into a two- The objective of this project is to open and secure literature, and we dimensional Lagrangian code. develop the capability to investigate extended methods that we had Capabilities of this new code include the effects of crystallographic texture developed for conventional weapons. an axisymmetric polar decomposition (the preferred orientation of single- In our modeling, textured materials for rotations, a directional yield crystal grains in a polycrystalline are treated as polycrystals. Individual function, and a geometric-"normal" material) on the behavior of high- grains deform by shears on several iterative return to the yield surface explosives (HEs). Preferred orienta- slip systems (a slip system is com- that is performed in a fixed material tions are consequences of metal- posed of a particular shear plane plus frame. working and other thermomechanical a particular direction in that plane), processes and result in both strength each slip system has a critical stress, and elastic anisotropies. This research and a maximum work criterion selects Publications includes three components: state-of- five independent systems. For a given Maudlin, P.J., and S.K. Schiferl, the-art survey, model development, strain, the model obtains the tensor "Computational Anisotropic Plasticity and implementation of models in yield strength by averaging the for High-Rate Forming Application," design code. Our research will stresses over all the grains and then Comput. Methods Appl. Mech. Engin. improve the predictive capabilities fits the resulting yield "points" to an 131, 1 (1996). that became an essential part of analytic function. The textures we stockpile stewardship after under- investigated are typical for processing Schiferl, S.K., and P.J. Maudlin, ground nuclear testing was banned. weapons materials. We normalized "Evolution of Plastic Anisotropy for We used crystallographic-texture the yield functions using experimental High-Strain-Rate Computations" (to modeling concepts from both the data. be published in Comput. Methods Appl. Mech. Engin.).

18 Los Alamos FYI996 LDRD Progress Report Interfacial Charge Transport in Organic Publications Electronic Materials: The Key to a New Albrecht, J.D., L. Cong, P.P. Ruden, et al., "Resonant Tunneling in (100) and Electronics Technology (111) Oriented Double Barrier Heterostructures," J. Appl. Phys. 79, Darryl Smith 7763 (1996). Campbell, I.H., P.S. Davids, J.P. device, we must understand interfacial Organic electronic materials and Ferraris, et al., "Probing Electronic charge transport to realize the devices are poised to revolutionize State Charging in Organic Electronic potential of these materials and major technological areas, such as Devices Using Electroabsorption devices. Our primary goal is to information display and optical Spectroscopy," Synth. Metals 80, 105 develop this basic scientific under- communication, because of their (1996). processing advantages, the tunability standing. of their electronic properties, and their In this first year of the project, we Davids, P.S., A. Saxena, and D.L. materials and design flexibility. We have developed a theory to describe Smith, "Bipolaron Lattice Formation can make the complex structures the electronic structure of metal/ at Metal-Polymer Interfaces," Phys. necessary for the technology cheaply polymer interfaces. This theory Rev. B 53, 4823 (1996). predicts the behavior of Schottky and easily. We can modify the Heller, CM., I.H. Campbell, B.K. energy barriers at these interfaces. electronic properties of these materi- Laurich, et al., "Solid State We have also taken a series of als in a controlled way by making Concentration-Effects on the Optical electroabsorption and internal systematic changes in their molecular Absorption and Emission of Poly (p- photoemission measurements on structure. We would have many phenylene vinylene) Related interfaces between the conjugated design options at both the molecular Materials," Phys. Rev. B 54, 551 polymer MEH-PPV (a derivative of and mesoscopic scales for organic (1996). electronic materials and devices if we poly[phenylene vinylene]) and a had a better fundamental understand- series of metals. We were able to Smith, D.L, and S.M. Kogan, "Theory ing of their properties. Because successfully interpret these measure- of Ballistic Electron Emission interfaces are the essential active ments in terms of our theoretical Microscopy of Buried Semiconductor elements in every organic electronic model. Heterojunctions," Phys. Rev. B 54, 10354 (1996).

Thermodynamic and Electrodynamic variants the best choices for an Ettingshausen cooler. We have also Studies of Unusual Narrow-Gap advanced the state of the theory of the Ettingshausen effect and have shown Semiconductors it to be fundamentally different from the Peltier effect. Ettingshausen Albert Migliori coolers, unlike Peltier coolers, can approach Carnot efficiency when Cryogenic solid-state refrigerators objective is to select from such phonon thermal conductivity is based on the Ettingshausen effect materials those of highest perform- controlled. We have also constructed (heat transport by carriers in a ance. In parallel we are developing a and used an apparatus to make all the magnetic field) can provide vastly comprehensive theory to be used to necessary measurements. These superior performance to Peltier tune the selected systems (Bi-Sb measurements (resistivity, Hall devices, and can thus create new systems) to produce maximum resistivity, thermopower, transverse markets in electronics, superconduc- transverse thermopowers below thermopower, and thermal conductiv- tor, and medical applications. The 200 K. ity) were made on single crystals of goals of this project are to design and We have eliminated many of the Bi, Bi-2%Sb, Bi-8.5%Sb-0.05%Sn, create new materials, to study their hybridization-gap semiconductors and Bi-14%Sb, SmB6 and other materials. transport and thermodynamic proper- skutterudites from consideration and We found astonishingly high trans- ties to determine if they are appropri- discovered a possible new explanation verse thermopowers in BiSb alloys at ate for such devices, and to optimize for the high mobilities in Bi-Sb alloys small magnetic fields (less than 2 T) their performance. Our specific that may make certain little-studied at temperatures near 50 K.

Individual Projects—Materials Science 19 A Molecular Architectural Approach to Li, D., X. Yang, and D. McBranch, "Molecular Architectural Approaches Novel Electrooptical Materials to Nonlinear Optical Materials," Technical Digest, Opt. Soc. Am. 11, 409 (1996). DeQuan Li Li, D., X. Yang, and D. McBranch, Optical devices are used in a variety First, we synthesized various long- "Molecular Architecture of of applications, including optical chain surfactants [BrCH2-(CO)-O- Calixarenes and Their Self- computing, data storage, and optical (CH)n-SiCl3 and BrCH2-C6H4- Assembled Mono- and Multilayers communication. A number of optical (CH2)i6-SiCl3]. The advantages of for Nonlinear Optical (NLO) devices contain electrooptical (EO) these surfactants are that the active Applications" (to be published in materials—materials in which bromine group can react with pyridyl Synth. Met.). applying an electric field changes the groups at room temperature and that Li, D., X. Yang, et al., "Molecular indices of refraction—that are used to the long alkyl chains will provide in- Architecture of Calixarenes and Their manipulate light. Improving the plane ordering effects in the self- Self-Assembled Mono- and performance of EO materials, and assembled monolayers. Second, we Multilayers for Nonlinear Optical thus increasing the amount of carried out the multilayer growth by (NLO) Applications" (International information transmitted by the optical alternating an electron-rich building Conference on Science and devices, is a constant concern. block, nickel phthalocyanine Technology of Synthetic Metals '96, The goal of our project is to tetrasulfonate (NiPc), with a slightly Snowbird, Utah, July 28-August 2, construct polar multilayers with EO electron-deficient building block, 1996). coefficients much larger than those of poly(diallyldimethyl)ammonium classical inorganic crystals such as (PDDA). The ionic bonds formed very Yang, X., D. McBranch, et al., potassium dihydrogen phosphate or rapidly. We were able to manually grow "Synthesis and NLO Properties of quartz. Our approach incorporates thin films of NiPc and PDDA with as Polar Self-Assemblies of Molecular ionic and covalent bonding among many as 100 bilayers (x-ray Pyramids Covalently Bound on Oxide layers that contain preassembled reflectivity/thickness = -0.08 um; Surfaces," Angew. Chem. 35 (5), 538 chromophores—highly aligned dipole spectroscopic ellipsometry/nfllm = -1.7). (1996). arrays that have stable and efficient The accompanying plots show the x- Yang, X., L. Smilowitz, C. Buscher, et EO properties. Furthermore, we ray reflectivity data from four of our al., "Molecular Architectural intend to determine the fundamental films. mechanisms controlling the formation Approach to Self-Assembled of polar self-assembled multilayers so Monolayers as NLO materials," that we can design advanced materials Publications Mater. Res. Soc. Symp. Proc. 413, 241 (1996). with high performance. Li, D., and O. Ramos Jr., "Molecular In this first year, we focused on the Self-Assemblies as Advanced fundamentals of molecular self- Materials" in Electrical and Optical assemblies, in which molecular Polymer Systems, D.L. Wise, Ed. components spontaneously organize (World Scientific, in press). into ordered structures. These Li, D., C.T. Buscher, and D. fundamentals included the efficient McBranch, "Understanding the interlayer bonding, the functionalities Relationship between Surface within molecular building blocks, and Coverage and Molecular Orientation new techniques for monitoring in Polar Self-Assembled Mono- multilayer growth. We took two layers," J. Am. Chem. Soc. 128 (12), approaches to tackle the interlayer 2950 (1996). bonding issues: (1) covalent bond formation at mild conditions and (2) multiple electrostatic-charge interactions between layers.

20 Los Alamos FY1996 LDRD Progress Report 10

!io2 X-ray reflectivity data (diamonds) and theoretical fit (solid line) for the 0.1 0.2 0.3 0.4 substrate (top left), 3 bilayers (top right), 9 bilayers (bottom left), and 27 bilayers (bottom right). The vertical axis measures the intensity of the reflected x-ray, and the horizontal axis measures the momentum (qz) of the x-ray along the z-direction. The number of fringes clearly increases as the number of layers increases. 10 0.1 0.2 0.3 0.4 0.5 0.10 0.20 0.30

Characterization and Manipulation of Broken-Symmetry Materials at Phase Boundaries

Robert Donohoe

The goal of this project is to scattering from samples in the bore of We examined both of these features understand the magnetic properties of the 20-T magnet at the National High for a weak CDW material (PtI) and low-dimensional materials. Magnetic Magnetic Field Laboratory at Los for the SDW NiBr MX chain. In parameters can help determine both Alamos in this investigation. neither instance was there a clear the ground- and defect-state proper- We are attempting to manipulate indication of phase transition as a ties and the photodynamics of solid- SDW or other non-Peierls distorted function of applied magnetic fields state materials. These measurements quasi-one-dimensional solids com- (0-18 T). We could not conclusively can reveal important physical proper- posed of halogen-bridged linear demonstrate detection of a magnon in ties that we can relate to the chemical chains (MX) into new ground states the NiBr material, although we composition of materials and thereby by applying concerted and indepen- observed a weak, broad band near 1 better control a material's electronic dent variations of the temperature and 1500 cm" that exhibited some and photophysical properties. magnetic field. The experimental temperature dependence in accord Our focus is to gain a fundamental approach includes the detection of with the expected behavior for such understanding of ground-state inelastic scattered light from the MX an excitation. instabilities induced in the spin materials within a magnetic field with density wave (SDW) and weak charge the objective of detecting phase density wave (CDW) materials by the transitions by observation of changes application of magnetic fields. We in Raman vibrational features and have primarily used Raman/magnon magnons.

Individual Projects—Materials Science 21

Engineering and Base Technologies

Development of New and Efficient characteristically has low rates of Hard-Rock Mining Methods Using material ablation.

Pulsed-Laser Excavation Publications Multari, R.A., L.E. Foster, et al., David Cremers "Effect of Sampling Geometry on Elemental Emissions in Laser- We are investigating the application thick produced strong coupling of the Induced Breakdown Spectroscopy," of pulsed lasers to hard-rock mining. laser-pulse energy into the sample. Appl. Spectrosc. 50,1483 (1996). We believe that pulsed-laser excava- This strong coupling efficiency Pichahchy, A.E., D.A. Cremers, and tion will be a more efficient method produced high rates of material M.J. Ferris, "Elemental Analysis of of hard-rock mining than either ablation. On the other hand, high Metals Under Water Using Laser- conventional mining methods or laser-pulse repetition rates reduced Induced Breakdown Spectroscopy" inefficient laser techniques based on energy coupling because the forma- (to be published in Spectrochimica thermal processing. The new pulsed- tion of bubbles on the surface Ada B). laser techniques that we investigated duplicated laser ablation in air, which include hydraulic trapping of laser pulse energy at the rock surface (laser pulse/hydraulic effect) and resonant amplification of the shock waves induced through repetitive pulsing. We are also working to develop a method to deliver high-power laser Virtual Reality and Telepresence pulses through a fiber-optic cable. We will in part use the results of this Control of Robots Used in work to design a hard-rock mining instrument based on pulsed-laser Hazardous Environments excavation. This year we investigated the effect John W. Elling of sampling geometry (lens focal length, angle-of-incidence, lens type, The objective of this project is to We developed a method to incorpo- and lens-to-sample distance) on the develop virtual reality and tele- rate learning and adapting capabilities coupling of laser-pulse energy in a presence control for robots used in into traditional rule-based descrip- solid matrix (soils and metals). hazardous environments. Such control tions of environments. The learning Sampling geometry has practical of manipulators would allow opera- and adapting capability is critical to applicability to laser-based hard-rock tors to work on hazardous materials robot programming for highly mining. We found that the laser plume while being completely removed from unstructured and variable environ- temperature, emissions signals, and the danger of exposure. However, the ments such as inside glove boxes. We mass ablated from the solid were simulated environment in which the based our method on a hybrid expert strongly dependent on geometry, and operators would work must be as system technology called expert we determined the optimum values of representative of the actual hazardous networks and developed it with the these parameters. environment as possible. Our method associated knowledge capture We also investigated energy allows for component-based genera- techniques. Users will be able to coupling into a solid sample located tion of software, which greatly apply our method to established under water. Our experiments verified reduces system implementation and simulation packages for virtual reality that a water layer several millimeters development costs. and telepresence control.

Individual Projects—Engineering and Base Technologies 23 Nuclear Magnetic Resonance Imaging with Hyperpolarized Noble Gases

David Schmidt

Our objective is to demonstrate nuclear magnetic resonance (NMR) imaging of gas pressure distributions or porosity size distributions of objects containing a noble gas. In conventional magnetic resonance imaging (MRI), the signal is derived from nuclei that are thermally polarized in the presence of a large magnetic field. In contrast, the nuclei of noble gases can be hyperpolarized through laser-driven spin exchange. Furthermore, these gases have both a strong signal and a large diffusion coefficient. We exploited this fact in two different experiments and made great progress in our goal of demonstrating diffusion imaging. First, we inverted the polarization in a thin central section of a cylinder of The series of 1-D images of the 3He gas in the cylinder over a period of 5 s, one hyperpolarized 3He gas and made a image every 0.2 s. The polarization in the central portion of the cylinder is series of one-dimensional (1-D) being filled in by other nuclei diffusing into this section, rather than by thermal images of the cylinder over time in repolarization, which is what would happen in water, for example. order to see the diffusion of the two populations of nuclei (see first figure). Without Temperature Gradient With Temperature Gradient We measured a diffusion coefficient Diffusion Weighted I of D = 12.3 ± 0.2 mm2/s. The second experiment was to make diffusion-weighted images of the gas. We calculated a diffusion coefficient at each point in the image by taking the ratio of the image intensities with and without a previous magnetic field gradient in place. We show this process in the second figure, where the effects of temperature and of boundaries are reflected in the diffusion images. Disto-ce Alcnq Cel Just as the relaxation parameters Tx (a) (b) and T2 are used to highlight differ- 3 ences in physical environments in Two 1-D diffusion images of the He gas. (a) A diffusion image with the gas at NMR and MRI, we believe that the thermal equilibrium at room temperature. The diffusion coefficient away from diffusion coefficient D can be used to the ends of the cylinder matches that measured earlier by a completely different highlight environmental differences. diffusion-inflow method. The lowering of the diffusion coefficient near the walls Possible applications include charac- of the cylinder is due to the walls restricting the diffusion in this area, (b) A terizing porosity of materials and diffusion image when the cylinder had a thermal gradient produced by holding dynamically imaging pressure the right-hand end of the cell in a liquid-nitrogen exhaust plume. For an ideal distributions in biological or acousti- gas, the diffusion coefficient is proportional to the square root of the absolute cal systems. temperature. The thermal gradient is nicely represented by the diffusion gradient in this image. Again, the lowering of the diffusion coefficient at the ends is due to restricted diffusion.

24 Los Alamos FYI996 LDRD Progress Report The Development of Fullerene-Based by a platinum strip located above the fullerene sample. Reversible isother- Hydrogen Storage Systems mal hydrogen uptake levels for the unmodified fullerene were 0.9% at 200°C, 1.4% at 300°C, and 2.6% at Shimshon Gottesfeld 400°C. We suspect that hydrogenation The objectives of our project are to 600°C under high vacuum to remove proceeds by incipient sublimation of evaluate hydrogen uptake of fullerene residual carbonyl groups. This form fullerenes, as indicated by our thermo- substrates and to probe the potential of modified fullerene was designed to gravimetric analysis measurements. of the hydrogen/fullerene system for provide effective hydrogenation These results provide original, signifi- hydrogen fuel storage. We have made catalysis as well as increased intermo- cant data on the extent and mecha- significant progress in demonstrating lecular gaps in solid fullerenes. We nism of hydrogen uptake/release by conditions for substantial and used a hydrogen pressure cycle (0 to fullerenes and, consequently, on the reversible hydrogen uptake/release by 140 to 0 bars) to measure reversible viability of the hydrogen/fullerene fullerenes. We have completed and hydrogen uptake/release by the system for hydrogen storage. Of tested a system for measuring fullerene-ruthenium sample at particular interest is our demonstra- hydrogen uptake that is capable of constant temperature. The threshold tion of reversible uptake/release at handling both a vacuum of temperature for significant hydrogen levels exceeding 2% for isothermal- 1 x 106 torr and pressures greater uptake was somewhat over 200°C, pressure-swing conditions. We hope than 200 bars. Operation of the and reversible uptake/release levels to increase hydrogen uptake further system is fully automated and measured for the fullerene-ruthenium by optimizing the composition and controlled by computer. sample were 1.2% at 270°C and 2.0% structure of the catalyzed fullerene We obtained the first promising at 350°C. Later, we discovered that an sample. results using fullerene-ruthenium unmodified fullerene exhibits similar samples prepared by reacting hydrogen uptake/release behavior fullerenes with ruthenium carbonyl under similar pressure-swing condi- and then annealing the samples at tions when hydrogenation is catalyzed

Optical Imaging through Turbid Media Using a Degenerate, Four-Wave, Mixing Correlation Time Gate

Irving Bigio

There is a significant need for a technique of degenerate four-wave our component specifications to safer alternative to x-ray imaging for mixing as a very fast correlation time obtain excellent resolution of the applications such as mammography, gate. This method generates a short, crosshair images. Finally, we also dentistry, and brain imaging, and well-defined optical gate for the began designing a cesium-vapor cell near-IR optical diagnostics could fit imaging signal, which ensures that for the nonlinear medium, which we the bill. However, because tissue only the least-scattered photons are expect to provide several orders of strongly scatters light, resulting in detected and imaged. magnitude further improvement in the diffuse or fuzzy images, a method is This year we designed and as- signal-to-noise ratio. needed for selecting and amplifying sembled a tunable near-IR laser only the small number of photons that (CrLiSAF) and explored the use of Publications have traveled nearly unscattered new nonlinear media, identifying a through the tissue medium. Practi- specific dye solution in toluene that Zerkle, D.K., I.J. Bigio, and N. Nogar, cally, this is equivalent to detecting improves the signal-to-noise ratios. In "Imaging through Turbid Media with only those photons that have taken the addition, we generated the first a Nonlinear-Optical Correlation Time straightest (that is, the shortest images of a crosshair test pattern, at Gate," OSA Trends in Optics and temporal) path through the medium. wavelengths appropriate for imaging Photonics 2, 103 (1996). The goal of this project is to in tissue, through 2 cm of scattering develop an optical imaging diagnostic medium. We improved the configura- based on the nonlinear optical tion of the optical system and refined

Individual Projects—Engineering and Base Technologies 25 High-Average-Power, Intense Ion Beam Davis, H.A., et. al., "Progress Toward a Microsecond Duration, Repetitive, for Materials Modification and Other Intense Ion Beam for Active Spectroscopic Measurements on Applications ITER," Rev. Sci. lustrum. 68, 332-335 (1997). Harold A. Davis Jiang,W., et al, "Thermal Imaging Experiments on the Anaconda Ion We are developing a 1- to 2-Hz accelerator and fast-coil circuits, and Beam Generator," in Proc. 11th Int. repetitive, intense, ion-beam source we have also modeled the plasma Conf. High Power Particle Beam for materials studies (see figure). formation and acceleration process (Tiskarna, K., Ltd, Prague, Czech Specifications call for a beam energy with a snowplow model (i.e., coupled- Republic, 1996), Vol. 2, p. 890. of 200-250 keV, a beam current of circuit and momentum equations). 10-15 kA, and a pulse length 1 ms. Rej, D.J., et al, "Materials Processing The beam will be produced in a with Intense Ion Beams" (to be magnetically insulated diode with an Publications published in/. Vac. Sci. Technol). active plasma anode. Applications for Davis, H.A., et al., "Intense Ion Beam Rej, D.J., et al., "Materials Processing the source include (1) materials Treatment of Materials," Bull. Mater. with Intense Pulsed Ion Beams" surface treatment through rapid melt Res. Soc. 21 (8), 58-62 (1996). (submitted to J. Vac. Sci. Technol.). and resolidification, (2) coating at high rates through vaporization of Davis, H.A., et al., "Progress Toward targets and deposition onto substrates, a Microsecond Duration, Repetitively Pulsed, Intense Ion Beam," in Proc. (3) a diagnostic neutral beam for the 11th Int. Conf. High Power Particle next generation of tokamaks, and Beam (Tiskarna, K., Ltd, Prague, (4) an intense pulsed-neutron source Czech Republic, 1996), Vol. 1, for detecting land mines and produc- Magnetic p. 263. ing medical isotopes. Flux SurfacesN The major accomplishments this past year have been in the area of Plasma designing and fabricating the ion- Induction^ beam system. We have designed a Coil- layout of components for the high- voltage modulator, sized the overall beam and power supply system, and completed design of the diode and vacuum system (including the anode- Cathode Cones plasma generation system, the vacuum interface, the diode vacuum chamber, the beam transport and materials processing chamber, and the vacuum pumps, valve mounting, and plasma diagnostic vacuum chamber). Fabrication of these parts is under way. The first attempt to encapsulate the active plasma, high-voltage coil was unsuccessful, requiring a rede- sign; fabrication on this part is out for bid now. We also built and tested the plasma-anode and puff-valve drive circuits. In addition, we have successfully modeled the thermal transport in the plasma coil with a finite-element code and determined cooling requirements Insulating for the anode-plasma induction coil. Field Design for intense ion-beam source. Coils We have modeled and optimized the

26 Los Alamos FY1996 LDRD Progress Report Rej, D.J., et al., "Preparation of Rej, D.J., et al., "Surface Modification Diamond-like Carbon and Boron of AISI-4620 Steel with Intense Nitride Films by High-Intensity Pulsed Ion Beams" (to be published in Pulsed Ion Beam Deposition," in Nucl. Instrum. Methods Phys. Res. B). Proc. 3rd Int. Conf. on Applications of Yatsui, K., et al., "Preparation of Thin Diamond Films and Related Films by Ablation with the Anaconda Materials, A. Feldman et al., Eds. Ion Beam Generator," in Proc. 11th (National Institute of Standards and Int. Conf. High Power Particle Beam Technology, Gaithersburg, Md., (Tiskarna, K., Ltd, Prague, Czech 1995), p. 723. Republic, 1996), Vol. 2, p. 894.

Multichip Module Technology Development design tools can generate files that can be transferred to the MCM foundry as planned. Our Oak Ridge Jon Kapustinsky National Laboratory collaborators transferred technical information In this project we are exploring analog-to-digital converter (ADC), about the PHENIX preamplifier, whether several instruments under and control chips to produce a small analog memory, ADC, and control development at Los Alamos could be (approximately 5- to 10-die) MCM. chips that we incorporated into the miniaturized using new multichip We successfully created specifica- design. We procured bare die parts, module (MCM) technology for the tions for the small MCM, designed it, and we also developed the conceptual electronics and instrument readout. To and submitted it for fabrication. To design of bare die testing. We will that end, we addressed the problems accomplish this process we had to take measurements of the completed associated with getting dies of the engage in significant amounts of multichip modules so that we can required precision. We worked with a communication and collaboration determine the accuracy to which those vendor and used a prototype PHENIX with the fabrication team, and we tests must be performed to ensure silicon preamplifier, analog memory, demonstrated that the Los Alamos acceptable yields.

Magnetic Resonance Force Microscope Publications Development Hammel, PC, Z. Zhang, et al., "Sub- Surface Imaging with the Magnetic Resonance Force Microscope," /. Low P. Chris Hammel Temp. Phys. 101, 59 (1995). Zhang, Z., P.C. Hammel, and G.J. Our central objective is to build a resonators (the subject of a patent Moore, "Application of a Novel tool applicable to a wide range of application in preparation); and RF Coil Design to the Magnetic studies of technologically important (4) developed new RF hardware Resonance Force Microscope," Rev. systems, specifically layered magnetic especially appropriate for MRFM. Sci. Instr. 67, 3307(1996). and semiconductor systems. We have These last two advances are directly accomplished four important goals in in support of our ongoing work with Zhang, Z., P.C. Hammel, and P.E. our program to apply the emerging our California Institute of Technology Wigen, "Observation of Ferro- capabilities of the magnetic resonance collaborators on development of the magnetic Resonance in a Micro- force microscope (MRFM). We have next-generation high-performance scopic Sample Using Magnetic (1) quantified the sensitivity and microresonators and on incorporation Resonance Force Microscopy," Appl. resolution of the MRFM in a pub- of these resonators into the MRFM Phys. Lett. 68, 2005 (1996). lished article; (2) applied the MRFM instrument. These accomplishments Zhang, Z., M.L. Roukes, and P.C. to ferromagnetic resonance (FMR) are crucial steps in our program to Hammel, "Sensitivity and Spatial studies of microscopic ferromagnetic apply the emerging MRFM technol- Resolution for Electron-Spin- samples and thus opened up a new ogy to important technological Resonance Detection by Magnetic arena of study; (3) developed a new problems in interface science. Resonance Force Microscopy," /. approach to MRFM that will enable Potential applications include buried Appl. Phys. 80, 6931-6938 (1996). the use of novel, high-performance interfaces in layered microelectronic and magnetoelectronic devices.

Individual Projects—Engineering and Base Technologies 27 Femtosecond Scanning Publications Tunneling Microscope Rodriguez, G., and A.J. Taylor, "Screening of the Bias Fieldirom Terahertz Generation from Antoinette Taylor Photoconductors," Opt. Lett. 21,1046 (1996). By combining scanning tunneling signal by briefly illuminating the Taylor, A.J., and G. Rodriguez, microscopy with ultrafast optical photoswitch, which is fabricated from "Ultrafast Field Dynamics in GaAs techniques, we are developing a novel radiation-damaged GaAs and has an Photoconductors" (submitted to Appl. tool to probe phenomena on atomic "open" time on the order of 600 fs. Phys. Lett.). time-and-length scales. The goal of We have obtained a time resolution of this project is to build the first 2.5 ps with a few tens of picoamps of femtosecond scanning tunneling average transient tunneling current. microscope (STM). The

28 Los Alamos FY1996 LDRD Progress Report w E cc o Ultrafast tunneling signal, Q. demonstrating picosecond resolution of the femtosecond STM: (a) Tip crashed into sample, (b) Tip weakly contacting sample (total resistance of O GaAs switch and tunneling junction is 10 M). (c) True tunneling with a total resistance ofl6M. (d) True co tunneling with total resistance of 33 M. Note that the waveform of a true tunneling signal is the derivative of the signal obtained with the tip in contact with the sample (a). -20 -15 - 5 10 15 20 Time Delay (psec)

Exploration of Technologies for Improving undue weight and that it may be used by civilian police forces. Structural Civil Security Laminates, a company with which we established a collaboration, donated some aluminum/fiberglass laminate Eugene Farnum that we used in experiments on Class Ha ballistic vests donated for testing Of the utmost importance to our disposal containers, two companies by the New Mexico State Police. The security forces and to our government that were interested in having us tile-protected vests were successful in is the security of civilians, and new evaluate their technologies fabricated defeating hand thrusts with sharpened technologies for improving security such containers, which did not ice picks. We also designed an ice- are continually sought. Our project is incorporate our flexible-tile technol- pick test fixture capable of meeting aimed at increasing civilian protection ogy, and delivered them to Los the California Department of Correc- by exploring the use of flexible-tile Alamos for testing. The companies' tions Penetration Standard. technology for bomb disposal involvement was sponsored by the Finally, for portable armor we containers, protective vests, and Industrial Partnership Office. Test designed an armored blanket that will portable armor and then evaluating results suggested that our flexible-tile provide portable protection of police how the tiles, when combined with technology would substantially vehicles from rifle fire. For the functional graded ceramics and improve explosive containment blanket, we acquired off-the-shelf ballistic modeling codes, can be used devices and led to a Los Alamos ceramic/cermet tiles (similar to those to improve security systems. After proposal to the National Institute of previously used at Los Alamos in interviewing civil security forces, Justice for further technology developing armor for the C-141 both state and Laboratory, to deter- development. aircraft) and a bolt of appropriate mine issues and needs, we reviewed During our study of protective Kevlar™ cloth, but lack of sufficient the state of the art in security-system vests, we learned that Kevlar™ vests resources prevented us from complet- materials and contacted potential can be penetrated by ice picks. A ing and testing the blanket. collaborators. collaboration with the New Mexico Work this year focused on the State Police established that our merits of using flexible tiles for flexible-tile technology will signifi- improving bomb disposal containers, cantly increase the protection offered protective vests, and portable armor. by ballistic vests against ice picks and During our investigation of bomb other pointed weapons without adding

Individual Projects—Engineering and Base Technologies 29 Fiber-Optic Communications Publications Cruz-Pacheco, G., and B.P. Luce, Using Solitons (FOCUS) "The Relationship between Periodic Wavetrains and Solitary Waves in Darryl D. Holm Optical Fiber Communications" (to be published in Phys. Lett. A). The telecommunications industry is reliably generating soliton pulses is a Gabitov, I., D.D. Holm, and B.P. currently developing soliton-based precondition for their use in optical Luce, "Generation of Soliton Pulse optical-fiber networks in the hope of transmission systems.) We have also Trains from Sinusoidally Modulated sending many scores of gigabits per developed a new perturbation tech- CW Beams with Nonlinear second of digital data over fiber-optic nique for the study of optical-fiber Amplifying Loop Mirrors" (to be links between computers and into amplifiers that should help guide published in Opt. Lett.). homes and businesses. These soliton- future design developments and based optical-fiber networks would facilitate benchmarking of numerical Gabitov, I., D.D. Holm, and B.P. use solitons (stable nonlinear optical simulation results. Next year we plan Luce, "Low-Noise Picosecond Soliton pulses in nearly transparent fibers) as to continue our study of pulse- Transmission Using Concatenated information bit carriers. Such reshaping devices and apply our Nonlinear Amplifying Loop Mirrors" networks would take advantage of the perturbation technique to the develop- (to be published in J. Opt. Soc. Am. B). intrinsic stability of soliton solutions ment of numerical methods and Gabitov, I., D.D. Holm, et al., of the nonlinear Schrodinger equa- algorithms for accurately computing "Recovery of Solitons with Nonlinear tion, which to leading order describes soliton pulse propagation in optical Amplifying Loop Mirrors," Opt. Lett. the evolution of optical pulses in a fibers. lossless fiber. However, even in the 20, 2490 (1996). highest-purity fibers, unavoidable energy losses cause soliton pulses to decay and disperse, thereby limiting data transmission rates. Reversing this dispersion, and thereby improving the rate of information transmission, New Applications for requires devices that can reshape Zeeman Interferometry pulses. In this project we are designing and developing these devices theoretically and numerically by using Roger Johnston and extending a general mathematical framework for analysis of nonlinear Our objective is to develop and This year we made significant pulse transmission in optical-fiber explore new applications for the progress in devising new applications networks. Zeeman Refractive Index (RI) for the technology, in making the Detector, which received an R&D 100 instrumentation simpler, and in This year we designed and analyzed Award in 1992. The RI of a sample is discovering new ways to use the a novel pulse recovery scheme using the ratio of the speed of light in instrument for ultrasensitive specia- nonlinear optical loop mirrors. vacuum to the speed of light as it tion. These new methods may Because of the initial success of our passes through the sample. Our ultimately prove to be patentable. results and the potential for their instrument detects and measures Progress made during this project has application in optical-fiber networks, changes as small as one part in a led to two new cooperative research the University of California decided billion in the RI of a time-varying and development agreements to seek a patent on our pulse recovery sample, such as a flowing gas or (CRADAs), one of which is for scheme. We also invented a way of liquid. We developed the Zeeman RI pollution and process monitoring. using nonlinear optical loop mirrors Detector initially for monitoring air or to generate high-quality soliton pulse gas samples for small changes in trains. (Of course, a method of composition or contamination. Publications Among the new applications for the Johnston, R.G., "On the Matter of technology explored in this project is 'Ratioing'" (to be published in Am. a detector for gel electrophoresis, a Stat.). detector for chromatography, and ultrasensitive thermooptic spectroscopy (a type of ultrasensitive spectro- photometry).

30 Los Alamos FYI996 LDRD Progress Report A Comprehensive Monitoring System for it enhances our ability to detect damage in structures and mechanical Damage Identification and Location in systems. Large Structural and Mechanical Systems Publications

Charles R. Farrar Doebling, S.W., and L.D. Peterson, "Computing Statically Complete It would be very helpful if we could of assembling these algorithms into a Flexibility from Dynamically identify damage to large structures interactive computer code. Measured Flexibility" (submitted to /. and mechanical systems at the earliest This year we developed robust Sound Vib.). possible stage, before permanent damage identification algorithms Doebling, S.W., L.D. Peterson, and damage to the structure or system, or through numerical and experimental K.F. Alvin, "Estimate of Reciprocal injury to individuals, occurs. For this simulations. To quantify and locate Residual Flexibility from Experi- project we are developing and damage using global vibration mental Modal Data," AIAA J. 34, experimentally verifying a software response measurements, we primarily 1678-1685 (1996). package comprising state-of-the-art looked at changes in strain energy structural monitoring/damage- stored in the structures; we deter- Doebling, S.W., L.D. Peterson, and detection algorithms. mined the strain energy changes from K.F. Alvin, "Experimental During the past two years of this changes in the mode shape curvature Determination of Local Structural research effort, we have reviewed the of the structures. We also developed Stiffness by Disassembly of Measured existing state-of-the-art methods of and implemented statistical analysis Flexibility Matrices" (submitted to /. structural damage identification by methods whereby we can distinguish Vib. and Acoustics). measuring changes in the vibration between changes in measured Farrar, C.R., "System Identification characteristics of civil, mechanical, parameters caused by damage and from Ambient Vibration Measure- and aerospace structures; we also those caused by random experimental ments on a Bridge" (submitted to J. developed new algorithms that better error. This feature of our damage Sound Vib.). detect damage. We are in the process identification procedure is unique, and

Quantum Cryptography for During the past year, we have designed, constructed, and tested a Secure Communications to quantum cryptography system that creates and transmits—using single- Low-Earth-Orbit Satellites photon transmissions—cryptographic random numbers between a sending- and-receiving instrument within our Richard Hughes laboratory. The system is based on the propagation and detection of non- Cryptanalysis techniques and Quantum cryptography uses single orthogonal polarization states of algorithms are advancing rapidly and photons to create and transfer single photons in free space at a by the start of the twenty-first century information in a way that utilizes the wavelength (771 nm) for which the will necessitate the development and laws of quantum mechanics to afford atmosphere has a very low attenua- use of new encryption technologies to absolute security. Our calculations tion. We are now taking the steps ensure secure communications to show that with quantum cryptography, required to preserve the intellectual satellites. The aim of our project is to completely secure, random "seeds" property rights to this invention develop quantum cryptography to (cryptographic keys) can be generated before publishing papers or making provide absolutely secure encryption between a ground station and satellite public presentations about our system of communications to low-Earth- in real time. By eliminating any prior and its performance. orbiting satellites. We will develop record of a key, quantum cryptogra- and demonstrate the cryptographic phy removes the possibility of hostile technology to a stage where it can be interception of communications, feasibly incorporated into new making the entire encryption process satellites. both simpler and more assured.

Individual Projects—Engineering and Base Technologies 31 Application of Intense Surface Discharge Publications VUV Light Sources to Photoresist Ashing Hatanaka, H., and R.C. Sze, "Development of an Intense Surface in Semiconductor Manufacturing Discharge Pumped Vacuum Ultraviolet Lamp" (Tenth IEEE Electron Devices Pulse Power Robert Sze Conference, Albuquerque, N. Mex., July 1995). This project deals with the develop- in helium, neon, argon, and krypton, Sze, R.C., "Intense UV Light Source ment of a sliding-arc light source that as well as typical KrF and ArF for Semiconductor and Flat Panel would have sufficient intensity in the excimer-laser gas mixtures and Display Processing" (Conference on ultraviolet spectral region to do fluorine-containing gas mixtures in material processing over a very large attempts to maximize uv production Lasers and Electrooptics, Baltimore, area. The ability to melt thin-film in these sliding-arc discharges. The Md., May 1995). materials in a single shot can have a first accompanying figure gives an Sze, R.C.,"Large-Area Surface major impact (for example, on the flat example of such a study in argon. The Discharge UV Light Source for panel display industry) in such second figure gives a comparison in Materials Processing Applications" applications as the conversion of the 160- to 360-nm UV range for (to be presented at Gas and Chemical amorphous to polysilicon circuits on argon and krypton. Krypton shows Lasers Conference, San Jose, Calif., glass substrates used in liquid-crystal higher UV content, although the February 17, 1997). flat panel displays and in the activa- rising slope in UV light from black- tion of phosphors on electrolumines- body radiation is judged similar in cent flat panel displays. both gases. The third figure shows The device we designed has a that energy deposition into the 6-in. x 6-in. discharge area on a discharge is greatly enhanced with dielectric surface for studies that have increasing pressure as a result of been made on alumina, teflon, and increasing discharge impedance. plate glass. At a charge voltage of 30 kV, the system stores some 2 kJ in pulse power. At this operating point we have shown a surface intensity uniformity of better than 5% across the entire surface area of the light flash. Integrated light-energy outputs on the surface from 200 nm to the infrared have been measured at 1500 greater than 800 mJ/cm2. Preliminary attempts to crystallize amorphous silicon were unsuccessful, but 1000- crystallization was attempted at distances very far from the flash surface. This year we focused our experimental efforts toward obtaining detailed light spectra of the flash. We have obtained instrumental distortion- Wavelength (nm) corrected spectra from 160 to 735 nm Flash spectra in 1000-torr argon gas on alumina dielectric from 160 to 735 nm.

32 Los Alamos FYI996 LDRD Progress Report 1400-

1200

1000

Flash spectra comparison at 1000- torr pressure between argon and krypton in the 160- to 360-nm UV range on alumina dielectric. 160 180 200 220 240 260 280 300 320 340 360 Wavelength (nm)

700

Flash spectra in argon at 500-, 750- and 1000-torr pressure on alumina dielectric. 260 460 Wavelength (nm)

All-Solid-State Four-Color Laser

Timothy R. Gosnell

The goal of this project is to Our main accomplishment this year develop a solid-state laser that was to verifiy and quantify the nature produces visible output wavelengths, of the energy-transfer processes, in including the commercially compel- particular a "photon avalanche" ling blue wavelength. The device process, responsible for the efficient consists of a single-mode optical fiber population of the upper laser level. doped with Pr3* and Yb3+ ions. When These results will be used to design a the ions are simultaneously pumped new geometry for the optical fiber, with a near-infrared laser (860 nm), which was initially unoptimized, in complex energy-transfer processes order to enhance device performance. involving multiple excited ions lead to population of a high-lying energy level of Pr3+.

Individual Projects—Engineering and Base Technologies 33 Material Processing for temperatures, we have been designing and building special, small, low-cost Self-Assembling Machine Systems furnaces. We have reduced iron oxides and pure iron silicates with metallic silicon at 1600°C in air. Klaus Lackner Avoiding the need for a protective atmosphere is a major achievement We are developing the foundation critical issues in developing the new because it greatly simplifies the for a new technology based on self- technology is the design of a process ultimate design of the extraction reproducing machine systems. Of the that will extract all the important process for self-replicating machines. numerous issues that need to be chemical elements from raw dirt. This We succeeded in extracting small iron considered and resolved before our process differs from conventional pellets from raw materials. At the vision of the new technology can be extraction metallurgy in that it uses same time, our experimental results implemented, material extraction is only abundant elements, because point to the need for a careful choice one, and it is the focus of our project. almost the entire mass of the self- of the material for the containment Limitations in energy and nonrenew- replicating system is channeled vessel, which tends to be attacked by able resources and the need to control through the process. However, such the melted charge. We have tested a deleterious side effects of human extraction processes are of interest number of materials and are optimiz- activities on the environment are even to conventional metallurgy ing our choice. Discover magazine major problems for the coming because they do not involve use of (October 1995) referred to our decades. Self-reproducing machine expensive and sometimes hazardous concept as one of seven ideas that systems could be their solution. materials. could change the world. Machine systems that build and This year, we have successfully maintain themselves promise an collected a set of sample materials— increase in industrial productivity as for example, basalts—that are typical Publications dramatic as that of the industrial for the basic extraction process. Lackner, K.S., and C.H. Wendt, revolution. A system that can build However, most of our work to date "Exponential Growth of Large Self- itself must procure all raw materials has been performed on pure oxides Reproducing Machine Systems," from its natural surroundings. Thus, and minerals. Because our new Math. Comput. Modelling 21, 55-81 next to automation, one of the most extraction processes occur at high (1995).

Diode Laser Development frequency-offset techniques using modulators and/or ultrastable cavities for Quantum Computation to reference the 866-nm and 397-nm wavelengths to stable atomic lines. Typically, the wavelength of the light Richard Hughes emitted by the laser must be controlled with respect to a reference Quantum computation is much technology for this application, but wavelength, which is near to the more powerful than classical compu- they are expensive, require a laser desired wavelength. For our diode tation because it allows computing expert, use over 40 kW of power, and lasers, we can reference light wave- with quantum-mechanical superposi- fill an entire laser table. The objective lengths to an absolute atomic standard tions of many numbers at once. In a of our project is to develop diode or to a very stable optical cavity that quantum computer, binary numbers lasers for this application because resonates at a very well defined will be represented by quantum- they are easy to use, low in cost, and frequency. mechanical states ("qubits")- We have compact. At the same time, we have worked been developing a quantum computa- This year, we have developed diode with two companies to determine if tional device in which the qubits will lasers at the 866-nm and 794-nm the frequency-doubling cavities that be two electronic states of calcium wavelengths that are required for they market would give the necessary ions that have been cooled with a cooling calcium ions. (In the next few amount of output power and would laser to rest at a particular location in months, we will double the frequency provide adequate beam quality for our the ion trap. We will then perform of the 794-nm light to obtain 397-nm 397-nm wavelength requirements. quantum logical operations with a light.) We have assembled Finally, we have studied the laser beam that is resonant with the external-cavity diode laser systems Drever-Hall stabilization technique qubit transition frequency and is and, with a prototype, demonstrated for external-cavity lasers as a means directed at individual ions. Titanium- locking to an existing frequency for producing laser linewidths of sapphire lasers are a proven standard. We have developed better than 100 kHz.

34 Los Alamos FYI996 LDRD Progress Report Designing a Micromechanical Transistor discovered that the numerically computed resonances had errors that grew exponentially fast with the Ronnie Mainieri resonance number. The errors also follow a universal curve independent Micromechanical electronic chips to have a mechanical device, of the shape of the device. The errors systems are chips with moving parts. i.e., a mechanical transistor, that can in the resonances imply an error for They are fabricated using the same change its behavior in response to a the time evolution of the system and techniques for manufacturing elec- small input. may also be present in other equa- tronic chips, sharing their low cost. Large responses caused by small tions. This exponential growth in Micromechanical chips can also changes are the hallmark of chaotic errors makes it impossible to use contain electronic components. The dynamics so most of the transistor traditional numerical techniques, and combination of mechanical parts and designs we have considered corre- we are now characterizing the electronic parts makes it possible for spond to chaotic systems. The chaos problem and approaching its solution chips to process signals mechanically. is in the ray dynamics of sound using methods developed for the To achieve designs comparable with propagation. When we tried to study of nonlinear dynamical systems. those obtained with electronic compute the resonances of systems The basic idea is to combine Monte components, it is necessary for these with chaotic ray dynamics, we Carlo data with analytic methods.

High-Sensitivity, Solid-State Carbon parts per million sensitivities, good selectivity, and fast response times. Monoxide Sensor Development The current commercial sensor technologies cannot detect carbon monoxide below dangerous threshold Fernando Garzon levels—tens of parts per million—nor do they respond quickly at the Carbon monoxide gas (CO) is a sensor technologies for this gas are hundreds of parts per million levels. deadly, colorless, odorless gas that needed to protect people in their We have produced, tested, and results from incomplete combustion workplaces and homes. Our objective optimized solid-state electrochemical of typical fuels. It is the most com- is to develop simple, low-cost, sensors that use thin-film perovskite- mon form of death due to asphyxiant electrochemical sensors for the or fluorite-structure catalysts as gases in the United States. Better detection of CO in air with tens of sensing electrodes deposited on oxygen-ion, conducting solid electro- lytes for monitoring carbon monoxide Acoustic Resonance Spectroscopy in air. Our sensors show excellent sensitivity: the ability to detect less Randy S. Roberts than 1 ppm CO, rapid response time, and good return to baseline character- US government agencies have We have developed an approach istics. They also show good long-term successfully applied Acoustic that appears to be a promising durability—over 1000 hours of Resonance Spectroscopy (ARS) to the solution to this problem. The ap- operation under a variety of condi- problem of noninvasive classification proach involves successively adding tions. of chemical munitions. The classifica- new signatures to the template and We have studied the cross sensitiv- tion technique compares templates monitoring discrepancies between ity of these sensors to carbon dioxide, formed from the acoustic signature of successive templates. At this point we water vapor, propane, methane, known munitions to acoustic signa- are evaluating the technique on ethanol, and hydrogen. We have also tures of unknown munitions. One several data sets. Additional work on demonstrated that variants of this problem with this approach is this project included reporting a technology can be used to sense other template construction—specifically, liquid-solid discrimination algorithm gases, such as hydrocarbons, sulfur determining which combination of and exploring the application of ARS dioxide, and nitric oxides. Our tech- signatures yields the best template. to such areas as gas-bottle inspection nology may replace semiconductor- The objective of this project was to and pit surveillance. We obtained based sensors currently in use because develop a technique to determine the promising results in the former of the new devices' superior response best set of signatures to construct a application, and results are forthcom- characteristics. We have filed a patent template. ing in the latter. application for this invention.

Individual Projects—Engineering and Base Technologies 35 Liquid-Metal, Focused-lon-Beam (depending on the local, spatial ion dose) and that no organic or inorganic Etch Sensitization and Related resist is required. We developed these unique features sufficiently during the Data Transmission Processes past year to file several patent actions on applying this process to the Bruce Lamartine production of both digital and human- readable grayscale data on archival Ultrahigh-vacuum focused-ion- media and transmission formats for media such as silicon and other single beam micromilling is a method of rapid digital transfer. In addition, we crystals or amorphous coatings. recording data permanently at very intend to explore, in hardware, the Furthermore, we showed that several high density. The process can poten- feasibility of a charge-coupled-device micromachined data media can be tially be significantly improved by data transfer scheme that can send used for human-readable formats ion-beam sensitization to wet or dry data at video rates. (either pictures or print): silicon (100) anisotropic chemical etch reactions. The ion-beam micromilling can be read by a phase-sensitive The objective of this project is to process, while already successful, can interference microscope, silicon (100) explore the general phenomenon of be enhanced by ion-beam sensitiza- and silicon (111) can be read by a ion-beam etch sensitization in several tion to wet or dry anisotropic chemi- laser intensity feedback microscope, media—e.g., silicon (100), gallium cal etch reactions. Ion-beam and tantalum oxide can be read by a arsenide, and tantalum oxide on sensitization differs from conventional conventional scanning-electron tantalum—for optimal pixel or bit lithography in that many levels of microscope. contrast and to search for optimal feature depth are potentially available

Experimental Validation of The hand-held SQUID sensor system is nearing completion as of the Superconducting Quantum writing of this report. The battery- powered cryogenic cooler has been Interference Device Sensors procured by SNL and the last parts of the dewar are in fabrication. The Robert Kraus dewar design uses a thick aluminum wall for eddy-current cancellation of Along with Sandia National background fields sufficiently that all but low-frequency signals, Laboratories (SNL) and the Univer- they will not overwhelm the dynamic reducing further the ambient back- sity of New Mexico, we have sup- range of the SQUID. We implemented ground at the SQUID, while allowing ported the collaborative development this novel approach developed as part most of the biomagnetic frequencies of two critical components for a hand- of this LDRD project in a prototype of interest through the wall to the held, low-field magnetic sensor based system that enables cancellation of SQUID sensor. on superconducting quantum interfer- more than 99% of the background A second hand-held dewar has been ence device (SQUID) technology. The magnetic field at the SQUID. We used designed using G-10 glass-epoxy two components are a digital signal the principle of superposition of composite that will allow the entire processing (DSP) algorithm for magnetic fields. electromagnetic spectrum to pass background noise rejection and a Using state-of-the-art electronics through to the SQUID. The aluminum small, hand-held, dewar cooled by a and digital circuits, we anticipate design will enable use of the proto- cryocooler (supplied by SNL). being able to cancel at least 80 dB type DSP background cancellation We reported the results of the DSP (99.99%) of the background signal. system, since it is less reliant on algorithm implementation at the 10th This level of background cancellation complete removal of the background. International Conference on at the SQUID makes applications The composite dewar will require Biomagnetism. Traditionally SQUIDs such as monitoring head trauma or highly efficient background rejection. have been operated in magnetically cardiac function in the field a realistic shielded rooms, costing approxi- prospect and one that we will develop. mately $500,000 or more, to reduce

36 Los Alamos FY1996 LDRD Progress Report Plasmas, Fluids, and Particle Beams

High-Power, High-Frequency, Publications Carlsten, B.E., "Axial Free-Electron Annular-Beam Free-Electron Maser Laser Interaction between an Annular Electron Beam and an Axisymmetric Michael Fazio TM Mode," IEEE J. Quantum Electron. 31, 1753 (1995). Free-electron masers (FEMs) (2) demonstrate a phase-stability operating in the microwave regime scheme in which the RF phase of the Carlsten, B.E., "Enhanced Phase have demonstrated both high beam- output power is not affected by small Stability for a Raman Free-Electron to-RF power extraction efficiencies fluctuations in the electron beam Laser Amplifier in the Exponential (-30%) and high output power voltage. We have derived theoretical Growth Regime," Phys. Plasmas 2, (~GWs). In addition, FEMs are phase-stability criteria and designed a 3880 (1995). potential candidates for driving high-power FEM using the axial FEM Carlsten, B.E., CM. Fortgang, J.M. advanced particle-beam accelerators interaction that satisfied these phase- Potter, et al., "Microwave Axial Free- at relatively high frequencies (greater stability criteria. Electron Laser with Enhanced Phase than 10 GHz). However, current FEM Most recently we have concentrated Stability," Nucl. lustrum. Methods technology does not lead to adequate on prototyping and fabricating Phys. Res. A 375, 171-174 (1996). phase stability for this application. components for a high-power experi- Furthermore, high output power has ment. Because of the uniqueness of Carlsten, B.E., W.B. Haynes, and R.L. been demonstrated only with FEMs this experiment, completely new Sheffield, "Particle Acceleration by driven by induction accelerators at diagnostic techniques and RF the Inverse Axial-Free-Electron Laser higher voltage than practical for matching components are needed. In Interaction," Particle Accelerators 51, driving long accelerators. Such a particular, we have designed and built 121-133 (1995). high-power RF source would enable an input coupler, a high-power load, a the construction of future linear slow-wave structure, directional colliders that are simply too expensive couplers, and high-power calorim- to build with existing technology. eters. We are now assembling the The objectives of this project are to high-power experiment. (1) demonstrate high output power (0.5 GW) at high frequency (17 GHz), using a high-current but relatively low-voltage electron beam, and

Directional Rippled-Wall Coupler Input Section Structure 6 Port Input Coupler

Beam Load and A schematic of the high-power free-electron maser experiment. Dump Calorimeter

Individual Projects—Plasmas, Fluids, and Particle Beams 37 Determination of Optical Field-lonization argon, krypton, and xenon as a function of pressure and pump Dynamics in Plasmas through Direct intensity (see plot of phase vs time) and measured strong-field ionization Measurement of the Optical-Phase rates of these gases. We modeled the Change ionization dynamics using strong-field tunneling theories—both Keldysh and Ammosov-Delone-Krainov (ADK)— Antoinette Taylor and compared the results with our measurements (see plot of density vs The interaction of ultrashort, high- change of an optical pulse. We can time). intensity laser pulses with solid and then use this technique to investigate gas targets is a field of growing femtosecond field-ionization dynam- interest. Highly ionized, atmospheric- ics in atomic and molecular gases and Publications density plasmas are a potential source to study solid-target laser-plasma Clement, T.S., G. Rodriguez, et al., of coherent visible-ultraviolet and interactions. "Characterization of Ultrafast x-ray light, as well as a potential This year, we developed this novel Interactions with Materials through medium for charged-particle accelera- technique and used it to investigate Direct Measurement of the Optical tion. The interaction of a high-intensity, femtosecond field-ionization dynam- Phase," Proc. Soc. Photo- ultrashort pulse with a solid target is of ics in atmospheric-pressure noble Instrumentation Eng. 2701, 229 14 interest both scientifically and as a gases. We focused an intense (10 to (1996). source of ultrashort x-ray pulses. 1016 W/cm2), ultrafast (100-fs) pulse New, quantitative experimental into a cell containing a noble gas at a Kane, D.J., T.S. Clement, et al., diagnostics compatible with ultrafast pressure of 1 atm or less; this pulse "Simultaneous Measurement of Two time scales are needed to measure the ionized the gas. We then measured the Ultrashort Laser Pulses from a Single ionization and the subsequent plasma change in the optical phase and Spectrogram in a Single Shot" (to be dynamics that give rise to these amplitude induced by the presence of published in J. Opt. Soc. Am. B). conditions. The goal of this project is free electrons in the ionized gas using Wood, W.M., M. Cyza, et al., to develop a technique for characteriz- the technique of frequency-resolved "Determination of Strong Field ing laser-plasma interactions with optical gating. With this setup we Ionization Rates through Direct femtosecond resolution based on the determined the evolution of the Measurement of the Optical Phase," direct measurement of the phase ionization dynamics in helium, neon, in Ultrafast Phenomena X (Springer- Verlag, Berlin, in press).

0.5 —

Phase Changes in Neon 0.4 —

0.3 —

0.2

Measurement of the phase change of the optical pulse due to the creation 0.1 - of the plasma in neon gas reveals that the magnitude of the effect scales with pressure, as expected. Consistent with theory, the onset of ionization occurs 0.0 rapidly in the early stages of the pulse. -300 -200 -100 0 100 200 300 Time ffs)

38 Los Alamos FY1996 LDRD Progress Report 1.0

Intensity

\ Keldysh Theory 0.8 — \ ADK Theory \ WMMH Measured: 10 torr I \ - - - - Measured: 20 torr

\ 0.6 — \ Density vs Time 1 Neon

0.4 o Z We analyzed the phase measurements from the other figure to yield the free- electron density as a function of time. 0.2 The results are compared with calculations from both the Keldysh and ADK theories. The measured results demonstrate higher ionization rates earlier in the pulse than either 0.0 of the theories suggests. -200 200 Time (fs)

Delta-f and Hydrodynamic Methods The plug-and-play nature of PCUBED has allowed use of the code for Semiconductor Transport in new areas such as neutron transport, brain tomography, and gas-core nuclear rocketry. Finally, we have Lester E. Thode shown that existing FORTRAN codes The most sophisticated simulation codes. PCUBED utilizes advanced can be standardized with respect to technique for semiconductor carrier input and output capabilities and input, output, restart, and graphics, transport is the Monte Carlo method. includes interactive graphical which, if implemented, would lead to Unfortunately, the Monte Carlo debugging. increased productivity of design method is computationally costly. In We imported the code MINIMOS efforts. this work we are investigating into PCUBED to provide the drift- whether the delta-f method, developed diffusion, energy-balance, and Publications within the magnetic fusion commu- hydrodynamic models for the nity, can be successfully applied to fluidlike part of the delta-f method. Gray, M., T. Booth, et al., "Multi- semiconductor transport. In addition, For the particle-tracking part of the Comb Variance for Monte Carlo we are working to develop a single delta-f method, we imported a new Semiconductor Simulators" architecture to allow users to select C++ object-oriented Monte Carlo (submitted to IEEE Trans. Electron fluidlike models, a Monte Carlo code into PCUBED. We also devel- Devices). model, or a delta-f model. oped new approaches to solve the Thode, L., R. Hotchkiss, C. Snell, et Development of a C++ prototype nonlinear Poisson equation. To al., "Plug-and-Play Environment for plug-and-play code (PCUBED) is calculate moments of the distribution, Algorithm Development" (U), now complete. PCUBED allows the we developed a general particle (Nuclear Explosives Code Developers integration of different code lan- accumulation approach. To reduce Conference, San Diego, Calif., guages within a single architecture, noise, we are investigating higher- October 1996). including C++, C, and FORTRAN order particle-weighting schemes.

Individual Projects—Plasmas, Fluids, and Particle Beams 39 A Compact Compton-Backscattering several approaches to increase the yield of x-rays via Compton backscat- X-Ray Source for Mammography and tering in order to meet our objectives. Coronary Angiography Publications Dinh C. Nguyen Nguyen, D.C., and B.E. Carlsten, "Amplified Coherent Emission from We are developing a compact, signal arose from the Compton- Electron Beams Prebunched in a tunable, monochromatic x-ray source backscattered x-rays because it did Masked Chicane," Nucl. Instrum. for applications in medical imaging not completely go away when the Methods Phys. Res. Sect. A 375, 597 such as mammography and coronary laser was blocked. We are working on (1996). angiography. Using monochromatic x-rays in such applications will reduce the x-ray dose to patients and Collision Electron at the same time enhance the film Beam Point Accelerator image by reducing unwanted scatter. Transport Our technical goal is to demonstrate the generation of a large flux of X-rays monochromatic x-rays in the keV energy range. We accomplish this goal by colliding a visible laser beam against a relativistic beam of electrons in a process known as Compton / A backscattering. Beam The experimental setup for Dump Compton-backscattering x-ray Li! generation includes a linear accelera- The major components of the tor to produce the relativistic electron Compton-backscattering experiment. beam, a high-powered laser, and an optical resonator to trap the laser beam and to increase its intensity. For detecting the x-rays, we use a scintillator coupled to a light pipe that Equation of State of Dense Plasmas directs the visible fluorescence from the scintillator to a photomultiplier tube. These components are shown in John Benage the accompanying figure. In our experiments, the laser beam is used to The goal of our project is to preliminary tests of the new capacitor generate electrons through a photo- measure the equation of state of a bank; when these tests are completed, emission process, and the trajectory of dense aluminum plasma. We will we will begin tests on the production the electrons is timed so that they accomplish this goal by using a laser of the aluminum plasma plume. collide with the laser beam at a known to produce a shock in a uniform We also did a series of simulations position. aluminum plasma plume. We will of this experiment to determine the measure the velocity of the shock, the requirements for the laser that will be We have successfully tested the density in front of and behind the used to produce the shock in the scintillation x-ray detector and found shock, and the temperature. From plasma. These calculations showed that it exhibits good sensitivity and these measurements, we will deter- that we need a 0.53-um laser with a good spatial discrimination against mine the equation of state. pulse width of 1-2 ns and an intensity background radiation. We used a at the plasma of 10 TW or greater. picosecond streak camera coupled to In the past year, we designed and From these results, we designed a a charge-coupled device camera to completed the construction of the new laser system which takes advantage of overlap the electron beam and the capacitor bank which we will use to the system we already possess and, laser beam in both space and time. produce our plasma. The laser we will with a minimum cost, gives us the Although the x-ray detector registered use to produce x-rays for the density laser we need. We expect this laser to a positive reading, we could not measurements is operational, and we become operational by the middle of conclusively demonstrate that the have begun tests on the production of these x-rays. We are just beginning next year.

40 Los Alamos FY1996 LDRD Progress Report Turbulence and Turbulence Spectra various models of the correlations. We have analyzed the self-similarity in Complex Fluid Flows observed in spectral model calculations of a free-shear layer. Computations with more-advanced models of triple Timothy Clark correlations yielded more-complicated and physically accurate self-similar Turbulence possesses a rich spec- the model predictions, we reduce forms; these results will assist us in trum of time and length scales that these models to tractable approxima- improving engineering models. This is defy direct computation because of the tions for engineering calculations. the most complete rigorous application inability of foreseeable computers to This year we have developed a of spectral theory to an inhomoge- resolve all scales. Turbulence strongly computer program to simulate neous turbulence yet accomplished. affects flows—e.g., mixing rates of inhomogeneous turbulence. We then The geometry is consistent with our pollutants, fuel in a combustor, or used this program to isolate effects of simulations. The formulation employs constituents in an inertial confinement triple- and pressure-velocity correla- an elegant methodology for specifying fusion capsule. We are developing tions from mean-flow effects. The eigenstates for a wide variety of theoretical models of turbulence in resulting database is unique in the geometries. parallel with direct numerical simula- amount and quality of information tions of flows to produce tractable, regarding these correlations. We used accurate models for use in computer this data to determine the necessity of Publications codes. We proceed from spectral maintaining certain tensorial and Sandoval, D.L., J.J. Riley, and T.T. models that describe turbulence in physical properties of the above Clark, "Buoyancy-Generated Variable- terms of a range of length scales. By correlations. Our simulations were Density Turbulence," in IUTAM exploiting emergent self-similarities of uniquely appropriate to evaluate the Proceedings of the Low-Speed Variable-Density Flow Conference A Water-Filled, Radio-Frequency (Kluwer Academic Publishers, Boston, Accelerating Cavity in press). Steinkamp, M.J., T.T. Clark, and F.H. Rickey J. Faehl Harlow, "Two-Point Description of Two-Fluid Turbulent Mixing, Part 1: The objective of this project is to showed excellent agreement with the Model Formulation" (submitted to Int. study water-filled resonant cavities as numerical results. Simulations of the J. Multiphase Flow). a high-energy-density source to drive high-field, high-current mode of Steinkamp, M.J., T.T. Clark, and F.H. high-current accelerator configura- operation indicated that charged- Harlow, "Two-Point Description of tions. Basic considerations lead to the particle loss on the dielectric win- Two-Fluid Turbulent Mixing, Part 2: expectation that a dielectric-filled dows, which separate the cavity from Numerical Solutions" (submitted to cavity should be able to store up to the beamline, must be carefully Int. J. Multiphase Flow). e/e0 (the ratio of the material to the controlled to avoid significant vacuum dielectric constant), as much distortion of the axial fields. Turner, L., "The Driven-Dissipative energy as a vacuum would with the Euler's Equations for a Rigid Body: A same dimensions, and thus be capable Chaotic System Relevant to Fluid of accelerating a proportionately Publications Dynamics," Phys. Rev. £54, 5822 larger amount of charge before cavity Faehl, R.J., R.K. Keinigs, and E.W (1996). depletion occurs. Pogue, "Dielectric-filled Turner, L., "EDQNM Model of During this period, we confirmed Radiofrequency Linacs," in BEAMS Evolution of Homogeneous, Anisotropic that water-filled cavities with e/eo = 96, 11th Intl. Conf. on High Power Turbulence in a Helicity Representation" 60-80 did indeed behave with the Particle Beams Proc, K. Jungwirth, (submitted to Phys. Rev. E). expected characteristics, in terms of and J. Ullschmied, Eds. (Academy of resonant TM modes and cavity Q. We Sciences of Czech Republic, Prague, Turner, L., "Remarks on Statistical accomplished this result with numeri- 1996), pp. 636-639. Mechanics of Discrete and Continuous cal cavity eigenvalue codes, with fully Media with Magnetohydrodynamic electromagnetic, two-dimensional, Faehl, R.J., R.K. Keinigs, E.W. Pogue, Dynamo" (to be published in J. Plasma particle-in-cell codes, and most "New Initiatives for Producing High Phys.). Current Electron Accelerators" (to be significantly with scaled experiments Turner, L., "A Tractable Model of performed in water-filled aluminum published in AIP 14th Intl. Conf. Appl. Accel, in Ind. & Res. Proc). Incompressible, Inhomogeneous cavities. The low-power experiments Turbulence" (submitted to Phys. Rev. E).

Individual Projects—Plasmas, Fluids, and Particle Beams 41 A Target Plasma Experiment Publications Idzorek, G., and R. Kirkpatrick, for Magnetized Target Fusion "Analysis of Filtered Silicon Diode Data from the MAGO 2 and MAGO Frederick Wysocki 3" (Seventh International Conference on Megagauss Field Generation, Achieving controlled fusion is a plasma current, a 1.3-um laser Sarov, Russia, August 1996). scientific "grand challenge" that interferometer to determine plasma Kirkpatrick, R., and D. Smitherman, mankind has been pursuing for over density, an optical framing camera, a "Energetic Alpha Transport in a 40 years. Fusion energy would help gated optical multichannel analyzer Magnetized Fusion Target" (to be satisfy the long-term energy needs of for visible spectroscopy, a visible to published in Fusion Technol). the growing population on Earth. near-ultraviolet monochromator with Magnetized target fusion (MTF) is an time resolution for spectral time Kirkpatrick, R., P. Sheehey, et al., approach to controlled fusion in history, photodiodes to measure light "Proposed Generation and which a premagnetized, preheated emission, and the usual capacitor- Compression of a Target Plasma for target plasma is near-adiabatically bank monitors. MTF" (Tenth IEEE International compressed to fusion conditions. The The data show that we are generat- Pulsed Power Conference, objective of this project is to develop ing a plasma that lasts 10-20 us with Albuquerque, N.Mex., July 10-13, the ability to generate suitable target no obvious signs of impurities. 1995). plasmas for MTF, the first critical Further analysis of the data is Lindemuth, I., R. Reinovsky, et al., milestone in the development path for ongoing. The results from the 1.3-um achieving fusion with the MTF "Target Plasma Formation for interferometer show that we need to Magnetic Compression/Magnetized concept. Our approach involves go to a shorter-wavelength laser driving a fast-rising electrical current Target Fusion," Phys. Rev. Lett. 75, interferometer to reduce beam 1953 (1995). reaching 1-2 MA through a fiber of deflection caused by density gradients cryogenically frozen deuterium about in the plasma and to reduce the Sheehey, P., R. Faehl, et al., 200 urn in diameter. The fiber rapidly overall sensitivity of the system. In "Computational Modeling of turns to plasma, heats, and expands to accordance, we have borrowed a Magnetically Driven Liner-on-Plasma fill a plasma-containment chamber, HeCd laser, purchased the supporting Fusion Experiments" (Seventh thus becoming confined by the walls optics, and assembled and bench- International Conference on of the chamber. This project relies tested the new interferometer. We will Megagauss Magnetic Field heavily on existing facilities and install the new interferometer on the Generation, Sarov, Russia, equipment at the Laboratory that are actual plasma chamber in the upcom- August 1996). adapted to our needs. ing weeks. We are also refurbishing Sheehey, P., J. Guzik, et al., This year, we designed and con- the cryostat used for making the "Calculations of Proposed structed a power-flow-channel and cryogenically frozen deuterium fibers Magnetized Target Fusion plasma-chamber system, and we and will be installing it on the plasma Experiments" (Tenth Biennial incorporated this system into the chamber in the next two months. Nuclear Explosives Design Physics Laboratory's Colt capacitor-bank Conference, Los Alamos, N.Mex., facility. The capacitor bank has a October 1995). maximum stored energy of 0.25 MJ, and it delivers a maximum of 3 MA Sheehey, P., J. Guzik, R. Kirkpatrick, of current with a rise time of 2-3 us. et al., "Computational and We have performed initial plasma- Experimental Investigation of formation experiments using a static Magnetized Target Fusion" (to be fill of hydrogen gas. The diagnostics published in Fusion Technol.). that we have fielded include an array of 12 B-dot probes used to determine

42 Los Alamos FY1996 LDRD Progress Report Developing Electron-Beam Bunching Carlsten, B.E., "Nonlinear Subpicosecond Electron-Bunch Technology at Subpicosecond Pulse Compressor," Nucl. lustrum. Methods Lengths for Improving Photon Sources Phys. Res. A 380, 505 (1996). Carlsten, B.E., and J.C. Goldstein, "Emittance Growth of a Short Bruce Carlsten Electron Bunch in Circular Motion" (to be published Nucl. lustrum. The purpose of this project is to This year we used this compressed Methods in Phys. Res. A). extend the current electron-bunch electron beam to generate as short as compression technology by develop- 22-nm-wavelength ultraviolet light, Carlsten, B.E., and D.C. Nguyen, ing a small experiment to study the demonstrating tremendous improve- "Electron Bunch Compression Due to essential physics associated with ment in an associated photon source. RF Forces in an RF Photoinjector for subpicosecond bunch compression, We analyzed additional compression Small RF Launch Phases" (to be and to probe the fundamental limits effects in radio-frequency photo- published in Part. Accel.). associated with compression. In injectors, and theoretically derived Carlsten, B.E., and SJ. Russell, particular, our goal was to bunch 1 nC important formulas describing the "Subpicosecond Compression of of charge to less than 1 ps, which nonlinear coherent synchrotron 0.1-1 nC Electron Bunches with a would represent more than an order of radiation force and the noninertial Magnetic Chicane at 8 MeV," Phys. magnitude increase in compression space-charge force that lead to Rev. E 53, 2072 (1996). over previous experiments. emittance growth in compressor In previous years, we analyzed the systems. Finally, we developed a new Carlsten, B.E., D.W. Feldman, dominant emittance growth mecha- root-mean-square emittance diagnos- J.M. Kinross-Wright, et al., nism and designed a second-order tic that can be used to study the "Subpicosecond Compression compressor. We also built a sub- emittance growth from these nonlin- Experiments at Los Alamos National picosecond compressor on a new ear effects. Laboratory," AIP Conf. Proc. 367, 21 accelerator that was constructed for (1996). a plasma light-source. Using this Publications compressor, we demonstrated compression of 0.1 nC from 20 to Carlsten, B.E., "Calculation of the 0.25 ps and compression of 1.1 nC Noninertial Space-Charge Force and from 20 to 0.75 ps. These levels of the Coherent Synchrotron Radiation compression far exceed previous Force for Short Electron Bunches in results and provide important guid- Circular Motion Using the Retarded ance to advanced compressor designs. Green's Function Technique," Phys. Rev. E 54, 838 (1996).

Individual Projects—Plasmas, Fluids, and Particle Beams 43 High-Intensity Laser-Matter We also measured the reflected and transmitted light for different delays Interaction Physics (plasma densities). Even at the low- plasma densities used, transmission James A. Cobble was less than expected. There appears to be an anomalous absorption that is During the first year of research, we tion of the light. Our experiment used possibly related to the ultrahigh employed the short-pulse capability of plasmas of 1% to 5% of the critical irradiance of the probe laser beam. the Trident laser at Los Alamos to density. The probe beam was focused We are pursuing this possibility with measure the penetration of a high- with an f/2.5 parabola. We found that theoretical studies to model the intensity beam through a 1-mm scale the beam f number increased upon behavior of the beam in the plasma. length plasma. The highest laser passing through the plasma. It was We are planning more experiments for irradiance was 7 x 1018 W/cm2. The more collimated because of its the coming year. plasma density depends on the delay interaction with the plasma. In order between a low-intensity plasma to measure this effect, we allowed the Publications formation beam and the high-intensity transmitted beam to strike a diffuser probe in striking the plastic target. plate behind the target. A camera Cobble, J.A., R.P. Johnson, and RJ. The critical plasma density is one imaged the scattered light from the Mason, "Exploded Foil Transmission above which the plasma oscillates plate to produce the data shown in the Experiments with an Ultra-Intense quickly enough to reject the penetra- figure. Laser," 26th Annual Anomalous Absorption Conf. Proc. 26, 116 (1996).

The f number of the probe beam is approximately doubled on passage through a 3% critical density plasma. The case with no plasma is shown in (a); the case with a plasma is shown in (b). Each frame is a 250 x 250 pixel array.

44 Los Alamos FY1996 LDRD Progress Report Chemistry

New Fullerene-Based Mixed Materials: Klimov, V., et al, "Strong Optical Nonlinearities in Porous Femtosecond Synthesis and Characterization Nonlinear Transmission Study," Phys. RevB. 62, 16989(1995).

Duncan McBranch McBranch, D., et al, "Femtosecond Excited-State Absorption Dynamics Our goal is to develop novel is a crucial parameter in the optical- and Optical Limiting in Fullerene Solutions, Sol-Gel Glasses, and Thin composites of derivatized C60 limiting effectiveness for nanosecond (fullerene) in inorganic glass hosts. pulses. Fullerene/sol-gel glasses are Films" (to be published in SPIE We seek to (1) understand the one of the most promising solid-state Fullerenes and Photonics III). nonlinear optical properties of the optical limiters in the near-IR spectral McBranch, D., et al, "Optical fullerenes and (2) form optimized range. Limiting in Fullerene Solutions and solid-state materials with properties Doped Glasses," SPIE Fullerenes and that allow rapid change of optical Photonics II2530, 196 (1995). transparency as a function of light Publications intensity (for protection of eyes and Klimov, V., et al, "Femtosecond to Smilowitz, L.S., et. al., "Enhanced sensors from harmful pulsed lasers). Nanosecond Dynamics in Fullerenes: Optical Limiting in Derivatized We have formed glass composites Implications for Excited-State Fullerenes," Opt. Lett. 21, 922 (1996). containing C60 and soluble derivatives Nonlinearities" (to be published in using our patented sol-gel techniques. Res. Chem. Intermed.). We have demonstrated that the fullerene concentration in these glasses can be controlled over a wide range and that the resulting materials can be polished to high-quality surfaces and have optical damage thresholds much higher than those of plastic host materials. We have observed enhanced optical limiting in solutions of a derivatized fullerene. Our transient absorption measurements determined the spectral and temporal regions of interest for optical limiting in C60 and derivatives and predicted enhanced limiting at longer wavelengths. Intensity- dependent transmission measurements confirmed these results. The increased solubility and broadened ground-state absorption of the functionalized C60 make it a more effective limiter in the red and near-IR spectral regions than Incident fluence (J/cm ) the pure C60 (see accompanying figure). Intensity-dependent transmission (T)for C60 at 532 nm (open squares, low- intensity transmission, T = 80%) and 700 nm (solid squares, T = 80%) and for We also used transient absorption to the monosubstituted fullerene 6,6phenyl-C61-butyric cholesteryl acid at 700 nm (1) determine the magnitudes of the (open circles, T = 80%; solid circles, T = 50%). The solid line indicates linear excited-state cross sections as a transmission of 80%. function of wavelength and (2) demonstrate that the morphology of the fullerene molecules in the solid state

Individual Projects—Chemistry 45 Uses of Novel Selenium-Containing Chiral trapped the enolate with two different aldehydes. Although di-n-butylboron Derivatizing Agents: Potential Catalysis for triflate is useful for generating the aldol product, the di-n-butylboron is the Chiral Oxidation of Simple Alkenes difficult to remove from our desired and Chiral-Promoted Aldol Reactions product. To get around this problem, we replaced di-n-butylboron triflate with a boron-based Lewis acid that Louis A. Silks degrades in the presence of water. More interesting is the use of The last frontier for chemical phenylglycinol- and norephedrine- titanium tetrachloride as the Lewis catalysis is the design of chiral and derived selone, by reacting an allylic acid. From the proton nuclear- environmentally benign chemical bromide with a chiral selone (see first magnetic-resonance spectra, we know processes. Our goals are to develop set of reactions). We then oxidized that the stereochemistry of the (1) a new oxidative catalytic process these CDAs with m-chloroperbenzoic titanium-promoted aldol products to generate chiral allylic alcohols and acid (MCPBA) to produce the allylic differs from that of the boron- (2) new chiral aldol reactions. We are alcohol (see second reaction). promoted products. This difference using derivatives of selone reagents as Because the optical purity of the shows that we can reverse the product chiral derivatizing agents (CDAs) for oxidation reaction was low, we are of the aldol reaction at the b-carbon both goals. The arrangement of evaluating other oxidants and lower atom by changing the acid compo- phenyl and methyl groups on these temperatures. nent. In an effort to rigorously CDAs allows us to produce chiral Chiral aldol reactions are another determine the stereochemical out- products with predictable chirality productive area for developing new come of the reactions, we are cur- from nonchiral starting materials. methods for chiral inductions. For rently attempting to grow crystals Simple allylic chiral alcohols are example, we can form two new chiral and obtain x-ray structures of our precursors of many pharmaceuticals centers by enolizing an acylated titanium- and boron-promoted aldol and agrochemicals. The successful selone with di-n-butylboron triflate (a products. synthesis of these alcohols would Lewis acid) to generate an £-enolate benefit chemical industry because the that has boron chelated to both the method would be catalytic, an easily oxygen anion and the selenium atom recoverable co-oxidant could be used, (see third set of reactions). We have and low levels of byproducts would Ph be produced and, therefore, waste would be minimized. We success- Se fully made the CDA adducts, NO

Se Ph LI JK. Alkyl Halides N O 80-90% yield Synthesis of the starting adducts of the selone CDAs from a chiral selone R1 R" and an allylic bromide. The upper product (adduct) is a phenylglycinol- derived selone, and the lower product is a norephedrine-derived selone. R',R" = alkyl and aryl groups

Se MCPBA HO -50% Ph

Ph The oxidation reaction that produces the allylic alcohol.

46 Los Alamos FY1996 LDRD Progress Report Publications Wu, R., L.A. Silks, et al., "Highly n-Biu •n-Bu Sensitive Spectroscopic Detection of 77 Se Chiral Molecular Stractures by Se 1 NMR Spectroscopy," Spectroscopy 11 R (6), 37 (1996). Wu, R., G. Hernandez, L.A. Silks, et al., "Simple Enantiomeric Excess Determination of Amines Using R= methyl, O-benzyl Chiral Selones: Unusual N-H-Se R'= alkyl, aryl Bonding Detected by HMQC 1H/77Se The aldol reaction that generates a product NMR Spectroscopy," /. Chem. Soc., containing two new chiral centers. Di-n-butylboron Chem. Commun., 1125 (1996). triflate is the Lewis acid used.

Metal-Ligand "Multiple" Bonding: Publications Revelations in the Electronic Structure of Arney, D.S.J., R.C. Schnabel, et al., "Preparation of Actinide Complexes of High-Valent f-Elements Phosphinidene Complexes," J. Am. Chem. Soc. 118, 6780 (1996). Carol Burns Barnhart, D., CJ. Burns, et al., "Synthesis of Neutral and Anionic Complexes of the f-elements During the final year of this project, Uranyl Aryloxide Complexes," Inorg. containing multiply bonded functional we have demonstrated important Chem. 34, 4079 (1995). groups (e.g., oxo, sulfido, imido, and differences between the chemistry of Burns, C.J., and D.S.J. Arney, phosphinidene groups) are important the actinide elements and that of "Synthesis and Properties of High- in actinide environmental science, d-transition metals in bonding to main Valent Organouranium Complexes," J. waste management, and actinide group elements. We have developed Am. Chem. Soc. Ill, 9448 (1995). materials chemistry research. For new multiple-electron-transfer example, actinide hydrolysis yielding synthetic pathways to prepare England, A., R. Schnabel, J. Huffman, oxo- and hydroxide-containing complexes with organoimido and oxo et al., "Structure-Reactivity Relation- species is important in dilute aqueous functional groups, which are unique ships in Elimination Reactions: solution under certain pH conditions, to actinide elements. Theoretical Solution and Solid State Structures and binary oxides and nitrides are studies suggest that f-orbitals may of Cp2Zr(Me)(o-MeOC6H4) and important solid-state phases as both play a significant role in stabilizing Cp*2Th(Me)(o-MeOC6H4)" nuclear fuels and, in the case of multiply bonded functional groups. (submitted to Organometallics). oxides, as potential waste forms. We have exploited these same Little is known, however, about the multiple-electron-transfer pathways in Radu, N.S., S.L. Buchwald, et al., energetics and chemical behavior of examining coupling reactions of "Carbon-Hydrogen Bond Activation these functional groups at actinide alkynes at actinide centers. Important of Aromatic Imines by (Cp*2SmH)2," metal centers (important to the differences exist between the reactiv- Organometallics 15, 3913 (1996). evaluation of the nature of interac- ity of actinide and d-transition metal Warner, B., C J. Burns, "Synthesis of tions between f-metals and main analogs, suggesting that organo- Uranium (VI) Imido Complexes by a group elements such as carbon, actinide complexes may have unique Uranium (II) Synthon and the Four nitrogen, and oxygen). The goal of value in organic synthesis. Electron Reduction of Azobenzene" our project is to extend the develop- (submitted to /. Am.Chem. Soc). ment of the field of metal-ligand multiple bonding in coordination chemistry to include f-element analogs.

Individual Projects—Chemistry 47 Chemistry and Catalysis in Supercritical Media

William Tumas liq-COj

Our aim in this research is to Time T(°C) Conversion Products explore the potential of supercritical fluids as reaction media for stoichio- CH3- H- 24h 25°C (85*) (15%) metric and catalytic chemical trans- nCH3CH2CIfc- H- 24h 2S'C formations in an effort to develop new, environmentally friendly methods for chemical synthesis or CHj- CHj- 14h 2S°C processing. This approach offers the possibility of opening up substantially CH3- 24h 2S°C different chemical pathways, increasing selectivity while enhancing reaction rates, facilitating downstream CH3- 24h 25°C >99% separations, and mitigating the need for hazardous solvents. We investigated a number of catalytic processes for which carbon dioxide represents a viable solvent o replacement. In several cases we have C OR cat T^OiPr)^ L* * _ H-jfOH observed significant enhancements in -• -HO-^H liq. COj, ffluOOH/( C OR selectivity and/or reactivity relative to 2000psi, 0°C 72 h conventional organic solvents. We 6 have investigated the following catalytic processes: (1) selective L»,R = Conversion Selectivity oxidation including dihydroxylation (CH ) CH- >99% 89% 87.4% and epoxidation, as shown in the first 3 2 two figures, (2) asymmetric hydrogenation (see third figure) and hydrogen-transfer reduction (see fourth Selected results from the epoxidation catalysis: (top) vanadium-catalyzed figure), (3) Lewis acid-catalyzed epoxidation ofprochiral allylic and homoallylic alcohols using VO(Oi-Prj3 acylation and alkylation, and (4) cou- and t-butylhydroperoxide; (bottom) enantioselective epoxidation of 2-hexenol pling of amines with carbon dioxide using titanium catalysts containing chiral tartrate ligands. to make isocyanates. OH

Publications Burk, M.J., S.G. Feng, M.F. Gross, et al., "Asymmetric Hydrogenation in Supercritical Carbon Dioxide," /. Am. Fluorinated iron Chem. Soc. 117, 8277-8278 (1995). 60 —#—FelTFPPICI 60 porphryin air- _.*... FefTFPPfirjCI CO 55 55 oxidation of Morgenstern, D.A., R.M. LeLacheur, cyclohexene: much D.K. Morita, et al., "Supercritical 50 50 higher selectivities to Carbon Dioxide as a Substitute epoxide (cyclohexene 45 45 Solvent for Chemical Synthesis and oxide) are observed Catalysis," in Green Chemistry, P.T. 40 acetonitrile 40 in supercritical car- Anastas, and T.C. Williamson, Eds. bon dioxide relative (American Chemical Society 35 35 to conventional Symposium Series 626, Washington, organic solvents. D.C., 1996), pp. 132-151. 30 30 10 15 20 25 30 35 40 dielectric constant

48 Los Alamos FY1996 LDRD Progress Report CO2Me 1 (02 mol %)

scCO2/H2(5000psig) N(H}Ac N(H)Ac 40 °C, 24 h 5 6

1 (0.2 mol %) CO2Me • CO2Me

seCO2/H2(S000psig) N(H)Ac 40°C,24h N(H)Ac 7 8

%ee Substrate Catalyst MeOH hexane Supercritical CO2 Table illustrates Rh-DuPhos 5 la 62.6 69.5 84.7 enantioselective hydrogenation of S lb 67.4 70.4 88.4 enamides: higher enantioselectivity in 7 la 81.1 76.2 96.8 supercritical carbon dioxide is 7 lb 95.0 91.2 92.5 observed for several substrates. Structures shown below the table Hydrogenation of p.P-disubstituted a-enamides with catalysts I" illustrate the generality of high enantioselectivity for asymmetric hydrogenation in supercritical carbon dioxide. N(H)Ac N(H)Ac N(H)Ac 97.2% ee 94.2% ee 95.6% ee Me CO Me Et 2 N(H)Ac 97.0% ee 73% ee

N(H)Ac N(H)Ac 95.2% ee 96.8% ee

1 or 2/NEt3 + CO2 HCO2H + N(H)Ac SCCO2 N(H)Ac 5 24 h 6

Substrate Temperature Hexane SCCO2

5a H 55 95.6 Sa H 35 96.5 Asymmetric hydrogen transfer 5b Ph 55 no reaction reduction of a-enamides using (r)-BINAP-ruthenium catalysts Sc 55 no reaction using formic acid/triethylamine. 5d Et 55 89.6

Individual Projects—Chemistry 49 Decay of Surface Nanostructures The initial adatom executes diffusive hops for about 1.1 us, at which time it Via Long-Time-Scale Dynamics exchanges with a substrate atom as shown in the third figure. This 2.9-ns simulation took four days on a scalar Arthur Voter workstation, but would require almost a year of computer time with direct MD. The main goal of this project is to Both adatom-hopping events and develop a method for simulating adatom substrate-exchange events infrequent molecular dynamics (MD) occur at rates that are verified against Publications events even when the subsequent exact calculations. The system is Voter, A.F., "A Method for states of the system following the shown in the first figure. The evolu- Accelerating the Molecular Dynamics events are not known in advance. We tion of the hypertime at T = 400 K is Simulation of Infrequent Events" have achieved a breakthrough this shown in the second figure, corre- (submitted to /. Chem. Phys). year and have in place a new working sponding to a boost factor of 1500. method. This method, which we term "hyper-MD," significantly extends the AG/AG(100) t=0 time period over which we can 14.0 simulate classical molecular dynam- Surface-normal (z) view of the ics. To achieve this end, we aug- 10.6 - Ag/Ag(100) system. Atoms interact mented the true potential energy through an embedded-atom-method function with a bias potential that (EAM) potential. The system is raises the energy in regions other than periodic in the x and y directions. at the saddle points. The top three layers are allowed to For strongly coupled, solid-state move during the dynamics, while systems, we can construct such a bias two more-rigid layers below potential from the local gradient and maintain the fcc(100) structure. Hessian for the potential. An MD The adatom is shaded for clarity. simulation performed on this modi- 12.0 fied potential allows transitions from basin to basin to occur at an acceler- Ag/Ag(100) T=400K 3.5 ated pace, while the total time evolved . > j i i i i I i i i becomes a statistical property of the Evolution of the calculated 3.0 L system. This hyper-MD method boosted time (or "hypertime ") during the hyper-MD simulation. should be most useful when the time 2.5 ~T scale of interest cannot be accessed The system reaches 2.9 /us after with direct (or conventional) MD 2 ns ofMD time, for a boost of 2.0 '- J about 1500. Because each hyper- simulation, which is typically limited t.5 -_ MD step requires about 20 times r ~T / to a few nanoseconds, and when a. future events cannot be inferred from more work than a simple MD 1.0 - simple models. step, the net computational gain / is a factor of 1500/20 = 75. 0.5 -_ We are presently testing the method r/ by applying it to the diffusion of a 0 . . 1 .... 1 ... i , , , , i , , , ,'z 0.5 1.0 1.5 2.0 2.5 silver atom on the Ag(100) surface. Ag/Ag(100) T=400K MD time (ns) 10

Time evolution of the x and z positions of atom 1, which is initially the adatom. After hopping for about 1.1 us, atom 1 exchanges with a top- layer substrate atom, which becomes the new adatom. For the remaining 1.9 us, atom 1 simply vibrates about its equilibrium position in the 1.0 1.5 2.0 0 3.5 substrate. hypertime

50 Los Alamos FY 1996 LDRD Progress Report Solvation and Ionic Transport multigrid techniques in the dielectric solvation model to enable the study of in Polymer Electrolyte Membranes the solvation of larger molecules. We developed the needed techniques for the determination of the Thomas Zawodzinski high-frequency (1-1000 GHz) dielectric response of ion-exchange In this project we have studied the (1) good electronic structure calcula- polymers. Measurements on mem- fundamentals of ion and solvent tions of appropriate models of the branes of variable hydration state transport in polymer electrolyte Nation side-chain as one input for the revealed features in the gigahertz membranes. Such membranes are a theory, and (2) refinement of the range that are attributable to water vital tool in separation and filtration dielectric continuum approach for the relaxation. This is the first such result processes that can be used in the description of confined water layers. on a highly conducting system at such nuclear complex, particularly in We carried out electronic structure high frequencies. The electrophoretic environmental aspects of those calculations in trifluoromethane nuclear-magnetic-resonance method missions. In addition, these materials sulfonic acid (triflic acid), the anion will allow us to isolate the transport of are of key importance in emerging (triflate), and several examples of individual ions in mixed ionic or battery and fuel-cell technologies. clusters of a water molecule. mixed solvent systems, and thus Our ability to radically change We also developed Monte Carlo obtain their mobilities and transfer- performance is greatly increased by methods to simulate water-oil- ence numbers. We have recently built gaining an understanding of these polymer mixtures. We expect that a new apparatus that allows us to fundamentals. these techniques will allow us to study membranes. We also designed We have begun calculations on construct physically reasonable and constructed an electrochemical model systems to develop two aspects models of hydrated Nation mem- system with well-defined electrode needed for the final theory approach: branes. Finally, we implemented processes for mobility measurements.

Heterogenization of Homogeneous linking the homogeneous catalysts to them. In addition, we started the Catalysts: The Effect of the Support process of synthesizing high-surface- area silica with controlled pores. We will use these synthesized silica William Earl instead of commercial silica. Eventu- ally, the solid materials will be The goal of our project is to In the past year, we made progress characterized using a number of covalently bind known solution in establishing the infrastructure and different spectroscopic probes. During (homogeneous) catalysts to the in synthesizing the starting materials the past year, we began some of these surfaces of high-surface-area, solid required for the project. The first step techniques, but the samples are, as materials and to investigate the effects was to synthesize the substrate to be yet, only partially characterized. due to binding. We vary the structure used in the catalysis reactions. Al- We ran several homogeneous of the solid surface and the chemical though this was a relatively straight- reactions before Unking the catalyst to link between the catalyst and surface forward synthesis, the compounds the surface, and we established the and measure the catalytic activity. were not commercially available and methods to measure catalytic activity. This allows us to determine if there is it was a multistep synthesis. The These methods are applicable to a correlation between the final homogeneous catalyst used was fairly homogeneous solutions and will be structure and catalytic activity. This easy to synthesize. The difficult step modified as we proceed to supported project includes two phases of in this work was modifying the catalysts. At present, we are unable to investigating heterogeneous catalysis. homogeneous catalyst to allow quantitatively reproduce the literature The first is to duplicate unusual data linking it to the surfaces. The prepara- results. that already exists, as reported in the tion process reported in the literature literature, and the second is to use did not work as presented. We also similar compounds and syntheses to acquired several zeolites and made understand these results. minor modifications to them to allow

Individual Projects—Chemistry 51 Photoredox Reactions: Energy Storage Chisholm, M., G. Christou, K. Folting, et al., "Solution Studies of n+ and Halocarbon Degradation Ru2(O2CR)4 Complexes (n = 0, 1; O2CR = Octanoate, Crotonate, Dimefhylacrylate, Benzoate, p- William Woodruff Toluate) and Solid-State Structures of Ru (O C-/?-tolyl) (THF) ,[Ru (O C- Our project had five objectives: Our results include studies of 2 2 4 2 2 2 p-tolyl) (THF) ]+[BF ], and Ru (O C- (1) to characterize the structures and tungsten and molybdenum clusters 4 2 4 2 2 /?-tolyl) (CH CN) : Investigations of the structural dynamics of the singlet with potential multielectron excited- 4 3 2 the Axial Ligation of the Ru Core," and triplet states of selected metal- state redox reactivity, metal-metal 2 Inorg. Chem. 35 (12), 3643-58 metal bonded systems; (2) to charac- bonded dimers sequestered in liquid- (1996). terize the postexcitation, intra- crystal environments, d7 dimers with molecular electron-transfer reactions long-lived photocycles, and photo- James, C, D. Morris, S. Doom, et al., of these complexes; (3) to investigate chemically produced oxygen-fluorine "Photochemistry of Deca(acetonitrile) strongly adiabatic photo-oxidative systems. These results have been Dirhodium(II) Cation: Evidence for addition reactions, including the reported in three research articles. Kilosecond-lived Photoinduced addition of halocarbons to the Charge Separation," Inorg. Chim. electronically excited complexes and Ada 242 (1-2), 91-96 (1996). their hydrogen-evolving reactions; Publications Schoonover, J., T. Zietlow, D. Clark, (4) to seek effective reductant systems Abney, K., P. Eller, M. Eastman, et et al., "Resonance Raman Spectra of that will function in catalytic cycles al., "Thermal Decomposition [M X Y ]2- Cluster Complexes (M = and regenerate the original, reduced Reactions of Gaseous Dioxygen 6 8 6 Mo, W; X, Y = Cl, Br, I)," Inorg. dimer; and (5) to explore the chemis- Difluoride and Dioxygen Fluoride at Chem. 35 (22), 6606-13 (1996). try of metals less expensive than Ambient Temperature," J. Fluorine iridium or platinum with regard to Chem. 73 (2), 137-46 (1995). their potential for photochemical reactivity.

Reactivity at Metal Centers 2,3-bis(diphenylphosphino)maleicanhydride (L); (3) development of methodology Bound to Water-Soluble Catalysts for attaching the chelating ligand L to organic nucleophiles; (4) synthesis and characterization of the molecular Nancy Sauer system with ring-opened chelating diphosphines 2,3-bis(diphenyl- We are examining water-soluble Our work this year has focused on phosphino)maleic acid monoethyl polymers as supports for homoge- the attachment of phosphine ligands ester (L2) and 2,3-bis(diphenyl- neous catalysts. Our approach is to to the polymers. To demonstrate the phosphino)maleic acid mono- covalently attach the catalyst precur- reactivity of soluble supported metal ethylenediamine amide (L3); and sors to these soluble polymers. The centers, we have devised methods to (5) screening of hydrogenation resulting macromolecular materials prepare phosphine-functionalized activity and selectivity for rhodium will mitigate loss of precious metals polymers for incorporation of complexes with the three phosphine by modifying the solubility of the catalytically active metals into our ligands L, L2, and L3. homogeneous catalyst. This approach soluble polymer systems. The work will permit more benign solvent to be began with rhodium-phosphine used and potentially will engender hydrogenation catalysts that are active unusual substrate selectivity in the in aqueous solution. Accomplish- catalytic systems. The initial focus of ments for this year include (1) prepa- the project has been incorporation of ration and screening of the baseline + phosphine ligand onto water-soluble catalyst: [Rh(NBD)(PPh3)2] (NBD is polymers as ligands for catalytically Norbornadiene); (2) synthesis and active metals such as rhodium. We are characterization of the molecular exploring the rate and selectivity of system with the chelating diphosphine these systems.

52 Los Alamos FYI996 LDRD Progress Report Cyclodextrin-Based Chemical derivatives with charged functional groups and measured the sensors' Microsensors for Volatile Organic responses to vapors containing known concentrations of VOCs. The results Compounds (VOCs) of these measurements indicate that it is feasible to construct sensor arrays to identify a wide variety of VOCs. DeQuan Li

The goal of this project is to To reach the targeted goals, we Publications construct thin films of well-con- used modified cyclodextrins ("host trolled, assembled nanotubes as novel compounds," so called because they Li, D., J. Shi, et al., "Microsensors sensing materials for chemical are able to bind and surround smaller Based on Self-Assembled Cyclodextrin Host Thin Films for microsensor applications. These "guest" molecules) as the basic Volatile Organic Compounds" nanotubes provide a well-defined, building units. We functionalized (Spectrum '96, Seattle, Wash., July hydrophilic porosity suitable for these building blocks with various 1996). detecting small VOCs (such as organic groups, including linear alkyl benzene, toluene, chloroform, and chains and aromatic rings. These Swanson, B., and D. Li, trichloroethylene) that may contami- functional groups allow the "Cyclodextrin-Based Microsensors nate water supplies. We can use our cyclodextrins to self-assemble into for Volatile Organic Compounds" sensing materials for chemical tubular structures. We are currently in (1996 American Chemical Society separations and environmental the process of purifying the building National Meeting, Orlando, Fla., cleanup, applications that are essential blocks that will self-assemble into August 1996). both for improving our health and nanotubes. safety and for saving money and In another approach to constructing Swanson, B., and D. Li, "Smart Film resources. Our microsensor technol- our thin films of nanotubes, we used Sensor for Halogenated Hydrocarbons and Volatile Organic Compounds" ogy received an R&D 100 Award in charge interactions (the attraction of (Incineration and Thermal Treatment 1995. The accompanying figure positive to negative charges) to Technologies, Savannah, Ga., May shows a schematic drawing of the assemble surface-receptors. We 1996). sensor configuration. fabricated thin films from cyclodextrin

Sensing Layer Oxide Layer | Electrodes Reflectors

Host-Guest Interactions Side View Functionalized Inside Cavity Cyclodextrin/ Calix[n]arene Sensing Layer

Top View

Surface Acoustic Wave Thin-Film Chemical Microsensors

Schematic illustration of a chemical microsensor based on surface-bound receptor molecules. This illustration shows an example of a cyclodextrin sensing layer on a surface acoustic device.

Individual Projects—Chemistry 53 Binding of Hydrocarbons and Other Extremely Weak Ligands to Transition-Metal Complexes that Coordinate Hydrogen: Investigation of Cis-Interactions and Delocalized Bonding Involving Sigma Bonds

Gregory Kubas

+ At the forefront of chemistry are In the molybdenum and manganese [Mn(H2)(CO)(PP)2] and efforts to catalytically transform gas- complexes, however, the metal RuH2(H2)2[P(cyclohexyl)3]2 by INS, or oil-derived hydrocarbons into interacts with intramolecular (inter- which allowed us to probe atom useful products such as gasoline with nal) carbon-hydrogen bonds (see exchange and interactions between metal compounds that chemically second figure). These carbon- hydride and H2. bind and break the inert carbon- hydrogen bonds are reversibly hydrogen sigma bonds. Our first goal displaced by H , N , and silanes, 2 2 Publications is to bind hydrocarbons, silanes, and which bind weakly to the positively germanes to metal complexes via their charged manganese center. We have H-Y bonds (where Y is carbon, supported the manganese cation on Butts, M.D., G.J. Kubas, and J.C. silicon, or germanium), analogous to alumina, and our calculations show Bryan, "Temperature-Dependent our discovery of hydrogen (H2) that this material can be used to bind Behavior of Agostic Complexes binding to metals. Studies of these and separate hydrogen isotopes (H2, W(CO)3(PR3)2. Structures of Products unique "sigma complexes" (M—H-Y, D2, and T2) at room temperature of N2, Ethylene, and Silanes" (to be where M is a transition metal) will aid rather than at the extremely low published in Inorg. Chem.). in developing new catalyst, sensor, temperatures now used. This tech- Butts, M.D., B.L. Scott, and G.J. and separation technologies. A second nology could be useful in tritium Kubas, "Synthesis and Structure of goal is to probe atom exchange processing. Alkyl and Aryl Halide Complexes of between sigma-bonded molecules and In the course of our study, we were the Type [(PiPr )PtH(ri1-XR)]BAr and other atoms bonded to the metal with able to prepare the first germane 3 f techniques such as inelastic neutron Analogues with Et,O, THF, and H2 complex, Mo(CO)(PP) (GeH ), which scattering (INS). Such atom transfers, 2 4 Ligands," J. Am. Chem. Soc. 118, relates to our discovery of the SiH typically involving hydrogen, are the 4 11831 (1996). binding that models methane binding. heart of catalysis, the lifeblood of the We also studied H rotation on chemical industry and many biologi- 2 cal processes. We studied several transition-metal systems, including the molybdenum C!2I CI3I CMObl complex Mo(CO)(PP)2, the manga- + nese complex [Mn(CO)(PP)2] , and + the platinum complex [PtH(PR3)2] . Cll2bl In these complexes, PP is Ph2PC2H4PPh2 (where Ph is phenyl), and R is isopropyl. The platinum complex weakly binds the hydrogen- hydrogen bonds of H2 and the carbon- chlorine or carbon-iodine bonds of halocarbons such as methylene Ct11bl chloride and iodobenzene (see first C(9b) figure). The binding between the platinum and the carbon-hydrogen CtHol bonds is too weak to be observed. CIBal

+ Molecular x-ray crystal structure of [PtH(P-i-Pr3)2(PhI)] showing iodobenzene (Phi) binding to platinum. P-i-Pr3 is tri-isopropylphosphine. This platinum complex is stable to air, a rare feature for such weak molecular binding but a feature that is highly desirable for sensor and separation technologies.

54 Los Alamos FYI996 LDRD Progress Report Eckert, J., A. Albinati, et al., "Nature of the Rh-H2 Bond in a Dihydrogen Complex Stabilized Only by Nitrogen Bonds. Inelastic Neutron Scattering 2 Study of TpRhH2(r| -H2) (Tp = Hydrotris(3,5-dimethylpyrazolyl)borate)," Inorg. Chem. 35,1292 (1996). Kubas, G.J., "Metal-Silane Complexes" in McGraw-Hill Yearbook of Science and Technology, S.P. Parker, Ed. (McGraw-Hill Professional Book Group, New York, 1996), pp. 350-351. Limbach, H.-H., S. Ulrich, S. Sabo- Etienne, et al., "NMR and INS Lineshapes of Transition Metal Hydrides in the Presence of Coherent and Incoherent Dihydrogen Exchange" (submitted to J. Am. Chem. Soc). Rodriguez, V., S. Sabo-Etienne, B. Chaudret, et al., "Spectroscopic

Studies and Reactivity of the Bis- + Dihydrogen Complex Molecular x-ray crystal structure of [Mn(CO)(Ph2PC2H4PPh2)2] showing the interaction (dotted lines) of the manganese(I) center with two carbon-hydrogen RuH2(H2)2(PCy3)2 in Freons and bonds located on separate phenyl (Ph) rings of the diphenylphosphine (PPh2) CHC13. Synthesis of a Ruthenium IV groups. Multiple carbon-hydrogen interactions are rare. The analogous zero- Dihydride: RuH2Cl2(PCy3)2" (submitted to Inorg. Chim. Actd). valent molybdenum complex has only one such interaction.

Asymmetric Catalysis in Organic in the same reaction gave better yields than the simple Schiff-base ligand, but Synthesis the optical purities of the product were rather low, reaching a maximum of 38% in the case of erbium. John Watkin We have also examined the use of chiral diolate ligands chelated to a This research project is aimed at asymmetric Meerwein-Ponndorf- lanthanide-metal center for the MPV developing new catalysts for the Verley (MPV) reduction of acetophe- reduction. In this case, the yields were enantioselective formation of organic none to a secondary alcohol. In one very good (>85%), but the optical molecules that may be used in a wide case, we have employed a Schiff-base purity was low (<20%), which we range of industrial applications. Our ligand, prepared from norephedrine believe was due to the lack of rigidity primary goal is to develop lanthanide- and 2-hydroxynaphthaldehyde, in the diolate ligands. The results based catalyst systems that feature chelated to a gadolinium-metal center obtained to date have provided chiral alkoxide or Schiff-base to perform the MPV reduction with an extensive information that will help us supporting ligands. optical purity of 52%. Other lan- design more effective chiral ligands in During the past year, we have thanide metals such as samarium, the future. systematically examined the use of a neodymium, and erbium were found wide range of lanthanide complexes to give somewhat lower optical purity containing chiral diolate and Schiff- in analogous reactions. The commer- base ligands as catalysts for the cially available Jacobsen ligand used

Individual Projects—Chemistry 55 Temperatures and Vibrational Frequencies The vibrational temperatures obtained for the nitrogen/oxygen mixtures were of Liquid N2/O2 and CO/O2 Mixtures used to improve the oxygen potential function that is used to calculate Shock-Compressed to 10 GPa and 2000 K equation-of-state pressures and temperatures. The measured linewidths for CO, N , and O were Stephen C. Schmidt 2 2 different for the different mixtures, but did not appear to depend signifi- The purpose of this project was to carbon monoxide/oxygen and cantly on mixture ratios. The broaden- experimentally determine the tem- nitrogen/oxygen mixtures. The ing of all spectral lines suggested that peratures and vibrational frequencies experimental spectra were compared the vibrational dephasing time for of N2/O2 and CO/O2 mixtures that with synthetic spectra calculated with each species decreased to a few have been shock-compressed to a semiclassical model for CARS picoseconds at the highest-pressure pressures of -10 GPa and tempera- intensities and using best-fit vibra- shock states. tures of -2000 K. The results obtained tional frequencies, peak Raman The accompanying figure shows are used to improve the equation of susceptibilities, and Raman linewidths representative CARS spectra of a state that describes mixtures at for each mixture component. Up to a liquid 67% CO/33% O mixture conditions characteristic of the maximum shock pressure of 7 GPa 2 shock-compressed to 6.8 GPa at a expansion of explosive products. The for the carbon monoxide/oxygen temperature of 1286 K. measured molecular vibrational mixtures and 13 GPa for the nitrogen/ frequency shifts can be used to help oxygen mixtures, the CO, N2, and O2 develop molecular-potential functions vibrational frequencies were all found Publications that will allow calculations of to increase monotonically with Schmidt, S.C., D.S. Moore, and M.S. thermodynamic equations of state. pressure and depended on the carbon Shaw, "Coherent Anti-Stokes Raman We used a two-stage light-gas gun monoxide/oxygen and nitrogen/ Spectroscopy of Shock-Compressed and single-pulse, multiplex, coherent oxygen mixture ratios. The transition Liquid Carbon Monoxide/Oxygen and anti-Stokes Raman scattering (CARS) intensity and linewidth data suggest Nitrogen/Oxygen Mixtures" (to be to obtain vibrational spectra of carbon that thermal equilibrium of the published in /. Chem. Phys.). monoxide, nitrogen, and oxygen for vibrational levels is attained in less several high-temperature, dense-fluid than 10 ns at these shock pressures.

1.0

Representative coherent anti- Stokes Raman spectra of a liquid c 3 67% CO/33% O2 mixture shock- compressed to 6.8 GPa at a temperature of 1286 K. The tall sharp features are the spectra of S unshocked carbon monoxide and oxygen, and the lesser peaks are the vibrational progressions from the shocked fluids. The solid curves are the experimental data, and the dotted curves are computed spectra. -2200 -2100 -1600 -1500 Raman Shift (cm"1)

56 Los Alamos FYI996 LDRD Progress Report Catalysts for Hydrocarbon Oxidation catalytic reactor to be installed this fall into the High Intensity Powder Diffractometer, an instrument for Kevin Ott determining the structure of materials, at the Los Alamos Neutron Science We are investigating the structure titanium, we have used neutron Center. This catalytic reactor will and reactivity of site-isolated catalysts diffraction to determine that there is a allow us to obtain diffraction and PDF that selectively oxidize hydrocarbon surprising nonrandom distribution of data on catalyst structures during substrates. As the starting point for titanium in the lattice. reaction. our studies, we are examining a We are applying a novel technique prototypical site-isolated oxidation called Pair Distribution Function Publications catalyst, TS-l.TS-1 selectively (PDF) to zeolites. PDF is an analysis oxidizes hydrocarbon substrates to of diffuse neutron scattering to obtain Szanyi, J., and M. Paffett, "The useful products using hydrogen information about local structure of Adsorption of NO and Reaction of peroxide as the oxidant. TS-1 is a materials rather than the long-range NO with O2 on H-, NaH-, CuH-, and microporous silicate with a small order afforded by more conventional Cu-ZSM-5: An In Situ FTIR percentage of the silicon atoms diffraction experiments. We are Investigation," J. Catal. 194,232-245 replaced by titanium. primarily interested in the local (1996). The titanium ions promote the structure of the titanium ions in TS-1. Szanyi, J., and M. Paffett, oxidation chemistry via hydroperox- Preliminary results indicate the PDF "Coadsorption of Nitriles and CO on ide intermediates. We are incorporat- data include shifts to larger distances Cu-ZSM-5: An In Situ FTIR ing additional metal ions capable of relative to the published data on Spectroscopic Study" (to be published activating and utilizing molecular silicalite, a material analogous to in Mater. Res. Soc, Symp. P Proc). oxygen into the structure of TS-1 and TS-1 but that does not contain similar compounds. It is necessary to titanium. We believe these shifts are Szanyi, J., and M. Paffett, "AFTIR know the placement of secondary likely due to Ti-0 bond lengths that Investigation of the Coadsorption of metal ions such as cobalt, iron, are longer than Si-O bond lengths. Acetonitrile and CO on Cu-ZSM-5" manganese, and chromium with Knowledge of the structure of the (to be published in Faraday respect to the titanium ions. Because active site is fundamental to under- Transactions of The Chem. Soc). x-ray diffraction techniques are not standing the function of any catalyst. useful in determining the location of We have designed and constructed a

Fundamental Studies of Polymer Filtration further troubleshooting with our industrial partner to help get a large- scale pilot unit of the polymer Barbara F. Smith filtration technology installed in a large electroplating facility. The The objectives of this project are to incrementally functionalized the problem addressed involved determin- develop an enhanced fundamental backbone polymers with a metal- ing the effect of chromium(VI) on understanding of the coordination binding ligand. Then we developed a nickel(II) binding to the polymers. chemistry of hazardous-metal-ion procedure and analytical method to complexation with water-soluble determine the absolute level of Publications metal-binding polymers and to exploit functionalization and correlated the this knowledge to develop improved results with the elemental analysis, Smith, B.F., T.W. Robison, et al., separations for analytical methods, viscosity, and molecular size. We will "Polymer Filtration: A New metals processing, and waste treatment. use these results as a quality assur- Technology for Selective Metals We investigated features of water- ance measure for these polymers once Recovery" (SUR-FIN95 Conference soluble metal-binding polymers that we transfer them to our industrial of the American Electroplaters and affect their binding of and selectivity partner for commercialization. Surface Finishers Society, Baltimore, for selected transition metal ions. We Next, we performed a large-scale Md., June 26-29, 1995). evaluated backbone polymers using synthesis of the optimized polymers light-scattering and ultrafiltration to confirm that there were no prob- techniques to determine the effect of lems with scale-up of the synthesis. pH and ionic strength on the molecu- Both large- and small-scale synthesis lar volume of the polymers. First, we produced the same materials. We did

Individual Projects—Chemistry 57 Modification of Heterogeneous Chennistry that the reported reactivities of HC1 with C1ONO2 on NAT may be by Realistic Substrate Complexity underestimated by as much as a factor of 10.

Bryan Henson Publications Henson, B.F., K.R. Wilson, and J.M. This project explores a set of surfaces and with H2O on nitric acid Robinson, "Chlorine Nitrate chemical reactions on porous surfaces trihydrate (NAT) surfaces. For a given Reactivity on Simulated Polar that play an important role in the system, we model the laboratory data Stratospheric Cloud Surfaces" (211th observed depletion of stratospheric using only two parameters: the American Chemical Society Meeting, ozone over Antarctica every polar measured reaction probability on a New Orleans, La., March 1996). spring. We specifically study a series neat ice surface and a constant from of coupled heterogeneous reactions of Brunnauer-Emmett-Teller (BET) Henson, B.F., K.R. Wilson, and J.M. Robinson, "Modeling the Relative chlorine nitrate (C10N02) that are of theory. This theory describes the considerable current interest in polar fraction of an acid-hydrate surface Humidity Dependence of C1ONO2 ozone depletion: covered by water as a function of Reactivity on Ices" (1996 Inter- relative humidity. The agreement national Symposium on the Physics and Chemistry of Ice, Hanover, N.H., C10N02 + H2O -> HOC1 + HNO3 between calculations of reaction August 1996). HOC1 + HC1 -» Cl2 + H2O probability based on this model and C1ONO2 + HC1 -» Cl2 + HNO3 laboratory measurements is shown in Henson, B.F., K.R. Wilson, and J.M. the accompanying figure. Robinson, "Modeling the Relative These reactions proceed on polar We have used a surface-specific Humidity Dependence of stratospheric clouds which form laser technique to quantify the Heterogeneous Reactions on Polar during the winter, releasing Cl2 gas coverage of water on a porous NAT Stratospheric Clouds" (1995 Fall that subsequently attacks ozone when surface. Thus, for the hydrolysis of Meeting of the American Geophysical sunlight returns during the spring. C1ONO2 on NAT, all parameters in Union, San Francisco, Calif., We have developed a model of the model are fixed by laboratory December 1995). heterogeneous reactivity based on measurements. The model indicates physical adsorption. This model that C1ONO2 reactivity with both H2O Henson, B.F., K.R. Wilson, and J.M. describes how the observed relative and HC1 on SAT and with H2O on Robinson, "A Physical Adsorption humidity affects the reactivity of NAT is controlled by the surface Model of the Dependence of C1ONO2 Heterogeneous Reactivity," Geophys. C1ONO2 with H2O and HC1 on coverage of H2O. Our model suggests sulfuric acid tetrahydrate (SAT) ice Res. Lett. 23,1021 (1996). Henson, B.F., K.R. Wilson, and J.M. Robinson, "Thermodynamics of Heterogeneous Surfaces from Nonlinear Light Scattering" (New l.OOE-01 Mexico Chapter of the American Vacuum Society Annual Meeting, Albuquerque, N.Mex., April 1996).

The hydrolysis ofClONO2 on NAT and SAT surfaces. The data are plotted by reaction probability as a function of fractional relative humidity. The curve through the NAT data is calculated from our physical adsorption model with no variable parameters. The curve through the SAT data is a best fit using the same model, which predicts that the coverage of water on SAT is parameterized by the BET constant, c = 0.2. The data 1.00E-06 0 0.5 1 are from several different laboratories, as referenced in Henson et al, Geophys. Res. Lett. 23, 1021 (1996). Relative Humidity P/Po

58 Los Alamos FYI996 LDRD Progress Report lonically Conducting Polymers for This spectroscopic technique helped us correlate the ion-pairing threshold High-Energy-Density Batteries of lithium salts with the electrical conductivity results. We also investigated lithium nuclear magnetic Robert Hermes resonance as a tool to estimate ionic diffusion coefficients. Using polymer synthesis and polyelectrolytes, we reproduced the In the three years of this project, we electrochemical characterization outstanding electrical conductivity have developed techniques that can be techniques, we set out to understand results achieved in 1995 and were used to predict the interaction of the ionic transport chemistry of the able to double the room-temperature lithium and lithium-imide salt with polyelectrolyte component of solid- conductivity from 1.1 xlO"4 S/cm to 4 the polyelectrolytes we synthesized in state lithium batteries. Lithium-ion 2.2 x 10" S/cm with two newly our laboratory. We also achieved the transport is the mechanism by which synthesized polyelectrolytes. highest room-temperature conductiv- charge is carried through the poly- This result has validated the essence ity for an "unplasticized" solid electrolyte. of our original hypothesis: mixed polyelectrolyte. This year we synthesized several ether side-chains for increased oligooxyethylene-modified poly- mobility and decreased lithium salt phosphazenes and tested them for together induce crystallinity. We electrical conductivity and lithium-ion obtained Raman spectra from various transport characteristics, each at salt/polyelectrolyte compositions. several lithium-imide-salt loadings and temperatures, under drybox conditions. With fresh batches of

Advanced Polymer Chemistry Publications of Organometallic Anions Balaich, G.J., S.A. Fino, et al., "Synthesis of an Organometallic Polyamide of Cobalt Dicarbollide" Rebecca M. Chamberlin (submitted to Inorg. Chem.). Chamberlin, R.M., B.L. Scott, et al., The objective of the project was to reactions, most notably a dicarboxylic "Butyllithiurn Deprotonation Versus prepare and characterize new poly- acid, [Co(C2B9H10)2(COOH)2]-. The mers incorporating the cobalt dicarboxylic acid forms organometal- Alkali Metal Reduction of Cobalt Dicarbollide: A New Route to C- dicarbollide anion, [Co(C2B9Hn)2]~. lic polymers via condensation with Cobalt dicarbollide is well known as amines such as hexamethylene Substituted Derivatives" (to be an extraction agent for removing diamine, by two different routes. The published in Inorg. Chem.). radioactive cesium and strontium first route is conversion of the from nuclear waste. Polymers dicarboxylic acid to a di(acid chlo- containing cobalt dicarbollide in the ride), which reacts with the diamine main chain are expected to have novel in solution to form an insoluble, red applications in ion exchange, cataly- polyamide. The second route is direct sis, and medical radiotherapy. reaction of the dicarboxylic acid with During this year we characterized the diamine, forming an amine salt. the scope and stereochemical outcome The amine salt is thermolyzed in a of the twofold deprotonation and thermogravimetric analysis/differen- nucleophilic substitution reactions of tial thermal analysis (TGA-DTA) experiment to form the polymer while [Co(C2B9Hn)2]" and generated a publication on this topic. We also releasing water. synthesized several reactive mono- mers using nucleophilic substitution

Individual Projects—Chemistry 59 Reaction Kinetics Relevant to the Recycle and acts as an initiator for hydride- catalyzed reaction of the metal with Hydride-Dehydride Process for Plutonium air. This process consumes both oxygen and nitrogen and continues Recovery until reactants are depleted. The catalyzed corrosion rate of plutonium 8 John Haschke is 10 times faster than the corrosion rate of the metal in dry air. The Objectives of this project were to Therefore, formation of an oxide hydride-catalyzed reaction transforms expand fundamental knowledge of hydride layer by reaction with water plutonium into a fine oxide nitride plutonium chemistry and to develop may catalytically enhance the powder with a high potential for information for enhancing plutonium oxidation of plutonium while avoid- aerosolization and environmental recovery methods and weapons safety. ing safety problems associated with dispersal. Catalyzed reaction with Plutonium oxide monohydride, using hydrogen in the recycle process. oxygen produces plutonium dioxide, PuO(H), is a novel, but incompletely We used pressure-volume-tempera- the chemical form needed to prepare characterized, compound that forms ture experiments to produce a surface mixed-oxide fuel for nuclear-power when plutonium metal is exposed to layer of PuO(H) by aqueous corrosion generation, and is potentially appli- water. Like other compounds of of plutonium metal. We then tested cable as a method for direct recovery plutonium(III), it is expected to be the behavior of moist and dried of plutonium as PuO2. Wet PuO(H) is highly reactive with oxygen and can samples by rapid exposure to oxygen nonpyrophoric, and the safety hazard promote reactions between metal and and air. Results of these kinetic posed by formation of oxide hydride air in a manner similar to that studies demonstrate that the monoxide is reduced if the material remains observed for plutonium hydride. monohydride is pyrophoric when dry moist.

Ultrafast Laser Studies of Solution Reactivity

William Woodruff

Fast chemical dynamics generally folding. We have found that a general must be initiated photochemically. lifetime of alpha-helix formation is This fact limits the applicability of about 100 ns and that tertiary folds (in modern laser methods for following apomyoglobin) form in about 100 us. the structural changes that occur This work has been reported in two during chemical and biological publications. reactions to those systems that have an electronic chromophore that produces a significant yield of Publications photoproduct when excited. Our Gilmanshin, R., S. Williams, R. project has developed a new and Callender, et al., "Fast Events in entirely general approach to ultrafast Protein Folding: Relaxation Dynamics initiation of reactions in solution: of Secondary and Tertiary Structure in laser-induced temperature jump. This Native Apomyoglobin" (to be approach opens entirely new fields of published in Proc. Nat. Acad. Sci.). study of ultrafast molecular dynamics in solution. Williams, S., T. Causgrove, R. Gilmanshin, et al., "Fast Events in We have demonstrated the tempera- Protein Folding: Helix Melting and ture-jump technique on timescales of Formation in a Small Peptide," 50 ps and longer and have applied it Biochem. 35 (3), 691-97 (1996). to the study of fast events in protein

60 Los Alamos FYI996 LDRD Progress Report Mathematics and Computational Sciences

Parallel Three-Dimensional algorithms and an associated parallel code based upon a Pn, or spherical- Spherical-Harmonics Transport Methods harmonics, discretization in angle. Such a capability is unique to Los Alamos as well as to the entire DOE Jim Morel complex. This year we completed a parallel Solution of the Boltzmann transport difficulties arise in applying the Sn Pn code for the Connection Machine 5 equation is essential in modeling a discretization on finite-element computer. This code is based upon a wide variety of physical phenomena. meshes because many cells in typical new self-adjoint form of the transport The standard angular discretization meshes are re-entrant. The Pn, or operator that offers significant technique used in production transport spherical-harmonics, method is the advantages over previous forms. We codes is the Sn, or discrete-ordinates, only deterministic method that also generalized our parallel algo- method. However, this method does preserves the rotational invariance of rithm, which used unstructured not preserve the rotational invariance the analytic transport operator. The tetrahedral meshes, to use unstruc- of the transport operator, and hence Pn method does not suffer from ray tured meshes of arbitrary combina- gives rise to nonphysical "ray effects." effects and can be applied on finite- tions of hexahedra and degenerate Such ray effects make the Sn dis- element meshes. hexahedra, e.g., wedges, pyramids, cretization unsuitable in problems The primary goal of our project is and tetrahedra. with localized sources and optically to develop three-dimensional, thin regions. In addition, fundamental unstructured-mesh radiation transport

Adaptive, Composite, Overlapping codes. Parallel infrastructures are hidden from the user of this library. Mesh Algorithms on Message- The Overture framework contains C++ class libraries that handle Passing Architectures overlapping meshes, arrays of data on those meshes, and difference opera- David L. Brown tors. We developed PDE codes for compressible and incompressible flow We have developed computational in which relatively high-level compu- problems as well as an "all-speed" methods and a programming frame- tational objects may be assembled solver that handles flows with a range work for adaptive, composite, into solvers for partial differential of Mach numbers from near zero to overlapping meshes to be used on equations (PDEs). With this frame- Mach 1 using these class libraries. serial and parallel computers. The work users can create solvers that are portable across a wide variety of need for high-level tools to aid in the Publications modeling of large-scale, complex, computer architectures and seam- physical processes described in lessly incorporate software that uses Brown, D.L., and W.D. Henshaw, complex geometries by fluid-flow adaptive, composite overlapping "Overture: An Advanced Object- equations prompted this research. meshes. Oriented Software System for Moving Parallel tools are based on object- We developed a number of C++ Overlapping Grid Computations" oriented, message-passing techniques. class libraries as part of this project. (NASA Computational Aerosciences We used an object-oriented approach The A++/P++ library handles basic Workshop, Ames, Calif., August based on the C++ language to create array operations required in scientific 1996). the Overture programming framework

Individual Projects—Math and Computational Sciences 61 A Self-Consistent Multiscale Theory of prescribed wave displacements, such as those of Andrews and Mclntyre. Internal-Wave, Mean-Flow Interactions in the Ocean Publications Allen, J.S., and D.D. Holm, Darryl D. Holm "Extended-Geostrophic Hamiltonian Models for Rotating Shallow Water This research is directed toward Hamilton's principle shows that the Motion," Physica D 98, 229-248 applications of nonlinear dynamics resulting equations possess a Kelvin (1996). and kinetic theory in developing new circulation theorem, conserve a Gjaja, I., and D.D. Holm, "Self- model equations and better analysis potential vorticity, and are Lie- Consistent Wave-Mean Flow tools for nonlinear problems, such as Poisson Hamiltonian dynamical Interaction Dynamics and Its ocean dynamics, involving multiple systems in the Eulerian variables. The Hamiltonian Formulat," Physica D time- and length-scales. At present it derivation from Euler's equations 98, 343-378 (1996). is not feasible to resolve all of these confirms the validity of the derivation scales and their interactions in from Hamilton's principle. Passage to Holm, D.D., "Hamiltonian Balance numerical simulations. We propose a the Lie-Poisson Hamiltonian formula- Equations," Physica D 98, 379^14 fundamental approach for describing tion brings the WMFI theory into a (1996). the effects of these interactions by framework in which formal and Holm, D.D., "The Ideal Craik- developing a self-consistent nonlinear stability analysis can be Leibovich Equations," Physica D 98, multiscale theory of internal-wave, applied. 415^41 (1996). resolved-flow interactions. To do this, We have also found relations of we take advantage of the remarkable these results to the Charney-Drazin Camassa, R., D.D. Holm, and CD. statistical homogeneity of the internal nonacceleration theorem, Whifham Levermore, "Long-Time Effects of wave field observed nearly every- averaging, Wentzel-Kramers-Brilluoin Bottom Topography in Shallow where in the ocean—the empirical (WKB) stability theory, and Water," Physica D 98, 258-286 Garrett-Munk spectrum. Lagrangian-mean fluid equations for (1996). We have derived a hierarchy of approximate models of wave, mean- flow interaction (WMFI) for modeling ocean dynamics by using asymptotic expansions. One small parameter for these expansions is the ratio of time scales between internal Geometry in the Large and waves at most wave numbers and the Hyperbolic Chaos mesoscale mean-flow of an inviscid, stratified, rotating fluid. This "adiabatic ratio" is small and is comparable Brosl Hasslacher to the ratio of space scales for the class of initial conditions that support Chaos theory continues to be original dynamical system is en- internal waves. Another small central to the modeling and under- tangled in an unknown way through- parameter available in these expan- standing of complex mathematical out the orbit sequence. sions is the ratio of the internal-wave and real systems, and the tools being This year we have successfully used amplitude to its wavelength. developed to model these systems geometrical methods from modern The new self-consistent WMFI continue to expand. This project is mathematics and recent connections equations are derived in two ways: aimed at providing an important new between global geometrical and first, by requiring Euler's equations to capability to better understand such modern quantum field theory to study preserve the wave, mean-flow systems. In strongly chaotic systems, the natural geometrical objects decomposition to linear order in the one common difficulty is that the belonging to hard chaos, i.e., hyper- wave amplitude; and second, by calculation of useful observables is bolic manifolds. In this way we can substituting this decomposition into often blocked by the lack of a better interpret global geometrical Hamilton's principle for Euler's workable orbit classification for such information and so ultimately equations and applying asymptotic systems. This is because global calculate useful observables in chaotic expansions and phase averaging to the geometrical information from the systems that otherwise would not be decomposition. The derivation from possible.

62 Los Alamos FY1996 LDRD Progress Report Industrial Processing of Complex Fluids: of motion on the fine scale are known. When these equations are not pre- Formulation and Modeling cisely known, they can be determined within a particular class by combining the Kalman filter with a maximum- James Scovel likelihood technique that we have developed. However, how to apply Many commercial materials such as We developed a model for the two- this technique in the case of nonlinear textile fibers, plastics, and fiber-optic scale system (where the two scales are equations of motion has not been cable are produced by cooling com- fine and coarse) based on a state- determined. plex fluids to form a solid. We are space representation in which the To test our maximum-likelihood developing models that can be used to transition equation must be modified technique, we applied it to the optimize the macroscopic properties so that the observation equation unsolved problem of disaggregation of such materials and to identify and corresponds to the mapping from the of time series. We developed and thus minimize sources of defects. fine to the coarse scale. The tradi- tested an algorithm for the disaggre- tional state-space representation The objective of our project is to gation of time series on several consists of two components: the first derive constitutive laws of complex classes of data generated by Auto component is a state vector that fluids in which the relaxation modes Regressive Integrated Moving cannot be observed but for which the are determined geometrically by the Average (ARIMA) processes. We dynamics (the transition equation) is different micro-, meso-, and macro- found that we can successfully understood. The second component is scale structures, and thus the modes estimate the parameters of the model a mapping from the state vector to a couple not only through the dissipa- generating the original data from the vector of observable quantities. For tive term but through geometrical aggregate data alone. In addition, our linear equations of motion, solutions relations. In addition, the coupling estimates of the disaggregate data are of this system can be found by using should evolve through the solidifica- superior to a naive estimate com- the Kalman filter when the equations tion phase. monly used in multigrid methods.

Dispersive Water Waves in long-time asymptotic effects of slowly varying bottom topography One and Two Dimensions and weak hydrostatic imbalance on the vertically averaged, horizontal velocity of an incompressible fluid Darryl D. Holm with a free surface moving under the force of gravity. In this work we With applications in mind for the complex algebraic geometry of considered the regime in which the geophysical ocean dynamics, we are Riemann surfaces. Froude number is much smaller than using multiple-time-scale perturbation We developed several aspects of the aspect ratio of the shallow theory to derive new equations for the the required mathematical tools in domain. long-time asymptotic behavior of the course of this investigation: dispersive shallow-water flow in a (1) inverse scattering with degenerate thin domain over a varying bottom in potentials, (2) asymptotic reduction Publications one and two dimensions. This past of the angle representations, (3) year we continued to analyze our new geometric singular perturbation Alber, M., R. Camassa, et al., "On the shallow-water equations and related theory, and (4) modulation theory and Link Between Umbilic Geodesies and systems of equations while develop- singularity tracking for completely Soliton Solutions on Nonlinear ing new directions for the mathemat- integrable equations. PDEs," Roy. Soc. Proc. 450, 677-692 (1995). ics underlying the integrability of We also studied models that admit these systems. In particular, we weak solutions, i.e., solutions with Camassa, R., D. Holm, and C. applied the generating equation discontinuous derivatives in the form Levermore, "Long-Time Effects of method to create and study new of corners or cusps. These appear Bottom Topography in Shallow integrable systems of nonlinear partial even though the models we are Water," Physica D 98, 258-286 differential equations related to our studying are integrable, a property (1996). shallow-water equations. We also that is often incorrectly assumed to investigated the solutions of these imply smooth solution behavior. We Camassa, R., and C. Levermore, systems of equations on a periodic also derived new shallow-water "Layer-Mean Quantities, Local spatial domain by using methods from equations in two dimensions. These Conservation Laws, and Vorticity," equations provide an estimate of the Phys. Rev. Lett. 78, 650 (1997).

Individual Projects—Math and Computational Sciences 63 Mimetic Difference Approximations Hyman, J., M. Shashkov, and S. Steinberg, "The Numerical Solution of Partial Differential Equations of Diffusion Problems in Strongly Heterogeneous Non-Isotropic Materials" (to be published in J. James Hyman Comp. Phys.). The goal of this research has been the negative of the adjoint of the Hyman, J., M. Shashkov, and S. to construct local, high-order differ- discrete gradient, and consequently Steinberg, "Problems with ence approximations of differential the Laplacian is a symmetric negative Heterogeneous and Non-Isotropic operators on nonuniform grids that operator. The new methods we are Media or Distorted Grids," in mimic the symmetry properties of the deriving are local, accurate, reliable, Proceedings of Finite Volumes for continuum differential operators. and efficient difference methods that Complex Applications, Problems and Partial differential equations solved mimic symmetry, conservation, Perspectives, F. Benkhaldoun and R. with these mimetic difference stability, the duality relationships, and Vilsmeier, Eds. (Hermes, Paris, 1996), approximations automatically satisfy the identities between the gradient, pp. 249-260. discrete versions of conservation laws curl, and divergence operators on Hyman, J., J. Castillo, et al., "High- and of analogies to Stake's theorem; nonuniform grids. These methods are Order Mimetic Finite Difference because these versions are true in the especially powerful on coarse Methods on Nonuniform Grids," in continuum, they are more likely to nonuniform grids and in calculations Proceedings Third International produce physically faithful results. in which the mesh moves to track Conference on Spectral and High- Continuum symmetries are easily interfaces or shocks, such as in Order Methods, A.V. Ilin and R R. preserved by local, discrete high-order modeling fluid dynamics. approximations on uniform grids, but Scott, Eds. (Houston Journal of they are difficult to retain in high- Mathematics, Houston, Tex., 1996), order approximations on nonuniform Publications pp. 347-361. grids. The approximations must also Hyman, J., and M. Shashkov, "Adjoint Hyman, J., J. Castillo, et al., "The be local and use only function values Operators for the Natural Discrete Sensitivity and Accuracy of Fourth at nearby points in the computational Divergence, Gradient, and Curl" (to Order Finite Difference Schemes on grid; these methods are especially be published in Appl. Numerical Nonuniform Grids in One Dimen- efficient on computers with distrib- Math.). sion," Comput. Math. Appl. 30 (8), uted memory. 41-55 (1995). Hyman, J., and M. Shashkov, We have derived new, mimetic, "Natural Discretizations for the fourth-order, finite-difference Shashkov, M,. and S. Steinberg, Divergence, Gradient, and Curl on discretizations of the divergence, "Solving Diffusion Equations with Logically Rectangular Grids" (to be gradient, and Laplacian on nonuni- Rough Coefficients in Rough Grids," published in Comput. Math. Appl.). form grids. The discrete divergence is /. Comp. Phys. 129, 383-405 (1996).

Wavelet Transforms as Solutions the parent wavelet for a continuous wavelet transform in pattern recogni- of Partial Differential Equations tion applications were developed, and (2) the computation of continuous wavelet transforms was made more George Zweig efficient by understanding the relationship between discrete wavelet A significant recent development in the "parent wavelet." Such wavelet transforms and discretized continuous applied mathematics is the study of transforms are useful in representing wavelet transforms. wavelet transforms, both continuous "transients" whose time and fre- and discrete. Like Fourier transforms, quency structure reflects the dynamics wavelet transforms express functions of an underlying physical system. Publications in terms of simple building blocks; in Speech sound, pressure in turbulent particular, wavelet transforms de- fluid flow, or engine sound in automo- Zweig, G., and C.A. Shera, "The compose functions into components biles are excellent candidates for Origin of Periodicity in the Spectrum with respect to a set of expansion wavelet analysis. of Evoked Otoacoustic Emissions," /. Acoust. Soc. Am. 98, 2018-2047 functions that are dilations and We made significant progress in (1995). translations of a single function called two areas: (1) methods for choosing

64 Los Alamos FY1996 LDRD Progress Report Dispersive, Internal, Long-Wave Models is now evident that the traditional weakly nonlinear models are unable to deal with most regimes encoun- Roberto Camassa tered experimentally. However, these regimes can be accurately described This work is a joint analytical and between upper and lower layer by our new equations, with minimal numerical study of internal, dispersive depths, and by assuming uni- loss of simplicity with respect to the water-wave propagation in a stratified directionality of wave propagation, known models. two-layer fluid, a problem that has we have shown that our model important geophysical applications. equations reduce to the known cases Two-layer models can capture the of coupled Boussinesq, intermediate Publications main baroclinic (density dependent) long-wave, and Benjamin-Ono Camassa, R., and W. Choi, "Long effects. They also support the ob- equations. We have implemented Internal Waves of Finite Amplitude," served large-amplitude, internal wave finite-difference and pseudo-spectral Phys. Rev. Lett. 77,1759 (1996). motion at the interface between layers codes for solving numerically the as well as a large shear in the velocity traveling wave solutions for the one- Camassa, R., and W. Choi, "Nonlinear field, which cannot be described by dimensional version of the model and Internal Waves in a Two-Layer Fluid," the simpler barotropic (vertically also carried out simulations of inter- J. Fluid Mechanics 313, 83 (1996). integrated) models. acting waves. Camassa, R., and D. Levermore, We have derived model equations One breakthrough made possible by "Layer-Mean Quantities, Local for two-layer, stratified fluid in the retaining the full nonlinearity of the Conservation Laws, and Vorticity" (to fully nonlinear regimes for finite and fundamental dynamics of the two- be published in Phys. Rev. Lett). infinite depth of the lower layer. By layer fluid finally clarifies experimen- considering the weakly nonlinear tal observations that have been left Choi, W., "On the Fission of regimes in various limits of the ratio unexplained for more than 15 years. It Algebraic Solitons" (to be published in Proc. R. Soc. Lond. A).

Solution-Adaptive Methods for that we have extended to treat flows at all Mach numbers. The second Low-Speed and All-Speed Flows approach uses a semi-implicit discretization for low Mach numbers that requires the solution of only one Jeffrey S. Saltzman scalar Poisson equation. The latter method switches to a standard We are developing solution- flows. In regions of the domain where compressible solver when the Mach adaptive methods for efficiently the flow is compressible, we switch to number becomes sufficiently large. computing fluid problems that involve an existing high-quality shock- We used the "Overture" class libraries low-speed flows and problems that capturing method. As another to write the solvers; the Overture are a mixture of low-speed and high- possibility, there may be parts of the libraries provide a high-level interface speed flows. A solution-adaptive domain where only sound waves are for solving partial differential method switches to different solvers present, and in this case we would use equations on moving, overlapping and/or algorithms as needed in a method that is optimized for the grids. This method provides for different regions of the problem wave equation of acoustics. significant reuse of code between the domain. In regions where the flow is We have developed and are now solvers, meaning that future solvers slightly compressible (low-speed), we comparing two promising approaches will be easier to write. The require- use a scheme based on efficient and for all-speed flow solvers. The first is ments of the solvers have also accurate methods that have been based on a novel Godunov-Projection influenced the design and capabilities recently developed for incompressible algorithm for incompressible flows of the Overture library.

Individual Projects—Math and Computational Sciences 65 Combinatorics, Geometry, Chen, W.Y.C., and J.D. Louck, "The Combinatorial Power of the and Mathematical Physics Companion Matrix," Linear Algebra Appl. 232, 261-78 (1996). William Chen Chen, W.Y.C., and J.D. Louck, "Interpolation for Symmetric Combinatorics and geometry are Publications Functions," Adv. Math. 117,147-56 among the most active areas of (1996). Beyer, W.A., and J.D. Louck, mathematics today, and this project is "Transfinite Function Iteration and Chen, W.Y.C., and J.D. Louck, particularly focused on the areas of Surreal Numbers" (to be published in "Necklaces, MSS Sequences and unitary symmetry and combinatorics, DNA Sequences" (to be published in q-extensions of hypergeometric Adv. Appl. Math.). Discrete Math.). functions, and Hopf algebras. These Chen, W.Y.C., and Z.G. Liu, areas of mathematics will continue to "Parameter Augmentation for Basic Louck, J.D., "Conway Numbers and be important for the next several Hypergeometric Series, I" (Rotafest Iteration Theory" (to be published in decades because of the power they Conference, Cambridge, Mass., April Adv. Appl. Math.). bring both in new techniques and in 1996). the linkages that have emerged Louck, J.D., "MacMahon's Master between them and several established Chen, W.Y.C., and Z.G. Liu, Theorem, Double Tableau, and fields. In this work, we extend these "Parameter Augmentation for Basic Groups," Adv. Appl. Math. 17,143-68 linkages to an area of mathematical Hypergeometric Series, II" (submitted (1996). physics dealing with symmetry and to SIAMJ. Math. Anal). the quantum description of many- particle systems. As a result, we have identified a specific area of applied The Fundamental Role of Solitons in mathematics with applications to physics, chemistry, and perhaps Nonlinear Partial Differential Equations biology. During the two years of this project, James Hyman we have advanced our goal of bringing combinatorics to bear on Numerical simulations and math- This year we discovered a new physical problems by the publication ematical analysis have proved crucial multiple-humped, pulsating soliton of six papers (three in 1995) dealing to understanding the fundamental role for a related fifth-order KdV equation. with these subjects and by five more of solitons in the evolution of general This multihumped solitary wave papers accepted by refereed journals. initial data for quasilinear, dispersive shares many of the properties of the These papers are in each of the stated partial differential equations, such as traditional single-humped solitons areas of unitary symmetry and the Korteweg-de Vries (KdV) previously seen in KdV-like equa- combinatorics, q-extensions of nonlinear Schrodinger and the tions. We have observed multi- hypergeometric functions, and Hopf Kadomtsev-Petviashvili equations. humped solitary waves, with up to algebras. We expect that these latter These equations have linear disper- eleven humps, that are dynamically two "hot topics" will feed back to the sion, and the solitons have infinite stable in multisoliton collisions first one and advance that subject. support. emerge spontaneously from initial Finally, we have in advanced stages of Recently, we discovered a new class data. preparation nine more papers coming of solitons with compact support for We also began a new research under the purview of our proposal, similar equations with nonlinear project to investigate a new nonlinear about half of which have resulted in dispersion. These 'compactons' dispersive equation based on a requests to present our work in invited display the same modal decomposi- Lagrangian approach to another fifth- talks at scientific conferences. We tions and structural stability observed order KdV-like equation. The solu- have made and are still making in earlier integrable partial differential tions of this new family of equations substantive contributions in the cross- equations. They form from arbitrary possess a rich variety of compact and fertilization of combinatorics and its initial data, are nonlinearly self- noncompact solitons. This research is applications. stabilizing, and maintain their the opening for a far-reaching and coherence after multiple collisions, new understanding of the central role even though the equations are not of solitons in nonlinear dispersion. integrable.

66 Los Alamos FYI996 LDRD Progress Report Elliptic Solvers for Adaptive the adaptive solvers) can run in parallel using the P++ array class Mesh Refinement Grids (parallel array class); we originally developed the solvers in the serial environment using the A++ array Daniel Quinlan class (serial array class). This demonstration illustrated the usefulness of We are developing multigrid techniques into this new setting. The the simplified application develop- methods that will efficiently solve approach applies the Los Alamos ment environment provided by the elliptic problems with anisotropic and object-oriented class libraries that object-oriented A++/P++ class discontinuous coefficients on adaptive greatly simplify the development. libraries. We completed extending grids. The final result will be a library We focused on the extended P++ for use with adaptive mesh that provides for the simplified development of the software tools for refinement and tested its robustness solution of such problems. This parallel adaptive mesh refinement and on different parallel environments. library will directly benefit efforts in their application to a simplified As part of the AMR++ work scientific computing, geoanalysis, adaptive mesh refinement. The initial (AMR++ is an object-oriented library fluid dynamics, mathematical application involved the Fast Adaptive for adaptive mesh refinement meth- modeling and analysis, radiation Composite and Asynchronous Fast ods), we installed a sophisticated transport, and others. The focus of Adaptive Composite solution methods graphics and visualization system that this work is research on serial and using Multigrid single-grid solvers. permits simplified debugging and parallel elliptic algorithms and the We demonstrated that Multigrid interpretation of adaptive results. This inclusion of our black-box multigrid solvers (an important component of work has proved to be an important tool in the research on numerical algorithms for problems difficult to analyze. We have nearly completed additional work on parallel load balancing Studies of Structure of Turbulence by specific to adaptive mesh refinement. High-Resolution Simulation and Theory This work has focused on fast optimal complexity algorithms for the load balancing and distribution of the Shiyi Chen adaptive refinement grid across a large number of processors. The This project is a study of the turbulence with normal and hypervis- algorithms are specific to structured structures of fluid turbulence through cosity to study inertial-range statis- grid adaptive mesh refinement, and high-resolution, direct numerical tics. We found that both the scalings we expect them to be applicable to simulation and the development of and the probability distribution many other parallel structured theory based on those simulations. functions are independent of the applications as well. Significant advances have been made dissipation mechanism, while the in the study of fundamental fluid near-dissipation-range fluctuations turbulence through our numerical and (smaller-scale motions) show signifi- Publications theoretical work. cant structural differences. Shapira, Y., "Black-Box Multigrid Using the equations of motion, we We studied the statistics and Solver for Definite and Indefinite have predicted analytically the scaling structures of pressure field, vorticity, Problems," in Algebraic Multi-Level exponents for anomalous diffusion and dissipation in 3-D, incompress- Iteration Methods with Applications, involving fluid turbulence, and we ible, isotropic turbulence. We also O. Axelsson and B. Polman, Eds. have verified these exponents through investigated the statistical relations (University of Nijmegen, Nijmegen, a large-scale simulation with 8,192 among pressure, vorticity, dissipation, The Netherlands, 1996), pp. 235-250. mesh points. This research is the first and kinetic energy using a conditional instance in which anomalous scaling averaging process. Finally, we studied Shapira, Y., "Domain Decomposition exponents for a turbulence problem the conditionally averaged velocity Multigrid for Unstructured Grids" have been deduced from the equations increments as a function of the locally (Ninth International Conference on of motion. averaged dissipation. Our results Domain Decomposition Methods, Ullensvang, Norway, June 3-8, 1996). We carried out high-resolution, provide direct evidence that supports direct numerical simulations of three- the refined similarity hypothesis. Shapira, Y, "Multigrid for Refined dimensional (3-D) Navier-Stokes Triangle Meshes" (submitted to BIT).

Individual Projects—Math and Computational Sciences 67 Computational Three-Dimensional seismic (acoustic) records into a visual representation of the explored Inversion for Seismic Exploration medium. This method was stable and robust, and although it did not provide an accurate velocity distribution Eugene Gavrilov because of a phase shift, it nevertheless captured the major features of the We are working to develop and computer, Cray T3D, that was imple- velocity structure. In fact, this implement a three-dimensional mented at the Advanced Computing method could be of great use in computational inversion tool for Laboratory; the code will serve as a test ultrasound medical imaging. The third seismic exploration that will signifi- tool that we can use to solve the method we explored was based on the cantly improve the effectiveness of forward problem, whose solution is coupled-phase (eikonal) and ampli- current seismic technology. Our critical to solving the inverse problem. tude equations. With this method we technique allows more efficient data We used the three-dimensional forward were able to recover the phase from gathering and analysis and, most code to explore three different methods records and then solve the amplitude important, automates the current for solving the inverse problem, or the equation for the whole investigated inversion process, eliminating the inversion process. domain, thereby achieving an accurate current need for human "interpreters." Unfortunately, the first method, mathematical representation of the In addition, our technique has the based on the inverse matrix, was undistorted velocity in three dimen- potential to dramatically improve unstable for three-dimensional cases sions. Our initial results from this medical imaging technology for and did not produce the expected method are very promising, but we shortwave diagnostics. results. The second method, three- must explore it further to verify its We modified a three-dimensional dimensional computational acoustic usefulness and effectiveness. acoustic code for the massively parallel holography, allowed us to convert

Super-Speed Computer another parameter, network latency, as being critical to these applications. Interfaces and Networks For the applications to perform well, we estimate that a network latency of less than 1 us is the upper bound. Donald Tolmie For this project we have performed an exhaustive evaluation of current Researchers studying super-speed this project we were working to network technologies. Based on the computer interfaces and networks identify and understand critical criteria above, we found that no single have focused on identifying the net- requirements and to explore ways to technology meets all of the require- working requirements of computation- develop super-speed networks. When ments. This finding triggered a intensive applications that are critical the necessary network components collaboration of Los Alamos research- to DOE programs. In particular, both become available, we plan to conduct ers with computer and networking the Energy Research, High-Perfor- early experiments on network switch vendors to develop a 6.4-Gbit network mance Computing Research Centers and diagnostic techniques. specification called HIPPI-6400. We (HPCRCs) and the Defense Programs, According to application developers are leading the effort to develop the Accelerated Strategic Computing at Los Alamos and other research HIPPI-6400 specification as an Initiative (ASCI) have planned institutes, the new super-speed American National Standard. We have applications that will require large network requirements fall in the 5- to also started to develop a tester to increases in network bandwidth. In 10-Gbit range. We have also identified verify and measure the performance of HIPPI-6400 implementations.

68 Los Alamos FY1996 LDRD Progress Report Particles and Patterns On the basis of this methodology, an atlas was generated of the range of in Cellular Automata backgrounds, particle types, and particle for one particular elementary local interaction scheme. Based on Erica Jen this atlas, an appropriate filter was constructed to study the pattern We developed a general methodol- through its rule table, and certain evolution, self-organization, and ogy to study particles and domains in macroscopic features—including computational characteristics of this one-dimensional cellular automata. pattern formation and computational system. Finally a deterministic A cellular automaton is a discrete capabilities—that characterize its description of the filtered system was dynamical system that consists of a evolution. The central point is that derived that permits the characteriza- lattice of sites whose values evolve these automata are characterized by tion of interactions resulting in through a local interaction rule. their generation of mesoscopic (1) annihilation of particles by Newly obtained results in the math- structures that can be viewed as backgrounds, (2) annihilation of ematics of one-dimensional cellular particles and backgrounds, and the backgrounds by particles, and (3) automata promise to provide for the global behavior of the automata may spatial translation of particles induced first time a method for analyzing the be described through a reformulation by collisions with backgrounds. relationship between an automaton's of the automaton in terms of collision microscopic-level specification rules on this mesoscopic scale.

High-Quality Finite-Difference Schemes Hyman, J., and M. Shashkov, "The Adjoint Operators for the Natural for Partial Differential Equations and Discretizations of the Divergence, Discrete Vector and Tensor Analysis Gradient, and Curl on Logically Rectangular Grids" (submitted to IMACS J. Appl. Num. Math.). Mikhail Shashkov Hyman, J., and M. Shashkov, "Discrete Analogs of Invariant First- Our primary goal in this project is operators. Using discrete analogs of Order Operators on Logically to develop new, general techniques for divergence and gradient, we devel- Rectangular Grids" (to be published performing large-scale numerical oped new finite-difference schemes in Int. J. Comput. Math. Appl.). simulations based on approximating for two-dimensional diffusion the solution of partial differential equations with a discontinuous, Hyman, J., M. Shashkov, and S. equations. The basis of these new nondiagonal matrix of coefficients on Steinberg, "The Numerical Solution techniques is the design of discrete a logically rectangular grid. We also of Diffusion Problems in Strongly operators that preserve certain tested our new schemes on practical Heterogenous Non-Isotropic essential properties of, and relation- problems. We analyzed problems Materials" (to be published in /. ships between, their corresponding involving the conservation laws and Comput. Phys.). analytic operators. The techniques the presence of parasitic modes in will significantly extend the well- Lagrangian codes, formulating these Hyman, J., M. Shashkov, and S. known and useful finite-volume problems in terms of vector and Steinberg, "Problems with methods and are designed to more tensor analysis. Our goal is to find the Heterogenous and Non-Isotropic faithfully represent important proper- relationship between the desired Media or Distorted Grids," Proc. First ties of physical processes and the properties of finite-difference Int. Symp. Finite Volumes for Complex continuum mathematical models for schemes (i.e., maintaining conserva- Applications, 249 (July 19, 1996). such processes. Algorithms based on tion laws but suppressing parasitic Shashkov, M, and S. Steinberg, these techniques can be used for modes) and the properties of the "Solving Diffusion Equation with modeling high-speed flows, porous- objects of vector analysis. Rough Coefficients in Rough Grids" media flows, diffusion processes, and (to be published in J. Comput. Phys). geophysical flows. Publications This year we constructed discrete analogs of the invariant first-order Castillo, J., J. Hyman, et al., "High- operators—div, grad, and curl—on a Order Mimetic Finite-Difference logically rectangular grid and proved Methods on Non-Uniform Grids," discrete analogs of the main theorems Houston J. Math., Special Issue, 347 of vector analysis related to these (1996).

Individual Projects—Math and Computational Sciences 69 Modeling Mesoscopic Phenomena Kenkre, V., S. Raghavan, et al., "Relation between Dynamic in Extended Dynamical Systems Localization in Crystals and Trapping in Two-Level Atoms," Phys. Rev. A 54 (R), 1781 (1996). Alan Bishop Konno, H., and P.S. Lomdahl, Our research goals were to develop Publications "Generalized Birth-Death Stochastic appropriate analytical and numerical Processes in Nonequilibrium Open Bishop, A.R., "Disorder-Induced techniques to describe the formation Systems," /. Phys. Soc. 64,1936 Breakdown of Soliton and Polaron and dynamics of collective, coherent (1995). Particles in Nonlinear Systems," in structures in extended nonlinear Noise, Nonlinearity and Fluctuation dynamical systems and their role in Konno, H., and P.S. Lomdahl, Phenomena, A.R. Bishop et al., Eds. macroscopic space-time complexity. "Stochastic Process of Annihilation (World Scientific, Singapore, 1995). The influence of nonlinearity, and Creation of Solitons in Open Systems," (1995 International classical and quantum stochasticity, Cai, D., A.R. Bishop, N. Gronbech- Symposium on Nonlinear Theory and lattice discreteness has also been Jensen, "Perturbation Theories for (NOLTA '95), Las Vegas, Nev., addressed and classified in some Perturbed Ablowitz-Ladik Nonlinear December 10-14, 1995). cases. Lattices," Phys. Rev. 53,4131 (1996). Our major achievements were as Cai, D., A.R. Bishop, N. Gronbech- Salkola, M., A.R. Bishop, et al., follows: Jensen, "Spatially Localized, "Coupled Quasiparticle-Boson Temporally Quasiperiodic Discrete Systems: The Semiclassical • We have obtained classes of Nonlinear Excitations," Phys. Rev. E Approximation and Nonlinear nonlinear solutions on curved 53,1202(1996). Schrodinger Equation," Phys. Rev. B geometries that demonstrate a 52 (R), 3824 (1995). novel interplay between topology Cai, D., A.R. Bishop, N. Gronbech- and geometric frustration relevant Jensen, et al., "Interaction of a Soliton Salkola, M., A.R. Bishop, et al., "Coupled Spin-Boson Systems Far for nanoscale systems. with Point Impurities in an from Equilibrium" (to be published in Inhomogeous Discrete Nonlinear Phys. Rev. B.). • We have analyzed the nature and Schroedinger System" (to be stability of localized, oscillatory published in Phys. Rev. B.). Villain-Guillot, S., R. Dandoloff, et nonlinear excitations (multiphonon Christiansen, P.S., N. Gronbech- al., "Toplogical Solitons and bound states) on discrete nonlinear Geometrical Frustration," Phys. Rev. Jensen, et al., "Oscillations of chains, including demonstrations A 52,6712(1995). Eccentric Pulsons" (submitted to of successful perturbation theories, Physica Scripta). existence of quasiperiodic excita- Wang W.Z., J.T. Gammel, et al., "Quantum Breathers in a Nonlinear tions, response to external statisti- Dandoloff, R., A. Saxena, A.R. cal time-dependent fields and point Bishop, "Violation of Self-Duality for Lattice," Phys. Rev. Lett. 76, 3598 impurities, robustness in the Topological Solitons due to Soliton- (1996). presence of quantum fluctuations, Soliton Interaction," Phys. Rev. Lett. and effects of boundary conditions. 74, 813 (1995). Gronbech-Jensen, N., P. S. Lomdahl, • We have demonstrated multi- M. Cirillo, "Uniform Coupling of timescale effects for nonlinear Microwaves to Nonlinear Resonant Schrodinger descriptions and have Modes in Josephson Junctions," Phys. shown the success of memory Rev. B 51, 11690(1995). function approaches for going beyond these approximations. Kenkre, V., S. Raghavan, et al., "Memory Function Approach to • In addition we have developed a Interacting Quasiparticle-Boson generalized rate-equation frame- Systems," Phys. Rev. B 53, 5407 work that allows analysis of the (1996). important creation/annihilation processes in driven nonlinear, nonequilibrium systems.

70 Los Alamos FYI996 LDRD Progress Report Atomic and Molecular Physics

State-to-State Photodetachment detachment in competition with the single-photon process was previously in the Two-Electron Hydrogen Ion unknown in either ions or neutrals. This year, we also assembled a Charlie E. M. Strauss vacuum ultraviolet (VUV) laser with which to examine, as a function of Experimental observation of the detachment resonance. This is the first VUV wavelength and electron energy negative hydrogen ion, which consists time that a multiphoton detachment distribution, the Feschbach and Shape of only two electrons and a proton, is resonance has been seen in a negative resonances in the negative hydrogen fundamentally important to the atomic ion. The analogous process in ion near 113 nm. Our collaborators development of three-body quantum neutral atoms, multiphoton ionization, from the University of New Mexico mechanics. We have observed the differs from multiphoton detachment are continuing research on both negative hydrogen ion in a regime in resonance because ions exhibit a long- multiphoton and VUV spectroscopy, which the optical electric fields are range coulombic binding potential. and they are searching for similar becoming comparable to the binding The yield (as a function of laser phenomena in the deuterium ana- fields of the ion (that is, high-field wavelength) of electrons ejected with logue. physics). The principal objective of kinetic energy in excess of the single- observing the low-field one-photon photon energy showed a pronounced Publications spectroscopy of the negative hydrogen Fano-profile-shaped peak, consistent system was overshadowed by our with theoretical predictions. Second, Zhao, X.M., M.S. Gulley, H.C. observation of two new physical we observed nonresonant excess Bryant, et al., "Nonresonant Excess processes. photon detachment with photons of Photon Detachment of Negative First, the negative hydrogen system energy exceeding the ion's binding Hydrogen Ions" (to be published in exhibited multiphoton excitation to a energy. Nonresonant excess photon Phys. Rev. Lett).

Transient Quantum Mechanical Processes the interaction of a short-pulse laser with a dimer of potassium in order to study the interference effects between Lee Collins vibrational wave packets in different electronic states. Initial calculations The principal objective of this project requires the development of sophisti- using simple models for the molecular is the theoretical investigation of cated, large-scale computational interactions yielded qualitative agree- transient quantum mechanical events approaches to solve the time-dependent ment with experiment. They indicated a such as coherent control of molecular Schrodinger equation, which represents clear correlation between the signal and processes and artificial atoms. Rapid the basic physics of these fleeting the vibrational motion of the wave advances in laser technology have encounters. One major goal of our packet. To improve the agreement, we made control of quantal processes project involves modeling various have begun calculating better molecular possible. Since the duration of laser molecular-control experiments con- parameters such as potential energy pulses has become much shorter than ducted at Los Alamos. curves and coupling matrix elements. that of many molecular interactions, a This year, we have developed and laser will act as a strobe that probes the extensively tested two independent evolution of the system. Electrons methods for efficiently and accurately Publications passing through layers of composite solving the time-dependent Schrodinger Collins, L., R. Walker, and J. Kress, materials that are many nanometers equation for these processes. The "Quantum Control of Molecular thick also behave as quantum mechani- methods are based on the real- Processes," Bull. Am. Phys. Soc. 41, cal entities, despite the large-scale space-product and discrete-variable- 1145(1996). nature of the medium. However, the representation formulations, respec- study of such transient processes tively. We first applied the methods to

Individual Projects—Atomic and Molecular Physics 71 Calculation of Satellite Line Structures at an electron temperature near 200 eV and a electron density of in Highly Stripped Plasmas 1022/cm3. The number of hot electrons is fixed at 10% of the electron density. Note the significant difference Joseph Abdullah Jr. between the relative intensities predicted for the two different cases. Recently developed high-resolution matching the experimental results The second figure shows the good x-ray spectrographs have made it with calculations. agreement of the measured Trident possible to measure satellite line Model calculations were performed spectrum with calculations that structures from various plasma using an electron distribution consist- include the effect of hot electrons. sources with great detail. These are ing of a thermal Maxwellian part and weak, optically thin lines caused by a nonthermal, high-energy Gaussian the decay of autoionizing states and part to determine if hot electrons Publications generally accompany the resonance could be responsible for the anoma- Abdallah, J. Jr., A. Ya Faenov, D. lines of hydrogen-like and helium-like lous structure of satellite lines ob- Hammer, et al., "Electron Beam ions. The goal is to use Los Alamos served in the Trident experiments. The Effects on the Spectroscopy of atomic physics and nonequilibrium first figure is a comparison of the Satellite Lines in Aluminum X-Pinch kinetics codes to calculate the line calculated spectra for magnesium Experiments," Phys. Scr. 53,705 structure and compare it with high- shown with and without hot electrons resolution experiments. Consequently, (1996). we are able to interpret and understand the physical processes in plasma. The results can be used to develop plasma temperature and density diagnostics using the signature of satellite structures. Such diagnostics will have wide application to Laboratory programs. The study also provides a fundamental understanding of the atomic physics processes in different plasma environments. Collaborations with A. Ya Faenov, T. A. Pikuz, and S. A. Pikuz of Russia add tremendous value to the research. 13301332 1334 1336 1338 1340 1342 1344 1346 1348 1350 Photon Energy (eV) The accomplishments for this year include the analysis of satellite spectra taken from various plasma sources, including a silicon spectrum measured at the Los Alamos Bright Source Facility. We studied data from aluminum X-Pinch experiments performed at Cornell University that showed a strong dependence on electron-beam effects. Data on magnesium have been taken from the Russian Multicharged Ion Spectra Data Center carbon dioxide laser facility and the Los Alamos Trident laser. The observed satellite structures show strong dependence on hot 1330 1332 1334 1336 1338 1340 1342 1344 1346 1348 1350 electrons for both the Russian and the Photon Energy (eV) Trident laser (500 fs, 1054 nm) (Top) A comparison of calculated spectra for magnesium showing the effect of measurements. We have determined 22 electron densities, thermal tempera- hot electrons at an electron temperature near 200 eV and a density of 10 tures, and hot-electron fractions by electrons per cubic centimeter. (Bottom) A comparison of the calculated spectrum including the effect of hot electrons with the observed Trident spectrum.

72 Los Alamos FY1996 LDRD Progress Report Optical Wave Packets (Optical Bullets): A Publications Zhao, X.M., R.J. Jones, D.J. Funk, et New, Diffraction-Free Form of Light Travel al., "Evolution Characteristics and Control of Self-Filamentation in the David J. Funk Atmosphere" (submitted to Opt. Lett.). In this work we study the propaga- enon and turn it into a useful tool for tion of self-confined packets of light controlling lightning discharge (as an through the atmosphere. At suffi- example) by providing an ionization ciently high intensities, pulses of light path for the lightning to discharge will not only self-focus, but may along. propagate indefinitely without active optics or guiding media in the form of a fine filament until the intensity of 20 — . .1 i \ : ; i j the pulse falls below a measurable ; •: Experiment i : ; / critical value. A Calculation : i \ / 15 - ! f ! j : J/ We are analyzing the phase and structure of the pulse above, near, and below that critical intensity to < ; understand the origin of this phenom- 10 - j '•• i i j/. enon. We are also investigating the o use of the filament path as a I waveguide for low-intensity laser 5 pulses. The ability to focus intense light at large distances and collect the scattered light may revolutionize 0 .—— - ' I active remote sensing and long-range energy transmission. Applications 1 i 1 I i include remote sensing and range -2 4 6 10 finding in battlefield conditions, long- Chirp (AWd) range energy transmission, and Effect of chirp on filament formation distance. The graph shows that the pulse guiding lightning discharge. forms most readily when blue light precedes red light (large Al/ldj as expected Our studies have concentrated on from a simple, group-velocity dispersion analysis. the demonstration and understanding of the fundamental physics associated : i j with this phenomenon and the proof O L=3'4m : i M L=12m : of the existence of these wave packets : •» L=20m in air. We have successfully (1) gener- :3K L=27m 1500- i i ated filaments, (2) set up a frequency- : ] 4E : resolved, optical-gating analysis I station, (3) measured the energy in the filament as a function of travel 1000- distance in the laboratory, (4) exam- .a *• i * • • : : t: ined the effect of chirp on the pulse (both on filament formation distance : *! and conical emission), as shown in the 500- first figure, and (5) spectrally dis- S;• * persed and autocorrelated the filament as a function of distance traveled in the laboratory. 0- i > i We have also found that the pulse -10 -6 -4 -2 0 2 10 splits into two pulses as it propagates, Chirp (Al/ld) as predicted by various theories that Effect of chirp on pulse splitting as a function of propagation distance L. The fold in the nonlinear interaction of graph shows that the pulse splits most readily when blue light precedes red intense electromagnetic fields with light (large Al/l ), as expected from a simple, self-phase modulation and group- matter (see second figure). Our goal d velocity dispersion analysis. is to be able to control this phenom-

Individual Projects—Atomic and Molecular Physics 73 Nonlinear Atom Optics analyzed the modification of van der Waals interactions in both thermal and laser fields. Peter Milonni The natural framework for the many-particle system of interest, The objective of this project is to situation of particular interest in including the two-body dipole-dipole develop the quantum field theory of "lasers for atoms" with which interactions and the quantum statis- atom optics and, in particular, to relatively intense atom waves, rather tics, is quantum field theory. In this explore the possibilities for realizing than photon waves, will be produced. case, the requisite formalism is nonlinear wave effects in atom optics. We have outlined the basic nonrelativistic, and it leads to Our progress in the basic physics and structure of a coherence theory of computationally workable, coupled, in the development of very promising atom optics, along the lines of the nonlinear wave equations. We have applications has been rapid. We are optical theory of coherence. A few developed this formalism and are focusing on nonlinear atom-optical issues involving the treatment of preparing it for publication, following effects including wave phenomena atom-atom interactions remain to be the numerical simulation of a few such as self-focusing, solitary-wave worked out before the theory is examples based on the formalism. We formation, wave mixing, and phase written up and submitted for publica- have also begun to study the applica- conjugation, which can arise from tion. One of the issues is the modifi- tions of this theory to the recently long-range dipole-dipole interactions. cation of atom-atom interactions in observed Bose-Einstein condensation Such effects occur when more than the case of cold atomic samples that in cold atom traps. one atom can occupy a single "mode" are of interest in atom optics. For the of the many-body wave function, a case of ground-state atoms, we have

Dynamics of Quantum Wave Packets

Timothy R. Gosnell

The time-domain investigation of the time and spectral content (or localized vibrational wave functions chirp) of the pump pulse. The ultimate in diatomic molecules is possible with goal is to develop a broader tool set femtosecond laser sources. In our for controlling chemical reactions experiment, a femtosecond pump with laser light. pulse creates a wave packet on an This year we improved the signal- excited potential surface of gas-phase to-noise ratio in our wave-packet K2 molecules. The packet oscillates detector and confirmed chirp-induced within the well, much as one expects effects on the shape of the packets. A classically, but then disperses as a theoretical investigation helped clarify result of rotational effects and wave-packet dynamics, but continued dispersion within the the weakly theoretical studies are needed to anharmonic potential well. The understand the specific wave-packet purpose of the experiment is not just shapes and decay patterns observed in to create and observe such packets but our experiments. to alter their shape by manipulating

74 Los Alamos FYI996 LDRD Progress Report Geoscience, Space Science, and Astrophysics

Low-Energy Neutral Atom Imager LENA energy, and (4) a detector subsystem that provides trajectory and coincidence measurements. Herbert 0. Funsten and In this first year we have success- David J. McComas fully completed the design, procurement, and fabrication of imager Remote imaging from space is The goal of this project is to fly the components. We assembled and tested contributing more and more to our first low-energy neutral atom (LENA) the collimator, door, and detector understanding of the space environ- imager capable of imaging neutral subassemblies. As a demonstration of ment around Earth. Sensing of atoms with energies less than 30 keV. new technology, the LENA imager magnetospheric plasma ions that have As shown in the accompanying figure, been neutralized by charge exchange the imager consists of (1) alternately uses thin-walled, hemispherical, with geocoronal neutral atoms biased collimator plates to reject electrostatic energy analyzer plates promises to be the next major ambient plasma particles, (2) an that were formed by electroplating, diagnostic of magnetospheric physics ultrathin, 50-A foil that ionizes a which is considerably less expensive and may provide global snapshots of fraction of the neutral atoms that than traditional machining. the structure and dynamics of the transit the foil, (3) electrostatic energy The LENA imager, which will be terrestrial magnetosphere. analyzer plates that measure the fully flight qualified, is positioned to fly on the first ride of opportunity. The LENA imager will provide the first neutral atom measurements for its energy range with image integration times of several minutes.

Publications Funsten, H.O., DJ. McComas, and M.A. Gruntman, "Mechanisms for Neutral Atom Imaging" (submitted to Am. Geophys. Union Monograph CHARGE Series, Measurement Techniques for CONVERSION FOIL Space Plasmas). Start Foil Hesse, M., D. Mitchell, E. Roelof, et al., "Neutral Atom Imaging of the HEMISPHERICAL Plasma Sheet: Measurement ANALYZER Predictions" (submitted to Geophys. Res. Lett.). McComas, D.J., H.O. Funsten, and E.E. Scime, "Advances in Low Energy Neutral Atom Imaging" Los Alamos low-energy neutral atom (LENA) imager. (submitted to Am. Geophys. Union Monograph Series, Measurement Techniques for Space Plasmas).

Individual Projects—Geoscience, Space Science, and Astrophysics 75 Nonlinear Processes in Earthquakes submitted to the National Science Foundation. We also applied the AFD code to Eric Jones study path effects on seismic signals in Western China, and we completed a Characterizing the source of three-dimensional seismograms, the parameter study to isolate the effects seismic signals is important both for differences between the synthetic of major geologic features along the distinguishing clandestine nuclear seismograms calculated with and path, such as the Tarim Basin and the tests from earthquakes and for without the slab are significant. Our Moho root of the Himalayas (see understanding the mechanisms of collaborators at the University of diagram of the major geologic earthquakes. However, geologic Texas planned to use existing analysis features in this region). As shown the structures near the source and along techniques to show that inferred accompanying vertical-velocity the propagation path can modify the seismic moment tensors would seismograms, the low-velocity basin seismic signals and complicate source contain non-double-couple compo- is particularly effective in converting analyses. nents. However, by midyear we compressive (P-wave) energy from an We applied a three-dimensional, realized that we first needed to explosive source into the shear wave elastic-wave-propagation code, known develop methods to utilize seismic (S-wave) energy characteristic of an as the AFD code, to model an histories at the outer boundaries of the earthquake. earthquake near the upper boundary numerical grid. Our initial numerical of a subducting slab. As shown in the results were used in a proposal Station 40

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76 Los Alamos FY1996 LDRD Progress Report -5.0x10

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The geologic structures along a path from the Chinese nuclear test site at Lop Nor (left) to a seismic station in northern Pakistan (right). The major features include the low-velocity Tarim Basin, which lies between 100 and 400 km from Lop Nor, and the deep Moho depression underneath the Tibetan Plateau from 1100 km to the right side of the computational region.

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X 10+2 Vertical-velocity seismogram atx = 1100 km for a case not including (top) and including (bottom) the Tarim Basin. In the upper portion of the figure, the first arrival from an explosive source is at about 140 seconds and is a compressive wave which travels mostly through the high-velocity mantle material. Arrivals starting at 190 seconds represent compressive energy ducted in the crust. In the lower portion of the figure, the arrivals between 200 and 225 seconds represent compressive-to-shear (PS) energy conversion at the upward sloping edge of the basin between x = 600 km and x = 1000 km, and the arrivals between 340 and 360 seconds represent PS conversions on the downward slope of the basin between x = 100 and x — 500. The large-amplitude arrivals after 400 seconds represent surface waves created in the basin. In a simpler geologic setting, the shear-wave arrivals would be characteristic of an earthquake source and not an explosive source.

Individual Projects—Geoscience, Space Science, and Astrophysics 77 Lead Immobilization in Thermally Publications Remediated Soils and Igneous Rocks Eppler, A.S., D.A. Cremers, D.D. Hickmott, et al., "Matrix Effects in the Detection of Pb and Ba in Soils Donald D. Hickmott using LIBS," Appl. Spectrosc. 50, 1175(1996). Cleanup of rocks, soils, and methods to immobilize lead. We aquifers contaminated with mixtures modeled the thermodynamics and Hickmott, D.D., J.M. Herrin, R.A. of lead and organic or high-explosive kinetics of the precipitation of lead Abell, et al., "Environmental wastes is a problem of considerable immobilizers at both ambient and Applications of Nuclear Micro- importance across the nation. This high temperatures. Experiments probes" (submitted to Nucl. lustrum. project is designed to (1) investigate determined that Na2HPO4 amendment Phys. Res. B). the speciation of lead in soils and of lead chloride can produce lead Larocque, A.C.L., C.E. Chapin, et al., igneous rocks; (2) use numerical phosphates at high temperatures "Metal-Residence Sites in Mine techniques to investigate phases that (400°C) but that lead carbonate and Tailings in the Magdalena District, may immobilize lead; and (3) perform lead oxide are stable relative to lead New Mexico," in Mineral Deposits, laboratory-scale experiments in which phosphate in most bulk compositions Pasava, Kribek, and Zak, Eds., (A.A. lead is immobilized by thermal at the temperatures investigated. Balkema, Rotterdam, Netherlands, treatment of soils. Our project will Clearly, kinetic factors influence 1995), pp. 661-664. result in an understanding of factors our ability to produce thermodynami- that control whether the mobility of cally stable, lead-phosphate-bearing Stimac, J.A., D.D. Hickmott, R.A. lead in soil can be minimized by assemblages in thermal remediation Abell, et al., "Redistribution of Pb and thermal treatments. experiments. Further investigation of Other Volatile Trace Metals during In this review period we have the dissolution/precipitation kinetics Eruption," J. Volcanol. Geotherm. successfully identified lead phos- of lead-immobilizing phases is Res. 73, 245 (1996). phates as the most likely phases required before thermal immobiliza- suitable for using thermal-treatment tion of metals in soils can be implemented on a wide scale.

Experimental Studies of during the recovery phase of substorms and often became re- Auroral-Arc Generators energized during the growth phase of successive substorms. This observa- David Suszcynsky tion supported the idea that the precipitating particles are supplied The focus of our project was the general discrete arc activity, no directly by injection events. We found preliminary analysis of all-sky and specific features in orbit could be that a black aurora, a rarely observed satellite data and the identification of associated with individual arc and studied phenomenon, was phenomena/events for future studies. structures. This information leads us associated with counterstreaming 0.2- We completed two analyses. The first to conclude that the fine structure of to 2-keV ions and is much more was a survey of the satellite and discrete arcs is generated at lower common than previously reported. ground data to identify signatures of altitudes than the equatorial magneto- discrete auroral arcs at geosynchro- sphere. Publications nous orbit. The second analysis In characterizing the geosynchro- characterized the geosynchronous nous environment during pulsating Suszcynsky, D.M., J.E. Borovsky, environment during pulsating aurora aurora and black-aurora events, we et al., "Coordinated Ground-Based and black-aurora events. learned that the geosynchronous orbit and Geosynchronous Satellite-Based In the effort to identify signatures is dominated by electron pitch-angle Measurements of Auroral Pulsations" of discrete auroral arcs, we discovered anisotropies (pancake distributions) (Twenty-third Conference on Optical that although specific conditions at and fluxes, as predicted by leading Methods for Atmospheric Research, geosynchronous orbit could be pulsation theories. As expected, we Kiev, Ukraine, September 2-6, 1996). associated with the occurrence of observed that the pulsations occurred

78 Los Alamos FY1996 LDRD Progress Report Fundamentals of Laser Ablation Publications Koskelo, A., and T. Gamble, "Laser in the Analysis of Geological Materials Ablation of Geological Materials" (Federation of Analytical Chemistry Aaron Koskelo and Spectroscopy Society, October 1996). Our goal is to determine the the ionic line. This effect is explained Koskelo, A., T. Gamble, and T. parameters that contribute to matrix by a shot-to-shot change in electron Lippert, "Laser Induced Breakdown effects in laser ablation of materials. density in the plume. There are also Spectroscopy of Geological Laser ablation underlies many of the indications that the degree of anti- Materials" (Winter Conference on methods that hold promise for real- correlation depends on how easily the Plasma Spectroscopy, January 1996). time materials recognition and rapid element is ionized. chemical analyses of environmental This year we also gained experience Koskelo, A., C. Mahan, et al., "Direct samples. However, laser ablation has in the use of infrared pump-probe Chemical Analysis at Los Alamos not yet gained widespread use as a technology for monitoring bond National Laboratory (SPIE National method of analysis nor regulatory breaking in materials. We expect to Meeting, Denver, Colo., August acceptance because of matrix effects. extend this technology to use in 1996). Different sample types exhibit complex materials like geological Lippert, T., A. Koskelo, and P. different sensitivities under laser materials. Stoutland, "Direct Observation of a ablation. This effect arises from the We studied the photodecomposition Photoinduced Wolff Rearrangement in complex and not-yet-understood of diazo-Meldrum's acid in a polym- PMMA Using Ultrafast Infrared ablation process itself, particularly in efhyl methacrylate (PMMA) matrix Spectroscopy," J. Am. Chem. Soc. mixed or inhomogeneous materials. and found that the intermediate keto- 118, 1551 (1996). We are developing new techniques to ketene appeared within 20 ps of the examine the causes of the difference photoexcitation. This work indicates Lippert, T, A. Koskelo, and P. in sensitivity of different materials, that the path through the keto-ketene Stoutland, "Laser-induced Reactions with particular emphasis on funda- is the primary reaction pathway to the in a Deep UV Resist System: Studied mental measurements of processes stable carboxylic acid. It is the with Picosecond Infrared involved in the laser ablation of carboxylic acid that makes this system Spectroscopy," Mater. Res. Soc. Proc. geological materials and soils useful for base-soluble photoresists. 397, 661 (1996). This year we developed the use of correlations in laser-induced breakdown spectroscopy (LIBS) spectra to examine the inhomogeneity of soils and mine tailings. We obtained a series of single-shot LIBS spectra and calculated interwavelength correlation matrices that reveal the correlation between different species emitting in the laser ablation plume. The work reveals that some Resource Conserva- tion and Recovery Act (RCRA) metals correlate well with iron-containing components of the soil matrix but not with titanium components. We have also seen indications that atomic and ionic lines in the laser ablation plume are anticorrelated, as J shown in the accompanying figure. 3240 3260 3280 3300 3320 3340 3360 3380 3400 3420 3440 Strong correlation to the titanium ion WAVELENGTH (A) emission line at 3360.96 A occurs for Correlation spectrum obtained from a sample of mine tailings from Butte, every ionic line in this emission Montana. The spectrum shown is the average of 910 spectra taken as the spectrum. Every atomic line in the sample moved continuously under repetitive laser sparks. Each data point is the spectrum—regardless of atomic correlation coefficient of the wavelength channel to that of a channel species from which the line corresponding to Ti(II) emission. Note the strong correlation to Ti(II) for all originates—exhibits anticorrelation to other Ti(II) lines. Atomic emission lines do not have a strong correlation to the Ti(II) lines and, indeed, do exhibit some anticorrelation.

Individual Projects—Geoscience, Space Science, and Astrophysics 79 Integrating Chemistry into Three-Dimensional Climate Models: Detailed Kinetics in the Troposphere and Stratosphere of a Global Climate Model

Chih-Yue J. Kao

Several atmospheric gases, includ- Publications Zhao, X., R.P. Turco, et al., "Aerosol ing ozone and methane, are both Induced Chemical Perturbations of Elliott, S., C.-YJ. Kao, F. Gifford, et radiatively and kinetically active. Stratospheric Ozone: Three- al., "Free Troposphere Ozone They influence global climate but are Dimensional Simulation and Analysis Production after Deep Convection of themselves controlled by photochemi- of Mechanisms" (submitted to /. Dispersing Tropical Urban Plumes" cal processes. The role of such Geophys. Res.). (to be published in Atmos. Environ.). molecules in the global system has Zhao, X., R.P. Turco, et al., "Numerical generally been simulated either in low Elliott, S., M. Shen, C.-YJ. Kao, et Simulation of Dynamical Response to dimensionality or with chemistry al., "A Streamlined Family Photo- the Arctic Vortex to Aerosol-Associated decoupled from dynamics. Three- chemistry Module Reproduces Chemical Perturbations in the Lower dimensional chemical models have Major Nonlinearities in the Global Stratosphere," Geophys. Res. Lett. 12, further sacrificed integrity by focusing Tropospheric Ozone System," J. 1525-1528 (1996). either above or below the tropopause. Comput. Chem. 20, 235-259 (1996). The goal of our research is to alleviate these restrictions by incorporating kinetics interactively into both Using Microspheres as Tracers the troposphere and stratosphere of a for Flow in Geologic Media global climate model (GCM) so that the chemical and thermodynamic effects of important atmospheric Bruce A. Robinson gases can be comprehensively modeled and used by decision-makers The goal of this study is to develop colloid-transport mechanisms and in coping with the changing earth- microspheres as groundwater tracers. retardation/attenuation mechanisms of atmosphere system. We expect to This capability will allow us to solute contaminants in saturated create the first truly interactive, three- investigate the movement of colloidal groundwater systems. Laboratory dimensional, chemical climate contaminants in groundwater and to experiments revealed that negatively simulations. Our work on this project gain insight into the movement of charged, carboxylate-modified has applications to photochemistry, dissolved and colloidal contaminants microspheres provided the most environmental sciences, chemical in fractured rock. We used polysty- mobile surface-charge characteristics transport, and monitoring. rene latex and silica microspheres in natural groundwater systems. Field This year we implemented the (0.25 to 1 um in diameter) tagged studies of fractured granite supported parameterization of aerosol formation with fluorescent dyes in laboratory our theory that microspheres travel and chemical heterogeneous reactions and field groundwater-tracer experi- slightly faster than dissolved tracers in in our photochemical module to study ments to (1) obtain insights into forced-gradient tests. However, the influence of aerosol on ozone colloidal contaminant transport in attenuation, possibly caused by concentrations. In particular, we geohydrologic systems, and (2) settling, also affects the field results. investigated the heterogeneous characterize geohydrologic systems This work has resulted in several chemistry occurring on the sulfate more thoroughly than we could using master's and doctoral theses at two particles from volcanic eruptions. We only dissolved tracers. universities. compared the simulated ozone We have measured microsphere concentrations in groundwater depletions with documented data from Publications eruptions such as El Chichon and samples at two to three orders of Pinatubo. magnitude below natural background Reimus, P.W., B.A. Robinson, et al., concentrations, using the unique "Simultaneous Transport of Synthetic capabilities of the flow cytometry Colloids and a Nonsorbing Solute laboratory at Los Alamos. Preliminary through Saturated Rock Fractures," results suggest that the use of Mat. Res. Soc. Symp. Proc. 353, microspheres in tracer experiments 363-370 (1995). can provide valuable insights into

80 Los Alamos FY1996 LDRD Progress Report Theoretical Research on with Villanova University, we have found various means of transporting Dwarf and Classical Novae this energy deeper into the star and extending the radiative region. Thus, Warren Sparks we may account for the long-puzzling missing boundary layer when we Previous simulations of accreting simulate this effect, we developed a consider the response of the WD to white dwarfs (WDs) have been one- new time-dependent zoning scheme in the accretion. dimensional. The recent identification which the time-dependent grid In collaboration with the University of the two-dimensional (2-D) belt follows the equipotential surfaces. of Wyoming, we investigated the structure on the WD surface in VW The standard alpha-model theory cause of the high and low accretion Hyi demands more realistic simula- predicts that during a dwarf nova states in AM Herculis binaries (AM tions using a 2-D model, which we outburst, the boundary layer between Hers). We proposed a model in which are developing. To allow the model to the WD surface and the inner disk the WD's rotation acts like an angular have time steps exceeding the limit set radiates away one-half of the accreted momentum storage battery for the by the Courant condition (the sound- energy from a small area of the WD binary orbit. The accreted material crossing time in a grid cell inside the stellar surface and has an effective from the Roche lobe-overflowing degenerate WD), the code has to be temperature as high as 500,000 K. secondary charges up this battery, implicit for numerical stability. Using Recent observations show that during whereas the magnetic torque of the an energy criterion of shear mixing a dwarf nova outburst, a significant WD on the secondary discharges it characterized by the Richardson portion of the gravitational energy back into the binary's orbit. The number, we find that the forced accreted onto the WD may not be Roche lobe's volume becomes convection is most efficient along the radiated away instantly from a narrow alternately larger and smaller than the equipotential surface of the differen- boundary layer as predicted by the secondary's volume. This alternation tially rotating WD atmosphere. To standard disk theory. In collaboration causes the mass flow to vary between a high and low rate.

Micro/Macroscale Coupling in for the properties of anisotropic protons near 10 eV (i.e., "warm" Magnetospheric Plasmas protons) in the outer magnetosphere provides an approximate upper bound for a selected set of warm-proton S. Peter Gary temperatures observed at geosynchronous orbit. Microscale plasma processes can using plasma theory, hybrid simula- significantly affect the large-scale tions, and spacecraft data analysis to Publications dynamics of a plasma, whereas large- develop additional new scaling scale computer models of space relations for the consequences of Convery, P.D., and S.P. Gary, plasmas cannot directly model kinetic small-scale instabilities in the "Electromagnetic Proton Cyclotron process and require special algorithms magnetosphere. These relationships Ring Instability: Threshold and to adequately represent small-scale significantly improve the predictive Saturation" (to be published in J. effects. Our goal is to develop new capabilities of the models. Geophys. Res.). scaling relations for proton param- We have recently published two Gary, S.P., M.E. McKean, and D. eters that allow good quantitative important results. The first, which was Winske, "Proton Temperature representation of the consequences of obtained through the use of two- Anisotropy in the Magnetosheath: microphysical processes that take dimensional computer simulations, is Hybrid Simulations," Geophys. Res. place in the magnetosphere. that the whistler anisotropy instability Lett. 21, 2887 (1996). We have recently developed the imposes an upper bound on the first scaling relation for the hot- temperature anisotropy of electrons Gary, S.P., M.F. Thomsen, J. Lee, proton-anisotropy upper bound in that have bi-Maxwellian velocity et al., "Warm Protons at Geo- magnetospheric plasmas and have distributions. This result is fully synchronous Orbit" (to be published used it as an algorithm in a computer analagous with the upper bound we in J. Geophys. Res.) model of the magnetotail to demon- have demonstrated for ion tempera- Gary, S.P., and J. Wang, "Whistler strate that it qualitatively affects the ture anisotropies. The second impor- Instability: Electron Anisotropy predictions of that model. We are tant result is that the scaling relation Upper Bound," J. Geophys. Res. 101, 10 (1996).

Individual Projects—Geoscience, Space Science, and Astrophysics 81 Numerical Simulations of Convection Publications Experiments and Earth's Interior Glatzmaier, G.A., and P.H. Roberts, "An Anelastic Geodynamo Simulation Driven by Compositional and Gary Glatzmaier Thermal Convection," Physica D 97, 81 (1996). Our project is targeted at providing we made for the core's rotation was new insights and explanations about recently supported by two indepen- Glatzmaier, G.A., and P.H. Roberts, the origin, structure, and evolution of dent seismic analyses. The radius of "The Growth, Topography, Rotation Earth's magnetic field through the the inner core grows at about 3 cm per and Magnetism of Earth's Inner development of a dynamically century as iron in the fluid alloy Core," Science 274,1887 (1996). consistent, three-dimensional com- above freezes onto the core. If one Glatzmaier, G.A., and P.H. Roberts, puter model of the geodynamo—the assumes the heat flow out of Earth's "On the Magnetic Sounding of convective mechanism in Earth's core has remained relatively constant, Planetary Interiors" (to be published outer fluid core that generates and the simulated growth rate implies that in Physics of the Earth and Planetary maintains the geomagnetic field. We the age of the solid inner core is only Interiors). have successfully developed the first about one-fourth the age of Earth. such model and have used it in a In the past year, we also conducted simulation that has maintained an computer simulations of the geophysi- Earth-like magnetic field for a cal fluid-flow cell experiment that simulation length of more than was flown aboard the NASA space 200,000 years. shuttle Columbia in November 1995. Our simulated magnetic field has an This experiment will improve our intensity and a dipole-dominated understanding of convection in structure that are very similar to rotating planetary interiors. Earth's (see accompanying figure). Our simulation also has a westward drift of about 0.2 degrees/year of the nondipolar structures of the field at the core-mantle boundary; this drift is similar to that measured on Earth. In our simulation, the solid inner core rotates about 2 to 3 degrees/year faster than the mantle. This prediction

A snapshot of the computer- simulated geomagnetic field. Magnetic field lines are drawn out to two Earth radii. The complicated interne field occurs in the fluid outer core where the field is generated; the field outside the outer core is a smooth potential field. The axis of rotation is vertical in this image.

82 Los Alamos FY1996 LDRD Progress Report galaxies. For example, the Burst and High-Velocity Neutron Stars Transient Source Experiment can observe March 5th-like bursts out to Edward Fenimore 5 Mpc, a volume that contains 70 galaxies. No events were found, The following three recent discov- namely, an apparent isotropic distribu- showing that they are less frequent eries could revolutionize our under- tion and uniform density of gamma- than the rate seen in our galactic standing of high-energy astrophysical ray bursts, a lack of events from the neighborhood. transients: many neutron stars have Andromeda Galaxy, the association of Second, we investigated what sufficient velocity to escape the SGRs with population I material, and would be necessary to detect gamma- galaxy; soft gamma repeaters (SGRs) the fact that a young neutron star was ray bursts from the Andromeda come from high-velocity neutron able to produce both SGRs and Galaxy in anticipation of possible stars; and one high-velocity neutron gamma-ray bursts. NASA gamma-ray-burst satellites that star may have produced a gamma-ray During this year we completed would attempt to detect bursts from burst. Our project goal is to under- three steps in understanding gamma- Andromeda. We published an analysis stand these phenomena and determine ray bursts from galactic high-velocity based on our models of high-velocity under what conditions the observed neutron stars. First, since the March neutron stars, which showed that only high-velocity neutron-star properties 5th burst event (which was the one class of models can be tested with (when applied to the local group of brightest event ever observed), we a next-generation satellite (the galaxies) can reproduce all of the have searched for fainter versions that "delayed turn-on" models), whereas properties of high-energy transients; might have come from nearby the other models (based on beaming) cannot be tested. Third, we evaluated what relativistic motion would be required to allow the escape of the observed very high Sedimentary Basin Response to energy photons from a neutron star. We found that much slower relativis- Strong Motion in Populous Regions tic motion could be present (Lorentz factors of only 5 rather than 50). The Paul Johnson slower motion will allow a wider range of high-velocity neutron-star An important origin of damage in strong-motion data from the main models. modern metropolitan areas during shock and aftershocks of the large earthquakes is the amplification Northridge earthquake to study site Publications of seismic shear waves. The amplifi- effects. Our preliminary analysis cation is due to both basin-geometry- shows strong nonlinear-induced Duncan, R.C., and H. Li, "The Halo induced resonance and local site resonance changes at several strong- Beaming Model for Gamma-Ray resonances. Examples of amplifica- motion sites in the Los Angeles basin. Bursts" (submitted to Astrophys. J.). tion include all of the most damaging A three-day conference at Los Fenimore, E.E., CD. Madras, and S. earthquakes of the latest decade, Alamos regarding preliminary Nayakshin, "Expanding Relativistic including the 1985 Michoacan progress was held in September 1996 Shells and Gamma-Ray Burst (Mexico), the 1989 Loma Prieta with all project participants. An Temporal Structure," Astrophys. J. (California), the 1994 Northridge exhaustive analysis of all strong- 473, 998 (1996). (California), and the 1995 Kobe motion sites has begun as a result of (Japan) earthquakes. These earth- observations and discussions. Li, H., and E.E. Fenimore, "Log- quakes cost thousands of lives, mostly Simultaneously, we began working Normal Distributions in Gamma-Ray resulting from structural failure, and with groups that are creating whole- Time Histories," Astrophys. J. Lett. cost tens of billions of dollars in basin, finite-element difference 469,115(1996). structural damage. Consequently, models of the Los Angeles basin. We Li, H., E.E. Fenimore, and E.T. Liang, understanding and mitigating the will incorporate observations and "Detectability of Gamma-Ray Burst effect of the uppermost sedimentary nonlinear response models being Excess toward M31," Astrophys. J. layers on ground motion and the developed at Los Alamos into basin Lett. 461, 73 (1996). resulting response of engineered models. We also recently obtained structures is of paramount impor- data, for additional studies, on the tance. Kobe earthquake and on several In the past year, we focused earthquakes in Taiwan. primarily on obtaining high-quality,

Individual Projects—Geoscience, Space Science, and Astrophysics 83 Heterogeneous Processing of Bromine Publications Henson, B.F., K.R. Wilson, and J.M. Compounds by Atmospheric Aerosols: Robinson, "A Physical Adsorption Relation to the Ozone Budget Model of the Dependence of C1ONO2 Heterogeneous Reactions," Geophys. Res. Lett. 23, 1021 (1996). Jeanne M. Robinson Henson, B.F., K.R. Wilson, and J.M. In this project we have studied the gous reactions and likely play a Robinson, "Porous HNO3(H2O) Ice adsorption of halogenated gases on significant role in ozone depletion in Films: Adsorption and Surface ice aerosols and the potential contri- the Arctic boundary layer. We use a Thermodynamics Measured by bution to ozone depletion. Before the nonlinear optical probe, second Second Harmonic Generation" discovery of the "ozone hole," these harmonic generation (SHG), to (submitted to J. Phys. Chem.). heterogeneous processes were ignored measure the thermodynamic behavior Robinson, J.M., B.F. Henson, and in atmospheric chemistry models. of porous ice films and adsorption of K.R. Wilson, "Second Harmonic Field measurements supported by bromine compounds on the ice. Our Generation Studies of Porous Ice laboratory experiments and modeling formalism allows us to measure the Films: Quantitative Measurement," have confirmed the pivotal role of adsorption isotherm for an adsorbate/ Nonlin. Opt. Mater. Fund. Appl. 1996 reactions of photoinactive (reservoir) ice system and quantify the adsorp- Tech. Dig., 11, 391 (1996). chlorine and nitrogen gases on ice and tion on these heterogeneous substrates nitric acid ice aerosols in the Antarctic in terms of the multilayer structure Wilson, K.R., B.F. Henson, JJ. Kim, polar vortex. It was subsequently and adsorbate coverage. We have used et al., "Equilibrium Thermodynamics recognized that heterogeneous SHG to measure the uptake of HBr by of HC1 Adsorption on Water Ice" processing on the background sulfuric water ice at low temperatures and to (211th American Chemical Soc. acid aerosols distributed worldwide at monitor the phase behavior of HBr Meeting, New Orleans, March 1996). mid-latitudes presented a potential hydrates as a function of temperature. threat for global ozone depletion. The adsorption isotherm shown here Attention is now turning to bromine resembles our results for HC1 adsorp- compounds that undergo the analo- tion at slow introduction rates.

Annealing Spectra 75 torr HBr on 0.5g Water Ice

130 180 230- 280 Temperature (K)

Adsorption Isotherm: HBr on H20 @18OK HBr adsorption into a porous water 4 T ice substrate. The upper panel shows the SHG intensity as a function of &= 2- temperature for a water ice with 0.7 monolayers HBr adsorbed. The lower panel shows an adsorption isotherm o> o -fc=«*f 5 10 15 for HBr at 180 K, which can be analyzed using Brunnaer-Emmett- COVERAGE HBr Teller multilayer adsorption theory.

84 Los Alamos FYI996 LDRD Progress Report Coronal Mass Ejections in the Solar Wind Publications Gosling, J.T., "Corotating and Transient Solar Wind Flows in Three John Gosling Dimensions," Annu. Rev. Astron. Astrophys. 34, 35 (1996). Coronal mass ejections (CMEs) are Our review of transient solar wind spectacular solar events in which flows showed that 3-D reconnection Gosling, J.T., "Physical Nature of the large amounts of material from the provides a logical framework for Low-Speed Solar Wind," in Robotic solar atmosphere are ejected into explaining a diverse set of solar and Exploration Close to the Sun: interplanetary space. The processes solar wind observations related to Scientific Basis, S.R. Habbal, Ed. that trigger the release of CMEs from CMEs. One new insight is that it is (American Institute of Physics, New the sun and the factors that determine the plasma beta (ratio of plasma to York, N.Y., in press). their sizes, their speeds, and their magnetic pressures) within a CME Gosling, J.T., and P. Riley, "The evolution in interplanetary space are that determines if 3-D reconnection Acceleration of Slow Coronal Mass only poorly understood. In this project will produce the nearly force-free Ejections in the High-Speed Solar we are studying CMEs in the solar structure characteristic of "magnetic Wind," Geophys. Res. Lett. 23, 2867 wind near Earth's orbit. clouds," which form an important (1996). Our overall goals are to distinguish subset (about one-third) of all CMEs and understand the physical processes observed in the solar wind near Gosling, J.T., M.F. Thomsen, et al., governing CME evolution in inter- Earth's orbit. "Observations of Magnetic planetary space and to learn how best We also found that -20% of all Reconnection at the Lobe to identify CMEs in solar wind CMEs previously identified in the Magnetopause," J. Geophys. Res. 101, plasma and magnetic field data. Of solar wind near Earth contain either 24765 (1996). particular interest is investigating the open or completely disconnected Roberts, D.A., and J.T. Gosling, "In role that three-dimensional (3-D) magnetic field lines, suggesting the Situ Measurement Requirements for a magnetic reconnection plays in presence of sustained 3-D recon- Solar Probe," in Robotic Exploration determining the overall magnetic nection in at least these events. Our Close to the Sun: Scientific Basis, topology of these vital interplanetary preliminary calculations show that the S.R. Habbal, Ed. (American Institute objects. We are analyzing and forces associated with rarefactions of Physics, New York, N.Y., in press). interpreting solar wind plasma and produced in front of slow CMEs are magnetic field data archived at Los insufficient to explain observed Alamos from a variety of space accelerations of such CMEs in the probes. solar wind.

Modeling Core-Collapse Supernovae our combined expertise in parallel computing and supernovae theory, we in Three Dimensions are beginning to carry out such simulations. We will then use the results to estimate the kick velocity Michael Warren imparted to neutron stars at birth, which has far-reaching implications at the heart of supernovae make them The deaths of massive stars in for models of gamma-ray burst a natural laboratory in which to test supernova explosions are the most sources. We have thus far extended an ideas about physics that are otherwise violent events ever witnessed by existing parallel, smooth-particle difficult to investigate on Earth. human beings. As a consequence, hydrodynamics code into a full- understanding core-collapse supemo- We have previously established that fledged supernova code. We have also vae represents a fascinating challenge the mechanism which powers begun developing a parallel, multidi- which requires the convergence of supernova explosions relies on large- mensional, mesh-refined, shock- such varied areas of expertise as scale convection driven by neutrino capturing method that should provide nuclear physics, neutrino transport, heating. However, determining the significantly improved simulation and hydrodynamics. In addition, the pattern of this convection demands capability. extreme conditions of density, three-dimensional simulations, which temperature, and gravity which reign have not yet been performed. Using

Individual Projects—Geoscience, Space Science, and Astrophysics 85 Deriving the Structure of and possible turbulent mixing below the solar convection zone. We are Presupernovae and Delta Scuti applying this code to model the more Stars Using Nonradial Oscillations rapidly rotating delta Scuti stars.

Publications Joyce Guzik Bradley, P.A., and J.A. Guzik, We are modeling the evolution and This year we updated and are now "Seismological Modeling of the Delta pulsation of luminous blue variables using a nonlinear hydrodynamics Scuti Star FG Vir," Bull. Am. Astron. (LBVs) and delta Scuti stars. The code to determine whether predicted Soc. 27, 1430 (1995). radial "strange" modes can grow to LBVs are massive stars and Type II Guzik, J.A., "What Have We Learned large amplitude and trigger LBV supernova progenitors, while the delta about the Solar Interior from Solar outbursts (see the second figure). We Scuti variables are slightly more Oscillations?" (The Sun and Beyond, compared observed and calculated massive than the sun. Both types of Ho Chi Minh City, Vietnam, October oscillation frequencies to derive stars pulsate in multiple radial and 23-27, 1995). nonradial modes that have significant stellar parameters for two delta Scuti amplitudes throughout the stellar stars, FG Vir and CD-24° 7599 (see Guzik, J.A., and P.A. Bradley, interior. We are improving the model the third figure). We participated in a "Models and Mode Identifications of physics and comparing predicted and very successful multisite observing the Delta Scuti Star FG Vir," Baltic observed pulsation properties to campaign for the delta Scuti star 4 Astron. 4, 442 (1995). CVn, which resulted in detection of constrain the interior structure of Guzik, J.A., A.N. Cox, and F.J. over 30 new frequencies. these stars (see the first figure). The Swenson, "The Last Few Microhertz," study of stellar interiors can contrib- In addition, we modified a two- Bull. Am. Astron. Soc. 27, 1454 ute to the understanding of fundamen- dimensional stellar evolution code to (1995). tal physics, such as equations of state handle convective envelopes present (EOSs) and opacities of dense in lower-mass stars and benchmarked Guzik, J.A., A.N. Cox, and FJ. plasmas, energy transport, and this code by calculating a rotating, Swenson, "Using Solar Oscillations to turbulent mixing. two-dimensional solar evolution Constrain the Equation of State and model. We used the hydrodynamic Low-Temperature Opacities," Bull. capabilities of this code to look for Astron. Soc. India 24, 161 (1996). rotation-generated shear instabilities Rogers, F.J., F.J. Swenson, and C.A. Iglesias, "OPAL Equation of State Tables for Astrophysical Applications," Astrophys. J. 456, 902 3 i 1 i (1996). 2.5 2 Soukup, M. S., and A.N. Cox, x "Theoretical Radial Pulsation 1,5 Properties of Massive Yellow : I \\ Supergiants," Bull. Am. Astron. Soc. Q 1 3 CT 28, 917 (1996). i£ 0.5 s 0 1 -0.5 o -1 The discrepancy between observed and calculated solar -1.5 oscillation frequencies vs calculated frequency for the low- 1 v\ degree (0, 1, 2, and 3) acoustic waves that travel through it -2 most of the solar interior. The solar model includes diffusive •o -2.5 settling of helium and heavier elements relative to hydrogen -3 and uses the latest opacity-library (OPAL) opacities and an U- analytical EOS developed by F Swenson (Los Alamos), F. o -3.5 Rogers (Lawrence Livermore National Laboratory), and A. -4 i i i Irwin. We can eliminate the remaining small discrepancy 2000 2500 3000 3500 4000 between observed and calculated frequencies by refining the Calculated Frequency (uHz) solar surface modeling.

86 Los Alamos FY1996 LDRD Progress Report 1.0 I I I

o 0.5 - 1CD o

0.0 o o / i / CO '-a -0.5 - i 1/

-1.0 I L I I I 0.0 1.0 2.0 3.0 4.0 5.0 6.0 Time (106 sec) Photosphere

Growth in surface radial velocity from hydrodynamic calculation of the LBV envelope model. This model represents a star of initial mass equal to 80 solar masses that has lost nearly half its mass because of an intense stellar wind, exposing layers where 50% of the original hydrogen has been converted to helium by nuclear fusion. Linear pulsation analysis shows that this model is unstable to radial "strange" mode pulsations. The model predicts that the kinetic energy of two modes, with periods of 7 and 15 days, more than doubles each period. Nonlinear analysis shows that for this model, the pulsation amplitude grows to about 100 km/sec (only about 1/3 escape velocity) before reaching a limiting amplitude.

1.50 1 j l ' 1 • 1 1.45 1.40 ~». N 1.35 - ^2.0 Ms - Vir © 1.30 s f —» \ 1.25 1 - N.9MQ • o / N s1.82Mo~ D-24 1.20 1.80 (Z=0.018>- 1.15 FGVir / s 1.10 1.05 / 1 1 1 1 | t , 3.95 3.90 3.85 3.80 3.75 3.70

Log Teff

Location in the Hertzsprung-Russell diagram (the log of the luminosity vs the log of the surface temperature) of best-fitting models for the delta Scuti stars FG Vir and CD-24° 7599, along with evolution tracks for 1.8, 1.9, and 2.0 solar mass models. Models of 1.9-2.0 solar masses and effective temperature 8200 K match most of the 13 reported oscillation frequencies ofCD-24° 7599. Models with effective temperature 7480 K, of either 1.8 or 2.0 solar masses, best match the 19 reported frequencies for FG Vir.

Individual Projects—Geoscience, Space Science, and Astrophysics 87 Magmatic Tritium compositions (water containing deuterium, oxygen-18, and tritium) to eliminate effects of meteoric contami- Fraser Goff nation and contamination by near- surface groundwaters. 3 Tritium ( H) is one of the reaction helium, mantle heat flow, and plate Targeted volcanoes for this past products that should be produced tectonics. year were White Island and Ruapehu during "cold fusion" in condensed The object of our work is to collect (New Zealand). We have not quite matter. We are trying to determine samples of high-temperature fumarole completed the data analysis for the whether anomalous quantities of condensates, thermal and nonthermal New Zealand samples, but we have tritium are universally present in groundwaters, precipitation, and fresh completed the analyses of samples magmatic waters from several volcanic products from one additional collected last year from Vulcano volcanoes of different magma types volcano to determine the tritium (Italy), Kudriavy (Russia), and and tectonic settings. The presence of content of its magmatic water. Our Panandayan (Indonesia) and found such tritium could provide indepen- approach is unique because we that their magmatic tritium is 0.0 dent evidence for cold fusion as a analyze water with three isotopic tritium units (T.U.). (1 T.U. = 3.193 potentially viable Earth process and pCi per kilogram oi water) After would require reevaluation of \isitinj. 14 volcanoes from 1988 accepted concepts on primordial through 1996, we conclude that

SUAS AGRIAS SPRINGS PLUG-DOME ANDESITE AND RELATED HYPA8YSSAL INTRUSIVE ROCKS, KFBB-1993 UCAMANCHA SPRINGS

ANDESITE FLOW, 1866 |D| ALTERED PORPHYRITIC DACITE

|FB| FUENTE BLANCA SPRINGS /VA?^ SUBVOICANIC AND HYTABYSSAL \£v!y INTRUSIVE ROCKS. PRE-1B66 GOLD-BEARING DOLOMITE-OUARTZ- SULFIOE-SULFOSAU VEIN VOLCANIC EDIFICE. PRE-1866 FLOWS. DOMES. PYROCLASTIC HOCKS. DEBRIS FLOWS. EPICLASTIC HOCKS MAGMATIC METEORIC PRECAMBRIAN-TERTIARY BASEMENT FLUIDS FLUIDS ..BOUNDARY OF POTENTIAL - PORPHYRY COPPER ZONE

Modified cut-away perspective drawing (viewed from the north) ofGaleras volcano, Colombia, showing the basic geology and configuration of the shallow hydrothermal system. Magmatic volatiles mix with young, near-surface groundwaters to form acid springs. Magmatic fluids discharging inside the volcano create conditions favorable for deposition of gold and copper. Magmatic fluids discharging at the summit mix with precipitation falling in the summit crater and cone. The resulting mixtures contain measurable tritium from the meteoric end-member but no detectable tritium from a deep source.

88 Los Alamos FYI996 LDRD Progress Report magmatic tritium is in all cases project also have application to Publications 0.0 T .U., subject to analytical and studies of natural cycling of meteoric Goff, R, "Vesicle Cylinders in Vapor- other errors. Thus, there are no tritium and of metals transport in differentiated Basalt Flows," J. identifiable magmatic tritium anoma- magmatic fluids, as well as for Volcanol. Geotherm. Res. 71,167 lies and no evidence for cold fusion in hazards monitoring at volcanoes. (1996). the deep Earth. The results of this Goff, F., C. Werner, C. Seibe, et al., "Geochemical Monitoring during

• Cold springs, wells, rain 1994-1995, Popocatepetl Volcano, B Cold streams -10 Mexico" (American Geophysical x Warm springs Union Fall Meeting, San Francisco, AA AguaAgrias -20 P Pandiaco Calif., December 15-19, 1996). Fe Iron-rich Magmatic Water -30 A Galeras fumaroles V Galeras rocks, 7/92 explosion • Other Galeras rocks -40 Rain <1/26/93)Q -50

-60 Most Galeras Streams -70

-80

-90 7 Plot of deuterium versus oxygen- (Xenolith) 18 for waters from Galeras -100 volcano. The fumarole condensates lie on a mixing line -110 between magmatic and meteoric end-members. The extrapolated -120 deuterium of the magmatic water -130 O= +7.37 ± 0.56 is about -35%o.

-140. -18 -16 -14 -12 -10 -8 (S18O<%c)

Plot of deuterium versus oxygen-18for Local waters from Galeras volcano. When the Meteoric tritium data for the fumaroles are Waters extrapolated to the oxygen-18 value for magma, the resulting magmatic tritium is 0.0 T.U. Rain (1/26/93) CO _ 65°C • g. Rain (1/13/93) A— BOX Boiling ^^Z^Fe (Respirador) Magmatic Deformes Tritium sO.O T.U. Besplima l^r -18 -16 -14 ^12^ ^10 -2

Individual Projects—Geoscience, Space Science, and Astrophysics 89 Minerals of Earth's Deep Interior the thermoelasticities of these materials and can be applied to modeling pressure-temperature David Schiferl systematics and mantle mineralogy.

The goal of this project is to gain a diffraction improves the absolute fundamental understanding of the accuracy in lattice constants over that Publications boundary between Earth's upper and obtained with powder diffraction by a Schiferl, D., and Y. Zhao, "High- lower mantle. The nature of this factor of 5 to 10. Pres sure/High-Temperature Diamond- boundary has been a major geophysi- We modified the DAC to ensure Anvil Cell System for Single-Crystal cal issue for the past two decades. stable high pressure at high tempera- X-Ray Diffraction" (to be published Specifically, we want to understand tures and observed seven points on the in Rev. Sci. Intrum.). the seismic velocity and density EOS of silicate perovskite. We also discontinuity at the boundary, which determined the pressure and tempera- Zhao, Y., D. Schiferl, and J.M. Zaug, lies at a depth of 670 km and has a ture derivatives of the bulk modulus "RSCU-SOS: A Rapid Intensity temperature of about 1900 K and a and thermal expansion for Searching and Centering Routine for Single Crystal Diffraction Studies at pressure of about 23 GPa. A phase orthoenstatite (MgSiO3) at up to change at this depth would represent a 1000 K at 1.5 GPa and at lower Simultaneous High Pressures and relatively small barrier to mantle temperatures with pressures up to Temperatures," /. Appl. Cryst. 29, 71 convection through the discontinuity, 4.5 GPa (see figure). These measure- (1996). but a compositional change would ments break previous records for Zhao, Y, R.B. Von Dreele, et al., "P- inhibit thermal convection throughout single-crystal diffraction at high V-T Data of Hexagonal Boron-Nitride the mantle. temperature and pressure and define a MBN and Determination of Pressure In our project, we are measuring new state of the art. and Temperature using Thermoelastic equation-of-state (EOS) parameters in In addition, we conducted large- Equation of State of Multiple Phases" mantle minerals as functions of high volume pressure diffraction experi- (to be published in High Pressure Res.). pressure and temperature using ments at up to 10 GPa and 1300 K single-crystal x-ray diffraction in a using a synchrotron x-ray radiation Zhao, Y, R.B. VonDreele, TJ. unique diamond-anvil cell (DAC). source. Experimental data on two Shankland, et al., "Thermoelastic Equation of State of Jadeite Measurements are made at up to materials, MBN and NaAlSi2O6 jadeite, 25 GPa and 1200 K. Single-crystal have improved our understanding of NaAlSi2O6: Energy-Dispersive Study of Low Symmetry and Multiple Phase Diffraction" (to be published in Geophys. Res. Lettr.).

850 0.69 Pressure dependence of the o thermal expansion ofMgSiO3. 1.23 I 840 — X - Open data points represent raw a pressure-volume-temperature _ i 5 Gf 2 ^-^•L52 data, with their pressures labeled >1.95 next to them. Solid points are 830 1.35 1.49 corrected data (using the 1.01 1.22 1.68 0 C5 thermoelastic equation of state) 1 9 2.48 ,i for two constant pressures: 1.5 820 s 3.28 • and 4.0 GPa. Data points c? , ir ^*- between these two constant U LU-*-^— pressures are corrected twice to 810 - 3.73 3.96 8- -^^ PC=4-OGpa both pressures; the dotted arrows 4.22 indicate the direction of 2- 4.52 correction. Two straight lines are 800 - - fit to obtain thermal expansions atP= 1.5 and 4.0 GPa. i i i i i i i i 300 400 500 600 700 800 900 1000 Temperature, K

90 Los Alamos FY1996 LDRD Progress Report Striation-lmage Monitoring of subset of the data that provided a clear indicator of instrumental effects. Plasmaspheric, L-Resolved In addition, we firmly established that the midnight sector is the Electrodynamics (SIMPLE) preferred site of plasmaspheric irregularities, with more day/night Abram Jacobson contrast during northern winter than during northern summer. There is a The plasmasphere is a region of One goal of this work is to develop striking correlation of the intensity relatively dense ionized gas in Earth's an entirely new approach to monitor- and incidence of these irregularities atmosphere, located in near-space ing how Earth's near-space environ- with increased levels of geomagnetic within a few Earth radii in geo- ment is affected by geomagnetic disturbance as measured by the Kp altitude, that is confined by Earth's disturbances, which are in turn related index. There is a prompt "turn-on" of magnetic field. Our project is aimed at to solar flares. This new method is the irregularities when the DST index detecting irregularities in the potentially two orders of magnitude plunges negative. plasmasphere using the electrical less expensive than existing means of phase of radio signals transmitted by monitoring near-space electric fields Publications geosynchronous satellites, which (such as incoherent-scatter radar and rotate with Earth over a fixed position polar-orbiting satellites) during Jacobson, A.R., R.C. Carlos, R.S. near the equator. The physics underly- geomagnetic disturbances. Massey, et al., "Total-Electron- ing this project is multiscale: the solar This past year has been one of Content Signatures of Plasmaspheric wind is the prime driver and energy enormous accomplishment and Motions," Geophys. Res. Lett. 22, source, the geomagnetic field is the encouragement. We succeeded in 2461 (1995). intermediate store of energy from the tracking three satellite beacons Jacobson, A.R., G. Hoogeveen, R.C. solar wind, and Earth's ionosphere simultaneously, significantly increas- Carlos, et al., "Observations of Inner and upper atmosphere are the electri- ing our ability to monitor Plasmasphere Irregularities with a cal load at the base of the geomag- plasmaspheric irregularities. In Satellite-Beacon Radio-Interferometer netic field. addition, we have better defined our Array," /. Geophys. Res. 101,19665 measurement error by examining a (1996).

Coupled Ocean-Atmosphere Model achieve temporal synchronization between the two regional models. System for Studies of Interannual-to- In the area of global modeling, we completed coupling the global ocean Decadal Climate Variability over the model constructed at Los Alamos North Pacific Basin with the global atmospheric model from the National Center for Atmo- spheric Research (NCAR); we also Chung-Chieng Lai completed a one-year simulation with several decades, and then use the the global COAM. To achieve This project will improve our results of this study to determine the coupling of the two models, we used understanding of fluctuations in effects of climate variability in the the "flux coupler" package developed precipitation (and, therefore, water North Pacific region on the precipita- at NCAR as part of the Climate resources) in the southwestern United tion over the Southwest. System Modeling Project. However, States. Only a coupled ocean- This year, we completed three we still need to improve the efficiency atmosphere model (COAM), like of the coupling process. ours, can track the path of water from major tasks. First, we built a meso- Finally, we designed the boundary oceans through the atmosphere to scale COAM for the west coast by interface for the global nested-grid land. The objectives of our project are taking advantage of an existing ocean models in cooperation with the to construct a global COAM, use the regional atmospheric model from the University of California, Los Angeles, model to explore climate variability University of California, Davis, and a where the North Pacific circulation over the North Pacific basin within a regional ocean model from Missis- model was developed and with period ranging from one year to sippi State University. However, we still need to define a consistent set of Mississippi State, where the Gulf of interface boundary conditions and to Mexico model was developed.

Individual Projects—Geoscience, Space Science, and Astrophysics 91 Particle Acceleration from Birn, J., M. Hesse, and K. Schindler, "MHD Simulations of Magnetotail Reconnection in the Geomagnetic Tail Dynamics," /. Geophys. Res. 101, 12939 (1996). Joachim Birn Birn, J., M. Hesse, M.F. Thomsen, et al., "Substorm Associated Ion One of the major consequences of accompanying figures show the ion Acceleration in the Dynamic the reconfiguration of the geomag- flux changes and ion distribution Magnetotail" (to be published in Proc. netic field associated with magneto- functions during an observed particle Third Intl. Conf. on Substorms). spheric substorms and the underlying injection and in the test particle magnetic reconnection process is the simulation. Birn, J., F. Iinoya, J.U. Brackbill, et acceleration of charged particles and The "injection region" inferred al., "A Comparison of MHD their injection into the ionosphere and from the test particles not only has a Simulations of Magnetotail the near-tail region of the magneto- sharp earthward boundary (the usual Dynamics," Geophys. Res. Lett. 23, sphere. The accelerated charged injection boundary) but also a sharp 323 (1996). particles in Earth's magnetosphere but ragged tailward boundary. The Birn, J., M.F. Thomsen, J.E. cause auroral brightening and may earthward portion of the enhanced ion Borovsky, et al., "Characteristic affect satellite safety and operations. flux can be traced to the enhanced Plasma Properties of Dispersionless We are investigating the mechanisms cross-tail electric field associated with Substorm Injections at of particle acceleration and heating the collapse and dipolarization of the Geosynchronous Orbit" (to be using self-consistent three-dimen- inner tail, whereas the tailward edge is published in J. Geophys. Res.). sional magnetohydrodynamic (MHD) closely associated with a magnetic simulations and by tracing test neutral line, the site of reconnection. Birn, J., M.F. Thomsen, J.E. particles in electromagnetic fields Borovsky, et al., "Plasma and obtained from these simulations. Energetic Particle Properties of Publications New MHD results indicate a much Dispersionless Substorm Injections at stronger, more rapidly rising electric Birn, J., and M. Hesse, "Details of Geosynchronous Orbit" (to be field in the region earthward of the Current Disruption and Diversion in published in Proc. Third Intl. Conf. on reconnection site, which has impor- Simulations of Magnetotail Substorms). tant consequences for the energy gain Dynamics," J. Geophys. Res. 101, Birn, J., M.F. Thomsen, J.E. and the increase in particle fluxes. 15345 (1996). Borovsky, et al., "Substorm Ion The energetic particle flux changes Birn, J., M. Hesse, and S.P. Gary, Injections: Geosynchronous estimated from the test particle orbits "The Role of Microprocesses in Observations and Test Particle Orbits" agree well with observations that Macroscale Magnetotail Dynamics," (to be published in J. Geophys. Res.). demonstrate rapid ion-flux increases in Cross-Scale Coupling in Space at energies above -20 keV but little Plasmas, Geophys. Monogr. Sen 93, change at lower energies. The 275 (1995).

ion injection 13 April 1990 Ion fluxes from test particle orbits 0.00 : i 5keV -1.00 j 20 keV fl ^ In J 1: -2.00 rv\ I 80 keV i ^_jS^, u ii|iy if -3.00 IgJ : -4.00 i ! : \ '\IU r '•] I? i : 1 180 keVi __^/' -5.00

-6.00

-7.00 :...:;....!....- . . , , i . , . , • 7:00:00 7:10:00 7:20:00 7:30:00 7:40:00 7:50:00 8:00:00 UT Ion flux increases observed during an injection at geosynchronous orbit (left panel) and obtained from test particle orbits integrated in the fields from an MHD simulation of the dynamic evolution of the magnetotail (right panel).

92 Los Alamos FY1996 LDRD Progress Report Hesse, M., J. Birn, M.M. Kuznetsova, Hesse, M., D. Winske, and J. Birn, Hesse, M., D. Winske, M. et al., "A Simple Model of Core Field "Hybrid Modeling of the Formation Kuznetsova, et al., "Hybrid Modeling Generation during Plasmoid and Structure of Thin Current Sheets of the Formation of Thin Current Evolution," /. Geophys. Res. 101, in the Magnetotail" (to be published Sheets in Magnetotail 10797 (1996). in Proc. Third Intl. Conf. on Configurations," /. Geomagn. Subs forms). Geoelec. 120,749 (1996).

ion distributions, 13 April 1990 ion distribution function from the simulation

105 e 0783 UT 0729 UT

103

102

10" 1 0-1

102 0.1 1000 10 100 1000 E (keV) Ion distribution functions for the previous figure; those observed during the injection (left panel) versus those calculated on the basis of the simulation (right panel).

Fluxes of Water and Energy in Physically Overall, this project demonstrated how spatial and temporal variations in Heterogeneous Environments fluxes of water and energy determine tight interrelationships between vegetation, soils, and climate in David D. Breshears semiarid environments. spatial neighborhood analyses that Fluxes of water and energy in the demonstrated how trees exploit near-surface environment are tightly canopy/intercanopy heterogeneity. Publications interrelated with the heterogeneous The spatial relations of trees reflect Breshears, D.D., P.M. Rich, and F.J. vegetation pattern that is a mosaic of spatial variability in fluxes of water Barnes, "Heterogeneity in Solar canopies of woody plants and and energy; our study is the first to intercanopy areas. Our objective was relate both of these fluxes with the Radiation and Soil Moisture Imposed to improve the predictability of these spatial pattern of a plant community. by Overstory with Intermediate interrelationships, which are relevant We developed a spatially explicit Closure" (submitted to Ecological to a variety of problems, including model for predicting near-ground Applications). global change, land management, and solar radiation and evaluated the Davenport, D.W., D.D. Breshears, et contaminant transport. Using spatial relative roles of tree cover, height, al., "Viewpoint: Sustainability of autocorrelation, we demonstrated that and spatial pattern for sites along a Piny on-Juniper Ecosystems: A vegetation overstory determines the grassland-forest continuum. We Unifying Perspective of Soil Erosion patterns of soil moisture and near- determined that a site's mean solar Thresholds" (submitted to J. Range ground solar radiation. The spatial radiation depended on the amount of Management). pattern of soil moisture varies groundcover and on tree height but temporally—intercanopy patches are was independent of the spatial pattern Martens, S.N., D.D. Breshears, et al., usually wetter than canopy patches, of canopy patches, whereas its "Scales of Above- and Below-Ground except after intense storms that variance depended on all three. Lastly, Competition as Detected from Spatial generate runoff. We developed a water we used our acquired knowledge and Pattern" (submitted to J. Vegetation balance model that predicted the our developed models collectively to Science). temporal shifts in soil moisture assess large-scale ecosystem re- between canopy and intercanopy sponses to those climate variations patches and conducted a suite of that also lead to accelerated erosion.

Individual Projects—Geoscience, Space Science, and Astrophysics 93 Flare Star Monitoring with a New Single-Photon-Counting Imaging Detector

Donald E. Casperson

The objective of this project is to characterize optical transient phenomena in the nighttime sky, most notably flares from red dwarf stars, using a single-photon-counting imaging detector presently under development in another project. In addition to providing photon-counting sensitivity, this detector, a microchannel plate with crossed delay-line readout (MCP/CDL), provides high spatial as well as high temporal resolution. This year, we achieved major improvements in the detector readout, resulting in significantly higher photon-counting rates; however, successive photocathode and vacuum failures in the sealed MCP/CDL units have so far prevented the collection of Sample image of a barred spiral galaxy from the NASA 3-m-aperture LMT. This any extensive data sets for our project. CCD camera image, courtesy of Mark Mulrooney (Lockheed-Martin/NASA/ As a result, we have shifted our Johnson Space Center), was obtained with the TDI method and represents 96 s optical transient measurement work to of total exposure. The V band stellar magnitude limit using this technique at the two other directions. LMT is approximately m - 22. First, we formed a collaboration with a NASA orbital debris tracking team that uses a charge-coupled device (CCD) camera at the 3-m- aperture Liquid Mirror Telescope (LMT) located in Cloudcroft, New Mexico. We have used a variant of this team's time-delay and integration (TDI) method for collecting stellar optical data with 1-s temporal resolution. The first accompanying figure shows an example of a barred spiral galaxy. The second figure shows stellar time-history tracks generated for this project. Both images were recorded with the CCD camera at the LMT. In another effort related to all-sky monitoring of optical transients, we have contributed to the ongoing development of a remotely operable observatory that will be capable of Raw CCD image of stellar time-history tracks generated at the LMT using a recording visible images (in both TDI variant of the TDI technique. For this image, the CCD sensor is rotated slightly and standard framing format) with relative to its position for the data of the previous figure. The 96-s integration of CCD cameras that are coupled to each stellar image is then uniformly distributed over a track of 100 CCD pixels, telescopes with programmable thus providing 1-s temporal resolution over each track. Lengthy TDI scans mounts. provide a very large database with which one can search for optical transients.

94 Los Alamos FYI996 LDRD Progress Report Close Encounters of Asteroids of atmospheric heights where an iron meteoroid would be captured into and Comets to Planets orbit by its energy dissipation in the atmosphere. However, stony meteoroids within a certain range of sizes Jack Hills can never be captured into bound orbit around Earth because they break We are studying the physics of tidal resources of these captured asteroids apart easily in the atmosphere at the encounters between comets, asteroids, for construction in space. heights needed to cause enough and planets. In this study, we are We have studied the tidal deforma- energy dissipation to allow capture. making heavy use of an existing, tion of asteroids using an N-Body Breakup greatly increases their robust few-body code to study code. Most asteroids make several dissipation cross section and causes encounters between the sun, planets, close approaches to Earth before they them to plunge to Earth. We have also and asteroids (including double impact it. Many of the asteroids that calculated the damage at ground level asteroids), and we are writing a code intersect the orbit of Earth have caused by such grazing colliders. to study the breakup of an asteroid by extremely elongated shapes. We have the tidal field of a planet. found that the tidal field of Earth can We believe that our work will produce elongations even larger than Publications explain a number of previously those yet observed if the asteroids Hills, J.G., and R. Carlson, "Statistics mysterious properties of asteroids have made close approaches to Earth. of Large Meteors Detected by whose orbits cross those of the inner If their shapes result from tidal Surveillance Satellites" (to be planets. We will also determine the deformation, they are likely composed published in Bull. Am. Astron. Soc). natural probability of capturing of loose blocks held together by asteroids into orbits around Earth and gravity. This structure will have to be Hills, J.G., and M.P. Goda, "Damage the other inner planets by the tidal allowed for in any effort to mitigate from the Impact of Small Asteroids interplay between the sun and planets their impact. and Comets" (submitted to Planet. (and for Earth, that between the moon We have used an improved atmo- Space Set). and Earth). In addition, we will spheric model for asteroid collisions Hills, J.G., and M.P. Goda, determine the probability of asteroid to study the capture of these objects "Meteoroids Captured in Earth Orbit capture—if the asteroid is double—by into bound orbits around Earth as the by Grazing Atmospheric Encounters" an exchange collision. We believe that result of grazing atmospheric colli- (submitted to Planet. Space ScL). this mechanism allowed Mars to sions. The model uses a spherical capture its small moons. The perma- atmosphere with a curve fit to the real Solem, J.C., and J.G. Hills, "Shaping nent capture of asteroids around Earth atmospheric density rather than a of Near-Earth Asteroids by Tidal would reduce the number of poten- plane-parallel atmosphere with Forces," Astron. J. Ill, 1382 (1996). tially dangerous collisions with Earth, exponential falloff in density. We have and it may allow us to utilize the found that there is a narrow window

Isotopic Prediction of Eruption Volume eruption volume and isotopic composition, we chose the samples to at Continental Volcanoes represent a range of eruption volumes. Samples from both volcanoes were analyzed for neodymium, strontium, Frank Perry and lead isotopic compositions at University of California, Berkeley, The goal of this project is to We obtained samples for two and for major- and trace-element forecast eruption volume at stratovol- stratovolcanoes, Pico de Orizaba in geochemistry at Los Alamos. Inter- canoes using the neodymium isotopic southern Mexico and Daisen in pretation of these data may lead to a composition of past eruptions. This southwest Japan. We selected these better understanding of what mecha- model is based on the premise that the volcanoes because their eruptive nisms control the magnitude of isotopic composition and volume of a history and eruption volumes are volcanic eruptions. magma are both controlled by influx reasonably well documented. In order of new magma into the system. to assess the correlation between

Individual Projects—Geoscience, Space Science, and Astrophysics 95 Experimental Cosmology: Publications Brainerd, T.G., B.C. Bromley, et al., The Early Universe "Velocity Dispersion and the Redshift-Space Power Spectrum," Wojciech Zurek Astrophys. J. Lett. 464, 103 (1996). Bromley, B.C., T.G. Brainerd, et al. We are using our N-body tree code Astrophysics. This finding is signifi- "On Cluster Cores and Redshift- on massively parallel supercomputers cant since velocity dispersion limits Space Power Spectra," in Clustering to test the standard cold dark matter had been previously used to rule out in the Universe: Proc. of the XXX (CDM) universe by conducting the model. Similarly, we have shown Rencontres de Moriond Meeting, S. numerical studies of structure forma- that the redshift-space power spec- Maurogordato, Ed. (Editions tion on the largest scales accessible to trum (also used to rule out CDM) Frontieres, Gif-sur-Yvette, France, observations. These phenomena have does not provide an unambiguous 1995). recently become accessible to constraint at small scales and is observations through both ground- consistent with the power spectrum Bromley, B.C., R. Laflamme, et al., based, very large telescope surveys measured in the Infrared Astronomi- "The Distribution of Matter around and dedicated satellites. cal Satellite galaxy catalog. The Luminous Galaxies," in Dark Matter Our simulations of the CDM model comparison between the numerical in Cosmology, Proc. of the XXXI on parallel supercomputers (see the experiments and the observations is Rencontres de Moriond Meeting first two figures) have shown that the not as straightforward as was usually R. Ansari, Ed. (Editions Frontieres, galaxy-galaxy velocity dispersion at assumed because of radial velocity Gif-sur-Yvette, France, 1996). small scales is consistent with results skewness (a significant scatter of velocity dispersions between different Bromley, B.C., M.S. Warren, and obtained from the sky survey done by W.H. Zurek, "Estimating Omega from the Harvard-Smithsonian Center for observation-sized samples) and the importance of galaxy clusters. Galaxy Redshifts: Linear Flow Distortions and Nonlinear Clustering," Astrophys. J. Lett. 475, 414 (1997).

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96 Los Alamos FY1996 LDRD Progress Report A high-resolution plot of every particle (about 250,000 of them) in l/50th of the total system (indicated by the small square in the previous figure), with the circles representing the location of galaxy halos.

<6v> = -280 km/s

Distribution of the number of pairs as a function ofpairwise radial velocity. The triangular shape of this histogram over a large range of radial velocity difference (8V) implies that the distribution is indeed exponential, and the fact that the diagram appears isosceles allows us to infer the velocity dispersion (av) from the slope.

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Individual Projects—Geoscience, Space Science, and Astrophysics 97 Cosmology with Massive Neutrinos Rencontres de Moriond Meeting, S. Maurogordato, Ed. (Editions Frontieres, Gif-sur-Yvette, France, Wojciech Zurek 1995).

The goal of this project is to Publications Bromley, B.C., R. Laflamme, et al., understand the implications for "The Distribution of Matter around Brainerd, T.G., B.C. Bromley, et al., cosmology of massive neutrinos and Luminous Galaxies," in Dark Matter "Velocity Dispersion and the Redshift is motivated by the recent evidence in Cosmology, Proc. of the XXXI for the neutrino mass obtained by the Space Power Spectrum," Astrophys. J. Rencontres de Moriond Meeting Liquid Scintillator Neutrino Detector Lett. 464, 103 (1996). R. Ansari, Ed. (Editions Frontieres, experiment. We are conducting Bromley, B.C., M.S. Warren, and Gif-sur-Yvette, France, 1996). numerical studies of cosmological W.H. Zurek, "Estimating Omega from Warren, M.S., and J.K. Salmon, models with a significant mass Galaxy Redshifts: Linear Flow "Abstractions and Techniques for fraction (20%-30%) attributable to Distortions and Nonlinear Clustering" Parallel N-Body Simulation," in light (several electron volt) neutrinos. (to be published in Astrophys. J.). Parallel Object-Oriented Methods We are focusing on two aspects of and Applications '96 (published on cosmic structure formation: (1) the Bromley, B.C., T.G. Brainerd, et al. the Web, http://www.acl.lanl.gov/ present-day distribution and structure "On Cluster Cores and Redshift- Pooma96/abstracts/warren.ps, 1996). of galaxies and clusters; and (2) the Space Power Spectra," in Clustering number density of protogalactic in the Universe: Proc. of the XXX objects at early times (redshift z of approximately 2). In this research, an objective is to run fast, parallel-supercomputer Global Climate Effects of the Emerging simulations of massive-neutrino Chinese Transportation System cosmogonies with a resolution that is an order of magnitude better than has been previously attempted. The speed Scott Elliott (more than 10 Gflops) and accuracy (-10 kpc spatial force resolution) of Nonpolluting bicycles have long precursor oxidation. We then corrobo- our code avoids problems of over- been the predominant means of local rated the estimates through two- merging that have been reported by surface transportation in the People's dimensional modeling of photo- others, enabling us to understand the Republic of China. A major automo- chemistry in springtime airflow off implications of massive neutrinos for bile manufacturing/importing effort the Asian land mass. cosmology, while setting cosmologi- has begun in the country, and plan- We expect the projected automobile cal constraints on neutrino mass. ning documents indicate that the fleet sizes to increase coastal and Chinese are making plans to acquire The main accomplishment this first remote oceanic ozone by tens of parts more than 100 million vehicles by year is the development of a high- per billion. We studied influences on early in the next century. We expect performance simulation code. Our the tropospheric aerosol system and both regional- and global-scale parallel treecode now evolves on the major greenhouse gas, carbon pollution effects, judging from what cosmological density fields with dioxide, only peripherally. Nitrogen the western world has experienced as periodic boundary conditions and oxides created during the vehicular a result of its large automotive fleets. hierarchical grids. Both are essential internal combustion process will to accurately model large-scale We are using the latest projections contribute to nitrate pollution levels neutrino free-streaming and formation for the manufacture of Chinese that will be measured in the Pacific. It of collapsed objects (galaxies and automobiles to calculate potential is also likely that soot and fugitive clusters) on small scales. In addition, pollution generation. For this investi- dust will increase and that a signifi- we completed a battery of analysis gation we are focusing on the oxidant, cant rise in global carbon dioxide codes, including redshift-space ozone. We have constructed emissions inputs will ensue. power-spectrum estimators and of the precursor species nitrogen gravitational lensing/ray tracers. oxides and volatile organics based on data for the eastern United States. We Publications first estimated ozone production from Elliott, S., et al., "Atmospheric Effects values that we measured for continen- of the Emerging Mainland Chinese tal/oceanic-scale yields relative to Transportation System" (to be published in J. Atmos. Chem.).

98 Los Alamos FYI996 LDRD Progress Report We investigated the signature of the Geometrodynamics in Support Lund-Regge metric on spaces of of Gravity Wave Astronomy simplicial three-geometries, which are important in some formulations of Raymond Laflamme quantum gravity. Tetrahedra can be joined together to make a three- dimensional, piecewise, linear The exciting feature of the emerg- geometry is modeled by a lattice of manifold. A metric on this manifold is ing field of gravity wave astronomy is four-dimensional triangles (simplices) specified by assigning a flat metric to that these waves will allow us to in direct analogy with the two- the interior of the tetrahedra and probe deeper into cosmic events than dimensional triangulated nature of a values to their squared edge-lengths. we can by any other known means. geodesic dome. Recent developments The subset of the space of squared While it is true that the parameterized in RC promise to make this truly edge-lengths obeying triangle and post-Newtonian calculations have independent tool numerically superior analogous inequalities is the simpli- brought us far toward supporting such as compared with the finite-difference cial configuration space. We have a probe, nevertheless, any integrated approaches. We are exploiting the derived the Lund-Regge metric on effect of cosmic coalescence will no unique geometric properties of RC this space and showed how it provides doubt require the numerical solution and applying this numerical technique the shortest distance between simpli- of Einstein's equations. to the analysis of astrophysically cial three-geometries among all We propose to solve Einstein's relevant gravity wave generation and choices of gauge inside the simplices equations by employing the innova- its subsequent detection by the Laser for defining this metric (Regge gauge tive and beautifully geometric Interferometry Gravitational Observa- freedom). approach known as Regge calculus tory (LIGO). (RC) in which the curved space-time We showed analytically that there is always at least one timelike direction in simplicial configuration space and provided a lower bound on the number of spacelike directions. We propose to further evaluate the signature numerically for the simplicial configuration spaces based on some simple triangulations of the three-dimensional sphere (S3) and Remote Sensing of Thundercloud torus (T3). For the surface of a four- simplex triangulation of S3, we find Electric-Field Airglow one timelike direction and all the rest spacelike over all of the simplicial Joseph Borovsky configuration space. For the triangulation of T3 around flat space, we find We predict that strong electric fields In Fort Collins, Colorado, we made degeneracies in the simplicial will enhance the cosmic-ray-produced a ground-based campaign in the supermetric as well as a few gauge background of airglow. The objectives summer of 1996 and obtained images modes corresponding to a positive of this project are to experimentally of sprites and sprite tendrils above eigenvalue. We propose to extend this confirm the electric-field enhance- thunderclouds and photometric data triangulation to a 600-cell model of a ment of the cosmic-ray-produced of the sprites. We used three intensi- three-dimensional sphere. At each airglow near thunderclouds with fied television cameras and one stage, we compared our results with photometers, measure the magnitude filtered photometer. Presently we are the known properties of continuum of the enhancement with photometers analyzing this data and preparing a superspace. and compare the measurements with manuscript. models, and spatially image the Publications regions of enhanced airglow around thunderclouds. These images might Hartle, J.B., W.A. Miller, and R.M. allow a simple, reliable prediction of Williams, "Signature of the Simplicial lightning. Supermetric" (submitted to Class. Quantum Grav.).

Individual Projects—Geoscience, Space Science, and Astrophysics 99 Accretion onto Black Holes: Publications Bromley, G.C., K. Chen, and W.A. The Power-Generating Mechanism Miller, "Line Emission from an Accretion Disk around a Rotating Warner Miller Black Hole: Toward a Measurement of Frame Dragging," Astrophys. J. Most objects in the observable the evolution from the early universe 475, 57 (1997). universe have a reasonable explana- to star formation. We have made Bromley, B.C., K. Chen, and W.A. tion in terms of physics, although the progress in this understanding. Miller, "Rotation of the Supermassive details in depth may be missing or Black Hole in MCG-6-30-15" inconsistent. The outstanding few for (submitted to Astrophys. J.). which the basic concept is still elusive are gamma-ray bursts and the combination of quasars, so-called active galactic nuclei (AGN), and a.-0.07 their associated collimated radio Lyman a Cloud sources or jets. Our project is directed i= 0.001 a/cm2 towards a consistent model of AGN contraction =! and their jets. The most likely ex- Bar Instability planation of AGN is accretion onto a black hole from a Keplerian accretion =3/2 disk, which is almost a unique explanation of the frequently observed, double-peaked, ultraviolet emission lines due to near-relativistic velocities in the disk. We emphasized the physical Faster rotation relationships among the various i contraction phenomena: accretion disks, quasars, Tidal torque black holes, collimated radio sources, transfers angular and galactic dynamos. Previously, momentum these topics had been only weakly related without explicit cause and effect. We have constructed a model Contraction Accretion Disc and merger of the physical evolution from large, = 107 primordial density perturbations to X>QA "damped" Lyman-alpha clouds, to galaxy formation, to black holes, jets, Thickness = x = and the galactic dynamo. We have Gravitational Black Hole lOtoioog/cm2 derived the general relativistic Separation distortions of radiation emitted from close to the black hole, thereby dJ/J = dM/M Thickness obtaining a new observational test of J = M » vR KBI/2 / p . ,1 .-. v = M/R = 2 -1 the central engine. See the accompa- Otential x = M/R oc M' const J if Kep t = 100,M=10 nying two diagrams and the image for .-. M <* R exemplary information about the 12 AGN model. The collapse of a Lyman-alpha cloud of about 10 M@ (M@ = solar mass). The cloud is subject to barlike instabilities that form the bars during collapse and cause The physics of accretion disks, the the bars to break up into smaller bars. The smaller bars collapse further and rotate astrophysical dynamo, and magnetic faster. The mass of the arms of the smaller bars then torque the larger mass (m) at reconnection are the least understood larger radii of the larger bars, and an exchange of angular momentum takes place. physical phenomena in astrophysics. The angular momenta (J) scales such that dJ/J - dm/m. Then, the Keplerian They are still less understood in the velocity of the orbits of it is a constant. This constant velocity, independent of general relativistic field close to the radius, is what is observed for almost all galaxies and leads to what is called aflat black hole. This lack of physical rotation curve and the prediction of dark matter. This scaling also leads to the mass understanding frustrates a quantitative 8 (10 M&) at which an accretion disk forms at the center of the galaxy; M@ is what evaluation of observations that define is needed to make the massive black hole.

100 Los Alamos FY1996 LDRD Progress Report Stars that continuously collide 4 Disk Dynamo (10 times) with the accretion disk Expanding collision plume (described in the previous figure) (Broad emission lines) before disruption. These collisions rotated trapped explain the "broad emission lines" toroidal flux observed from quasars. Each collision makes a large plume of matter torn lose from the disk that will rise far above the disk. This plume will entrain any toroidal magnetic flux embedded in the PoSloidal quadrapole disk. The expanding plume increases its bias fie Accretion moment of inertia and so will rotate disk more slowly than the rotating frame of the disk. This relative rotation of the plume and the disk twists any entrained magnetic flux, giving rise to the "alpha" effect in the alpha-omega Black hole Inner radius dynamo. The omega deformation is the at6M shear in the rotation rate of matter as a function of the radius of a Keplerian disk. This dynamo should make enough magnetic flux in the age of the disk, 10 8 years, to fill the galaxy with the 6 observed galactic field of 3 x lOr G. Star in orbit around Black hole

Image of a geometrically thin and optically thick accretion disk around a maximally rotating black hole of mass M. The inner radius and outer radius are at 1.25 M and 10 M, respectively. This accretion disk is viewed at a 75° inclination. The false-gray-scale contour map indicates the ratio of observed frequency to emitted frequency; the dark, oval, shaded region at the top represents blue shift, and the bands around the radius indicate a red shift. The white (saturated) patch superimposed on the map contains the zero-frequency-shift contour.

Individual Projects—Geoscience, Space Science, and Astrophysics 101 Thermal Rocketing and the Laser on our model predictions. The resulting code will then be used to Geodynamic Satellite (LAGEOS-I) model the new optical-spin data. By predicting how thermal forces will Warner Miller cause the satellite's orbit to change, the code will predict the future LAGEOS-1 is the most accurately Of the five dominant sources for orientation of the satellite. tracked satellite in orbit. It is a totally error in measuring Earth's frame- This year, we completed the first passive, dense, spherical satellite dragging effect, the largest one two major tasks, and we used the code covered with 426 retroreflectors, involves interaction of the thermal to provide the first numerical model which cause laser light to be reflected forces on the surface of the satellite of the spin dynamics of LAGEOS-1. and returned along paths parallel to (or thermal rocketing) and the The results were consistent with the those of the corresponding incident influence of such interaction on the observations made at the University rays. Besides its great utility in nodal precession. The objective of our of Maryland. In particular, the drift of measuring the length of Earth's day project is to enhance an already the spin axes of LAGEOS-1 toward and the polar wobble, this satellite can available code developed at Los the North Pole was correctly modeled be used to measure, for the first time, Alamos to fit new optical-spin data for the first time. In addition, our code the general, relativistic frame- recently obtained at the University of predicts a spin-orbit resonance phase dragging effect of Earth. This frame- Maryland. that can dramatically affect the dragging effect causes the inertial Enhancing our code involves three orientation of the satellite. frames surrounding Earth to precess important tasks: (1) creating a more Our current code (including the and is the gravitational analogue of a realistic model of Earth's magnetic enhancements completed this year) is dipole magnetic field generated by a field, (2) including the tidal preces- more advanced than any other in the rotating current of charges. sion on the line of nodes of the field. It will serve as the new spin- satellite, and (3) estimating the effect dynamics model for future LAGEOS of the true geometry of LAGEOS-1 satellite missions.

Plasmasphere Refilling: New Numerical Gary, S.P, V. Vasquez, and D. Winske, "Electromagnetic Proton and Observational Tools Cyclotron Instability: Proton Velocity Distributions," /. Geophys. Res. 101, 13327 (1996). Dan Winske Gary, S.P., L. Yin, and D. Winske, The outflow of plasma from the incorporated these tools in a "Electromagnetic Proton Cyclotron ionosphere and its interactions within multispecies kinetic model of the Instability: Heating of Cool the inner regions of the magneto- outflow process. We also investigated Magnetospheric Helium Ions," Ann. sphere remain important problems in electromagnetic instabilities in the Geophys. 14, 1 (1996). space physics. While outflow is a outer magnetosphere to understand continuous process, it becomes even their contribution to the heating of Jones, M.E., D.S. Lemons, RJ. more important after geomagnetic upflowing protons and minority ions Mason, et al., "A Grid Based substorms, when magnetic field lines (such as helium). In addition, we have Interparticle Collision Model for PIC that have been vented of plasma are used new observational techniques to Codes,"/ Comput. Phys. 123,169 reconnected and the empty flux tubes analyze low-energy plasma data from (1996). are refilled with outflowing plasma. satellites in geosynchronous orbit and Lemons, D.S., J. Lackman, et al., The purpose of this project is to to assess the effect of a spacecraft's "Noise-Induced Instability in Self- develop new computational, theoreti- electric potential (typically a few Consistent Monte Carlo cal, and observational tools to study volts) on these data. Calculations," Phys. Rev. E. 52, 6855 the dynamics and heating associated (1995). with the plasma outflow and refilling processes. Publications Miller, R.H., C.E. Rasmussen, M. R. Combi, et al., "Ponderomotive We developed new numerical tools Gary, S.P., M.F. Thomsen, et al., Acceleration in the Auroral Zone: A to model the transition from colli- "Electromagnetic Proton Cyclotron Kinetic Simulation," /. Geophys. Res. sional plasma flow at low altitudes Instability: Interactions with Protons," 100,23916(1995). (-200 km) to collisionless behavior at J. Geophys. Res. 100, 21961 (1995). high altitudes (-4000 km) and

102 Los Alamos FY1996 LDRD Progress Report Nuclear and Particle Physics

Time-Reversal Tests in separated nB. These cells are needed for work with cold neutrons because Polarized Neutron Reactions the absorption cross section of natural boron for low-energy neutrons is J. David Bowman large. We have measured the polarization of neutron beams polarized by 3 The goal of this project is to collisions. In order to use these He with an accuracy of 1% by using develop cells of polarized 3He to use polarizers and analyzers in tests of the parametric relationship between as polarizers and analyzers of neutron time reversal, it is necessary to the transmission of neutrons through spin. The interaction of polarized 3He construct cells, polarize the 3He, and the cells and their polarization. We with neutrons is highly spin depen- measure the polarization of the have developed the apparatus and dent. Neutrons that have their spin neutrons after passage through the techniques needed to improve the parallel to the 3He polarization are cells. accuracy to 0.1%. The accompanying 3 absorbed. The He nuclei are polar- We have built the apparatus needed figure shows the measurement ized when cells containing rubidium to produce cells of polarized 3He. This apparatus. vapor are illuminated with circularly apparatus incorporates diode lasers, polarized light from diode lasers. The optics, Helmholtz coils, nuclear Publications valence electron in the rubidium atom magnetic resonance pickup coils, and absorbs the laser light and becomes lock-in amplifiers. We are developing Bowman, J.D., and Y. Masuda, "Time polarized. The atomic polarization is cells in which the natural boron in the Reversal Tests in Neutron-Spin 3 transferred to the He nuclei by glass is replaced by isotopically Optics" (submitted to Phys. Rev. Lett.).

source beam background He-3 cells: neutron monitor wheel - polarized detector - unpolarized

CZZ3 T collimator

Apparatus to measure precisely the polarization of a neutron beam prepared by a 3He polarizer. The Manuel Lujan Jr. Neutron Scattering Center neutron source produces a short, intense pulse of neutrons having a broad range of energies. The neutron energy is precisely measured by observations of the time it takes each neutron to reach the detector, located 56 mfrom the source. The polarized 3He cell and a dummy cell are alternately placed in the beam. The ratio of transmissions, R(0), is measured with the 3He cell unpolarized. The 3He cell is polarized, and the ratio R(p) is measured. The polarization of the neutron beam, P, is then obtained as P = [1+{R(O)/R(p)}2]1/2.

Individual Projects—Nuclear and Particle Physics 103 Exploring and Testing the Dorey, N., V.V. Khoze, and M.P. Mattis, "Multiinstanton Calculus in Standard Model and Beyond N-2 Supersymmetric Gauge-Theory," Phys. Rev. D 54, 2921 (1996). Geoffrey West Dorey, N., V.V. Khoze, and M.P. Mattis, "Multiinstanton Check of the In this project we are primarily Publications Relation between the Prepotential-F working to understand, and ultimately Anglin, J., and S. Habib, "Classical and the Modulus-U in N=2 Susy to explore, the limitations of the Dynamics for Linear-Systems: The Yang-Mills Theory," Phys. Lett. B universally accepted Standard Model Case of Quantum Brownian-Motion," 390, 205 (1997). of elementary particles, which incorporates their strong and Modern Phys. Lett. A 11, 2655 Dorey, N., V.V. Khoze, and M.P. electro weak interactions. As an (1996). Mattis, "A 2-Instanton Test of the outgrowth of that, we are investigat- Bender, CM., F. Cooper, and P.N. Exact Solution of N=2 Super- ing possibilities for unifying all of the Meisinger, "Spherically Symmetrical symmetric QCD," Phys Lett. B 388, fundamental forces of nature, includ- Random-Walks . 1. Representation in 324 (1996). ing gravity. We anticipate that such Terms of Orthogonal Polynomials" Habib, S., E. Mottola, and P. frontier research will have phenom- Phys. Rev. E 54 (1), 100 (1996). Tinyakov, "Winding Transitions at enological implications for prospec- Finite Energy and Temperature: An tive programs and experiments. Cooper, R, Y. Kluger, and E. Mottola, "Anomalous Transverse-Distribution 0(3) Model," Phys. Rev. D 54 (12), Last year we worked on the of Pions as a Signal for the 7774 (1996). unification of the concepts of scaling Production of Disoriented Chiral," and fractals with the renormalization Lampert, M.A., J.F. Dawson, and F. Phys. Rev. C 54 (6), 3298 (1996). group. This year we extended our Cooper, "Time Evolution of the work to give a fractal description of Dorey, N., and M.P. Mattis, Chiral Phase-Transition during a the nucleon in a generalized quantum "Lagrangians, to Chiral Bags, to Spherical Expansion," Phys. Rev. D chromodynamics (QCD) parton Skyrmions with the Large-N-C 54 (3), 2213 (1996). model to biophysical systems such as Renormalization-Group," Phys. Rev. the cardiovascular and respiratory D 52, 2891 (1995). systems. We showed how duality in supersymmetric QCD follows from nonpertubative instanton configura- L3 Physics at the Z Resonance tions. We estimated the masses of light quarks using lattice QCD—our and a Search for the Higgs Particle estimates are considerably smaller than the values commonly used and W. Kinnison have important implications for the charge-parity-violating parameters. This project is a study of the information and analysis techniques Also this year, we continued to Standard Model of electroweak for several components of the L3 explore the interface of quantum and interactions using the L3 detector of detector including the "z chambers," classical chaos based on our discovery the Large Electron-Positron Collider which had never before been used of semiquantum chaos, and we (LEP) at the European Center for successfully to analyze L3 data. continued work on the conformal Nuclear Science. During the reporting Additionally, we used the silicon anomaly, proving the effects of the period, we developed a new method microvertex detector—which Los theory. We wrote several major of vertex finding that is applicable for Alamos had a major role in propos- reviews, some in response to solicita- most colliding-beam, high-energy ing, designing, building, and commis- tions. We were also invited to give physics experiments, and we used the sioning—for its first time in making a talks on our work at many major methodology to analyze L3 data for a complete physics analysis. Both the institutions worldwide as well as at published paper on Rb, which is a improvements in the overall analysis international conferences and work- measure of the amount of b-quark of L3 data and the specific new shops. production in hadronic decays of vertex-finding algorithms that we the Z°. developed are now being used by the To carry out the analysis, we entire L3 collaboration in many new invested a considerable amount of physics analysis projects, including effort in improving the alignment b-meson tagging, which is required for the Higgs meson search at LEP.

104 Los Alamos FY1996 LDR.D Progress Report Neutrinos and Theory of Weak surrounding a central cloud. Because the effective masses of the neutrinos Interactions may become equal and opposite in the regions in which the scalar field strength is rapidly varying, enhance- Joseph Carlson ment of neutrino-mixing oscillations may occur in such regions. We are studying low-energy extensions of the Standard Model by measurements of parity violation in determining observables where the nuclear systems, astrophysical effects of delta are suppressed. In the Publications reactions involved in solar neutrino Kobayashi-Maskawa model, CP- Goldman, T, "Source Dependence of production, neutrino interactions, and violating effects in beta decay (and in Neutrino Oscillations" (to be time-reversal violation in extensions other semileptonic processes) arise published in Phys. Lett. B; also to the Standard Model. also only in second order in the weak available from the LANL E-Print interaction. Parity Violation in Few-Body archive at http://xxx.lanl.gov as We have calculated the contribution Systems. We are analyzing the document hep-ph/9604357). of delta to the T-odd D- and R- prospects for measuring the parity- correlations in beta decay. These Herczeg, P. "Searches for T-Odd nonconserving asymmetry A in correleations are time-reversal-odd polarized neutron-plus-proton Interactions in Nuclear Processes," in radiative capture at the Los Alamos scalar products of the momentum of Dark Matter in Cosmology, Clocks, the electron and neutrino and the and Tests of Fundamental Laws, Proc. Neutron Science Center (LANSCE). 12 The goal of the experiment is to nuclear spin. We find D = 10~ and of the XXX Rencontre de Moriond, B. R = 10~14, compared with the best Guiderdoni et al., Eds. (Editions extract a definitive value for the weak 3 pion-nucleon coupling constant. present experimental limit of 10" . We Frontieres, Gif-sur-Yvette, France, Experimental work to date has have calculated D and R also for the 1995), p. 477. theta-tenn in the quantum chromody- produced only upper limits to this Herczeg, P., "A Note on Limits on namics Lagrangian, a second source coupling. New Interactions from the 7t—w(e)/ of CP violation in the Standard We have calculated the parity- jr—>(iv Branching Ratio," Phys. Rev. Model. With the present experimental conserving contributions to A, which D 52, 3949(1995). limit for theta, we obtain D =10~14 and had been tacitly assumed to be R = 1012. The small values of D and Herczeg, P., "Theoretical Aspects of negligible. We have shown that R in the Standard Model leave a large Searches for Time Reversal in Nutron experimental "tricks" are required to Transmission," in Parity and Time suppress this contribution to A below window in which to search for new the 108 level sought in our experi- types of CP-violating interactions. We Reversal Violation in Compound ments. We have also performed a have also investigated scalar-type, Nuclear States and Related Topics, microscopic analysis of parity CP-violating, muon-quark charged- J.D. Bowman and N. Auerback, Eds. violation in the transmission of current interactions in extensions of (World Scientific, Singapore, in polarized ultracold neutrons through the Standard Model These interac- press). tions contribute to T-odd observables helium. At these energies, the parity- Herczeg, P., "Time Reversal Violation in muon capture, which provide violating neutron-neutron interaction in Nuclear Processes," in Symmetries information complementary to that results in a spin rotation in the and Fundamental Interactions in provided by nuclear beta decay. polarized neutrons. We performed Nuclei, W.C. Haxton and E.M. microscopic five-body calculations of Neutrino Properties and Interac- Henley, Eds. (World Scientific, neutron-alpha scattering using tions. We extended our theory of an Singapore, 1995), p. 89. realistic two- and three-nucleon additional scalar interaction to forms Lowe, J., B. Bassalleck, H. Burkhardt, interactions. We continue to find that involving three neutrinos. The et al., "No Lambda Oscillations" (to the pion-exchange term is dominant, additional coupling introduced does be published in Phys. Lett. B; also but with the opposite sign to that not alter the successful phenomenol- available from the LANL E-Print predicted in simple models. ogy of the Standard Model. We find archive as document hep-ph/ that there is a repulsive effect from the Time-Reversal Violation. The most 9605234). scalar field of a large vacuum-mass economical explanation of charge- neutrino on the local density of a light Stephenson, G.J., T. Goldman, and conjugation parity (CP) violation in vacuum-mass neutrino. The result is B.H.J. McKellar, "Neutrino Clouds" the Standard Model is given by the that the neutrino clouds we found (to be published in Phys. Rev. D; also phase delta of the Kobayashi- previously may have a complex available from the LANL E-Print Maskawa model. One can search for internal structure, such as consisting archive as document hep-ph/ additional CP-violating interactions in of spherical annuli (with gaps) 9603392).

Individual Projects^Nuclear and Particle Physics 105 Weak Interaction Measurements with We have taken two steps to ensure high trapping efficiency. The first step Optically Trapped Radioactive Atoms is to use a special nonstick octa- decyltrichlorosilane (OTS) dry-film coating on the glass trapping cell to David Vieira prevent the "sticking" of alkali species to the walls. Using the OTS- The main objective of our project is atoms. A magneto-optical trap (MOT) coated glass cell shown in the second to develop the technology that will consists of six circularly polarized, figure, we have measured a trapping ultimately allow a high-precision test counterpropagating laser beams, efficiency of 20% (see the third of electroweak interactions in atomic which, in combination with a pair of figure). This efficiency exceeds nuclei. To achieve this, we are anti-Hehnholtz coils, enable the currently published trapping efficien- focusing our efforts on the beta- cooling and trapping of atoms. A cies by a factor of 3 and reflects the asymmetry measurements of polar- high-intensity MOT can easily trap improved trapping geometry of our ized S2Rb (t = 75 s). The key 1010 atoms out of the vapor state (see 1/2 MOT. The second step involves gas- technology needed to undertake this the first figure); however, the trapping free sample loading using a mass- work is the efficient optical and of radioactive atoms requires that the separator ion implantation and release magnetic trapping of radioactive trapping process also be efficient. method. To this end, we have recently coupled a MOT to an existing, and now upgraded, mass separator. We

An infrared picture of a fluorescing cloud of~10w cesium atoms trapped in a high-intensity, magneto-optical trap. The pancake-shaped cloud is approximately 15 mm in diam x 10 mm thick.

A picture of a dry-film-coated glass cell (50-mm cube) with two remotely controlled glass valves used in the MOT measurements of trapping efficiency. The valve on the left is connected to a cesium reservoir, and the valve in the background is connected to a 20-L/s ion pump.

106 Los Alamos FY1996 LDRD Progress Report have made good progress in implant- ing and releasing stable rubidium 7 species, and the high-efficiency close Cs reservoir trapping of 82Rb is near at hand. 6

5 close valve Publications to pump & 8 4 drop £*toms Vieira, D.J., R. Guckert, D.W. § Preston, et al., "Parity Non- $ 3 conservation Measurements in Radioactive Atoms: Experimental 2 Developments," in Proc. 4th Int. Symp. on Weak & EM Interactions in 1 Nuclei, H. Ejiri, T. Kishimoto, and T. Sato, Eds. (World Scientific, 0 Singapore, 1995), p. 97. 10 Guckert, R., E.P. Chamberlin, D.W Preston, et al., "Coupling an Optical Trap to a Mass Separator" (to be published in Nucl. Instrum. Meth. Phys. Res. B).

Results of fluorescence-derived efficiency measurements. The upper trace in the upper figure shows the trap filling as the valves to the cesium reservoir and ion pump are both open. At 5 s, the valve to the cesium reservoir is closed, and the fluorescence signal drops as atoms are slowly lost from the trap and untrapped cesium atoms are pumped out. At 7 s, the fluorescence signal is dominated by the number of trapped atoms, and the height of this signal measures their number. The trap is then turned off by shuttering the trapping laser light and turning off the magnetic field. At 7.5 s, the trap is turned back on and it refills. The relative height of the fluorescence signals measures the trapping efficiency. The bottom trace in the upper figure measures the background fluorescence signal obtained when the magnetic field is reversed in the nontrapping direction. The bottom figure shows the differences between the two traces given in the upper figure. A 20% retrapping efficiency is determined.

Individual Projects—Nuclear and Particle Physics 107 Neutrino Physics at Fermilab expected signal and background rates; and (3) design and simulation of a detector. Our baseline design for the Fred Federspiel neutrino production facility has met its design goal of providing a pure The Los Alamos liquid scintillator at Los Alamos. We are investigating muon-neutrino beam with contamina- neutrino detector (LSND) has recently the application of this new technology tion less than 0.5% electron neutrinos. reported strong evidence for neutrino to particle physics detectors. This The calculation of background rates oscillations (and, hence, neutrino promising new idea could potentially has allowed us to establish the mass). If verified, this result will have revolutionize the field of neutrino following particle identification profound consequences for nuclear physics by enabling the construction requirements for the detectors: fewer and particle physics, cosmology, and of massive, highly segmented than 0.1 % of muons along with fewer astrophysics. We plan to carry out an detectors at a cost of -100 times less than 1% of pions may survive experiment at Fermilab to verify the than a similar-sized, conventionally electron selection criteria. Now that LSND result and accurately determine instrumented detector. we have established these design the parameters of the oscillations. Our progress to date has been in goals for the detector, we are pursuing There has been considerable recent three areas: (1) design of a neutrino the development of capable detector progress in the development of high- production facility; (2) calculation of technologies. speed, charge-coupled detector arrays

A Continuous Watch of the Northern Sky bursts will continue when Milagrito comes on-line. At this time, the above 40TeV with the CYGNUS Array analysis of the CYGNUS data shows no evidence of UHE emission from any source. Cyrus Hoffman We have also used the pools at CYGNUS to experimentally test the We have been using the CYGNUS We could not continue the CYG- concept of searching for gamma-ray air-shower array to search for epi- NUS experiment after the repair emissions from gamma-ray bursts by sodes of ultra-high-energy (UHE, because a more powerful detector, monitoring the single rates of indi- >40 TeV) gamma-ray emission from Milagrito (a prototype for the Milagro vidual photomultiplier tubes in a astrophysical objects. Given that such detector), had been installed. water Cerenkov counter. The results emissions are only sporadic, it is Milagrito will be available for data of these tests are encouraging. If important to keep a continuous watch taking later in the fall of 1996. successful, this method should be on the sky. The array operated well Because of its lower energy threshold applicable to both Milagrito and during most of FY 1996 to allow our (-500 GeV), this new detector is Milagro and should enhance the research, but in August 1996 a fatal much more sensitive than CYGNUS sensitivity of these detectors to hardware error occurred in the to gamma-ray emission from astro- emissions from gamma-ray bursts. CYGNUS data-acquisition computer, physical objects; our sky watch shutting down the experiment. experiment for UHE gamma-ray

Neutron Measurements to Optimize characterize the experimental apparatus and approach and to take prelimi- Treatment of Cancer Patients with Fast nary data. This capability will put us in a good position for proposing a Neutrons larger experimental program in FY 1998. Some interest has been shown John Ullmann and Robert Haight in our capabilities by the Accelerator Production of Tritium program. Data for the interaction of neutrons produced by neutron interactions in the energy range up to 150 MeV. A with biological elements are impor- Publications tant for radiation therapy and radia- new beam line and new electronics tion protection dosimetry. Data for have been developed at the Weapons Chadwick, M.B., P.M. DeLuca Jr., carbon, and especially oxygen, are Neutron Research facility of the Los and R.C. Haight, "Nuclear Data greatly needed. We have set up a Alamos Neutron Science Center Needs for Neutron Therapy and system for detecting charged particles (LANSCE). We are beginning to Radiation Protection" (to be published in Radiation Protection Dosimetry).

108 Los Alamos FY 1996 LDRD Progress Report Antiquark Distributions in the Proton having at least six months of beam, which will allow us to achieve the sensitivities for a definitive measure- Jen-Chieh Peng ment of flavor symmetry of sea quarks in the proton. The study of quark and antiquark a high-resolution, high-rate magnetic distributions in the nucleon has been a spectrometer. Other experiments do Publications major endeavor in nuclear and particle not match the expected statistical physics. Results from a recent deep- accuracy and range of coverage in x Melnitchouk, W, and J.C. Peng, inelastic scattering experiment (fraction of nucleon momentum "Large-x d/u Ratio in W-Boson suggest the surprising possibility that carried by the antiquark). E866 will Production" (submitted to Phys. the up-and-down antiquark distribu- have sufficient accuracy to test all Lett). tions in the proton are not symmetric. theoretical models that predict Peng, J.C., and D.M. Jansen, "Probing We can directly determine the asymmetric up-and-down antiquark d/u Asymmetry in the Proton Via W antiquark distributions in the proton distributions. We will also obtain and Z Production," Phys. Lett. B 354, by comparing the Drell-Yan cross additional data on the production of 460 (1995). sections on hydrogen versus deute- J/\\f and v resonances (bound states of rium targets. A new experiment heavy quarks) in E866. Peng, J.C., D.M. Jansen, and Y.C. (E866) is in progress at Fermilab to The E866 has been taking data Chen, "Probing the d/u Asymmetry in carry out such measurements. since September 1996. Preliminary the Proton Via Quarkonium We are performing E866 with an results show that the apparatus is Production," Phys. Lett. B 344,1 800-GeV proton beam, together with working very well. We anticipate (1995).

Nucleon-Nucleon Data Analysis Publications McNaughton, M.W., K.H. Michael W. McNaughton McNaughton, G. Glass, et al., "np- Elastic Analyzing Power AnO at 485 The objective of this project was nucleon nucleus data obtained at and 788 MeV," Phys. Rev. C 53, 1092 to analyze and publish two sets of LAMPF over the past 20 years. (1996). nucleon-nucleon (NN) data. These are The analyzing power data resolve Simon, A.J., G.Glass, M.W. the final sets of data to complete the the ambiguity in the absolute normal- McNaughton, et al., "Absolute pp- set of NN measurements at the Los ization of the LAMPF polarized Elastic Cross Sections from 492 to Alamos Meson Physics Facility neutron beams. In addition, they 793 MeV," Phys. Rev. C 53, 30 (LAMPF) and determine the NN- strengthen the conclusion that isospin- (1996). scattering amplitudes from 485 to zero inelastic scattering is strongly 800 MeV. coupled to a pair of delta resonances, These new data are the most and is therefore very small at accurate in the world, with precision 800 MeV, since 800 MeV is far below better than 1% and absolute accuracy the mean energy of 1380 MeV about 1%. With the inclusion of these required to create two deltas. data, all known ambiguities in the phase-shift analysis are resolved, and the final phase-shift solutions are unique. The measurements of the proton- proton (pp) elastic cross section are in excellent agreement with previous results from LAMPF. These data have stabilized the NN phase-shift analysis and determine the absolute normaliza- tion of both nucleon-nucleon and

Individual Projects—Nuclear and Particle Physics 109 Solar Neutrino Physics sophisticated methods, such as event- by-event pulse-shape fitters, maximum entropy techniques, and neural Andrew Hime networks, which promise to maximize our ability to discriminate neutral- Our project focuses on extracting used in parallel with our detector test- current events from background the neutral-current signal from the bench studies to optimize our use of signals. Sudbury Neutrino Observatory (SNO) digitized waveforms to extract signals using an array of ultralow-background and identify events. We are currently 3He proportional counters. In the past using the information contained in the Publications year, the neutral-current detector digitized waveforms to extract in real Hime, A., "The Sudbury Neutrino (NCD) project moved from the R&D time the photodisintegration back- Observatory" (Seventh International phase toward full-scale construction. ground signals from the alpha Workshop on Neutrino Telescopes, Los Alamos has played the lead role distributions registered in the NCDs. Venice, Italy, February 29-March 2, in defining the operating parameters In the upcoming year, we will extend 1996). and constraints for the NCDs, these activities to include more including requirements for gas fill and purification and for optimizing the detectors to collect the most signifi- , , ,,, i • i i i I i i i i i i i i , 1 , , , , i , , , , cant data. 3.0- • Much of our effort has focused on designing and constructing a large 2.5- jSjg|Gompton/Beta gas-handling system, which has been \

combined with our main "NCD (sr i !] factory." While the optimization of 2.0- - - operating parameters is now essen- !i ^---~—~~~'~To ? tially complete, in the coming year we 1.5- He(n p)t'-' -^ '-

- 1 • will continue our detector test-bench CD CO studies to refine the front-end 3 1 D. 1.0- - electronics. This part of the project is related to our more general goal of * i^i£~——T~ •-.••••,:Buik '}'•• 0.5- - developing data reduction and '=y .''Alpha'" analysis tools for detecting neutral- current signals. 0.0- • 1111111 i i i i i | i i i i 1 • 11111111111111111111111 Monitoring and controlling back- 0 200 400 600 800 1000 grounds are still significant aspects of Energy (keV) 11111111 , I I . , . . i i , , i the NCD program. Our radioassays 1.0- played an important role during the 1 - design phase and will be used He(n,p)t 1

continuously during the production 0.8- - phase to monitor detector compo- 'B - Compton/Beta 1 - 1 • nents. Information on the radiopurity 1 of detector construction materials is 0.6- _ CO 1 essential for extracting the neutral- - - - I • current signal from SNO in the rbi t 1 presence of photodisintegration -2- 0.4- 1 —

LU • • backgrounds. - I n [JL 1• ; •T Lfl Bulk Alpha • We are continuing to study detec- 4— i 0.2- • u - tors at our low-background counting n • facility at the Waste Isolation Pilot - - Plant (WIPP). This work will help us Ik. - establish acceptable intrinsic back- 0-0 ~" TrTT|rrT'•"i'''' i''' niTi H () 200 400 600 800 1000 grounds and contribute to the devel- Energy (keV) opment of our signal extraction and pulse-shape discrimination techniques Scatter plot demonstrating our pulse-shape discrimination capabilities using (see accompanying figure). Data from event topology from He(n,p)t events, bulk alpha activity, and gamma-induced our low-background experiments is Compton electrons.

10 Los Alamos FY1996 LDRD Progress Report Chiral Symmetry in Finite Nuclei coupling constants are natural, as opposed to only six in our initial work. In fact, the new value of chi- David Madland square is also lower, but the predictive power is somewhat worse. The goal of our project is to search vector whose elements are of understand chiral symmetry in finite order unity if naturalness holds; and nuclei. As a first step, we have (3) deleting proton states that are only Publications published the physical reasoning and quasibound inside the Coulomb Friar, J.L., "Dimensional Power principal evidence demonstrating the barrier. Given a set of coupling Counting in Nuclei," (submitted to role of chiral symmetry in finite constants, the predictive algorithm Few-Body Systems). nuclei. To be able to continue this LANUC solving the Dirac-Hartree work, we have made the necessary equations self-consistently for each Friar, J.L., D.G. Madland, and B.W. changes and additions to our two test nucleus has been made compat- Lynn, "QCD Scales in Finite Nuclei," main computer codes. We have ible with (2) and has the change Phys. Rev. C 53, 3085 (1996). modified the generalized, nonlinear, specified in (3). Friar, J.L., G.A. Miller, and U. least-squares, adjustment algorithm We have also determined the main van Kolck, "The pp to pp.pi-zero LACHI that determines the coupling elements (existing FORTRAN Reaction near Threshold: A Chiral constants of the chiral Lagrangians. routines) that will be used to construct Power Continuing Approach," Phys. We have modified the algorithm by a new, nonlinear, least-squares, Rev.C 53, 2661 (1996). (1) introducing the covariance matrix adjustment algorithm that will be in order to study the correlations mounted on an Ultra-SPARC worksta- Van Kolck, U., J.L. Friar, and T. among the various coupling constants; tion. Finally, with the improved codes, Goldman, "Phenomenological (2) redefining the chiral Lagrangians we have found a new minimum chi- Aspects of Isospin Violation in the so that their coupling constants form a square for which seven of the nine Nuclear Force," Phys. Lett. B 371, 169 (1996).

Simulating the Decays of Bottom results (based on this data set for the mass spectrum and decay constants of and Charm Mesons heavy-light mesons). We are now in the process of adding in the physics analysis for the study of semileptonic Tanmoy Bhattacharya form factors and matrix elements of 4-fermion operators and increasing Our objective is to carry out a During the reporting period, we the statistical sample size. detailed study of the decay properties developed the code required to of bottom and charm mesons by simulate the bottom quark on a lattice simulating the Standard Model of with a view to carrying out a detailed Publications strong interactions on the lattice. We study of the decay properties of the believe that the capabilities of the bottom and charm mesons. The code Ali Khan, A., and T. Bhattacharya, massively parallel machine, CM5, at was developed in close collaboration "B and Be Mesons with NRQCD and the Advanced Computing Laboratory with the ACL on the CM5 there. The Clover Actions" (to be published in (ACL) will allow us to produce code uses the nonrelativistic formula- International Symp. on Lattice Field definitive predictions in this field, and tion of quantum chromodynamics to Theory Proc). put the standard model to stringent simulate the heavy quarks and the tests in present and proposed experi- 0(a) improved light fermions on a ments. In addition, we shall work in 16x16x16x48 lattice. The physics close collaboration with the staff analysis is done combining these two scientists at the ACL to help develop types of quarks together to study the hardware and software optimization properties of hadrons made up of tools and graphics, which will heavy-heavy, heavy-light, and light- contribute significantly to the light quarks. We have so far analyzed Laboratory's growth as a forerunner 75 lattices and have preliminary in advanced computing.

Individual Projects—Nuclear and Particle Physics 11 I Nonequilibrium Dynamics of the Quark- Publications Gluon Plasma in Heavy-Ion Collisions Cooper, R, Y. Kluger, "Nonequilibrium Dynamics of 4 Emil Mottola Symmetry Breaking in Lambda Phi Field Theory" (to be published in We have developed field theory and We have also studied dissipation Phys. Rev.). numerical methods for the general and decoherence due to particle Cooper, R, Y. Kluger, et al., problem of quantum back reaction on production in time-varying mean "Quantum Evolution of Disoriented classical fields, with applications to a fields. We modified numerical codes Chiral Condensates," Phys. Rev. D 51, wide variety of physical systems. Our previously developed for particle 2377 (1995). main focus was on particle production production in strong electric fields in processes in the time evolution of the quantum electrodynamics for the Cooper, R, E. Mottola, et al., quark-gluon plasma following an quantum chromodynamics problem. "Anomalous Transverse Distribu- ultra-relativistic heavy-ion collision. We have made specific predictions for tion of Pions as a Signal for the In particular, we studied in some energy-momentum flow and pion Production of DCCs," Phys. Rev. C detail the evolution of a disoriented production in the central rapidity 54, 3298 (1996). chiral condensate (DCC) produced in region of experiments to be performed Habib, S., Y. Kluger, et al., the chiral phase transition of nuclear at the Relativistic High-Intensity "Dissipation and Decoherence in matter in heavy-ion collision experi- Collider. Mean Field Theory," Phys. Rev. Lett. ments, as shown in both accompany- 76,4660 (1996). ing figures.

dc/dx=-l initial conditions 150.0

mean field approximation

100.0

•o UJ & 50.0 IA v~—^ Tc=m \> \ / /---v— \ ^ Jo=1.4m // / V .// n ft 0.0 2.0 4.0 kperp

Signature of the chiral phase transition in heavy-ion collisions. The curve labeled "mean field approximation" is the expected distribution of pions as a function of momentum perpendicular to the collision axis if a region of DCC is produced in the collision. For comparison, the other two curves are the pion distributions expected from strict adiabatic evolution from equilibrium at two different temperatures.

112 Los Alamos FY1996 LDRD Progress Report 30 f =92.5 MeV \ I ••• T=1.0 e — T=1.66 t=2.83 - i=4.80 1=7.92 II -- -c=12.96 x=19.29 C 10

0.5 1.5

. . • 1 • . . .

• v

2 -

II Q.

\ 1 - - -

0.5 1.5

Particle number distributions as functions of transverse (p) and longitudinal (k^) momentum for initial conditions corresponding to the formation of DCC (upper panels) compared with the locally thermal equilibrium number density nt (lower panels). Notice the strong enhancements at lowp and low k^ in the case where DCC is formed in the collision event.

Determination and Study of Cosmic-Ray In the past year, we successfully acquired data from a second observa- Composition above lOOTeV tion period of an air shower. The new- event sample is a factor of six larger than had previously been available. Constantine Sinnis Since the end of the second observation period, we have dismantled the The origin of cosmic radiation has at Los Alamos to allow simultaneous experimental setup, and we have eluded researchers for nearly a ground-based measurements of (1) the concentrated our effort on performing century. The composition of cosmic Cerenkov radiation produced in a the final detailed analysis of the data rays is perhaps the single most cosmic-ray-induced air shower and and improving the shower-reconstruc- important clue to their origin. Because (2) the electron and muon densities. tion algorithms. We have almost of the low flux of the cosmic rays, The Cerenkov photon density -100 m completed this work and will soon measurements above -10 TeV must from the air-shower core provides a begin the final analysis of cosmic-ray be done with ground-based detectors. relatively robust measurement of the composition using the combined We are exploring the feasibility of cosmic-ray energy. The steepness of Cerenkov, scintillator, and muon data. using a new approach to ground-based the lateral distribution of the Ceren- At the 24th International Cosmic observations. We have added an kov radiation and the muon content of Ray Conference in Rome, Italy, we experimental capability to the the air shower depend on the compo- presented preliminary results from the CYGNUS extensive air shower array sition and energy. first year's data.

Individual Projects—Nuclear and Particle Physics I 13 Nonperturbative Estimates of the Publications Bhattacharya, T., et al., "Decay Standard Model Parameters Constants with Wilson Fermions at Beta = 6.0," Phys. Rev. D 54,1155 Rajan Gupta (1996). Bhattacharya, T., et al., "Hadron Our project involves a comprehen- Hadron Spectrum. We obtained a Spectrum with Wilson Fermions," sive study of Standard Model physics detailed analysis of the chiral Phys. Rev. D 53, 6486 (1996). using large-scale simulations of the behavior of meson and baryon underlying quantum field theory. With masses and the pattern of symme- Bhattacharya, T., et al., "Lattice the advent of massively parallel try breaking for the octet and Analysis of Semi-Leptonic Form computers, lattice quantum chromo- decuplet baryon states. Factors," Nucl. Phys. B (Proc. Suppl.) dynamic (QCD) calculations are Quark Masses. We predicted the 47, 481 (1996). reaching a quantitative and predictive masses of light quarks by analyz- level. In the past year, we finished a ing the behavior of the masses of Bhattacharya, T., et al, "Status Report comprehensive analysis of standard- hadrons as a function of up, down, on Weak Matrix Element Calcula- model phenomenology-based and strange quark masses. Our tions," Nucl. Phys. B (Proc. Suppl.) simulations of lattice QCD on large results show that these quark 47, 549 (1996). lattices of size 32 x 32 x 32 x 64 and masses are almost a factor of 2 Grandy, J., et al., "Topological Density with high statistical precision. We smaller than conventionally and Instantons on the Lattice," Nucl. obtained and published state-of-the- accepted values. Phys. B (Proc. Suppl.) 42, 246 (1995). art results for the hadron spectrum, Semileptonic form factors for the Gupta, R., "Chiral Limit of QCD," meson-decay constants, semileptonic decaysD —> KevandD —> Nucl. Phys. B (Proc. Suppl.) 42, 85 form factors, form factors for the rare K*ev. The data is cleanest for (1995). decay B —> K* g, and weak-matrix D —> K e v so it is used to test the elements of 4-fermion operators. All pole-dominance hypothesis. By Gupta, R., et al., "Testing the Chiral these calculations were done using comparing the lattice result Behavior of the Hadron Spectrum," highly efficient computer codes on the /+(0) = 0.66(4) with the present Nucl. Phys. B (Proc. Suppl.) 47, 549 Thinking Machines Connection experimental values of 0.71(4) and (1996). Machine 5. 0.77(4), we postulate that the Results of these calculations have discretization and quenching errors impact on the 4 parameters that in these quantities are small. For describe the Cabibbo-Kobayashi- the pseudoscalar to vector decay Maskawa mixing matrix and the 3 D —> K*ev, our result for the light quarks, i.e., on 7 of the 19 hard-to measure-ratio A2/A! = 0.63 parameters of the Standard Model. (0.10) is in good agreement with Some of the highlights of our calcula- experiments. tions include the following results: Bparameters. These parameters measure the QCD corrections to weak-interaction processes involving charge-conjugation parity (CP) violation. Our new results for the electromagnetic penguin operators suggest an enhanced value for the direct CP violation parameter e'/e.

I 14 Los Alamos FYI996 LDRD Progress Report Biosciences

Biotechnology Approaches to Stable- fusion with thioredoxin, a region that encodes for polyhistidine (His-tag) Isotope Labeling for Biomolecular and a specific protease cleavage site. Thioredoxin stabilizes the fusion Structure/Function Studies protein against proteolysis. Based on the specific interaction of the His-tag Jill Trewhella region with a nickel matrix, the fusion protein is easy to purify. Finally, we A thorough understanding of is limited by the expense of labeling liberated the troponin I peptide from biological function at the molecular macromolecules with stable isotopes. the fusion protein by treating the level is essential for the development In this project we have developed fusion protein with enterokinase, of new therapies to treat diseases and biotechnology approaches to labeling which cleaves specifically the peptide for an increasing array of applications eukariotic proteins and peptides. bond to the C-terminal side of the in biotechnology. Knowledge of We have tested a large number of sequence Asp-Asp-Asp-Asp-Lys. biomolecular structure is a prerequi- commercial bacterial expression site for understanding biomolecular vectors for labeling peptide fragments Publications function, and stable isotopes are of troponin I (an avian muscle playing an increasingly important role protein). Because peptides are subject Hernandez, G., S.E. Rokop, P.A. in the structural determination of to nonspecific proteolysis and are Springer, et al., "NMR Studies of biological macromolecules. difficult to purify, expression of Troponin I (96-115): Free in Solution The application of stable isotopes relatively small peptides in bacteria and Bound to Troponin C," Biophys. is required for interpreting structural has been difficult. These problems J. 70, 384 (1996). data from a variety of biophysical can be circumvented by expressing techniques (such as neutron scatter- peptides as a fusion with proteins ing, nuclear magnetic resonance that are both stable and relatively spectroscopy, and vibrational spec- easy to purify. troscopies) that provide structural In our successful plasmid construc- information down to atomic resolution (see accompanying figure), we tion. The application of these tech- cloned the DNA encoding for niques to many important troponin I peptides into a biochemical problems multiple-cloning site such that the DNA was transcribed as a AmpK pET-32 -_ fl origin

Plasmid for expressing our fusion *'*// „„„. proteins.

Start codon Enterokinase lac operator 1 Polyhistidine cleavage site J T7 promotor Thioredoxin His-tag Asp-Asp-Asp-Asp-Lys Multiple- (109 amino acids) cloning site

Individual Projects—Biosciences I 15 Preparation and Utilization of I3C- and i5N-Labeled DNAs for the Determination of Unusual DNA Structures Relevant to the Human Genome Project by Nuclear Magnetic Resonance Spectroscopy

Louis A. Silks

Recent reports have highlighted the method for synthesizing glycerol from hydrogen bonding to the 6-amino involvement of DNA triplet repeats in labeled carbon dioxide and have group on the adenines. We are also a variety of human genetic diseases. applied for a patent on this new currently constructing the 15 15 15 The size and complexity of these process. Our efforts to devise a (C[ N2]TG)5 and (G[ N3]C[ N3]C)5 DNA motifs necessitate the use of straightforward procedure to construct repeats to explore the bonding stable isotope labeling for structural 2'-Deoxy[amino-15N]Adenosine, as environments around each of the determination by nuclear magnetic well as a new method for the synthe- labeled nitrogens. Ultimately, these resonance (NMR) spectroscopy. We sis of the unknown [9-15N]-2?- experiments will provide definitive are addressing this problem by deoxyadenosine, have been reported evidence for two- or three-centered developing novel and efficient means in the literature. In short, our proce- hydrogen bonding. for synthesizing these unusual DNAs, dures use water as the solvent, have which will allow their subsequent been scaled to provide gram quantities Publications structural determination by NMR in excellent yield, and do not require methods. Our ultimate goal is to any protection/deprotection steps. Orji, C, J. Kelly, D.A. Ashburn, et al., correlate the structure and function Furthermore, we have constructed "The First Synthesis of (3-2'-Deoxy- of these DNA motifs. 15 15 the (C[6- N]AG)5 repeat and opti- [9- N]Adenosine," J. Chem. Soc, We have begun to construct DNA mized its purification using semi- Perkin Trans. 1, 7, 595 (1996). molecules containing triplet repeats preparative reverse-phase (C6) Orji, C, and L.A. Silks, "The First from easily accessible precursors such high-performance liquid chromatogra- Synthesis of [9, amino-15N ]Adenine as labeled methanol, carbon dioxide, phy techniques. We are currently 2 and (3-2'-Deoxy-[9, Amino- and ammonia. The enzymatic syn- purifying the labeled (C[6-15N]AG) 5 15N ]Adenosine," /. Labelled Compds. thesis of ribose (one of the compo- repeat and expect subsequent solution 2 Radiopharm. 38, 852 (1996). nents of DNA) requires carbon- NMR studies to provide unambiguous labeled glycerol, so we developed a evidence of the type and nature of the

Applications of Strand-Specific known as lateral asymmetry, continued our investigation of aneuploidy- In Situ Hybridization inducing agents, and successfully detected isochromosomes and chromosomal inversions. Edwin Goodwin

Fluorescence in situ hybridization The goal of this project is to expand Publications (FISH) is used to determine the the range of applications of CO-FISH. location of specific DNA sequences Specifically, we intend to develop Bailey, S.M., E.H. Goodwin, J. on chromosomes. A strand-specific methods to examine altered gene ex- Meyne, et al., "CO-FISH Reveals version of FISH, called chromosomal pression associated with malignancy, Inversions Associated with orientation (CO)-FISH, was devel- investigate mechanisms of gene Isochromosome Formation," oped at Los Alamos. The procedure amplification, and facilitate genomic Mutagenesis 11, 139 (1996). reveals not only the location but also mapping. Goodwin, E.H., J. Meyne, S.M. the 5'-to-3' direction (or polarity) of a Using CO-FISH, we have observed Bailey, et al., "On the Origin of target sequence (such as the sense long-range molecular order in the Lateral Asymmetry," Chromosoma strand of a gene) and its orientation repetitive elements of tandemly 104, 345 (1996). relative to other sequences on the repeated satellite DNAs. In addition, same chromosome. This information this year we completed our investiga- is not obtainable by any other tion of the cytogenetic phenomenon cytogenetic method.

116 Los Alamos FY1996 LDRD Progress Report Computer Simulation of Protein Solvation, Garde, S., G. Hummer, A.E. Garcia, et al., "Hydrophobic Hydration: Hydrophobic Mapping, and the Oxygen Inhomogeneous Water Structure near Nonpolar Molecular Solutes," Phys. Effect in Radiation Biology Rev. £53,4310(1996). Garde, S., G. Hummer, A.E. Garcia, Lawrence Pratt et al., "Origin of Entropy Convergence in Hydrophobic Our work on the statistical mechan- in protein folding experiments. A Hydration and Protein Folding," ics of biomolecule solvation has commentary in the Proceedings of the Phys. Rev. Lett. 77, 4966 (1996). widespread applications in structural National Academy of Sciences U.S.A. and functional biology, including on our work notes that we "dramati- Hummer, G., S. Garde, A.E. Garcia, understanding the stabilization of cally extend ideas" from previous et al., "An Information Theory Model folded protein structures and the theories, that our Proc. Natl. Acad. of Hydrophobic Interactions," Proc. binding of DNA, ligands, and other Sci. U.S.A. paper is a "very interesting Natl. Acad. Sci. U.S.A. 93, 8951 biomolecules to proteins. Our work and important paper," and that our (1996). was motivated by the need to identify results are "remarkable." It is clear Hummer, G., L.R. Pratt, and A.E. hydrophobic and hydrophilic regions that our work constitutes a break- Garcia, "Free Energy of Ionic of biomolecules in water. The through on these difficult problems of Hydration," J. Phys. Chem. 100,1206 question that led to this work was, solvation of biological macromol- (1996). where would simple hydrophobic ecules. species such as an oxygen molecule Hummer, G., L.R. Pratt, and A.E. stick to a hydrated protein? We Garcia, 'The Hydration Free Energy Publications developed theoretical molecular of Water,"/. Phys. Chem. 99, 14188 models of hydration (incorporating B.J. Berne, "Inferring the (1995). both hydrophobic and hydrophilic Hydrophobic Interaction from the Pratt, L.R., "Molecular Theory of effects) and validated our models Properties of Neat Water," Proc. Natl. Hydrophoic Effects" (to be published through computer simulations. Acad. Sci. U.S.A. 93, 8800 (1996). in Encyclopedia of Computational These new models are now avail- Corcelli, S.A., J.D. Kress, L.R. Pratt, Chemistry, John Wiley and Sons, New able for use in structural biology et al., "Mixed Direct-Iterative York, 1997). studies when computer simulations Methods for Boundary Integral are either not feasible or not insight- Pratt, L.R., GJ. Tawa, G. Hummer, et Formulations of Continuum Dielectric ful. They have recently been used to al., "Boundary Integral Methods for Solvation Models," Pacific solve a longstanding puzzle in the Poisson Equation of Continuum Symposium on Biocomputing '96, L. molecular biophysics, explaining the Dielectric Solvation Models" Hunter and T. E. Klein, Eds. (World phenomenon of entropy convergence (submitted to Int. J. Quant. Chem.). Scientific, Singapore, 1995), p. 142.

Electromagnetic Inverse Applications for independent information (for example, from anatomical magnetic-resonance Functional Brain Imaging imaging) and (2) developing new algorithmic approaches to the problem based on recent developments in large- Charles Wood scale numerical methods. The results suggest that we can achieve significant This project addresses an important sources of electrical currents in the improvements in the accuracy and mathematical and computational brain from surface measurements. robustness of inverse solutions by these problem in functional brain imaging, Although this problem is ill-posed in two approaches. namely the electromagnetic "inverse its most general form, approximate problem." Two electromagnetic solutions are important for functional brain-imaging techniques, magneto- brain imaging used for diagnosing and Publications and electroencephalography, are based treating neurological disorders and for George, J.S., et al., "Mapping Function on measurements of magnetic fields basic research on the functional in the Human Brain with MEG, Ana- and electrical potentials at hundreds of organization of the human brain. tomical MRI, and Functional MRI," J. locations outside the human head. The We addressed the inverse problem Clin. Neurophysiol. 12, 406 (1995). inverse problem is the estimation of using two distinct approaches: (1) in- the locations, magnitudes, and time troducing constraints derived from

Individual Projects—Biosciences I 17 Gene Shuffling Using Flow Cytometry approach to enhancing the fluorescence of a naturally occurring fluorescent protein called fluorescent L. Scott Cram green protein. Eventually, our technique may be We are developing a technique to in vitro recombination of genes, and used to isolate proteins that turn genes engineer protein molecules with novel then we use flow cytometry to on and off in response to an externally properties. Our technique combines examine individual bacteria express- administered stimulus. In this case, the cell sorting capabilities of flow ing the genes. Finally, we select and we would replace the gene of interest cytometry with the genetic diversity sort out those bacteria expressing with the gene for green fluorescent made possible through gene shuffling proteins that are of particular interest protein and monitor the conditions techniques. using the fluorescent properties of the under which the green fluorescent Our technique is carried out in proteins or of other proteins in the cell protein is made. several steps. First, we create many that are affected by the proteins of different versions of a protein through interest. We have begun to apply this

Identification and Characterization of a a monoclonal antibody that binds specifically to the Ku80 subunit of Human DNA Double-Strand Break DNA-PK. The final product is approximately 90% pure. We employed both Repair Complex atomic force and electron microscopy to examine the behavior of the purified Ku70/80 and DNA-PK catalytic David Chen subunit. Direct observation of Ku/DNA complexes has shown that Ku will form Mutations that affect the expression defective repair of double-stranded nucleoprotein filaments in the presence or activity of the subunits of the DNA breaks. This project studies the of linear DNA. Moreover, the studies heteromeric enzyme DNA-dependent biochemical properties of this enzyme have revealed that Ku70/80 is capable protein kinase (DNA-PK) result in relevant to the repair of DNA strand of looping DNA, as the accompanying breaks. This work will allow us to figure shows. We also used the begin to assemble DNA double-strand immunoaffinity purification protocol to break repair complexes in vitro and screen for proteins that associate with better understand the role of DNA-PK the DNA-PK complex. The most in the repair process. abundant protein found to associate We have successfully designed a with DNA-PK was a 120-kD polypep- novel purification strategy that employs tide. This protein binds to DNA and is phosphorylated by purified DNA-PK. Atomic force microscopy (top) We have used a yeast two-hybrid and electron microscopy (middle) system for three studies: (1) mapping of the Ku70/80 associated with a the domains of DNA-PK subunits 2.6-kilobase-pair linear DNA involved in enzyme assembly, (2) fragment reveal the ability of KM identifying novel proteins associated to form DNA loops. End-to-end with DNA-PK, and (3) identifying tethering by the DNA-PK com- novel proteins associated with XRCC4, plex is shown here in atomic another protein that functions in the force micrographs of a 660-base- DNA double-strand break repair pair linear DNA circularized by pathway. We designed screens of two- interactions between two DNA- hybrid cDNA libraries using fragments bound DNA-PK complexes of the catalytic subunit of DNA-PK to (bottom). These results suggest identify novel proteins associated with that inside of the cell, DNA-PK the double-strand break repair complex. holds broken DNA strands The recently cloned XRCC4 cDNA has together until repair can occur. also been used in yeast two-hybrid Micrographs provided by Robert library screens. Gary.

118 Los Alamos FY1996 LDRD Progress Report Determining the Role of theTelomere on Wright, T.J., K. Denison, V. Johnson, et al., "High Resolution Analysis of the Severity of Birth Defects the Wolf Hirschhorn Syndrome Region on Chromosome 4ql6.3" (to be published in Cyto. Cell. Genet.). Michael Altherr Wright, T.J., K. Denison, D. Ricke, et The loss of genetic material near Publications al., "A Transcript Map of the 260 kb the ends, or termini, of chromosomes Wolf Hirschhorn Syndrome Critical Altherr, M.R., K. Denison, T.J. is associated with a variety of birth Region," Amer. J. Hum. Genet. 59,55 Wright, et al., "Delimiting the Wolf defects. Terminal deletions can arise (1996). by a variety of mechanisms, including Hirschhorn Syndrome Critical Region physical breaking of chromosomes by to 750 kb" (to be published in Amer. J. Wright, T.J., D. Ricke, K. Denison, et ionizing radiation and other clastogenic Med. Genet). al., "A Transcript Map of the Newly agents. At least one-third of human Defined 165 kb Wolf Hirschhorn chromosomes can have a terminal Syndrome Critical Region" (to be deletion but still result in a live birth, published in Human Molecular though the baby will likely exhibit Genetics). significant clinical abnormalities. Our goal is to better understand the Development of an Ultrasensitive role that telomeric sequences play in stabilizing chromosome breaks and and Rapid DNA Repair Assay how they affect local gene expression. Specifically, we are working to Min S. Park provide basic insight into the mechanism by which broken chromosomal The main objective of this project tested the functionality of the purified ends are healed; to determine whether was to develop a rapid, highly DNA repair protein (XPG) using the the position of the telomere to known sensitive, and quantitative DNA repair nonradioactive substrates. Our next genes can affect gene expression and assay. We expect such a kit to be goal is to refine this assay so that it contribute to the extreme variability useful for large-scale epidemiological can be readily converted into a user- of symptoms associated with terminal studies for skin cancer risk assess- friendly DNA repair assay kit. deletions; and to determine whether ment and for screening for new the position of the telomere affects potential environmental mutagens. It local chromatin structure and in turn might also be used to prescreen Publications: affects gene expression. cancer patients who might be highly Cloud, K.G., B. Shen, G.F. Strniste, et To meet these goals, we are sensitive to radiation so that doctors al., "XPG Protein Has a Structure- mapping a chromosome region can choose lower risk therapies. Specific Endonuclease Activity," associated with a specific terminal We recognized the need for such an Mutation Res. 347, 55 (1995). deletion syndrome. In the past year, assay after observing that the quantity Nolan, J.P., B. Shen, M.S. Park, et al., we have reduced the physical region of full-size, in vitro transcripts "Kinetic Analysis of Human Flap thought to be involved in the Wolf- synthesized from DNA templates Endonuclease-1 by Flow Cytometry," Hirschhorn syndrome to 10% of the decreases as a function of chemical- Biochem. 35,11668(1996). previous estimate, and we have or radiation-induced damage to the identified a number of genes in the DNA. By measuring the amount of Park, M.S., J.A. Knauf, S.H. missing region common to all patients new DNA produced after a template Pendergrass, et al., "UV-Induced with the disease. has been damaged, we can gauge the Movement of the Human DNA Repair In addition, we are using cell lines effectiveness of the DNA repair Protein XPG in the Nucleus," Proc. derived from patients with Wolf- mechanism and better estimate the Natl. Acad. Sci. U.S.A. 93, 8368 Hirschhorn syndrome to examine the ultimate impact of the damage. (1996). level of expression of cloned genes in First, we studied the incorporation Shen, B., J.P. Nolan, L.A. Sklar, et al., the vicinity of the novel termini. And kinetics of nonisotopic ribonucleotide "Essential Amino Acids for Substrate finally, we are employing cloned analogs in the in vitro transcription Binding and Catalysis of Human Flap genomic material to analyze chroma- reaction and worked to optimize the Endonuclease-1,"/. Biol. Chem. 271, tin from these cell lines to identify use of these nonradioactive, 9173 (1996). structural variations that may affect chemilumiscent substrates. Then, we gene expression.

Individual Projects—Biosciences I 19 Structure and Thermodynamics mucin/V3 polypeptides, a conclusion that we have confirmed by two- of Surface Recognition dimensional (2-D) NMR structural studies on the V3 region of two strains of HIV. Goutam Gupta Furthermore, we observed that the conserved GPGR crest in the V3 loop We are combining protein engineer- Although we are primarily focusing can be masked by the C-terminal ing, nuclear magnetic resonance on HIV, the methods we develop will sequence flanking the crest. In an (NMR) spectroscopy, and equilibrium also apply to other pathogens. attempt to unmask the conserved and kinetic binding experiments to First, we chemically synthesized a GPGR crest, we designed mini-V3 study the structural and thermody- series of polypeptides in which copies loops that contained the central 15 namic features of HIV surface of the V3 region of gpl20, which (out of 35) residues of the V3 loop in recognition—the features that enable contains the PND site, were linked the S-S bridged configuration. We HIV to bind to and enter susceptible with mucin (a glycoprotein found in carried out structural studies by 2-D cells and the features that alert the mucus) spacers. Using NMR and body's defenses to switch into high molecular modeling programs, we NMR on two such mini-V3 loops. gear. Our goal is to identify the found that longer V3 sequences (with These two mini-V3 loops adopted a structural characteristics required for six mucin/V3 repeats) more readily rigid beta-hairpin structure in solution enhanced antigenicity, or the ability to adopted a native conformation and and unmasked the conserved GPGR elicit a stronger immune response. were structurally more ordered than crest. We have targeted two well-separated those with fewer (i.e., three) repeats. sites on the HTV surface glycoprotein Next, we tested the antigenicity of Publications gpl20 for our binding studies: the our mucin/V3 polypeptides. However, Fontenot, D., J. Gatewood, S.V. principal neutralizing determinant the antisera produced by both the long Mariappan, et al., "Human (PND) site and the CD4 receptor- and short mucin/V3 polypeptides in Immunodeficiency Virus (HIV) binding site. For these studies we mice and monkeys showed no HIV Antigens: Structure and Serology of produced a set of synthetic antigens neutralizing ability, which we inter- and the mmiantibody/minireceptor preted to mean that the V3 region in Multivalent Human Mucin MUC1- molecules that mimic the binding native gpl20 may not be as accessible HIV Chimeric Proteins," Proc. Natl. affinity of the whole antibody/receptor. as the ones in the our synthesized Acad. Sci. U.S.A. 92, 315 (1995).

Neutron Structural Biology The completed design forms the basis for a first neutron instrument that will strengthen the local struc- Benno Schoenborn tural-biology effort and satisfy the DOE Office of Health and Environ- This project investigated design crystallographic applications, we have mental Research (OHER) goal to concepts of neutron-scattering designed a detector with a radius of bring major diffraction tools to the facilities for structural biology at 70 cm, a height of 20 cm, and an arc scientific community. OHER has spallation sources at the Los Alamos of 120°. Such a detector will have a indicated that it is interested in Neutron Science Center. Our work nearly 10-fold increased active area as funding these efforts in neutron included analyzing design parameters compared with the presently used structural science and supports an for protein crystallography and for detectors. In addition to such new external-users program. membrane-diffraction instruments. detectors, the new stations will use These instruments are designed for focusing optics to increase flux. The general use by scientists from optical systems will be based on Publications industry, universities, and other supermirror technology. We are Schoenborn, B.P., "A Protein national laboratories. studying further increases in flux by Crystallography Station at LANSCE,' employing coupled moderators The use of large detectors will be a in Neutrons in Biology, B.P. matched to the energy resolution major component of the planned new Schoenborn and R. Rnott, Eds. required. spectrometer. For the planned (Plenum Press, New York, 1996).

120 Los Alamos FY1996 LDRD Progress Report Sum-Frequency Generation Studies of Our initial studies have focused on the water/phospholipid interface of Membrane Transport Phenomena vesicles oriented randomly in solution and on supported hybrid bilayers on fused silica. We have also worked out R. Brian Dyer the biochemistry to reconstitute cytochrome c oxidase in liposome have focused on cytochrome c Vectorial pumping of ions, gener- vesicles. We expect the combination oxidase, a redox-driven transmem- ally carried out by membrane-bound of a carefully controlled membrane brane proton pump. proteins, is one of the most funda- composition and structure with the We have developed a nonlinear mental processes in living organisms, structural sensitivity and interfacial spectroscopic technique that is critical for energy transduction in specificity of the SFG technique to uniquely sensitive to membrane respiration and photosynthesis and for provide unique insight into the interfaces. Our approach uses a a wide variety of cellular signal- structures and dynamics that effect femtosecond titanium-sapphire laser transduction events. Because of the transmembrane ion transport. difficulty of obtaining structural and to parametrically generate broad-band dynamic information on membranes IR pulses throughout the mid-IR and membrane-bound proteins, a using the nonlinear optical materials Publications molecular-level understanding of [3-barium borate and silver thiogallate. Causgrove, T.P., and R.B. Dyer, proton and ion pumping has remained The IR pulses are combined in a "Picosecond Structural Dynamics of elusive. nonlinear SFG process at the mem- Myoglobin Following Photolysis of brane/water interface and are detected Our objective is to develop and CO," J. Phys. Chem. 100,3273 (1996). apply a new technique, sum-fre- by a multichannel SFG instrument, quency generation (SFG), to the study which we developed, that uses a Williams, S., T. Causgrove, of proton and ion transport across spectrograph and charge-coupled R.Gilmanshin, et al, "Fast Events in biological membranes. Our studies device detector to detect the broad- Protein Folding: Helix Melting and band, up-converted IR light. Formation in a Small Peptide," Biochem. 35, 691 (1996).

Engineering Sequence-Specific RNA and Publications Single-Stranded-DNA Binding Proteins Benevides, J.M., T.C. Terwiliger, S. Vhonik, et al., "Raman Spectroscopy of the Ff Gene V Protein and Thomas Terwilliger Complexes with poly(dA): Non- specific DNA Recognition and The technology to design a protein We have used the special properties Binding," Biochem. 35, 9603 (1996). that binds to any given RNA or of the gene 5 protein from bacterio- Cheng, X., A.C. Harms, P.N. single-stranded DNA sequence has phage f 1 along with our experience in Goudreau, et al., "Direct many potential applications. For protein engineering to set the frame- Measurement of Oligonucleotide example, viral diseases such as AIDS work for creating a set of proteins that Binding Stoichiometry of Gene V could be treated by transmitting a will bind to any specific sequence of Protein," Proc. Natl. Acad. Sci USA sequence-specific engineered protein RNA or single-stranded DNA. In the 93, 7022 (1996). into an infected cell, where it would past year, we constructed a four- bind to and inactivate a key messen- domain modular protein consisting of ger RNA. Our objective is to construct several tandem-linked gene 5 protein a group of protein modules, each of subunits that can be used as a tem- which recognizes a specific four- plate for generating a variety of nucleotide sequence of RNA or single- sequence-specific binding proteins. stranded DNA, and then to develop the By genetically linking the gene 5 technology to link four or more of these protein subunits, we can design modules in any order to generate proteins in which each domain can proteins that bind specifically to any 16 be modified individually. (or more) nucleotide sequence of RNA or single-stranded DNA.

Individual Projects-—Biosciences 121 Theoretical Studies of Allosteric Changes Publications and DNA Binding of a cAMP-Dependent Garcia, A.E., and J.G. Harman, "Simulations of CRP:(cAMP)2 in Transcription Activation Protein Noncrystalline Environments Show a Subunit Transition from the Open to the Closed Conformation," Protein Angel Garcia Science 5, 62-71 (1996).

The E. coli cAMP receptor protein CRP:(cAMP)2:DNA crystals). The Garcia, A.E., G. Hummer, and D.M. (CRP) plays an important role in simulation in solution showed that a Soumpasis, "Hydration of an Alpha mediating transcription activation of transition from the "open" to "closed" Helical Peptide: Comparison of several genes in enteric bacteria. CRP state also occurs when water is Theory and MD Simulations" (to be activation is a complex process explicitly included in the calculations. published in Proteins: Structure, involving the binding of cAMP, DNA, These calculations suggest that the Function and Genetics). and RNA polymerase. Although the asymmetric conformation results from crystal structures of CRP with two lattice interactions, and that the solution cAMP molecules bound and conformation is similar to the symmet- complexed with DNA have been ric (closed-closed) conformation. reported in the literature, a detailed understanding of the mechanism by which cAMP affects allosteric control over CRP activity remains unclear. In Engineering the Specificity of xylR: this project we model the structure, A Bacterial Protein that Detects dynamics, and function of CRP by means of molecular dynamics Chemicals in the Environment simulations in aqueous and crystal environments to determine structures Thomas Terwilliger for CRP in different binding states of cAMP and DNA. This method will Microorganisms have sensitive elucidate elements of the cAMP- During the first year of this project, systems that detect trace amounts of mediated activation pathway of CRP we have developed a system for organic compounds; these systems and provide the rationale for future mutagenesis and selection of xylR are based on the ability of certain experimentation. proteins. For efficient mutagenesis regulator proteins to bind these and selection of TCE-detecting In the crystalline environment, compounds. Binding of a compound variants of the xylR protein, we CRP:(cAMP)2 subunits are asym- to a regulator protein initiates a cell's constructed a plasmid that contains metrically related, with one subunit in response by activating the pathway to the natural xylR gene from P. putida a "closed" conformation and the degrade that compound into nontoxic under control of an inducible produc- second subunit in an "open" confor- metabolites useful to the cell. In this tion promoter. Separately, but on the mation. The CRP:(cAMP)2 project we manipulate the specificity same plasmid, we placed the xylR complexed with DNA shows both of such a detector protein to produce upper promoter region (which is subunits in a "closed" conformation. microorganisms better able to detect subject to xylR control) upstream of We performed molecular dynamics and degrade organic pollutants such the tetR gene, which controls the simulation of CRP:(cAMP)2 in a as trichloroethylene (TCE). Our expression of tetracycline resistance. noncrystalline environment for 625 ps approach is to modify the xylR The beta lactamase gene with its in vacuum and for 140 ps in solution. protein, a regulatory protein that promoter, which confers resistance to We used the crystal conformation in normally detects toluene, to detect ampicillin, is also present on this the absence of DNA as the initial TCE. We will determine the structure plasmid to select for transformation configuration. We sampled configura- of the toluene-binding domain of the into E. coli. This arrangement of the tions during the course of the simula- xylR protein bound to toluene using natural xylR gene, the xylR upper tions and analyzed them through x-ray crystallographic methods, promoter, and the tetR gene yields Molecule Optimal Dynamic Coordi- identify the parts of the protein in tetracycline resistance in the presence nate trajectories. Two optimal contact with the bound toluene, create of toluene, as the xylR protein will directions describe a transition of the a large number of variant proteins in activate the expression of the tetR "open" subunit to a "closed" subunit which the binding surfaces are gene when toluene is present. conformation during the first 125 ps altered, and identify variants that bind of simulation (a subunit conformation TCE but not toluene using a sensitive similar to the one observed in molecular bioassay.

122 Los Alamos FY1996 LDRD Progress Report Optimization and Monitoring of Kunz-Schughart, L.A., R.C. Habbersett, and J.P. Freyer, Hollow-Fiber Bioreactors "Mitochondrial Distribution and Activity in Oncogene-Transfected Rat Fibroblast Isolated from Multicellular James P. Freyer Spheroids" (to be published in Am. J. Physiol.:Cell. Physiol.). Hollow-fiber bioreactors (HFB) are Publications a system for culturing cells at very Stegman, L.D., O. Ben-Yoseph, et al., Freyer, J.P., "Mitochondrial Function high densities that is currently used "Phosphorous MRS Evaluation of of Proliferating and Quiescent Cells for the production of drugs and Cancer Gene Therapy Paradigm: Isolated from Multicellular Tumor antibodies from mammalian cell lines. Assessment of Ganciclovir Toxicity in Spheroids" (to be published in /. Cell. The original goals of this project were Glioma Tumors Stably Expressing the Physiol). to develop novel nuclear magnetic Herpes Simplex Virus Thymidine resonance (NMR) methods for Kunz-Schughart, L.A., and J.P. Kinase Gene" (to be published in imaging transport and cellular Freyer, "Adaptation of an Automated Magn. Reson. Med.). physiology within HFB, and to use Selective Dissociation Procedure to these techniques to optimize the Multicellular Spheroids of Oncogene- design of HFB. To date we have Transformed Fibroblasts" (to be developed NMR methods to measure published in In Vitro Cell. Dev. Biol). the transport of protons (essentially water) in HFB and methods for noninvasively assaying cell viability and proliferation in specific regions of a three-dimensional culture. Unfortu- medium medium nately, limitations of signal strength output input inherent in NMR microscopy have made it impossible to measure either cellular physiology or specific nutrients top cap within different regions of HFB. In response to these limitations we have developed a completely novel medium three-dimensional cell-culture system reservoir based on essentially one-dimensional nutrients nutrient supply through a flat, porous membrane membrane (see figure). We have noninvasively measured nutrient concentration gradients in this cell- t glass culture system. Unlike HFB, this new cylinder system has the added advantage of being able to recover intact, viable cells from precise locations. In this cells in way we are able to compare tradi- wastes matrix tional measures of cellular physiology with noninvasive NMR measures of nutrient concentrations and cellular bottom physiology. Thus, although the cap geometry is different from that A cutaway diagram along the axis of the cylinder of the new cell culture system employed in current HFB, the new for NMR analysis of microenvironment and physiology within three- system embodies the same relationships between the environment and dimensional cell-culture systems. Gradients in nutrients and waste products are the cells, but in a system that is established with a linear dependence on distance from the nutrient supply, as amenable to noninvasive NMR indicated on the left. The shading represents a gradient in cellular viability measurement. within the cell matrix, with viable cells (white) nearest the nutrient supply and dead cells (black) farthest from the supply.

Individual Projects—Biosciences 123 Optimal Screening Designs for t-design and panels illustrate the principles and practices of pooling Biomedical Technology molecules. We are investigating efficient nonadaptive pooling designs, such as David Torney optimum random sets designs. In nonadaptive pooling designs, all pools However, by testing groups or pools Screening many types of molecules are assigned in one pass, and all to isolate a few types with desirable of molecules, the desirable molecules clones occur in the same number of properties is essential in biomedical can be identified using a number of randomly selected pools. The results technology. Unfortunately, searching experiments that is proportional to the of optimizing the number of pools in for a particular molecule is often like logorithm of the total number of types which each clone occurs are shown in looking for a needle in a haystack. of molecules. The accompanying the accompanying logarithmic plots. YACs

| l|2|3|4J5|6|7|s| 9|iOJii|i2|i3|i4|iS 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 3i|32 33 34 35 36 r • ii BlB U wmim fclw H : • ,- \ rV' '. • J -••: 2 ^•iSI I Hi ••• I H'?- ;>} 1 r , '. • ; CO 3 SB I 11111111 miWm U mm '- T t _l 4 Hill Hill I Bill NT iHl I r [ ' 1- O s • I \ jm • I mm l • l M'a o 6 m Q. IS8ii H^ra I •'* i J •• .,' 8 - : r ' 1 "\ rrm B • 9 I1 I V* 10 MMIMM sif sm i | 77iw t-design depicts 36 yeast artificial chromosome (YAC) clones that we have put into 10 pools. A dark square indicates that a clone occurs in a pool. Each clone occurs in 5 pools, and each pool contains 18 clones. Assume that one of these clones is our desired "positive " product. When we test for the presence of our desired clone, we will identify the five pools containing the clone (the five positive pools). Using the information from the t-design for any four out of those five pools, we can identify our desired clone. Thus, we could identify any single positive clone even if there were a false-negative pool assay (that is, even if one of the five pools did not give a positive result, for whatever reason). This design would, however, perform poorly in the unusual circumstance that more than one of the clones is positive.

MINIMUM NUMBER OF POOLS: FRACTION OF DEFINITE POSITIVES-.95 OPTIMUM k; FRACTION OF DEFINITE POS1TIVES=.95 1.2 =

(a) (b) Results are plotted for clone libraries with a number of clones, n, between 103 and 10s and the average number of positive clones, c, between 0.25 and 16. It is required that the average number of definite positives (clones that must be positive) be 95% of the average number of positives. Plot (a) shows the minimum number of pools necessary to achieve this result using a random k-sets pooling design. Plot (b) shows the optimum values ofk, the number of pools in which each clone should occur. Our results show the minimum number of pools that would be required based on the optimum random k-sets design.

124 Los Alamos FY1996 LDRD Progress Report We have applied our ideas to pool interest. This technique works well Balding, D.J., and D.C. Torney, and screen clone libraries that are even if there are substantial rates of "Optimal Pooling Designs with Error used in the Human Genome Project. errors in the pool assay data. Detection," /. Comb. Theory A 74, These pooling and screening experi- 131(1996). ments required us to use liquid- Publications Bruno, W.J., F. Sun, and D.C. Torney, transferring robots, and for the largest "Optimizing Non-Adaptive Group clone libraries, we had to adapt Balding, D.J., WJ. Bruno, et al., "A Tests for Objects with Heterogeneous simpler, "row-column" pooling Comparative Survey of Non-Adaptive Priors" (to be published in SI AM J. designs. Given the pool assay results, Pooling Designs," in Genetic Map- Appl. Math.). we developed an optimum technique ping and DNA Sequencing, IMA for determining the probability that Volumes in Mathematics 81,133 Knil, E., A. Schliep, and D.C. Torney, each clone contains the sequence of (1996). "Interpretation of Pooling Experiments Using the Markov Chain Monte Carlo Method," J. Comp. Biol. 3,396 (1996).

(a) Primary YAC Pool H V " d2 d3 04 d5 do d7 diOdii di2 d13 ". • • O> Z

123

(b) Secondary YAC Pool of d14 E (c) Single YAC !c M PI P2 P3 W P5 P8 P7 P8 P9 P10 HO> z Y664 M tragmenl fragment Sengtli length {base (base pairs) pairs) 1107 — 881 - 615 — 492 - 3S9 - 246 - 123

These panels show the results of implementing the t-designfor batches of 36 clones from a 550-clone YAC library of human chromosome 16. In panel (a), the results of polymerase chain reaction (PCR) assays are shown for 15 batches of 36 clones, denoted dl through dl5. We determined the size of the PCR products by gel electrophoresis; the desired PCR product has a size of approximately 150 base pairs. The batch denoted dl4 is the only batch yielding the product. In panel (b) are the results of PCR assays of the ten pools created from the 36 clones in batch dl4. These pools are denoted PI through P10. The five pools that are positive (contain the desired PCR product) are PI, P2, P4, P5, and P8. Referring to our t-design (top figure, p. 124), we deduced that the positive clone should be clone 5. Panel (c) verifies that clone 5 is our desired clone. Note that the negative pools in panel (b) contain a pair of spurious bands, a frequent PCR artifact. Also, there is a trace of putative desired product in P9.

Individual Projects—Biosciences 125 Nuclear Magnetic Resonance (NMR) Formation of these structures also causes unwinding (and negative Spectroscopy of Unusual DNA Structures supercoiling) upstream of the transcription start site, which may and Functions Associated with Human facilitate transcription. We also found Disease that single-site mutations that disrupt the stem or loop structure of the hairpin G-quartet or the C+«C paired E. Morton Bradbury i-motif reduce the transcriptional activity of the insulin gene and that This work focuses on the structural structure of the human insulin mini- two or more site mutations block all biology of the insulin minisatellite, satellite. Our efforts have focused on transcriptional activity. These results which contains a region known as the a region of the ILPR in which one support our hypothesis that the insulin-linked polymorphic region strand is rich in guanine (G) and the structures of the hairpin G-quartet and (ILPR) that is associated with insulin- other in cytosine (C). the C+*C paired i-motif regulate dependent diabetes mellitus. The We have shown that the G-rich transcription of the insulin gene. human insulin minisatellite is located strand adopts a hairpin G-quartet upstream of the insulin gene and its structure, whereas the C-rich strand length is highly polymorphic. adopts an intercalated C+»C paired i- Publications We have performed two-dimen- motif structure (see accompanying Catasti, P., X. Chen, R.K. Moyzis, et sional NMR spectroscopy, gel figure). Formation of these structures al., "Structure-Function Correlations electrophoresis, digestion by single- causes slippage during replication, of the Insulin-Linked Polymorphic strand-specific PI nuclease, and in which might contribute to the Region," / Mol. Biol. 264,534 vitro replication to determine the observed length polymorphism. (1996).

y 5*

hairpin hairpin with ( «C paired (•quartet i-motif

A schematic representation of the structure of the multiple hairpin G-quartets and the C+*C paired i-motif.

126 Los Alamos FY1996 LDRD Progress Report Emerging Pathogens: Dynamics, Mutation, threat without compromising our future ability to respond to the same and Drug Resistance threat because of the emergence of drug-resistant pathogens. To this end, we have developed a quantitative Alan Perelson, Los Alamos National Laboratory model that describes the spread of one Frederick G. Hay den, University of Virginia infectious pathogen, influenza. We have fitted our model to data on one Pathogens that can grow rapidly However, before large-scale outbreak of influenza and found and mutate into drug-resistant forms treatment programs are begun, as excellent agreement. pose a serious health threat. One such might occur with a major outbreak or Our model suggests that large-scale pathogen, influenza, is one of the pandemic, the health significance of treatment of individuals once they world's greatest killers. In a normal potential drug-resistant viruses must become sick readily generates drug- "flu" season, between 20,000 and be addressed. Furthermore, treatment resistant variants. Prophylaxis, a 40,000 deaths in the United States are strategies must keep emergence of strategy in which individuals are attributable to influenza infection, and drug-resistant strains at reasonably given drug treatment before they in the 1918-1919 pandemic, over 21 low levels and still permit treatment become sick, leads to lower levels of million people died worldwide. Two of infected individuals. (Researchers infection and, hence, lower emergence antiviral drugs, amantadine and designing countermeasures to of drug-resistant variants. Because our rimantadine, are currently available biological agents released during model's predictions depend on how and in limited use against influenza warfare or by terrorist activities we assessed various parameters, infection; their use should prevent address similar public health issues.) extending our results to other patho- such large numbers of deaths if The goal of this project is to gens will require detailed knowledge another pandemic strikes. consider strategies to reduce the on the spread of the disease and the severity of an ongoing biological effects of treatment.

Optical Measurement of Drug properties similar to those of tissue. We were able to measure concentra- Concentrations in Tissue tion changes of an added absorber similar to what might be expected for drugs at typical therapeutic doses. The Irving Bigio results of this work have been submitted to Applied Optics for The goal of this project is to We performed Monte Carlo publication. develop noninvasive fiber-optic simulations of photon transport to methods for measuring drug concen- determine optimal fiber spacings and Finally, we measured the absor- trations (specifically, chemotherapeu- fiber sizes for measuring absorbance bance of some chemotherapeutic tic drugs) in tissue. Such a capability in highly scattering media such as drugs to determine whether they have would greatly benefit the study of tissue. Based on the results of the absorption bands in a wavelength chemotherapy drug kinetics (i.e., the Monte Carlo simulations, we de- range feasible for absorbance mea- time dependence of drug concentra- signed and constructed fiber-optic surements in tissue. tions) at specific targeted locations in probes and used them to take mea- the body after a drug has been surements on a variety of tissue Publications administered. Our specific objective phantoms (materials with optical is to develop a general method for properties similar to those of tissue). J.R. Mourant, I.J. Bigio, D.A. Jack, measuring the concentrations of We also developed a technique for et al., "Measuring Absorption optically absorbing compounds in measuring changes in absorption in a Coefficients in Small Volumes of turbid media by circumventing the medium with unknown scattering Highly Scattering Media: Source- problems caused by scattering. properties, and we tested our new Detector Separations for which Path technique on media with scattering Lengths Do Not Depend on Scattering Properties" (submitted to Applied Optics).

Individual Projects—Biosciences 127 Stable-Isotope Labeling of Oligosaccharide We are presently collaborating with the Danishefsky group on the synthe- Cell-Surface Antigens for Structural sis of the Lewis oligosaccharides and the NMR analysis of their solution Studies conformation.

Clifford Unkefer Publications The cellular envelopes of many Because most of the interesting Lodwig, S.N., and C.J. Unkefer, types of animal cells are coated with oligosaccharide structures derive from "Stereoselective Synthesis of Stable oligosaccharides that are involved in mammalian sources, biochemical Isotope-Labeled L-a-Amino Acids: important processes such as cell-cell approaches to labeling them are Electrophilic Amination of Oppolzer's recognition and adhesion. In addition, impossible. Recently, Danishefsky Acyl Sultams in the Synthesis of L- oligosaccharides are capable of and coworkers at Slone Kettering [15N]Alanine, L-[15N]Valine, L- eliciting immune responses and Cancer Center developed a method [15N]Leucine, L-[15N]Phenylalanine 15 differentiating, for example, the blood for the solid-phase chemical synthesis and L-[1-13C, N]Valine," J. Labelled groups (A, B, AB, and O). Cell- of oligosaccharides. The goal of our Compounds and Radiopharma- surface oligosaccharides are also LDRD project was to prepare ceuticals 38, 239 (1996). recognized by and serve as receptors uniformly 13C-labeled aldohexose Lodwig, S.N., L.A. Silks III, and C.J. for many infectious agents, including precursors required for the solid- Unkefer, "Synthesis of 1-Chloro-l- viruses and bacterial toxins. phase synthesis of the Lewis blood- 15 group antigenic determinants. [ N]Nitrosocyclohexane: an All of these functions of oligosac- Electrophilic Aminating Reagent," J. charides involve the specific binding The solid-phase synthesis of the Labelled Compounds and Radio- of the cell-surface oligosaccharide by Lewis oligosaccharides required three Pharmaceuticals 38, 161 (1996). a protein molecule. The design of precursors: a D-glucose or N-acetyl-D- pharmaceutic agents that can specifi- glucosamine precursor (1), a D- Oppenheimer, J., and L.A. Silks III, cally inhibit the binding of a bacterial galactose precursor (2), and an "Synthesis of 2-Phenyl-l,2- toxin to an oligosaccharide receptor L-fucose precursor (3). These precur- benziso [77Se] selenazol-3 (2H)-one; would be greatly facilitated by sors are shown in the accompanying 'Ebselen,'" J. Labelled Compounds knowledge of the conformation of figure. Compounds 1 and 2 contain and Radiopharmaceuticals 38, 281 both the free and bound forms of the three asymmetric centers (C3-C5); (1996). oligosaccharide. Advancing our compound 3 contains four asymmetric Orji, C.C., J. Kelly, et al., "The understanding of the conformation of centers (C2-C5). Using uniformly 15 13 First Synthesis of [9- N]-2'- oligosaccharides is dependent on the C-enriched D-glucose as a chiral application of methods such as precursor, we have prepared 1, 2, and Deoxyadenosine," J. Chem. Soc, nuclear magnetic resonance (NMR) 3 in good yield. In two steps we Perkin Trans. 1 7, 595 (1996). 13 for determining their structures. As converted D-[U- C6]glucose to 1; the Wu, R., and L.A. Silks III, "Synthesis has been demonstrated in the NMR stereochemistry at C3, C4, and C5 is of D-tl^^^^^-^CJGlucal and D- 13 analysis of protein structures, stable- retained. Synthesis of 2 required the [l,2,3,4,5,6- C6]Galactal Using D-[U- I3 isotope labeling is required for inversion of the center at C4. The C6]Glucose as the Sole Carbon increasing spectral resolution and conversion of D-glucose to L-fucose Source" (submitted to Carbohydr. assigning the resonances. At present it required the inversion of three Res.). is not possible to label most oligosac- asymmetric centers (C2, C3, and C5). charides with 13C.

OAc

H C AcO 3 OBn AcO OBn BnO 3

The precursors that we used in our solid-phase synthesis of the Lewis oligosaccharides (Ac is an acetyl group, and Bn is a benzyl group). Compound (1) is the precursor of D-glucose and N-acetyl-D-glucosamine, (2) is the precursor of D-galactose, and (3) is the precursor of L-fucose.

128 Los Alamos FY1996 LDRD Progress Report Protein Motions that Determine the measure the absorbance spectra of reaction center crystals and carry out Efficiency of Photosynthesis photoactivation. We have obtained the first-ever data set for a reaction center crystal at cryogenic temperatures, and Joel R. Berendzen it diffracts well. In collaboration with the National Institutes of Health, we In this project our goal is to energy transduction in the reaction have developed methods that allow understand the quantum efficiency of center, including the role that the accurate and efficient calculations of biomolecular photocells. Achieving various pigments and protein domains free-energy differences from simula- this goal requires that we combine play in preventing the unwanted tions of equilibrium states. These x-ray crystallography at cryogenic "back" reaction. methods will enable examination of temperatures with theoretical calcula- We have made substantial progress electron-transfer mechanisms. We tions to determine the structure of toward our goal. We have attracted the have also developed an electron- reaction centers under illumination collaboration of Nobel Prize winner transfer pathway analysis program and understand the changes in protein Hartmut Michel's group at the Max- based on a tree search that can find structure that occur upon charge Planck Institute for Biophysics, the 100 best electron-transfer path- transfer. These structural changes are Frankfurt, Germany, in carrying out ways in a small protein (such as thought to be responsible for the the crystallography. We constructed a cytochrome c with 1700 atoms) in just remarkable quantum efficiency novel instrument, an ultraviolet- a few seconds on a desktop worksta- (greater than 98%) of these cells. visible (UV-VIS) absorption spectrum tion. We will use this tool to analyze Understanding them could help to microspectrophotometer, designed for differences in pathways before and answer fundamental questions about on-line operation at a synchrotron to after illumination.

Studying Properties of Cell Suspensions are not. We found repeatable differences in light scattering properties of with Elastic Scattering the Ml and MR1 cells; however, the data on the RAT1 and RAT1-T1 cells is still inconclusive. Our preliminary Irving Bigio evidence suggests that the growth stage of the cells affects the scatter- Cancer diagnosis is commonly cancer of the bladder and colon. ing. We also developed two new verified with surgical biopsies These results were obtained empiri- methods for estimating the size of the followed by pathology assessment, an cally without a detailed understanding scatterers in highly scattering media invasive and time-consuming proce- of the sources of the spectral differ- and have determined that the pre- dure. Optical techniques for non- ences. The purpose of this project was dominant scattering centers average invasive tissue diagnosis are now to study suspensions of cancerous and only 0.3 microns in diameter. being developed, offering significant noncancerous cells in order to advantages over standard biopsy and determine the cause of the spectral cytology techniques, both in terms of changes. Publications patient care and medical costs. We have made measurements on J.R. Mourant, J.P. Freyer, and T.M. In previous work using elastic- Ml, MR1, RAT1, and RAT1-T1 cells, Johnson, "Measurements of scattering spectroscopy to detect which are derived from the same line Scattering and Absorption in cancer, we obtained sensitivities and of normal rat fibroblast cells. The Mammalian Cell Suspensions," SPIE specificities in the upper-90th MR1 and RAT1-T1 cells are capable Proc. 2679, 79-84 (1996). percentile range for some forms of of forming a tumor while the others

Individual Projects—Biosciences 129 Numerical Simulations of Biochemical We have developed both mean-field models and a particle model for the Self-Organization: Calcium Wave dynamics of microtubulelike objects in two space dimensions. To perform Propagation and Microtubule Growth ensemble averages of the particle dynamics, we have ported our code to the massively parallel Cray T3D, thus John Pearson generating several hundred realiza- We are investigating the calcium We have developed computer codes tions. The clumping phenomenon fertilization wave in xenopus eggs and for simulating the nonlinear dynamics observed in the particle simulations microtubule dynamics. These issues of the calcium wave propagation. was also observed in the mean-field are treated separately, although we These codes are in one, two, and three model. We performed a crude intend ultimately to couple the dimensions. We have performed a analytical calculation on the mean- calcium dynamics with the microtu- detailed analysis of the traveling wave field model that indicates such bule dynamics to create a plausible solutions in one dimension of the clumping should be expected. We numerical model of mitosis. We are nonlinear dynamical. This analysis have also developed mean-field also working to elucidate the differ- will be used as a guide in performing models for the dynamics of tubes with ences between the mature and numerical simulations in the more tail dynamics but these remain to be immature oocytes. realistic two- and three-dimensional explored. We have developed both particle models. This involves the numerical and mean-field models of microtubule continuation of the traveling wave Publications dynamics that reinforce our prelimi- solutions of the de Young-Keizer nary result that the generic behavior model as parameters are varied. It Reynolds, W., S. Ponce-Dawson, and of tubelike objects is to form clumps turns out that there are over a dozen J. Pearson, "Self-Replicating Spots" of growing tubes separated by empty parameters that are not well known in (to be published in Phys. Rev. E). regions. The separation between the case of the mature oocyte. We Baras, R, M. Mansour, and J. clumps is apparently determined by have extended our numerical models Pearson, "Microscopic Simulation of the rate of tubulin diffusion and of the to account for a nonuniform distribu- Chemical Bistability of Homogenous binding constants. tion of the endoplasmic reticulum, Systems," J. Chem. Phys. 105 (18), and we have begun the exploration of 8257 (1996). the effects of the endoplasmic reticulum distribution in the spherical oocyte.

130 Los Alamos FY1996 LDRD Progress Report

i^S=»^=?- r^^"^?j2=?:i

Materials Science

Actinide Crystal Structures with an of a solid that measures the sound velocity). An anharmonic model that Emphasis on Plutonium Alloys allows the Debye-Waller temperature to vary with temperature provided a better Joyce Roberts fit to the data than a simple Debye- Waller model (see plot of average mean-square displacements vs tem- Complexity of crystal structure is using neutron diffraction. We ob- perature). This outcome is consistent the outstanding scientific problem of served that the rhombohedral angle with our results from the light actinide crystal chemistry. We do not approaches 90° more closely than it actinides. know why the idiosyncratic structures did in our previous high-temperature of plutonium metal occur, and we do experiments, but that no further not know how they transform among transformations take place (see plot Publications themselves. The electronic instability of lattice constants vs temperature). of the 5f electronic shell that is just Completing the low-temperature Lawson, A.C., J.A. Goldstone, B. beginning to be filled in the light measurements allowed us to extend Cort, et al., "Structure of Zeta-Phase actinides causes "self-intermetallic" our analysis of the Debye-Waller Plutonium-Uranium," Acta compounds (in which the same temperature (a characteristic parameter Crystallogr. B 52, 32 (1996). element is in more than one valence state or crystallographic site) to be formed in both plutonium metal and 10.80 90.0 its alloys, and the formation of these Rhombohedral lattice compounds is responsible for the constants vs temperature observed complexity of structure and for the zeta-phase Pu-U 10,76 phase behavior. (a is the rhombohedral - 89.8 £: The goal of this project is to angle, and a is the lattice to 1 contribute to an understanding of this constant). During this 10.72 - complexity by determining the crystal study we added data taken - 89.6 structures of several actinide alloys: below room temperature Np-U, Pu-Th, and Pu-Zr. It is our to our previous data taken 10.68 - above room temperature. intention that this additional structural 89.4 data will eventually lead to a solution Error bars are smaller of the plutonium structure problem. than the plotted points. 10.64 200 400 600 The ultimate goal of this research is to Temperature (K) understand the complex phases of plutonium and the interrelations between them. 30 During the past year we made progress in the following areas: (1) We Mean-square thermal displacements of the atoms are establishing new sample-prepara- Obw=132(2)K tion facilities, and these facilities are isotropically averaged over 20 -0BW=(153- 0.042 *T)K nearly complete. (2) We spent several all crystallographic weeks on an unsuccessful attempt to directions for the zeta-phase 7 Pu-U vs temperature. The index our neutron data from the eta- v phase in the Pu-Np and Pu-U systems. o solid line is the anharmonic Although we have not yet indexed this 8 10 mode (in which the Debye- structure, this attempt has eliminated Waller temperature varies several blind alleys and will contribute with temperature) fit to these to the eventual success of this effort. data. The simple Debye- (3) We performed low-temperature Waller model is given by the dashed line. characterization of zeta-phase Pu-U 200 400 600 Temperature (K)

Competency Development Projects—Materials Science 135 The Implications of Diffraction In Situ independent slip systems reduces to one, the amount of slip increases with Loading Macro strain Measurements in the particle size, in line with the Composites and Finite-Element experiment and the model.

Interpretations Publications Shi, N., R.J. Arsenault, et al., Ning Shi "Relaxation of Thermal Mismatch in Discontinuously Reinforced The morphology of the evolution of and residual strain can be explained Materials," in Micromechanics of elastic macrostrain can be affected by neither by continuum theory nor by Advanced Composites, S.N.G. Chu, different physical processes, such as continuum-based dislocation mechan- P.K. Liaw, et al., Eds. (The Minerals, matrix plastic and creep flow and ics. This disagreement can be ex- Metals & Materials Society, reinforcement fracture. The onset of plained by the fact that insufficient Pittsburgh, Pa., 1995), p. 471. these processes sometimes cannot be independent slip systems in NiAl readily detected by conventional hinder plastic relaxation in individual Shi, N., M.A.M. Bourke, and J.A. methods. We are using neutron- grains when embedded into a crystal Roberts, "A Study of Internal Damage diffraction, in situ loading measure- aggregate because of the constraints of Metal Matrix Composites by ments, and finite-element analysis to by neighboring grains. As the particle Neutron Diffraction," in Neutron understand the evolution of the elastic size increases, a greater number of Scattering in Materials Science II macrostrain in composites with the grains participate in the relaxation 376, 441 (1995). objective of enabling nondestructive process, and a collaborative slip Shi, N., M.A.M. Bourke, et al., "Load assessment of internal damage. In among grains eases the constraints. Sharing during Loading in Ceramic addition, we are studying the effect That is, as the neighboring grains slip, Reinforced Al Composites" of in situ creep on the load sharing each individual grain does not have (submitted to Metall. Trans. A). between phases during isostress "rigid" surroundings. This model is loading. supported by the polycrystalline Shi, N., K. Xu, et al., "Thermal We have measured the dislocation plasticity calculations. Mismatch Dislocation Generation in density and thermal residual elastic The second figure is from a two- Polycrystalline Metal" (submitted to strains in NiAl reinforced by 20 vol % dimensional (2-D) crystal-plasticity Metall. Trans. A). A12O3 particulates. As the size of the calculation and shows that the total Song, S.G., N.Shi, etal., reinforcement increases, the average amount of slip stays almost un- "Reinforcement Shape Effects on the dislocation density increases and the changed relative to the particle size Fracture Behavior and Ductility of corresponding thermal residual elastic when the matrix possesses a sufficient Particulate-Reinforced 6061-A1 strain decreases, as shown in the first number of slip systems (three Matrix Composites," Metall. Trans. A figure. The changes with respect to independent slip systems are suffi- 27A, 3739-3746 (1996). particle size in the dislocation density cient for 2-D). As the number of

Matrix Strain for Equi-Axed Particle Composites 0.006

0.00S9 ^sj 1 1 0.0058

0.0057 :—J. j..J\i — — - -j -—j- : I 0.0056 I §, 200 " 0.0086

0.0054

Single Slip System < 0.0053 z Three Slip Systems '.... i i... i ....i....i.... 0.0052 0 50 100 150 200 250 300 350 400 Particle Size (|im) Normalized Particle Volume (V/v )

Measured NiAl thermal residual strain as a function Calculated average accumulated slip vs normalized of reinforcement size. individual particle volume. A comparison of single- and three-slip systems.

136 Los Alamos FY1996 LDRD Progress Report Chemical and Physicochemical Properties microscopy/energy electron loss spectroscopy (STEM/EELS). For all of Submicron Aerosol Agglomerates combinations of precursors, TEM/EDS revealed little variation in composition from particle to particle. The homoge- Ronald Scripsick neity from particle to particle suggests that chemical reactions of the precur- Nanometer-sized aerosol particles suggests that two simultaneous sors to form the condensable species are a by-product of high-thermal- pathways exist to metal-oxide aerosol are occurring simultaneously, and any energy processes including waste formation from solid-phase, metal-salt differences in chemical reaction incineration and explosions. They precursors: (1) vaporization and behavior of the precursors are insig- may also be intentionally generated chemical reaction followed by gas-to- nificant. The segregation within the for use as superconducting powders particle conversion, and (2) solid- particles is probably occurring by solid- and ultraviolet screening films. This phase reaction to the oxide. state diffusion during particle formation research focuses on the chemical Recent focus has been on the gas-to- as a result of the immiscibility of the properties of nanometer particles and particle pathway to aerosol formation. two oxide species. their agglomerates. In order to study the effect of precur- In previous experiments we sor chemistry on particle-composition generated binary aerosol mixtures of heterogeneity, we generated mixed Publications zinc oxide with magnesium oxide and SiO2/TiO2 aerosol in a flat flame Ehrman, S.H., and S.K. Friedlander, of copper oxide with magnesium burner from three sets of gas-phase "Formation of a Binary Aerosol in a oxide from aqueous solutions of metal precursors: SiBr4/TiCl4, SiCL4/TiCl4, High Temperature Process: Factors salts. We atomized, dried, and passed and hexamethyldisiloxane (HMDS)/ Influencing the Segregation of them through a flat flame burner. We TiCl4. We found SiO2/TiO2 an interest- Species" (Fifth World Cong, of Chem. found the agglomerate-particle mass ing system because no mixed phase Engineers, San Diego, Calif., distribution with respect to aerody- exists, nor is there any mermodynami- July 14-18, 1996). namic diameter to be bimodal for the cally stable solubility of SiO2in TiO2 zinc and magnesium in the ZnO/MgO in the solid phase. Ehrman, S.H., and S.K. Friedlander, system. In the CuO/MgO system, the We developed techniques to deter- "Formation of Binary Aerosols in a magnesium distribution was bimodal mine the scale of mixing using trans- High Temperature Process," (Am. and the copper was concentrated in mission electron microscopy/energy- Assoc. for Aerosol Res. Ann. Mtg., the smallest size ranges (particle dispersive spectroscopy (TEM/EDS) Pittsburgh, Pa., October 9-13, 1995). diameter < 0.5 micron). The bimodal and scanning transmission electron size-distribution of the aerosol

Characterization of Bioactive suspended films of lipid multilayers. Because these films are 5 cm x 5 cm Materials Using Neutron Reflectivity in area, they are appropriate for our neutron-reflectivity studies. We also and Atomic Force Microscopy began testing of the oven, and we have designed and are currently Gregory Smith constructing a new constant-humidity control system for use with the oven. The objective of this project is to This year we have prepared ori- We expect to begin a series of experi- apply neutron reflectivity and atomic ented films of the lipid DMPC on ments with simple lipid multi- force microscopy to characterize the silicon substrates. However, these membranes first and then lipids with structure and phase behavior, the films have not proved to be ideal for DNA, polyethylene glycol lipid, or interlayer and intermacromolecular these studies. Although the films lipoproteins. interactions, and the protein shape initially form well-oriented samples, stability of a fundamentally new class they delaminate from the substrates of bioactive molecular systems. This upon hydration. system is composed of reconstituted Our major accomplishment this and native self-assembled membrane year was to design and construct a proteins complexed with associating controlled-humidity oven that can be and surfactant polymers. used for producing oriented, freely

Competency Development Projects—Materials Science 137 Bulk Amorphous Materials produced by other preparation methods.

Ricardo B. Schwarz Publications

Bulk amorphous metallic alloys of 10-mm-diam rods. Being able to Desch, P.B., R.B. Schwarz, and P. (also know as "bulk metallic glasses") use less palladium represents a Nash, "Formation and Phase Stability are strong, corrosion-resistant significant reduction in the cost of of Ll2 Phases in the Al-Ti and Al-Zr materials that can be cast in near-net- these alloys. We have also discov- Systems Produced by Mechanical shape form by techniques such as ered the formation of bulk amor- Alloying" in Applications of injection molding. Because of these phous alloys in Pd-Cu-P and Thermodynamics in the Synthesis and characteristics, bulk metallic glasses Pd-Ni-Fe-P systems. Processing of Materials, P. Nash and are used to make such equipment as B. Sundman, Eds. (The Materials 3. Collaborations with Other gears (especially complicated shapes Society, Warrendale, Pa., 1995), pp. National Laboratories. We have that are difficult to machine), surgical 75-89. supplied samples of our alloys to tools, corrosion-resistant parts such as other national laboratories and Desch, P.B., R.B. Schwarz, and P. valves, and seamless tubes. universities to establish collabora- Nash, "Mechanical Alloying to The broad goal of our project is to tive work using their unique Produce Ll2 Phases in the Al-Zr develop novel materials with potential facilities and expertise (corrosion System," Scripta Materialia 34, 37 for industrial or defense applications. studies at Brookhaven National (1996). We are developing methods to synthe- Laboratory; structure determina- size and characterize bulk metallic He, Y., R.B. Schwarz, and J.I. tion at the National Synchrotron Archuleta, "Bulk Glass Formation in glasses and multiphase metastable Light Source, Brookhaven; and alloys formed by mechanical alloying. the Pd-Ni-P System," Appl. Phys. atom probe microscopy at Oak Lett. 69, 1861 (1996). We are researching the conditions for Ridge). forming these alloys and the basic He, Y., R.B. Schwarz, and D.G. properties of the alloys, including 4. Metal-Ceramic Composite Mandrus, "Thermal Expansion of thermal stability, mechanical proper- Powders. In another phase of our Bulk Amorphous Zr412TiJ3 gCu12 5," /. ties, and hydrogen storage character- research, we are using mechanical Mater. Res. 11, 1836 (1996). istics. Another goal of our research is alloying—a high-energy ball- to develop bulk magnetic glassy milling technique—to prepare He, Y, R.B. Schwarz, et. al, "Elastic materials. Currently, no such materi- metal-ceramic composite powders Moduli, Density, and Structural als exist, but the discovery of bulk from vanadium oxide, magnesium, Relaxation in Bulk Amorphous Zr-Ti- magnetic metallic glasses would lead and aluminum powders. The fine- Cu-Ni," (to be published in J. Non- to a tremendous energy savings grained powders that we produce Crystalline Solids). nationwide. by this method are quite resistant Schwarz, R.B., "Introduction to the This year we have achieved the to mechanical degradation in Viewpoint Set on Mechanical hostile radiation environments and following: Alloying," Scripta Metallurgica et do not crack as easily as the MaterialiaM, 1(1996). 1. Improvement in the Synthesis corresponding large-grain powders Techniques. We improved a melt- fluxing technique that we had developed last year. This technique enables us to produce l-in.-diam rods of amorphous Pd4ONi4<)P2o, the largest rod of this material ever produced (see accompanying figure). A patent application for this method is being processed by the Laboratory. 2. New Alloy Compositions. Previ- ously, bulk amorphous Pd-Ni-P alloys were only known at the composition of Pd40Ni40P20. This year, we were able to cast amor-

phous alloys containing only A l-in.-diam rod of amorphous Pd40Ni40P20 alloy prepared by our melt-fluxing 25 at. % of palladium in the form technique.

138 Los Alamos FY1996 LDRD Progress Report Schwarz, R.B., and Y. He, "Formation Solovioff, G., D. Eliezer, et al., Wasz, M.L., and R.B. Schwarz, and Properties of Bulk Amorphous Pd- "Hydrogen-Induced Cracking in an "Structure and Properties of Metal Ni-P Alloys" (International Symposium Al- Al3Ti- A14C3 Alloy," Scripta Hydrides Prepared by Mechanical on Metastable, Mechanically Alloyed, Metallurgica et Materialia 33, 1315 Alloying," Mater. Set Forum 225- and Nanocrystalline Materials, Rome, (1995). 227, 859 (1996). Italy, May 20-24,1996). Thakur, A.M., N.N. Thadhani, and Wasz, M.L., P.B. Desch, and R.B. Schwarz, R.B., and A.G. R.B. Schwarz, "Shock-Induced Schwarz, "The Effect of Tin Alloying Khachaturyan, "Thermodynamics of Martensitic Transformations in Near- on the Structure of LaNi5," Philos. Open Two-Phase Systems with Equiatomic NiTi Alloys" (to be Mag. A. 74,15 (1996). Coherent Interfaces," Phys. Rev. Lett. published in Metallurgical Trans.). Wasz, M.L., R.B. Schwarz, et al., 74, 2523 (1995). Ustiindag, E., K.E. Sickafus, Y. He, et "Sn-Substituted LaNi5 Alloys for Shi, N., R.B. Schwarz, and P.B. Desch, al., "Metal-Ceramic Composites for Metal Hydride Electrodes," Mater. "Formation of MoS^ Through Hostile Environment Application," in Res. Soc. Symp. Proc. 393, 237 Annealing of Ball-Milled Mo and Si Advances in Ceramic Matrix (1995). Composites HI, N.P. Bansal, Ed. Elemental Powders," in Applications of Yvon, P.J., R.B. Schwarz, et al., (American Ceramic Society, Thermodynamics in the Synthesis and "Covalent and Liquid-Like Westerville, Ohio, in press). Processing of Materials, P. Nash and B. Amorphous Phases in Al-Ge Alloys," Sundman, Eds. (The Materials Society, Philos. Mag. 72,167 (1995). Warrendale, Pa., 1995), pp. 63-74.

Characterization of Advanced Electronic Kwei, G.H., J.M. Lawrence, J.L. Sarrao, et al., "Structure and Disorder Materials in YbInCu4," Phys. Rev. B 54, 6011 (1996). Joe D. Thompson Mentink, S.A.M., H. Amitsuka, A. deVisser, et al., "Thermodynamic The ability to characterize (measure and charge-excitation spectra of a Study of the Magnetic Phase and interpret) properties of advanced correlation-driven semiconductor obey Transition in UNi4B" (submitted to electronic materials bridges the gap different functional dependences. Physica B). between materials synthesis and Analysis of the competition between theoretical modeling. This project magnetic and electronic interactions for Movshovich, R., T. Graf, D. Mandrus, builds on and extends the the ground states of several rare-earth et al., "Response of CeRh2Si2 to Laboratory's competency in nuclear and actinide intermetallic compounds Pressure," Physica B 223 & 224, 126 and advanced materials by character- has been made. (1996). izing the ground states of materials in Movshovich, R., T. Graf, D. Mandrus, which electronic correlations domi- et al., "Superconductivity in Heavy nate the materials' properties. Our Publications Fermion CeRh Si ," Phys. Rev. B 53, goal is to discover new physics by 2 2 Heffner, R.H. and M.R. Norman, 8241 (1996). understanding the complex interplay "Heavy Fermion Superconductivity," among microscopic interactions that Comments Condensed Matter Phys. Movshovich, R., M.F. Hundley, J.J. produce these ground states. 17, 361 (1996). Neumeier, et al., "Magnetism in This year we have discovered CePtPb," Phys. Rev. B 53, 5465 Heffner, R.H., L.P. Le, G.J. evidence for an unexpected form of (1996). Nieuwenhuys, et al., "Possible magnetism that develops in the Evidence for Spin or Orbital Sarrao, J.L., CD. Immer, C.L. superconducting state of B-doped Magnetism Below the Benton, et al., "YbInlxAgxCu4: UBe . We also used a broad range of 13 Superconducting Transition Evolution from First-Order Valence experimental techniques to study the Temperature in UBe B " Transition to Heavy Fermion evolution of a first-order, isostructural 1291 009 (submitted to Physica B). Behavior," Phys. Rev. B 54, 12014 valence transition with silver substitu- (1996). tion in YbIn!_xAgxCu4 and found that Hundley, M.F., J.J. Neumeier, J.D. interactions driving this transition are Thompson, et al., "Magnetostriction played out on the unit-cell scale. and Thermal Expansion of the Kondo Scaling analysis of thermodynamic Semiconductor Ce3Bi4Pt3," Physical data established that gaps in the spin- Phenomena at High Magnetic Fields- 7/2,203(1996).

Competency Development Projects—Materials Science 139 Neutron Scattering Studies on there is little basis for predicting the effect of an industrial processing Shear-Induced Structure in Polymers strategy on material properties. The task for this year was to design and construct the apparatus needed Rex Hjelm for this project. This work included completion of an improved Couilette- Our objective is to study polymer- molding. Thus the production of geometry shear-cell rig with better surface interactions and shear- fibers and molded parts in industrial thermal isolation and control and induced, polymer orientation in the applications naturally introduces flow better shear-cell alignment character- bulk. These aspects include self- shear, which affects the conformation istics as well as fabrication of lubrication effects in polymers under and orientation of polymer chains, aluminum, Couilette-geometry shear flow- and shear-induced phase making the effects of shear on poly- cells for high-temperature shear work. transitions in liquid crystal polymers. mer conformation and orientation of We also designed a cone and plate Shear is introduced in industrial considerable industrial interest. A rheometer for neutron reflectometry processing when a polymer melt or detailed understanding of the physics experiments. We prepared materials to concentrated solution is passed of polymers under shear that could be study shear flow characteristics of though an orifice, such as a spinner used to connect the structure of liquid crystal polymers for measure- used in fiber formation, or by injec- polymers with their unique rheologi- ments planned for early next year. tion into the mold used in injection cal properties has yet to emerge. Thus

Structural and Magnetic Characterization Based on these results, we plan to use neutron diffraction to investigate of Actinide Materials the nature of intriguing changes in the temperature dependence of the Barbara Cort resistivity of AmD2 5. We will also perform neutron diffraction experi- The focus of this project is to observed clear diffraction peaks, as ments to determine the structures of extend our fundamental research shown in the second figure, for 15 mg superstoichiometric oxides of plutonium produced from the reaction capability and to answer questions of of CaF2 counting for two hours on the practical importance to stockpile Manuel Lujan Jr. Neutron Scattering of plutonium oxides with water under integrity and long-term storage of Center's high-intensity powder storage conditions. nuclear material. We have success- diffractometer (HIPD). We used these fully used neutron scattering tech- results to calculate patterns for two Publications niques to investigate physicochemical actinides of interest, AmD2 and PuO2, properties of elements, compounds, each counted for 24 hours (see second Haschke, J.M., T.H. Allen, and J.L. and alloys of the light actinides for figure). We predict well-defined Stakebake, "Reaction Kinetics of the last ten years. We now address diffraction peaks. Plutonium with Oxygen, Water, and new issues vital to the Laboratory's Humid Air," J. Alloys Compounds mission such as long-term storage of Threaded end attaches 243, 23-35 (1996). to HIPD nuclear materials and aging of outer capsule plutonium in primaries in the nuclear stockpile. We made significant progress in development of encapsulation inner capsule techniques for milligram quantities of actinides for neutron scattering studies. These techniques are impor- neutron flight path tant for studies of rare isotopes welded caps available only in small quantities or actinide sample isotopes that are difficult to handle in support larger quantities because of their radiological properties. We performed a successful test on a nonradioactive sample using the encapsulation Assembly drawing of the small sample assembly shown in the first figure. We encapsulation; scale is 2:1, in inches.

140 Los Alamos FY1996 LDRD Progress Report test of small cans - 4132 Hist 3 Bank 3, 2-Theta 9 0.0, L-S cycle 22 Obsd. and Calc. Profiles I i i

o X

o - 3. 0

'musec . I 2. 0 coun t

- Norm . 1. 0 1 1 1 1.0 D-spacing, A

15 mg. CaF2 - 2 hours - measured

test of small cans Hist 5 Bank 3, 2-Theta 90.0, L-S cycle 13 Obsd. and Calc. Profiles

1.0 D-spacing, A

100 mg. AmD2 - 24 hours - calculated

500 mg PuO2 Hist 2 Bank 3, 2-Theta 90.0, L-S cycle 5 Obsd. and Calc. Profiles

1.0 >-spacing, A

500 mg. PuO2 - 24 hours - calculated

Neutron diffraction data for CaF2 (top) and calculated patterns for AmD2 and PuO2.

Competency Development Projects—Materials Science 141 Equation-of-State, Thermodynamic, Finally, because of recent developments in ab initio calculations of and Structural-Mechanical Properties linear response functions, we put aside our third goal of using fitted of Intermetallic Compounds potentials to generate a full-zone phonon spectrum in favor of the John Wills development of the resources to perform ab initio calculations of full- Intermetallic compounds have experimental data; theory and exper- zone phonon spectra using linear important applications as high- iment appear to be in significant response theory. We completed the temperature structural materials. disagreement. These calculations development of the theory of this Their elastic, mechanical, and were done on the related structural capability for the electronic structure method that we use. We also tested structural properties as a function of materials NbCr2 and HfV2 instead of temperature, pressure, and composi- the originally proposed Ti-Al and Ni- the calculation of forces for a variety tion are key measures of their Al systems because of the timely of materials. The capability to usefulness. The goal of this project availability of new experimental data calculate phonons with linear re- was to develop the theory and with which to compare. sponse is currently being written into resources to perform ab initio Toward our second goal, we our electronic structure codes. calculations of (1) the elastic proper- developed and tested a method for ties of high-temperature structural performing ab initio electronic Publications materials, (2) the structural properties structure calculations on ordered of ordered alloys, and (3) the equation alloys. This method improves on the Asta, M., R.C. Albers, et al., "First- of state of materials. virtual crystal approximation for full Principles Study of Intermetallic For our first goal, calculation of the potential calculations of inter-row Phase Stability in the Ternary Ti-Al- Nb" (proceedings of the fall meeting elastic constants of C15 NbCr2 was alloys. We applied this method to the completed during this fiscal year, as calculation of structural stability of of the Materials Research Society, well as calculations of the relative (Ti, Zr)-(V,Ta) alloys for comparison Boston, Mass., 1995). structural stability of C15, C14, and with experimental results; experimen- Ormeci, A., F. Chu, J.M. Wills, et al., C36 NbCr2 and HfV2. (C14, C15, and tal results are thus far disappointing, "Total-Energy Study of Electronic C36 designate various crystal struc- and we are applying the method to Structure and Mechanical Behavior of tures.) We calculated the isotropic elasticity in Nb-Cr alloys. C15 Laves" (to be published in Phys. shear modulus from Reuss/Voigt Rev. E). averages and compared them with

Neutron Scattering from dence of the 40-meV crystal-field Correlated-Electron Systems level in UPdSn, a search for crystal- field excitations in UPd2Pb, and a definitive experiment on the crystal- Robert Robinson field level in PuO2. The PuO2 experiment showed, in contrast to a previous The purpose of this project is to systems. The PDF method consists of lower-resolution experiment at exploit the neutron scattering facilities analyzing the data in real (rather than Argonne National Laboratory, that at the Los Alamos Neutron Science reciprocal) space, much as one does in there is no quadrupolar splitting of Center in the studies of correlated- measuring pair distribution functions in this level, but that there is some electron behavior in both f-electron glasses or liquids; it complements more residual broadening. systems (e.g., heavy fermions) and conventional crystallographic methods On the diffraction side, we studied transition-metal oxides (like the high- like Rietveld refinement. Inelastic the Li-doped version of La2Cu04, the temperature superconducting neutron scattering is the technique of parent compound for the high- cuprates). There are two main thrusts: choice for measuring the magnetic temperature superconductors, by (1) the use of pair-distribution- excitation spectra in such systems. means of conventional neutron function (PDF) structural methods to We performed a number of highly diffraction. Both the structural and study local disorder, particularly in successful inelastic scattering studies thermal parameters are unusual and the cuprates, and (2) the use of on the PHAROS high-resolution indicate that the local and average inelastic neutron scattering for the chopper spectrometer. These included structures are not identical. study of magnetic excitations in such a study of the temperature depen-

142 Los Alamos FY1996 LDRD Progress Report Advanced Deformation Process Modeling Maudlin, P.J., S.I. Wright, et al., "An Application of Multisurface Plasticity Theory: Yield Surfaces of Textured U.FredKocks Ta," in High Pressure Science & Technology (Warsaw Polish Academy The general aim of this project was Publications of Sciences, Warsaw, Poland, 1995), to improve the understanding of the pp. 138-140. Beaudoin, A.J., H. Mecking, and U.F. constitutive behavior of metals for use Kocks, "Development of Local Shear in deformation processing applica- Mecking, H., C. Hartig, and U.F. tions. This project has had two major Bands and Orientation Gradients in Kocks, "Deformation Modes in components: the description (on the FCC Polycrystals," in Simulation of Gamma-TiAl as Derived from the basis of dislocation mechanisms) of the Materials Processing (NUMIFORM- Single Crystal Yield Surface," Ada kinetics of flow and strain hardening 5) (Balkema, Rotterdam, the Mater. 44, 1309-1321(1996). Netherlands, 1995), pp. 225-230. and the description (on the basis of Mecking, H., U.F. Kocks, and C. polycrystal plasticity models and Beaudoin, A.J., H. Mecking, and U.F. Hartig, "Taylor Factors in Materials measured textures) of the anisotropy Kocks, "Development of Localized with Many Deformation Modes," Scr. of macroscopic strength properties. Orientation Gradients in FCC Mater. 35, 465^71 (1996). Progress was made on both fronts, Polycrystals," Philos. Mag. A 73, Poole, W.J., S. MacEwen, et al., with the following highlights. 1503-1517(1996). The overall status of our strain "Deformation Texture Development Beaudoin, A.J., P.R. Dawson, et al., hardening theory was reviewed and in a Model Composite System," Tenth "A Hybrid Finite Formulation for compared with some new proposals Int. Conf. Compo. Mat. II, 59-67 Polycrystal Plasticity with Considera- (which were found wanting). In (1995). tion of Macroscopic/Microscopic particular, the processes of dynamic Linking," Int. J. Plasticity 11, Wright, S.I., and U.F. Kocks, "A recovery seem well understood, but 501-521(1995). Comparison of Different Texture this knowledge is not always applied Analysis Techniques," in Textures of to best advantage. Some inroads have Beaudoin, A.J., T. Kota, H. Uto, et al., Materials (ICOTOM-llj been made into improving the general "Simulation of Sheet Metal Forming (International Academic Publishers, appreciation of this part of plasticity Using Polycrystal Plasticity," in Beijing, China, 1996), pp. 53-62. theory. Dynamic Plasticity and Structural For a long time, and according to Behaviors (Gordon & Breach, Boston, all investigators, the prediction of Mass., 1995), p. 221. deformation textures has suffered Kocks, U.F., S.I. Wright, and A.J. from yielding textures that are too sharp, compared with experiments. Beaudoin, "The Sensitivity of Yield A systematic investigation of the Surface Predictions to the Details of a influence of texture sharpness (real or Texture," in Textures of Materials perceived) on macroscopic properties (ICOTOM-11) (International has demonstrated that this effect is Academic Publishers, Beijing, China, negligible in most cases. On the other 1996), pp. 763-768. hand, slight shifts in the location of MacEwen, S.R., A. Langille, J. texture peaks, whether as a result of Savoie, et al., "Characterization, experimental errors or of faulty model Validation, and Finite Element predictions, can have significant Modelling of Extrusion," in effects on strain anisotropies, such as Simulation of Materials Processing those causing the so-called earing in (NUMIFORM-5) S.F. Shen and P.R. deep-drawn metal sheets. Dawson, Eds. (Balkema, Rotterdam, Continued cooperation with the Netherlands, 1995), pp. 95-100. Armand Beaudoin of Reynolds Metals Corporation and with Heinz Mecking of the Technical University Hamburg-Harburg (Germany) has been very effective, both from the modeling and from the applications point of view.

Competency Development Projects—Materials Science 143 Scanning Probe Microscopy Competency Publications Development Hawley, M.E., R.J. Houlton, et al., "The Effect of Temperature, Growth Kinetics, and Substrate on the Marilyn Hawley Microstructure of RF Off-Axis Sputter Deposited YBa2Cu3O7 Thin Our goal is to develop the ultra- metal and semiconductor materials. In Films," in Extended Abstracts of the high-vacuum (UHV) scanning addition, we have added magnetic and 1995 International Workshop on tunneling microscope system to electric force capabilities to the air Superconductivity (ISTEC & include in situ film fabrication and scanning probe and have used these Materials Research Society, Pittsburg, complementary analytical capabili- capabilities to perform growth and Pa., 1995), p. 113. ties. We plan to integrate this system characterization studies of magneto- with existing scanning probe and resistive films. We have obtained Hawley, M.E., CD. Adams, P.N. surface technologies. A broad range some preliminary data on magnetic Arendt, et al., "CMR Films' Structure of applications will be enhanced from structure of thin films and stressed as a Function of Growth and the existence of a range of scanning magnetic ribbons, as shown in the Processing" (to be published in /. probe instruments and the associated accompanying figure. Crystal Growth). state-of-the-art expertise, particularly The combined capabilities now Hawley, M.E., X.D. Wu, P.N. Arendt, at the nanoscale level. Of particular enable us to respond to a wide variety et al., "Microstructural Study of CMR value is an extension of the present of problems requiring localized Films as a Function of Growth capabilities for examining surfaces in imaging of conducting and noncon- Temperature, As-Deposited and air to include the measurement of ducting surfaces in liquids, air, UHV, Annealed," Mat. Res. Soc. Symp. surfaces prepared under clean and at low or elevated temperatures. Proc. 401, 531 (1996). (vacuum) conditions. We will further expand these capabili- We have now modified the system ties to include imaging during or after Hundley, M., J J. Neumeier, X.D. to include a new vacuum chamber, a in situ mechanical stressing of Wu, et al., "Transport-Magnetism new load-lock system for sample materials. Work has begun on adding Correlations in the Ferromagnetic insertion, and sample positioning and nanoindenting, scratching, and in situ Oxide La0 7Ca0 3Mn03," Appl. Phys. sample heating capabilities for both tensile stress capabilities. Lett. 67, 860 (1995). Jia, Q. X., F. Chu, X. D. Wu, et al., "Characteristics of Conductive ( - »•

144 Los Alamos FY1996 LDRD Progress Report Design and Implementation of an X-Ray strains are measured at each incre- ment of slot depth and are used to Strain Measurement Capability Using a solve for the original residual stresses. Using this technique, we compared Rotating Anode Machine the results of the crack compliance method with x-ray and neutron Joyce Roberts diffraction measurements. These comparisons are shown in the Residual stresses close to the residual stresses present in the accompanying figure. surface of materials can improve the alumina fall below the predicted reliability and lifetime of parts such as values. Publications gears, spindles, and axles for techno- Reduction reactions can also be logical applications. An exact applied to magnetic metal-ceramic Bourke, M.A.M., P. Rangaswamy, et knowledge of the stresses at the thin films. Nickel-spinel is reduced to al., "Complementary Neutron and surface and their depth distribution is obtain thin films containing nanoscale X-Ray Measurements in an Attempt important. X-ray diffraction plays a nickel. The nickel particles possess to Obtain a Strain Profile through a significant role in measuring surface interesting magnetic properties, Carburized Layer" (to be published in residual stresses. Our project is including perpendicular magnetiza- Mater. Sci. Eng. A). focused on developing an x-ray tion. Anisotropic residual stresses Jayaraman, N., and P. Rangaswamy, capability as a key to measuring and present in the nickel because of the "Oxide Scale Stresses in Poly- interpreting strain effects. volume shrinkage and the coefficient crystalline Cu/Cu2O System" (to be We used finite-element models to of thermal expansion mismatch are published in Adv. X-Ray Anal). predict the thermomechanical believed to be the cause of the processing effects on the residual perpendicular magnetization. Our Rangaswamy, P., M.A.M. Bourke, stresses in a unidirectionally rein- preliminary x-ray stress measure- A.C. Lawson, et al., "Residual Stress forced SCS-6/Ti-6-2-4-2 [0]6 ments have yielded tensile stresses of and Microstructural Characterization material, and we used x-ray and several hundred megapascals; these Using Rietveld Refinement of a neutron diffraction to measure the measurements correlate well with Carburized Layer in a 5120 Steel" (to effects. Both x-ray and neutron magnetic anisotropy data obtained at be published in Adv. X-Ray Anal). diffraction recorded a reduction in Cornell. Rangaswamy, P., M.A.M. Bourke, stresses in the processed material Another method for measuring P.K. Wright, et al., "Influence of compared with the as-fabricated stress, the crack-compliance method, Residual Stresses on Thermo- material. The decrease correlated with offers a unique capability for measur- mechanical Processing of SCS-6/T1-6- improvement in fatigue lifetime. ing stress variation with depth. A slot 2-4 Titanium Metal Matrix A novel approach developed at incrementally introduced into a part Composites" (to be published in Cornell University employs the containing residual stress causes local Mater. Sci. Eng. A). volume shrinkage that relaxation. The resulting surface accompanies reduction Gear Blank reactions to induce compressive residual XP5120PF MBCO 8H19M stresses in the Slot Tension surfaces of ceramics. In this approach, alumina is bonded to a nickel- spinel oxide sample during hot pressing. When the spinel is reduced, it shrinks, inducing compressive residual stresses in the Stress 0.0 0.2 0.4 0.6 0.8 1.0 alumina. Our prelimi- Measurement Depth from Surface (mm) Locations nary x-ray measurements indicate that the Front View Side View Comparison of stress measurements on a carburized gear blank (also shown) that were determined using x-ray and neutron diffraction and the crack-compliance method. The results from analysis are also shown for comparison.

Competency Development Projects—Materials Science 145 Computational Modeling of Materials investigated rod-in-tube processing and rolling with extra packing Processing and Processes material. The calculated deformations were then applied as boundary Terry C. Lowe conditions to the model we developed. We used the calculated results The objective of this research was Early in the project we developed a to interpret a set of prototypical to create a computational model to model to describe the mechanical rolling experiments designed to describe the processing of porous, behavior of BSCCO during deforma- investigate core morphologies anisotropic materials. The initial focus tion processing. The model combines resulting from various rolling environ- was on deformation processing of theories of deformation for porous, ments. Our goal was to understand the bulk, high-temperature, superconduct- elastic-viscoplastic, polycrystal deformations in the core of the OPIT ing oxides. The anisotropic mechani- materials. We conducted compaction workpiece and the resulting micro- cal properties of densified powders experiments on 2223 BSCCO powder structural evolution of the BSCCO composed of Bi-Sr-Ca-Cu-O in a confined channel-die environment powder. We were able to simulate the (BSCCO) are of paramount impor- to obtain data for calibrating the effects of multiple processing tance during thermomechanical model. We then compared the model parameters on the texture and density processing of superconducting tapes with other experimental results and of the superconducting material. One and wires. Maximum current trans- used them to resolve the effects of of the most significant results was the port requires high relative densities initial texture and confinement prediction of the important role of and high degrees of alignment of the pressure on the densification and shear deformation on the evolution of single-crystal superconducting planes ultimate formability of the BSCCO textural anisotropy. parallel to the plane of the tape. This powder. configuration causes high stresses We performed a detailed, finite- Publications during compressive processing modes element analysis of the tape-rolling and can lead to cracking and thus environment and calculated both Schoenfeld, S.E., S. Ahzi, et al., "The degrade the density and conductive pressures and shear strains in the core Bulk Processing of 2223 BSCCO properties of the tape. of oxide powder-in-tube (OPIT) Powders; Part I: Densification," processed tapes. In addition, we Philos. Mag. A 73,1565 (1996).

Nanometer-Scale Materials structures of self-assembled, monolayer systems (SAMs). Lateral force microscopy proved especially useful David Devlin in imaging patterned SAMs formed using microcontact printing tech- Our focus is the science and alumina support used. Impregnation niques. We were surprised to observe technology needed for molecular-level of MomCxNy into preformed alumina differences between SAMs of control of materials on a nanometer pellets resulted in a material that alkanethiols on gold in stamped scale—from advanced computing specifically isomerized n-heptane versus filled-in regions of u-contact, architectures to microelectronics and into equal amounts of 2- and 3- even when the molecules were catalysis. Molecular-level control that methylhexanes and iso-butane. We identical. We studied these patterned relies on artificial structures and saw no evidence of aromatic products SAMs, using Fourier transform nanometer-scale materials will help us at operating temperatures below infrared and other spectroscopic develop entirely new devices and 420°C. The product selectivity of the methods, and now attribute the chemistries. isomers was 56% at an n-heptane difference between stamped and Using the metal amide conversion efficiency of 57%. filled-in areas to density differences in Mo2(N(CH3)2)6 as a molecular precur- Impregnation of MomCxNy into an the SAMs. sor, we prepared highly selective, alumina powder resulted in an alumina-supported, molybdenum extremely selective aromatization carbonitrides by solution impregnation. and dehydrogenation material. The Publications On the basis of relative weight per- products from this material consist Barrera, J., and D.C. Smith, "Alumina cents, these materials demonstrate a 5- only of aromatics and n-heptenes Supported Molybdenum to 8-fold increase in catalytic activity with less than 2% isomerization or Carbonitrides: An Extremely over similar materials prepared by cracking products. Selective Material" (submitted to J. traditional, solid-state approaches. We developed scanning force Catalysis). The catalytic activities of these microscopies (atomic force and lateral materials depend on the type of force) to probe the microscopic

146 Los Alamos FY1996 LDRD Progress Report Science and Technology of Reduced- Laj xCaxMnO3: Inadequacy of the Nominal Mn(3+/4+) Valence Dimensional Magnetic Materials Approach" (submitted to Phys. Rev. B). Neumeier, J.J., A.L. Cornelius, and Robert Heffher M.F. Hundley, "Volume-Based Thermodynamic Considerations for Our research objective is to develop is consistent with a variety of experi- the Magnetoresistance Effect and a clear microscopic understanding of mental data (e.g., neutron pair- Metal-Insulator Transition of CMR the physical mechanisms responsible distribution function analysis, x-ray Manganese-Oxide Perovskites" for the unusual electronic transport absorption fine-structure analysis, (submitted to Phys. Rev. Lett.). properties exhibited by the transition- thermopower) and with the fact that Roder, H., J. Zang, and A.R. Bishop, metal oxides La1.xMxMnO3 (where M real materials involve orbital interac- "Lattice Effects in the Colossal can be calcium, barium, or strontium). tions, disorder, and Jahn-Teller Magnetoresistance Manganites," These materials typically undergo a electron-lattice coupling. very large reduction in resistance in Phys. Rev. Lett. 76,1356 (1996). modest magnetic fields near their Tyson, T.A., et al., "Evidence for a Publications ferromagnetic transition temperatures, Local Lattice Distortion in Ca-Doped making them strong candidates for Heffner, R.H., L.P. Le, M.F. Hundley, LaMnO3" (to be published in Phys. important technological applications. et al., "Ferromagnetic Ordering and Rev. B). Our efforts combine the three key Unusual Magnetic Ion Dynamics in Zang, J., A.R. Bishop, and H. Roder, tools of advanced materials research: La Ca MnO ," Phys. Rev. Lett. 77, 67 33 3 "Double Degeneracy and Jahn-Teller (1) materials synthesis (single-crystal 1869 (1996). Effects in Colossal and poly crystal growth techniques); Hundley, M.F., and J J. Neumeier, Magnetoresistance," Phys. Rev. B 53, (2) physical characterization (x-ray "Thermoelectric Power of 8840 (1996). diffraction, electronic transport, magnetization, thermopower, thermal expansion, and magnetostriction); and Complementary Neutron Diffraction and (3) theoretical modeling. Computational Micromechanics Studies of We have grown large single crystals (7 mm in diameter and 1 to 2 cm long) Polycrystalline Deformation in Advanced of the ferromagnet Lai_xMxMnO3 (where M can be calcium or stron- Materials tium) at the Los Alamos single-crystal facility in the Materials Science Mark A. M. Bourke Laboratory. Thermopower measurements on materials where M is The objectives of our project are to averaged over the bulk using neutron calcium and x = 0.0-0.45 indicate that use neutron diffraction to improve the diffraction. To date, we have observed conventional transport models with understanding of polycrystal deforma- good agreement between the predicted nominal valence cannot account for tion and to relate the results to and measured values for strains parallel the small (doping-independent) micromechanical models. The scope to the load, whereas we found signifi- magnitude of the high-temperature- includes measuring residual and in situ cant differences between the two values carrier contribution to the Seebeck loading strains, as well as thermal for strains perpendicular to the load. coefficient. Because the number of relaxation effects. We have selected In developing the experimental active carrier sites is less than 3+ several materials for study and, to date, capabilities, we purchased a 1200°C expected from the doping x (x = Mn have performed measurements on NiAl- controlled-atmosphere furnace and concentration), charge disproportion- 3+ 2+ 4+ A1N-A12O3 composites, CuMo, adapted it for operation on the neutron ation (2Mn goes to Mn + Mn ) austenitic steel, and NiTi composites. powder diffractometer at the Los may be important in these systems. Our effort in computational modeling Alamos Neutron Science Center. In the theoretical realm, we have has focused on validating a self- During the next year, we will use this carefully analyzed the double- consistent elastic-plastic model used to furnace to determine relaxation exchange model and found that the predict the response of a face-centered temperatures of NiAl-based compos- ground state and the low-lying cubic stainless steel. The model predicts ites. In a separate development, we magnetic excitations are far richer elastic lattice strains (that develop implemented two infrared lamp than often assumed in approximate within subsets of grains in predeter- heaters on an existing stress rig and and mean-field treatments. This result mined orientations) which are then are presently performing creep studies compared with the measured values on a model CuMo system.

Competency Development Projects—Materials Science 147 Characterization of Active Sites in the preferred adsorption sites and enabled us to identify secondary Zeolite Catalysts adsorption sites. Our INS studies of the adsorption of other small molecules (water, Juergen Eckert ethylene, and cyclopropane) serve as a benchmark for theoretical calcula- Atomic- or molecular-level details The unit cell of zeolite A is shown tions of the dynamics of adsorbates in of the interaction of adsorbed mole- in the accompanying figure. Each catalysts. We experimentally deter- cules with active sites in catalysts are vertex is occupied by either a silicon mined the modes of adsorbed ethyl- urgently needed to facilitate develop- or an aluminum atom, and these ene in zeolite NaX and found these ment of more effective and/or vertices are bonded to one another via modes to be in excellent agreement environmentally benign catalysts. To an oxygen atom. Cations, such as Na+, with the results of ab initio calcula- this end we are carrying out inelastic are located on extraframework sites. tions. We also demonstrated the utility neutron scattering (INS) studies Three of these cations are shown: Na I of INS spectroscopy to monitor slow combined with theoretical calcula- approximately in the plane of a six- reactions in zeolites by observing tions of the dynamics of small ring (a ring of six vertices), Na II in isomerization of cyclopropane in molecules inside the cavities of the plane of the large eight-ring (the 2+ partially Cu -exchanged zeolite A. zeolite catalysts. opening to the large cavity called the Our principal approach has been to supercage), and Na III above the four- utilize molecular hydrogen (H2) as a ring. With the aid of Quantum Monte Publications probe of active sites in the zeolite. Carlo simulations, we were able to Eckert, J., J.M. Nicol, et al., The interaction of H with adsorption show that an area near the four-ring is 2 "Adsorption of Hydrogen in Ca- sites gives rise to a barrier to rotation the most likely adsorption site for H 2 Exchanged Na-A Zeolites Probed by for the molecule, which is readily in zeolite A, and we established a Inelastic Neutron Scattering obtained by INS techniques. We trend for adsorption near a variety of Spectroscopy," J. Phys. Chem. 100, found that this barrier differed divalent cations (located near the six- 10646 (1996). substantially for different sites. rings) exchanged for Na+. Coadsorp- tion of N2 and H2 displaced H2 from Eckert, J., R. Varma, et al., "Effects of Cycling Conditions of Active Material from Discharged Ni Positive Plates Studied by Inelastic Neutron Scattering Spectroscopy" (submitted to J. Electrochem. Soc).

Na !M

Unit cell of zeolite A with three cationic sites. Adsorption ofH2 is strongest near Na III.

148 Los Alamos FY 1996 LDRD Progress Report New Initiatives in Materials Publications Becker, J.D., J.M. Wills, et al., Characterization, Modeling, and Synthesis "Electronic Structure of Pu Compounds with Group IIIB Metals: Don Parkin Two Regimes of Behavior," Phys. Rev. B 54, 17265 (1996). This project is a collaboration advances: "Ion Interactions and Griffin, A. Jr., J. Embury, M. Hundley, between Laboratory and external Radiation Damage," "Materials et al., "Residual Stress, Mechanical materials science researchers to explore Solidification," and "Fundamental Behavior and Electrical Properties of new techniques in a variety of areas Electronic Structure of Plutonium." Cu/Nb Thin Film Multilayers," Mater. related to the characterization, constitu- The radiation damage workshop Res. Soc. Proc. 382, 309 (1995). tive modeling, and synthesis of focused on fundamental aspects of materials. Specifically, in the area of radiation effects on ceramic materials Sickafus, K., R. Raj, and P. Prakash, characterization, the focus is on and nuclear material waste forms. The "Vanadium Metal-MGA1204 Spinel expanding strengths in electron, workshop on solidification focused on Composites for Structural Applicants scanning-probe, and atomic force casting processes, including pluto- in Neutron and Other Hostile microscopy and x-ray and neutron nium casting issues. The electronic Environments" (to be published in J. characterization of matter, and to do structure workshop addressed Nucl. Mater.). this in collaboration with outside fundamental issues in modeling the Ustundag, E., K. Sickafus, Y. He, academic institutions. In modeling, the electronic structure of f-electron et al., "Metal-Ceramic Composites for focus is on improving our ability to materials (actinides). Hostile Environment Applications," in model both the fundamental electronic In related activities, we developed Ceramic Matrix Composites Sym- structure of materials and their an alternative to the standard molecu- posium Proceedings, Vol. 74, N.P. mechanical behavior. Another goal is lar dynamics approach for atomistic Bansil, Ed. (American Ceramics an improved ability to synthesize simulation of dislocation crossing, Society, Westerville, Ohio, in press). different kinds of materials ranging annihilation, and short-range forces. Walter, K., K. Kern, J. Tesmer, et al., from electronic to structural materials. We also developed a high-temperature "Nitrogen and Boron Ion Implantation As part of the collaboration, we probe for operation in the National into Electrodeposited Hard Chrome," held three major workshops on the High Magnetic Field Laboratory's in Surface and Coatings Technology following topics to explore the state 20-T magnet and measured the high- (Elsevier, Oxford, U.K., in press). of the art and potential scientific temperature Hall constants.

Dynamics of Polymers at Interfaces both swollen and collapsed layers for several molecular weights. Collapsed layer thicknesses generally increased Gregory Smith with molecular weight. Data for swollen layers suggest diffuse segment-density This project addresses fundamental (poly)methyl methacrylate (H-PMMA) profiles. A detailed analysis will allow questions concerning the behavior of was spin-coated onto the quartz crystal us to verify the Guiselin theory of polymers at interfaces and poses the surfaces and subsequently annealed at adsorbed polymers, which in turn will following questions: What processes melt conditions. After cooling, un- allow us to predict the structure of control the formation of an adsorbed bound material was leached away in a nonequilibrium layers layer on a clean surface? Can we solvent bath. In a separate experiment, the residual accurately predict the structure of non- Using neutron reflection (NR), we layer was overcoated with a layer of equilibrium layers? What processes investigated the architecture of the deuterated PMMA (D-PMMA) and the control the desorption or displacement residual bound layer swollen in good system annealed at the melt conditions. of preadsorbed polymers? solvent (benzene) or collapsed against a Subsequent leaching and interrogation Last year we performed the first nonsolvent (D2O). The quartz crystals by NR indicated substantial replacement experiments to study the nonequi- were mounted in a specially designed of the strongly adsorbed H-PMMA by librium architecture of polymer layers cell, which placed the coated surfaces D-PMMA in the overcoating, suggest- strongly adsorbed from the polymer in contact with a solvent and at the ing that the residual H-PMMA layers melt. We constructed a sample holder same time permitted the NR studies. studied were formed by sudden for our film-spinner that supported the We measured the reflectivity of immobilization at the surface of an weight of the quartz crystals for the neutrons, R(q) vs q (q is the neutron's equilibrated melt. These studies give us experiment (the crystal dimensions momentum transfer) at the Manuel clues into the process of displacement of were 1.5 x 3 x 0.5 in.). Hydrogenated Lujan Jr. Neutron Scattering Center for adsorbed polymers.

Competency Development Projects—Materials Science 149 Understanding and Controlling Patterned Monolayers of Alkanethiols on Gold. Importance of Tip-Sample Contact Self-Assembly Area in Interpreting Force Modulation and Friction Force Microscopy Images" Basil Swanson (to be published in Langmuir). Bar, G., S. Rubin, A.N. Parikh, et al., The fields of self-assembly and self- frictional and compressional force "Tribology Studies of Organic Thin organizing mesoscale structures have differences that we observed with Films by Scanning Force Microscopy" grown rapidly over the past decade. In scanning force microscopies. Using (Materials Research Society 1996 Spring addition to fundamental research that spectroscopic techniques, we probed Meeting, San Francisco, Calif., April spans simple self-assembled monolayers the structures of different end- 1996). (SAMs) to complex, biologically functionalized, alkanethiol SAMs and inspired self-organizing structures, found the results to be consistent with Bar, G., S. Rubin, T.N. Taylor, et al., there has been increased interest in nanoscale cluster formation. We also "The Influence of Contamination on applying self-assembly to produce began studying new techniques (sum- the Compositional Imaging of Self- useful, functionalized materials. In frequency generation and surface- Assembled Monolayers by Scanning order to enhance useful materials enhanced Raman spectroscopy) for Force Microscopy" (to be published in properties, we must first understand characterizing the organic-inorganic Supramol. ScL). the relationships between structure and interface. Bar, G., S. Rubin, T.N. Taylor, et al., function in SAMs and in more com- To simulate the behavior of the "Self-Assembled Monolayer of plex self-assembled structures that SAMs of alkanethiols adsorbed on Ferrocene and Methyl Terminated incorporate specific functional groups gold, we wrote a new, large-scale, Alkanethiols on Gold: A Combined (for example, donor-acceptor com- massively parallel molecular dynamics Electrochemical, Scanning Probe plexes, molecules with high optical (MD) code. In addition, we performed Microscopy, and X-Ray Photoelectron nonlmearity, and reagents for molecu- ab initio, quantum-chemistry calcula- Study," J. Vac. Sci. Technol. A14 (3), lar recognition). tions of the sulfur-gold potential-energy 1794 (1996). The overall objectives of this project surface and used these calculations to Beardmore, K.M., N. Gr0nbech-Jensen, are to develop an in-depth understand- develop a detailed model of the and J.D. Kress, "Dynamical Simulation ing of how complex molecular struc- organic-inorganic (specifically, the of Perturbed Systems of Alkanethiols on tures form by self-assembly and how the sulfur-gold) surface. From this model Gold Surfaces" (American Vacuum individual molecular components and we developed an empirical function Society Symposium, Philadelphia, Pa., bulk functionality are interrelated. Our describing the sulfur-gold interaction October 1996). approach is to (1) experimentally and used in it in MD calculations. We characterize and theoretically model also further developed a three- Beardmore, K.M., J.D. Kress, et al., intra- and interplanar ordering of model dimensional analog of alkanethiol "Ab Initio Calculations of the Gold- SAMs in an effort to understand and SAMs and studied it using a variety of Sulfur Interaction for Alkanethiol control the self-assembly process, (2) structural and spectroscopic probes. Monolayers" (International Conference develop new experimental probes of on Synthetic Metals, Snowbird, Utah, mesoscale structure and use them to July 1996). augment more traditional characteriza- Publications Li, D., J.-X. Shi, et al., "Cyclodextrin- tion methods, (3) prepare well-ordered Bar, G., S. Rubin, A.N. Parikh, et al., Based Surface Acoustic Wave model SAMs and characterize their "AFM-Studien zum Materialkontrast Chemical Microsensors" (Spectrum mesoscale structures using the experi- an Diinnen Organischen Filmen" '96, Seattle, Wash., July 1996). mental probes, and (4) couple theory (Mikrosymposium Elektronenmi- and experiment to develop models that kroskopie in der Materialforschung, Parikh, A.N., G. Bar, et al., "Lateral will allow us to predict mesoscale Merseburg, 1996). Force Microscopy Characterization of structures and, thus, to synthesize SAMs Micro-Contact Printed Patterned with optimal physical properties. Bar, G., S. Rubin, A.N. Parikh, et al., Molecular Films" (Materials Research "Compositional Imaging of Patterned During this year we used scanning Self-Assembled Monolayers Using Society 1996 Fall Meeting, Boston, force microscopies to image patterned, Scanning Probe Microscopies: Effects Mass., November 1996). alkanethiol SAMs that we formed on of Chain Length, Packing, and gold using microcontact printing, and Yang, X., D. McBranch, et al., "Design, Density" (43rd National Symposium we correlated the results from the Construction, and Architecture of of the American Vacuum Society, imaging with spectroscopic studies. We Covalently Bound, Polar Self- Philadelphia, Pa., October 1996). discovered that the different densities of Assembled Molecular Pyramids on Oxide Surfaces," Angew. Chem., Int. Ed. stamped and solution-grown SAMs of Bar, G., S. Rubin, A.N. Parikh, et al., Engl. 35 (5), 538 (1996). hexadecanethiolate on gold caused the "Scanning Force Microscopy Study of

150 Los Alamos PC 1996 LDRD Progress Report Role of Charge Localization in the Basic Martin, R.L., "Electronic Localization in the Cuprates," Phys. Rev. B 53, High-Temperature Superconductivity 15501 (1996). Mechanism Martin, R.L., "Rehybridization and Pairing in the Cuprates," Phys. Rev. B R54, 9647 (1996). P. Chris Hammel Salkola, M., A.V. Balatsky, and Local structure profoundly affects c-direction; begun a systematic study D. Scalapino, "Theory of Scanning- the superconducting, normal elec- of spin-charge-lattice coupling in Tunneling-Microscopy Probe of tronic, mechanical (for example, Peierls-Hubbard models in the context Impurity States in a d-Wave elastic), and other response functions of charge (polaron) ordering in Superconductor," Phys. Rev. Lett. 77, of materials. By emphasizing LiLCO and in the context of striped 1841 (1996). cuprates, our project examines this superlattice phases in hole-doped Salkola, M., A.V. Balatsky, and difficult, important, and as yet barely CuO2 planes; understood the broken- J.R. Schrieffer, "Spectral Properties of studied problem of structure. We have symmetry solutions observed in ab Quasi-Particle Excitations Induced by been focusing on oxide superconduc- initio cluster calculations on the Magnetic Moments in Super- tors, and related nonsuperconducting Cu2On dimer in terms of an conductors" (to be published in Phys. compounds, by using an array of occupation-dependent hopping Rev. B). experimental and theoretical tech- integral and showed that this rehy- niques to characterize the local bridization produces an attractive Sarrao, J.L., D.P Young, Z. Fisk, structure and its correlations, measure interaction; and proposed a strong et al., "Structural, Magnetic and the effects of the local structure on coupling explanation for why pairing Transport Properties of superconducting and other macro- should have d-wave symmetry in the La2CUj xLixO4," Phys. Rev. B 54, scopic properties, and create a new presence of antiferromagnetic 12014 (1996). theoretical understanding of high- correlations. temperature superconductors. Scalapino, D.J., and S.A. Trugman, "Local Antiferromagnetic This year, we have used nuclear Publications Correlations and dx2 _yi Pairing," magnetic resonance to study the Phil. Mag. B 74 (5), 607 (1996). doped-hole state in La2Cu5Li5O4 Balatsky, A.V., and M. Salkola, (LiLCO) and found a surprisingly "Impurity States and the Absence of Schmeltzer, D., and A.R. Bishop, low-lying excitation. We have used Quasi-Particle Localization in "Bosonization of the 2-Dimensional electron, x-ray, and neutron diffrac- Disordered d-Wave Superconductors," t-J Model in the Continuum-Limit," tion to investigate the structure of Phys. Rev. Lett. 76, 2386 (1996). Phys. Rev. B 54 (6), 4293 (1996). LiLCO and its magnetometry, which Shenoy, S., V. Subrahmanyan, and will then enable us to characterize the Bishop, A.R., J.T. Gammel, and A.R. Bishop, "Quantum Paraelectric material's magnetic properties. We M. Salkola, "Local Polarizability, Model for Layered Superconductors" have found that the temperature and Structure, and Charge-Transfer in nickel-content dependencies of the High-Temperature Superconductors," (submitted to Phys. Rev. Lett.). thermal conductivity of several J. Superconductivity 8, 1 (1996). Yoshinari, Y, PC. Hammel, nickel-doped bismuth cuprates Bussmann-Holder, A., and J.A. Martindale, et al., "Magnetic (BSCCO) between 0.05 and 2 K are A.R. Bishop, "Time-Dependent Excitations of the Doped-Hole State contrary to theoretical predictions. Evolution of Double-Well Potentials in Diamagnetic LajCuQ 5Li05 O4," We have developed a self-consistent to Model Structural Anomalies," Phil. Phys. Rev. Lett. 77, 2069 (1996). treatment of magnetic and nonmag- Mag. 73, 657 (1996). netic impurity states in d-wave Bussmann-Holder, A., A.R. Bishop, superconductors, which result in et al., "3-Dimensional Gap Structure strongly anisotropic quasi-particle in Layered High-Temperature states; formulated a three-dimensional Superconductors," Phys. Rev. B R53, model for layered superconductors 11968(1996). that couples structural buckling and strong electron-electron interactions Hammel, PC, and D.J. Scalapino, in the a-b plane to antiferroelectric "Local Microstructure and the polarizability fluctuations in the Cuprate Spin Gap Puzzle," Phil. Mag. B 74 (5), 523 (1996).

Competency Development Projects—Materials Science 151 Measurement by Neutron Diffraction Publications Bourke, M.A.M., R. Vaidyanathan, of Strains in Advanced Engineering and D.C. Dunand, "Neutron Structural Materials including AlSiC Diffraction Measurement of Stress Induced Transformation in and AITiC Superelastic NiTi," Appl. Phys.Lett. 69 (17), 2477-2479 (1996). Mark A. M. Bourke, Los Alamos National Laboratory Dunand, D.C., D. Man, et al. David C. Dunand, Massachusetts Institute of Technology "Neutron Diffraction Study of NiTi during Compressive Deformation and Drawing on our earlier work with resulted from increasing elastic after Shape Memory Recovery," J. AITiC and given the similarity in compressive strains, while the Physique IV 5,653(1995). mechanical properties, we chose to decrease in intensity of the austenitic examine a shape-memory alloy peak and simultaneous increase in the composite (NiTiTiC). Initially we martensitic peak were due to transfor- concentrated on the composite's mation. The stress-dependence of the matrix (NiTi). Using neutron diffrac- phase volume fractions determined by tion, we studied the formation of these refinements are shown in the stress-induced martensite in second figure. One unexpected result superelastic NiTi during uniaxial was that about 90% of the austenite compressive loading and unloading. was trans-formed to martensite at a Using a Rietveld refinement with a macro-scopic strain of only -2.8%. March-Dollase texture formulation, we determined the martensitic and austenitic phase fractions as a function of the applied stress. Before loading, the specimen was fully 0.002 austenitic. At the highest applied stress (-625 MPa), about 90% of the austenitic phase had transformed to martensite, with a concomitant | 0.0015 - macroscopic strain of -2.8%. Upon unloading, all of the stress-induced -7 MPa (Final) martensite reverted to austenite, and -130 MPa -210 MPa the totality of the macroscopic strain -268 MPa o 0.001 - was recovered. We determined the -317 MPa propensity for various austenitic CO -439 MPa crystallographic orientations to -625 MPa transform at different stresses. -580 MPa -540 MPa After yield at a stress of about 0.0005 I- -490 MPa -350 MPa, plastic deformation -390 MPa resulted from the austenite-to- -261 MPa martensite transformation. The -132 MPa difference in structure between the -5 MPa (Initial) unstressed and stressed states was visible in the broad martensitic peaks 2.8 2.85 2.9 2.95 3.05 3.1 that were clearly discernible from the d spacing (A) sharp austenite peaks. The progression and reversibility of the transfor- Displaced spectra showing a short section of the diffraction patterns obtained mation are illustrated in the first with the scattering vector parallel to the loading direction. The austenitic [100] figure, which shows a short section of at 3.0 A r educes in intensity to 0 at -625 MPa. Conversely the martensitic the spectra for each stress level. Upon [100] at 2.86 A becomes visible at -490 MPa and reaches a maximum in loading, the shift to shorter d-spacings intensity at -625 MPa (bold line). The shift to shorter d-spacings is due to the increasing elastic compressive strain. The data has been smoothed and displaced vertically for clarity.

152 Los Alamos FYI996 LDRD Progress Report 100

The relative intensities of the 1 austenitic and martensitic diffraction CD patterns can be converted to volume fractions of the two phases. Martensite starts to form at compressive loads greater than CL 20 - -400 MPa; upon unloading, however, it remains present until below 0 - - -280 MPa. -700 -600 -500 -400 -300 -200 -100 Applied compressive stress (MPA)

Chemistry and Microstructure of High- Publications Jia, Q.X., X.D. Wu, and D. Reagor, Temperature Superconductor Interfaces "Material and Device Engineering in HTS Josephson Junctions," in Studies of Quanxi Jia High Temperature Superconductors, A. Narlikar, Ed. (Nova Science Publishers, The research objectives of this SQUIDs using an edge-geometry Inc., New York, 1996), p. 217. project are to investigate the interface superconductor/normal-metal/super- Jia, Q.X., D. Reagor, H. Kung, et al., chemistry, physics, and microstructure conductor (SNS) configuration. We "HTS Edge-Geometry SNS Junctions of superconductor and normal-metal used Ag-doped YBa2Cu3O7_-t: as with Engineered Normal-Metal composites and to use these compos- electrodes and PrBa2Cu3O7_J. as the Layers," Supercond. Sci. Technol. 9, ites to develop high-performance normal-metal barrier. The IcRn value superconducting quantum interference (the product of the critical current and 985 (1996). devices (SQUIDs) with controllable the junction resistance) was in the Jia, Q.X., D. Reagor, X.D. Wu, et al., and reproducible properties. SQUIDs range of 120-140 uV; we determined "Characterization of Ramp Edge- are state-of-the-art ultrasensitive this value from the current-vs-voltage Geometry SNS Junctions and dc devices that detect very low magnetic characteristic of the devices. The dc SQUIDs" (to be published in IEEE fields. Among other applications, they SQUIDs showed a differential-flux Trans. Appl. Supercond.). are used to nondestructively evaluate modulation depth, dV/d (where materials, measure the biomagnetism V is voltage and is flux), of Jia, Q.X., X.D. Wu, D. Reagor, et al., of human living organs, measure greater than 150 uV/<&0 at 75 K "Edge-Geometry SNS dc SQUIDs 15 gravity in mineral surveying, and (

Competency Development Projects—Materials Science 153 Texture Science and Technology WINDOWS desk-top computer and better coverage of orientation space. After comprehensively reviewing Michael Stevens orientation-imaging microscopes and data collection and analysis hardware The objectives of this project are to radiation with position-sensitive and software, we ordered a Philips (1) perform basic research on the detectors or for polychromatic radia- field-emission-gun scanning electron effects of texture on material proper- tion. Full diffraction spectra may now microscope (SEM). This SEM will ties, (2) increase the utilization of be used in the analysis, resulting in allow us to map orientations on a texture and anisotropy information maximum use of data. We applied our subgrain scale and determine mis- through texture analysis, and (3) im- advanced texture algorithm to a sample orientations between grains in prove our texture measurement and of experimentally deformed limestone polycrystalline aggregates. Mis- modeling capabilities. Texture refers and produced excellent simultaneous orientation data are essential for to studying the orientation, shape, and results on the sample's texture, crystal understanding the process of recrys- size of the individual crystals in structure, microstructure, and residual tallization, which is of interest in a polycrystalline materials. stress. It appears that the algorithm's variety of structural materials. We have made significant progress methodology is applicable to low- symmetry and polyphase materials with on advanced texture analysis algo- Publications rithms that use many pole figures complicated diffraction spectra; such (diffraction peaks) and a few sample materials presently elude quantitative Von Dreele, R., "Quantitative Texture orientations. Our new algorithm texture analysis. Analysis by Rietveld Refinement" (to greatly reduces the data collection Through our collaboration with the be published in /. Appl. Crystallogr.). time needed at a time-of-flight Geology Department at the University Wright, S., and U. Kocks, "A neutron diffraction facility. It com- of California, Berkeley, we refined Comparison of Different Texture bines crystallographic Rietveld our BEARTEX software to allow Analysis Techniques," in Textures of analysis of diffraction spectra with simultaneous goniometer control and Materials (ICOTOM-II), Z. Liang, L. calculations of orientation distribution data acquisition on both of our x-ray Zuo, and Y. Chu, Eds. (International functions. The algorithm is particu- texture diffractometers. The improve- Academic Publishers, Beijing, China, larly useful for monochromatic ments allow operation with a common 1996), pp. 53-62.

Microstructures of Transition Metal within two degrees of the transition temperature of the sample. Our Oxides Characterized by Neutron and analysis of the data is not yet complete. However, we can report that X-Ray Scattering startling changes in the atomic structures of the samples were not Michael Fitzsimmons observed at any time. We also examined the atomic The La-Mn perovskites of the type atomic and magnetic structures and structure of a single crystal of La1_JVI;tMnO3 (where M can be vibrational modes of the perovskites. LaMnO3 doped with 20 at. % cal- calcium, strontium, or barium, and x During the past year, we measured cium. We found the structure of this varies from 0 to 0.5) are materials the neutron diffraction patterns of two material to be monoclinic with which become ferromagnetic at low sintered polycrystalline LaMnO3 monoclinic symmetry. This result is temperatures. The transition tempera- samples. The samples were doped very surprising in light of the fact that ture, magnetoresistance, and atomic with 20 and 33 at. % calcium. The earlier studies of polycrystalline and magnetic structures of the most interesting and challenging samples, including ours, suggested materials are believed to be deter- experiment involved measuring the that the structure of this perovskite mined in part by the valence of effect of a 1-T magnetic field on the was orthorhombic with orthorhombic manganese, which can be changed atomic structure of the sample doped symmetry. through the doping of the M species. with 33 at. % calcium. We took the Our studies of these materials are measurements with field on and off concerned with using x-ray and and at a variety of temperatures neutron scattering to characterize the

154 Los Alamos FY1996 LDRD Progress Report AThermodynamically Consistent, also implemented the imperfect- bonding MOC model into our three- Damage-Dependent, Interface Debonding dimensional finite-difference codes. These models are sufficiently general Model for Composites to allow for laminated systems, long- fiber-reinforced composites, and Bradford E. Clements particulate (discontinuous reinforcement) composite systems. Further- The ability to design composite We have developed a method for more, the constituents of the com- materials and analyze processing analyzing interfacial debonding based posites are not restricted to elastic procedures relies on the availability of on the highly successful method of crystalline or amorphous solids; the constitutive models that describe the cells (MOC) homogenization tech- composites can also have viscoelastic composites' dynamic response nique for composite structures. When properties (i.e., polymeric materials). accurately. The strength, damage perfect interfacial bonding applies, evolution, and failure of interfaces displacement and traction continuity Publications within composites often dominate are conditions that are enforced by the their macroscopic performance but MOC analysis. On the other hand, for Addessio, F.L., and J.B. Aidun, are not well characterized. The design imperfect interfacial bonding, the "Analysis of Shock-Induced Damage of such composites for particular displacement becomes discontinuous in Fiber-Reinforced Composites" (to applications requires adequate at the interface. Imperfect bonding is be published in High-Pressure Shock knowledge of interfacial characteris- modeled by an interfacial constitutive Compression of Solids). tics. Given the large number of equation (ICE). Aidun, J.B., and F.L. Addessio, "An potential loading scenarios that an Our specific accomplishments in Enhanced Cell Model with Nonlinear engineering composite can be sub- the past year include quantifying the Elasticity," J. Composite Mater. 30, jected to, it is extremely beneficial to ICE model for tensile and shear 248 (1996). have reliable and accurate theoretical loading in plastic bonded explosives. methods for their quantitative Furthermore, we have used slightly Clements, B.E., J.N. Johnson, and treatment in numerical calculation. different ICE formulations to model R.S. Hixson, "Stress Waves in brittle and ductile interfaces. We have Composite Materials," Phys. Rev. E 54, 6876 (1996).

Zircon as a Host Phase for Plutonium approximately two hours of reaction time, the materials consist of zircon, Disposition although the reaction is not completed. Therefore, fabricating large John Huang quantities of plutonium-zircon is feasible. The most significant result To address problems involving the to plutonium-zircon. The emphasis of of our work is the evidence that minimization and long-term storage of our work, therefore, has been to develop container problems exist, which in nuclear waste, we have proposed zircon processing parameters that alleviate turn has suggested potential solutions to these problems. Experiments with (ZrSiO4) as a host medium for pluto- potential problems in containing nuclear nium and other actinides recovered materials during processing. a quartz inner container, a glass sealant, and a secondary metal outer from dismantled nuclear weapons. The We have subjected stoichiometric container are under way in order to objective of this project is to investigate mixtures of ZrO and SiO , in 100-g 2 2 find ways of confining contamination the feasibility of large-scale fabrication batches, to hot isostatic pressing at during processing. of plutonium-bearing zircon. Because temperatures near 1500°C and pres- PuO2 is thermodynamically less stable sures of 10,000 psi. Analysis of the than ZrO2, process parameters deter- product materials by x-ray powder mined for zircon can be safely applied diffraction has shown that after

Competency Development Projects—Materials Science 155 Many-Body Theory Research Butero, A., A. Fainstein, M. Tovar, et al., "Gd Concentration Dependence of the Spin Reorientation Critical Field Alexander Balatsky YBaCuO7," J. Appl. Phys. 79,6577 (1996). The foundations of the theory of Another researcher is working on both Fisk, Z., J.D. Thompson, and J.L. metals and superconductors have been electronic-structure and many-body Sarrao, "Heavy Fermions," Curr. shaken by a number of discoveries computational schemes that have Opin. Solid State Mater. Sci. 1, 42 over the last 15 years, including high- yielded insight into how magnetic (1996). temperature superconductors, organic states are formed in quasi-one- superconductors, and fullerenes. New dimensional systems. Hammel, P.C., and D.J. Scalapino, classes of materials, such as colossal All these described developments are "Local Microstructure and the magnetoresistive materials, cuprates, related to the core of our project: a self- Cuprate Spin Gap Puzzle" (submitted and organic polymers, have a number consistent treatment of the magnetic to Phil. Mag. B). of properties that favor a much richer and nonmagnetic impurity states in d- Hayden, S.M., G. Aeppli, H.A. Mook, spectrum of ground and excited states. wave superconductors. We developed et al., "Comparison of the High- These properties include strong this self-consistent treatment and found Frequency Magnetic Fluctuations in electronic and lattice correlations, that the impurity states have a strongly LaSrCuO ," Phys. Rev. Lett. 76,1344 reduced dimensionality, restricted anisotropic nature. 4 geometry, disorder, and nonlinearity. (1996). The interplay of different effects and Hayward, C.A., D. Poilblanc, and D.J. Publications the complexity of these materials Scalapino, "Optical Conductivity of a t- make the materials suitable for Abrahams, E., A. Balatsky, et al., J Ladder" (submitted to Phys. Rev. B). electronic applications. "Property of Odd Gap Super- Lawrence, J.M., T. Graf, M.F. In this project we are taking on one conductors," Phys. Rev. B 52,1271 Hundley, et al., "Kondo Hole of the biggest challenges in con- (1995). Behavior in Ce La Pd ," Phys. densed-matter theory today: we are 0 97 9 O3 3 Alverenga, A.D., D. Rao, J.A. attempting to understand the behavior Rev. B 53, 12559 (1996). Sanjurjo, et al., "Raman and Weak of these materials by developing Movshovich, R., T. Graf, D. Mandrus, Ferromagnetism in Eu Cu0 ," microscopic theories to describe 2 4 et al., "Superconductivity in Heavy- Physica B 223-224, 522 (1996). them. This year we focused on heavy- Fermion CeRh2/Si2," Phys. Rev. B 53, electron physics, including properties Alvarenga, A.D., D. Rao, J.A. 8241 (1996). of plutonium, and we are working Sanjurjo, et al., "Raman-Scattering and closely with collaborators at a number Weak-Ferromagnetism Studies in Movshovich, R., J.M. Lawrence, M.E. Hundley, et al., "Magnetism in of universities. One of our collabora- Eu2Cu04," Phys. Rev. B 53, 837 (1996). tors is developing a new model of CePtPb," Phys. Rev. B 53, 5465 volume collapse in alpha-delta phase Amann, A., P. Visani, K. Aupke, et al., (1996). "Unconventional Vortex Dynamics in plutonium. This model takes into Noack, R.M., S.R. White, and D.J. the Low-Field Superconducting account the electron-phonon interac- Scalapino, "The Doped Two Chain Eu CuO ," Europhys. Lett. 33, 303 tion as well as f-d hybridization. 2 4 Hubbard Model," Europhys. Lett. 30, (1996). Another research group is investigat- 163 (1995). ing the charge ordering in Cu-0 Andrews, A.B., J.J. Joyce, A.J. Arko, Park, C.-H., Z.-X. Shen, A.G. Loeser, ladder materials; they found that et al., "Momentum-Dependent Effects et al., "Direct Observation of a domain walls tend to form in these in 4f Photoemission Spectra from Cu-O systems. They also carried out Actinides," Phys. Rev. B 53, 3317 Narrow Band Near the Gap Edge of numerical calculations of the optical (1996). FeSi," Phys. Rev. B 52,16981 (1995). properties of the two-leg t-J ladder. Rettori, C, S.B. Oseroff, D. Rao, et Balatsky, A.V., and M. Salkola, A third collaborator has developed al., "ESR of Gd in Magnetically "Absence of Quasiparticle the theory that the spin gap in cuprates Ordered Eu Cu0 ," Phys. Rev. B 54, Localization in Disordered d-Wave 2 4 results from the precursor pairing in 1123(1996). Superconductors," Phys. Rev. Lett. 76, cuprates. Other collaborators investi- 2386 (1996). gated the role of lithium impurities in Salkola, M., A.V. Balatsky, and D. Scalapino, "Theory of Scanning La2CuO4 and found a novel insulating Bucher,B., Z. Schlesinger, D. Tunneling Microscopy Probe of phase (at 50% lithium doping) with a Mandrus, et al., "Charge Dynamics of Impurity States in d-Wave Super- spin gap of approximately 1500 K. Ce-Based Compounds," Phys. Rev. B conductors," Phys. Rev. Lett. 11, 1841 Work on the transport properties of 53, 2948 (1996). Kondo insulators continues as well. (1996).

156 Los Alamos FY1996 LDRD Progress Report Salkola, M, A.V. Balatsky, and J.R. Schrieffer, J.R., "Ward Identities and White, S.R., and D.J. Scalapino, Schrieffer, "Spectroscopy of the Suppression of Spin Fluctuation "Ground State Phases of the Doped 4- Superconducting Quasiparticle Superconductors," J. Low Temp. Phys. Leg t-J Ladder" (submitted to Phys. Induced by Magnetic Impurity" (to 99, 397 (1995). Rev. B). be published in Phys. Rev. B). Seaman, C.L., N.R. Dilley, M.C. de Yoshinari, Y, P.D. Hammel, J.A. Scalapino, D.J., and S.A. Trugman, Andrade, et al., "Superconductivity and Martindale, et al., "Magnetic "Local Antiferromagnetic Magnetism in the Heusler Alloys," Excitations of the Doped-Hole State Correlations and d-Wave Phys. Rev. B 53,2651 (1996). in Diamagnetic LaCu0 5LiQ 5O4," Phys. Rev. Lett. 11, 2069 (1996). Superconductivity," Phil. Mag. B 74, Statt, B.W., PC. Hammel, Z. Fisk, et 607 (1996). al., "Oxygen Ordering and Phase Schrieffer, J.R., "ARPES: Novel Separation in La2CuO4+d," Phys. Rev. Effects in Energy and Momentum B 52,15575 (1995). Distributions," J. Phys. Chem. Solids Uwatoko, Y., T. Ishii, G. Oomi, et al., 56,1673 (1995). "Pressure Collapse of Kondo Gap in Schrieffer, J.R., "ARPES: Novel Kondo Compound CeRhSb," J. Phys. Effects in the Energy and Momentum Soc. Jpn. 65, 27 (1996). Distributions" (Physical Phenomena at High Magnetic Fields-II, Tallahassee, Fla., April 1995).

Alloy Design and Phase Stability of Moreover, the stability of the omega phase (and the presence or absence of the Ternary Alloy Ti-AI-Nb an energy barrier) seems to track with d-electron occupation. We are very close to finishing some additional Robert Alters calculations that should show whether these differences can be correlated and Several classes of binary intermetal- intermetallics and to understand the explained by directional d-bonding lic compounds, such as Ti-Al, have correlation between the changes in important potential application as high- electronic properties and the improved forces due to the extra niobium temperature structural materials low-temperature properties in these d-electrons. because of their high melting tempera- materials. ture, low density, and high strength. During the past year, we focused on Publications The use of these binary alloys is the effects of alloying on the energetics limited, however, by their poor low- of the continuous structural pathway Asta, M., A.H. Ormeci, et al., "First temperature ductility and fracture that links the body-centered cubic Principles Study of Intermetallic toughness. Adding a third element (e.g.. phase of Ti-Al with the omega phase. Phase Stability in the Ternary," Mat. niobium) to these binary alloys is one Omega phase precipitates modify the Res. Soc. Symp. Proc. 364, 157 possibility for improving their low- mechanical properties of the quenched (1995). temperature properties without martensitic alloys by acting as a Chu, F., A.H. Ormeci, T.E. Mitchell, sacrificing, for example, the desirable strengthening element. Our calculations et al., "Stacking Fault Energy of the high-temperature ductility. show that under constant volume, pure NbCr2 Laves Phase," Phil. Mag. Lett. We are using high-precision Ti-Al has an energy barrier to this 72, 147 (1995). electronic-structure calculations and phase transition. In contrast, our molecular dynamics simulations to calculations also show that the addition Ormeci, A.H., F. Chu, J.M. Wills, et study the electronic and structural of niobium (substituted on one of the al., "Total-Energy Study of the properties of selected ternary interme- aluminum sites) removes this barrier. Electronic Structure and Mechanical tallic alloy systems. The goal of our The calculations show that the niobium Behavior of C15 Laves Phase research is to understand and predict alloy has a clearly different density of Compounds: NbCr2 and HfV2," Phys. the structural stability of these ternary states than the pure Ti-Al alloy. Rev. B 54, 12753 (1996).

Competency Development Projects—Materials Science 157 Unusual Magnetic Ion Dynamics in Synthesis and Characterization of ) La67Ca33MnO3,"/ /zyi'. Rev. Lett. 77, Correlated-Electron Materials 1869 (1996). Heffner, R.H., L.P. Le, M.F. Hundley, Joe D. Thompson et al., "Zero-Field uSR Study of the Colossal Magnetoresistance Material With discoveries—heavy fermions, We used pair-distribution-function La67Ca33MnO3" (submitted to conducting polymers, fullerenes, and and Debye-Waller analyses of neutron Hyperfine Interactions). colossal magnetoresistive materials— diffraction data to discover evidence Heffner, R.H., D.E. MacLaughlin, beyond traditional solid-state physics, for polaron formation (mesoscale G.M. Luke, et al., "Unusual we are at the beginning of a golden structure) and Jahn-Teller distortions Relaxational Dynamics in age for complex electronic materials. in manganite perovskites. We estab- Laj^Ca^MnOj" (submitted to These new materials are characterized lished that the polaron-binding energy Physica B). by strong electronic correlations that reflects strong coupling between arise from competitions between lattice and spin degrees of freedom, Hundley, M.F., and J J. Neumeier, microscopic electronic, magnetic, and and we discovered that a volume "Thermoelectric Power of structural degrees of freedom. Tuning change is required for a metal-insulator Laj^Ca^MnOj^: Inadequacy of the 3+ 4+ these competitions by performing transition in these materials. In Nominal Mn /Mn Valence chemical substitutions and by varying addition, we showed that the spin Approach" (submitted to Phys. Rev. the pressure, magnetic field, and dynamics and electronic structure are Lett.). temperature ultimately controls unusual for a ferromagnetic metal, and Maple, M.B., M.C. deAndrade, J. macroscopic functionalities that will we tested prevailing theories (multi- enable next-generation technologies Hermann, et al., "Non-Fermi-Liquid channel Kondo, proximity to a T = 0 ranging from magnetic sensors and Behavior in Chemically Substituted f- phase transition, and disordered Kondo thermoelectric coolers to plutonium Electron Compounds" (submitted to lattice) for the origin of non-Fermi- applications. Physica Q. liquid behavior in f-electron materials Our objective is to understand and with extensive measurements on Maple, M.B., D.A. Gajewski, R. control the coupling and competition cerium-, praseodynium-, and uranium- Chau, et al., "Fermi- and Non-Fermi- among spin, charge, and lattice based correlated-electron systems. This Liquid Groundstates in Mj^UJPdj degrees of freedom in these corre- experimental effort was closely (M = Sc, Y, La, Pr, Zr, Th) Systems" lated-electron materials through coordinated with a companion theoreti- (submitted to Physica B). coordinated efforts in synthesis, cal project, 'Theory and Modeling of Neumeier, J.J., A.L. Cornelius, and characterization, and modeling. Our Correlated-Electron Materials." M.F. Hundley, "Volume-Based research focuses on understanding (1) the role of electron-electron and Thermodynamic Considerations for electron-lattice interactions in Publications the Magnetoresistance Effect and Metal-Insulator Transition in CMR producing metal-insulator/magnetic- Billinge, S.J.J., R.G. DiFrancesco, nonmagnetic transitions in transition- Manganese-Oxide Perovskites" G.H. Kwei, et al., "Direct Observation (submitted to Phys. Rev. Lett.). metal perovskites (compounds with a of Lattice Polaron Formation in the cubic structure and chemical form Local Structure of La^Ca^MnO^" Yatskar, A., W.P. Beyermann, et al., ABO3), (2) the consequences of Phys. Rev. Lett. 77, 715* (1996). "Possible Correlated-Electron mesoscale structure on spin-charge- Behavior from Quadrupolar Heffner, R.H., L.P. Le, M.F. Hundley, lattice coupling, and (3) the origin of Fluctuations in PrInAg2" (to be non-Fermi-liquid behavior in et al., "Ferromagnetic Ordering and published in Phys. Rev. Lett.). f-electron materials.

158 Los Alamos FY1996 LDRD Progress Report Tailoring the Interfacial Electronic Mobility Insulators" (to be published in Appl. Phys. Lett.). Structure of Organic Electronic Materials Heller, CM., I.H. Campbell, D.L. and Devices Smith, et al., "Equilibrium Electron Transfer at Metal/C60 Doped Polymer Ian Campbell Interfaces" (submitted to Phys. Rev. B). Joswick, M.D., I.H. Campbell, et al., In this project, we are using self- Electronic Devices Using Self- "Systematic Investigation of the Effects assembled molecular coupling layers to Assembled Monolayers" (submitted to of Organic Film Structure on Light- tailor the electronic structure of metal/ Phys. Rev. B). Emitting Diode Performance," /. Appl. organic interfaces and organic/organic Davids, P.S., Sh.M. Kogan, et al., Phys. 80,2883 (1996). heterojunctions in order to control the "Charge Injection in Organic Light- electrical transport properties of these Smith, D.L., "Steady State Model for Emitting Diodes: Tunneling into Low interfaces. Metal/organic interfaces are the Polymer Light-Emitting Electrochemical essential active element in every organic Cells" (submitted to J. Appl. Phys). electronic device, and organic/organic heterojunctions are the key element in efficient, organic light-emitting diodes. Controlling Function of Polar Because of their processing advantages, Organic Multilayers the tunability of their electronic properties, and their flexibility in both materials and Duncan McBranch device design, organic electronic materials and devices are poised to revolutionize Charge separation on a molecular scale, transfer blend constitutes an entirely new such technological areas as information combined with the large polarizabilities of class of nonlinear optical material. display and optical communication. organic molecules, can be used to design A closely related problem involves the Learning to manipulate the electrical novel, nonlinear optical materials with design of biomimetic light-harvesting transport properties of these interfaces is greatly enhanced performance. Our project systems that use either photo-induced the key to realizing the potential of organic involves research in two areas: (1) the charge or energy transfer. We have electronics. design and measurement of new molecular studied model systems that incorporate This past year, we used self-assembly systems that exhibit charge separation and covalently linked porphyrins to mimic techniques to insert a controlled and transfer following photoexcitation and (2) natural photosynthetic pigments. Our characterized molecular coupling layer the design of approaches for synthesizing results demonstrate the feasibility of at metal/polymer interfaces. Molecular multilayers for solid-state electron-transfer designing biomimetic energy-transfer coupling layers with electric dipoles devices. pigments to produce efficient energy have been used to manipulate the Our strategy for synthesizing transfer with controlled rates. Further- Schottky energy barrier at these inter- multilayers involves self-assembly using more, high transfer efficiency can be faces. We used internal photoemission alternating positively and negatively realized without extensive perturbation and electroabsorption techniques to charged layers held together by multiple of the photophysical properties of the determine these Schottky energy ionic bonds. We have recently synthe- individual "building blocks." barriers and also to measure basic sized 100 bilayers of nickel phthalocyanine excitation energies in conjugated with poly(diallyldimethylammonium Publications polymers. We also developed a theoreti- chloride). This technique can be cal model that describes the current- generalized to other interesting photo- Maniloff, E.S., D. Vacar, et al., "Charge voltage characteristics of polymer synthetic systems such as conducting Transfer Polymers: A New Class of light-emitting diodes. polymers. When these conducting Nonlinear Optical Material" (to be polymers (donors) are mixed in blends published in SPIE Proc). Publications with fullerenes or other polymers Maniloff, E.S., D. Vacar, et al., (acceptors), electrons undergo charge "Femtosecond Charge Transfer Campbell, I.H., T.W. Hagler, et al., transfer in less than 300 fs. We have Holography in Conducting Polymer/Cg0 "Direct Measurement of Conjugated recently shown that this photo-induced Blends" (to be published in Synth. Polymer Electronic Excitation Energies charge transfer provides a recording Metals). Using Metal/Polymer/Metal Structures," mechanism for ultrafast photochromic Phys. Rev. Lett. 76,1900 (1996). gratings and allows the tailoring of the Maniloff, E.S., D. Vacar, et al., "Ultrafast Holography Using Charge Campbell, I.H., S. Rubin, T.A. decay dynamics of recorded holographic gratings. This type of composite charge- Transfer Polymers" (submitted to Opt. Zawodzinski, et al., "Controlling Lett). Schottky Energy Barriers in Organic

Competency Development Projects—Materials Science 159 Pinning Vortices and Enhancing Bulaevskii, L.N., V.M. Vinokur, and M. P. Maley, "Reversible High-Temperature Superconductor Magnetization of Irradiated High-Tc Superconductors," Phys. Rev. Lett. (HTS) Critical Currents 11, 936 (1996). Cho, J.H., M.P. Maley, et al., "Role of Martin Maley Superconducting Fluctuations in C- Axis Transport of Bi-2212 Super- We are investigating flux-pinning Our theoretical investigations conductors in High Magnetic Fields," mechanisms in high-temperature discovered a new collective "plasma Physica C 265, 277 (1996). superconductors to discover means of resonance" mode in layered HTS Dominguez, D., L.N. Bulaevskii, et enhancing HTS critical current conductors that is a measure of Jc al., "Interaction of Vortices with density (Jc)—a key performance normal to the superconducting layers. parameter for superconducting Ultrasound and the Acoustic Faraday materials. We have achieved large Effect in Type-II Superconductors," Publications enhancements in Jc at 75 K in barium- Phys. Rev. B 53, 6682 (1996). strontium-calcium-copper oxide/silver Bulaevskii, L.N., "Interaction of Maley, M.P., J.O. Willis, et al., (BSCCO/Ag) conductors by introduc- Pancake Vortices with C-Axis "Effects of Splayed Columnar Defects ing columnar defects, using fission Plasmons in Josephson Currents" (to Produced by Heavy Fission tracks induced by high-energy be published in Journale de Fragments on Vortex Dynamics in protons. We have worked to determine Physique). BSCCO Conductors," in Physical the optimum density of columnar Phenomena at High Magnetic Fields- Bulaevskii, L.N., "Intrinsic Josephson defects to maximize Jc and to gain II (World Scientific, Singapore, Effects in Layered Superconductors," understanding of the mechanisms. 1996), pp. 467-483. Turkish J. Phys. 20, 594 (1996). We also carried out two successful Safar, H., J.Y. Coulter, et al., studies: enhancing Jc through lower- Bulaevskii, L.N., D. Dominguez, et energy-proton irradiation (500 MeV) al., "Collective Mode and the C-Axis "Anisotropy and Lorentz-Force and irradiating stacked conductors. Critical Current of a Josephson- Dependence of the Critical Currents We were particularly interested in the Coupled Superconductor at High in YBa2Cu3O7 d Thick Films commercial feasibility of these Parallel Magnetic Fields," Phys. Rev. Deposited on Nickel Alloy processes. We discovered that, at high 5 53,14601(1996). Substrates," Phys. Rev. B (Rapid doses, the intergrain connections are Communications) 52, 9875 (1995). Bulaevskii, L.N., D. Dominguez, M. broken, but we found an annealing Safar, H., S.R. Foltyn, et al., "AB- procedure that heals grain-boundary P. Maley, et al., "Linewidth of C-Axis Plasma Resonance in Josephson- Plane Anisotropy of the Critical damage while retaining the enhanced Currents in Twinned YBa Cu 0 pinning. Coupled Superconductors," Phys. Rev. 2 3 7 d B 54, 7521 (1996). Superconductors," App. Phys. Lett. The new yttrium-barium-copper 68, 1853 (1996). oxide (YBCO) conductors prepared Bulaevskii, L.N., M. Maley, et al., by the ion-beam-assisted deposition "Angular Dependence of C-Axis Safar, H., S.R. Foltyn, et al., "Bose process contain strong pinning defects Plasma Frequency and Critical Glass Vortex Phase Transition in of unknown origin that allow them to Current in Josephson-Coupled Twinned YBa2Cu307 d Super- conductors," Philos. Mag. B 74, 647 maintain high Jc at 75 K in high Superconductors at High Magnetic fields. We determined the defects Fields," Phys. Rev. B 53, 6634 (1996). (1996). responsible and introduced additional Bulaevskii, L.N., V.L. Prokovsky, and Willis, J.O., H. Safar, et al., "High columnar defects by heavy-ion M.P. Maley, "Field Dependence of C- Energy Proton Irradiation Induced irradiation to seek further enhance- Pinning Centers in Bi-2212 and Bi- ments. Patterned bridges in these Axis Plasma Resonance in Josephson- Coupled Superconductors," Phys. Rev. 2223 Superconductors," in Advances films show a strong dependence of Jc in Superconductivity VIII (Springer- Lett. 76, 1719(1996). on the orientation between current Verlag, Tokyo, 1996), p. 509. and the twin structure. This and other evidence demonstrate that twin boundaries play a major role in the flux pinning. Heavy-ion irradiation produced further substantial enhancements when the magnetic field was aligned with the defects.

160 Los Alamos FY1996 LDRD Progress Report Nonlinearity in Structural and Publications Beardmore, K.M., et al., "Ab-Initio Electronic Materials Calculations of the Gold-Sulfur Interaction for Alkanethiol Mono- Alan Bishop layers" (1996ICSM Conference, Snowbird, Utah, July 29-August 2, This project has developed and junction arrays and layered 1996). applied a technology base of nonlin- superconductors. Beardmore, K.M., et al., "Molecular ear techniques that are relevant to a In addition to this work and as part Dynamics Simulation of Low-Energy variety of nonlinear, nonequilibrium of our communication with others in Boron and Arsenic Implant into problems in condensed matter and the field, we organized a seminar Silicon" (1996 IEEE Ion/Implant materials science. Our controlled series on nonlinear materials and Technology Conference, Austin, Tex., synthesis of, and experiments on, three international conferences on June 16-21, 1996). novel electronic and structural "Fracture, Friction, and Deformation," materials help motivate nonlinear "Nonequilibrium Phase Transitions," Bishop, A.R., et al, "Disorder-Induced science at Los Alamos, which in turn and "Landscape Paradigms in Physics Breakdown of Soliton and Polaron advances our understanding of the and Biology." We also gave several Particles," in Noise, Nonlinearity and processes that govern the structure invited talks, including talks at the Fluctuation Phenomena, A.R. Bishop and dynamics of today's complex international conferences on "Syn- et al., Eds. (World Scientific, materials. Important concepts from thetic Metals" and on "Quantum Singapore, in press). nonlinear science include (1) the Phase Transitions," at the 1996 Bishop, A.R., et al., "Nonlinear prevalence of coherent space-time CECAM Euroconference, and at the structures in strongly nonlinear Equations and Structural Phase 1995 Fall Meeting of the Materials Transitions," in Nonlinear classical and quantum systems, (2) the Research Society. possibility of deterministic chaos even Schrb'dinger and Klein-Gordon in low-dimensional dynamical Equations (World Scientific, systems, and (3) the coexistence of Singapore, in press). both coherence and chaos, leading to a rich variety of phenomena connoted by the term complexity. Our project studies these concepts and applies them to significant problems in condensed-matter physics and materials science. Achievements this year include the following: • large-scale simulations and microscopic modeling of nonlinear, coherent energy storage at the crack tips and sliding interfaces of lattice models (see figure); • large-scale simulation and microscopic elasticity theory for precursor microstructure and dynamics at solid-solid diffu- sionless phase transformations; • large-scale simulation of self- assembling, organic thin films on inorganic substrates; • analysis and simulation of the smoothing of rough atomic A 35-million-atom simulation of crack blunting by dislocation emission in surfaces; and copper under tensile loading. An elliptical crack (center of figure) in a 0.1-mm- • modeling and analysis of flux- thick copper sheet is placed under tension in the vertical direction. As the crack pattern formation in equilibrium attempts to propagate horizontally, it emits clouds of dislocations (white dots), and nonequilibrium Josephson some of which collide directly above the crack. Only atoms at the surface of the crack, or within the cores of dislocations, are depicted. The visualization technique used in the simulation suppresses atoms that are not displaced.

Competency Development Projects—Materials Science 161 Bishop, A.R., et al., "Simulations of Gumbsch, P., et al., "Molecular Shenoy, S., et al., "Quantum Current-Driven 3-Dimensional Dynamics Investigation of Dynamic Paraelectric Model for Layered Josephson Junction Arrays," Physica Crack Stability" (submitted to Phys. Superconductors" (submitted to Phys. B 222, 396 (1996). Rev. B). Rev. Lett.). Bronold, F.X., et al., "Nonlinear Hammerberg, J.E., et al., "Studies of Villain-Guillot, S., et al., "Topological Optics of Conjugated Polymers: A Sliding Friction in Compressed Solitons and Geometric Frustration," Coupled Exciton-Phonon Approach," Copper," in Proc. APS Topical Conf. Phys. Rev. A 52, 6712 (1995). Phys. Rev. B 53,13456 (1996). on Shock Compression in Condensed Wang, L., et al., "Charge Density Matter (North Holland, Amsterdam, Bussmann-Holder, A., et al., Wave of a Multiband Fermi Liquid," in press). "Quasiharmonic Periodic Traveling Phys. Rev. B 51, 7407 (1995). Wave Solutions in Anharmonic Holian, B.L., et al., "Molecular Zang, J., et al., "Lattice Effects in the Potentials," Phys. Rev. B 53, 11521 Dynamics Simulations of Fracture: Colossal Magnetoresistance (1996). An Overview of System Size and Manganites," Phys. Rev. Lett. 76, Other Effects," Mat. Res. Soc. Symp. Bussmann-Holder, A., et al., "Time- 1356(1996). Proc. 409, 3 (1995). Dependent Evolution of Double-Well Zharnitsky, V., "Resonances in a Potentials to Model Structural Jensen, N.G., et al., "Metastable Continuously Forced Anharmonic Anomalies," Philos. Mag. 73,657 Filamentary Vortex Flow in Thin Film Oscillator" (to be published in Phys. (1996). Superconductors," Phys. Rev. Lett. 76, Lett. A). 2985 (1996). Cai, D., et al., "Electric-Field-Driven Zhou, S.J., et al., "Dislocation Nonlinear Bloch Oscillations and Kenkre, V.M., et al., "Memory Emission from a Three-Dimensional Dynamic Localization," Phys. Rev. Function Approach to Interacting Crack—A Large-Scale Molecular Lett. 74, 1186(1995). Quasiparticle-Boson Systems," Phys. Dynamics Study" (to be published in Rev. 5 53,5407(1996). Cruz-Pacheco, G., et al., "The Proc. Ninth Int. Conf. Fracture). Relationship of Periodic Wavetrains Mertens, EG., et al., "Hierarchy of Zhou, S.J., et al., "Dynamic Crack and Solitary Waves in Optical Fiber Equations of Motion for Nonlinear Processes via Molecular Dynamics," Amplifiers Modeled by Complex Coherent Excitations Applied to Phys. Rev. Lett. 76, 2318 (1996). Ginzburg-Landau Type Equations" Magnetic Vortices" (submitted to (submitted to Phys. Lett. A). Phys. Rev. B). Zhou, S.J., et al., "Large-Scale Molecular Dynamics Simulations of Dandoloff, R., et al., "Violation of Raghavan, S., et al., "Validity of the Three-Dimensional Fracture" (to be Self-Duality for Topological Solitons Discrete Nonlinear Schrodinger published in Phys. Rev. Lett.). due to Soliton-Soliton Interaction on a Equation in the Context of the Cylindrical Geometry," Phys. Rev. Fluorescence Depolarization of a Zhou, S.J., et al., "Large-Scale Lett. 74, 813 (1995). Spin-Boson System," Phys. Rev. B 53, Molecular Dynamics Simulations of 8457 (1996). Fracture and Deformation" (to be Diez, E., et al., "Dynamical published in /. Computer-Aided Phenomena in Fibonacci Salkola, M., et al., "Coupled Mater.). Semiconductor Superlattices" (to be Quasiparticle-Boson Systems: The published in Phys. Rev. B). Semiclassical Approximation and Zhou, S.J., et al., "Study of Fiber Discrete Nonlinear Schrodinger Composite Failure Criterion," Mater. Dominguez, D., et al., "Resistive Equations," Phys. Rev. B 52, 3824 Res. Soc. Symp. Proc. 409, 267 Hysteresis and Nonlinear I-V (1995). (1995). Characteristics at the First Order Melting of the Abrikosov Vortex Sanchez, A., et al., "Roughening Lattice," Phys. Rev. Lett. 75, 4670 Transition of Driven Surface Growth," (1995). Phys. Rev. B 51, 14644 (1995). Dominguez, D., et al., "Transformer Sanchez, A., et al., "Smoothing of Configurations in 3-Dimensional Rough Surfaces," Phys. Rev. B 52, Josephson Lattices," Phys. Rev. Lett. 5433 (1995). 75, 717 (1995). Saxena, A., et al., "Hierarchical Farkas, D., et al., "Embedded Atom Twinning: Martensites as Pattern- Calculations of Unstable Stacking Forming Systems" (submitted to Fault Energies and Surface Energies Phys. Rev. Lett:). in Intermetallics" (to be published in J. Mater. Res).

162 Los Alamos FY1996 LDRD Progress Report High-Resolution Electron Microscopy of Chen, C.L., D. Zhou, et al., "Direct Observation of TaH Precipitation in Advanced Materials Tantalum-Hydrogen Solution," /. Vac. Sci. Tech. 14, 2551-2553 (1996). Terence Mitchell Chu, F., Y. He, et al., "Elastic Constants of the C15 Laves Phase Our objective has been to improve Recent examples of applications Compound NbCr2," Scripta Met. the key performance of a full range of include the characterization of defects Metall. 33, 1295-1300 (1995). spectroscopy instruments and so and interfaces in thin films of Chu, F, Q.X. Jia, et al., increase our ability to analyze YBa Cu 0 deposited on various 2 3 7 "Microstructures and Electrical advanced materials significantly. The substrates and buffer layers, HRTEM Properties of SrRuO Thin Films on instruments include a field-emission analysis of interfaces in various 3 LaA10 Substrates," J. Electron. scanning electron microscope (FE- ceramic composites, analysis of the 3 Mater. 25,1754-1759 (1996). SEM), a 100-kV field-emission core structures of dislocations scanning transmission electron produced in ceramics and intermetal- Chu, F, M. Lei, et al., "Single Crystal microscope (FE-STEM), a 300-kV lics by high-temperature deformation, Elastic Constants of C40 NbSi2" Phil. field-emission, high-resolution and analysis of nanolayered materials. Mag. B 71, 373-382 (1995). transmission electron microscope Future applications will involve elec- Chu, F, M. Lei, S.A. Maloy, et al., (FE-HRTEM), and a 300-kV analyti- tron holography by the incorporation "Elastic Properties of C40 Transition cal transmission electron microscope. of a biprism in the column of the FE- Metal Disilicides," Acta Metall. We are presently adding a new HRTEM. orientation-imaging microscope. Mater. 44, 3035-3048 (1996). X-ray energy dispersive spectrom- Chu, F, A.H. Ormeci, T.E. Mitchell, Publications eters for chemical analysis are et al., "Stacking Fault Energy of the available on all four microscopes, and Albert, D.E., and A.W. Thompson, NbCr2 Laves Phase," Phil. Mag. Lett. parallel electron energy loss spec- "Effect of Stress-Temperature 72, 147-153 (1995). trometers (PEELS) are operational on Regimes on Creep Mechanisms in Ti- Chu, F, D.P. Pope, and T.E. Mitchell, the FE-STEM and FE-HRTEM. The 24 Al-llNb," Mater. Set Engin. A. "Phase Stability and Elastic Properties PEELS systems enable evaluation of 210, 48-56 (1996). local atomic bonding as well as of C15 Compounds HfV2+Nb," in chemical composition in nanometer- Ablen, S.P., R.D. Field, and M. Mechanical Properties and Phase scale regions. We have successfully Mataya, "Elevated Temperature Transformations of Multi-Phase demonstrated the FE-HRTEM point- Stress-Strain Behavior of Beryllium Intermetallic Alloys, A.F. Giamei, K. to-point resolution of 1.6 A. In Powder Product," (Second IEA Inoue, and Y. Mishima, Eds. (The addition, because of the high bright- International Workshop on Beryllium Metals, Materials, and Minerals ness and coherency of the FE source, Technology for Fusion, Jackson Hole, Society, Warrendale, Pa., 1996), we have been able to push the Wyo., September 6-8, 1995). pp. 17-24. microcsope's resolution to its infor- Butt, D.P., D.A. Korzekwa, S.A. Cooper, E.A., H. Kung, and M. mation limit of 1 A by computer Maloy, et al., "Impression Creep Nastasi, "Systematic Study of the Ion reconstruction of a focal series of Behavior of SiC Particle-MoSL, Beam Mixing of Oxide Markers into images. Composites," J. Mater. Res. 11, No. 6 Alumina," Nucl. Instrum. Methods B We have used HRTEM to image the (1996). 106, 9-16 (1995). atomic structure of defects such as Butt, D.P., K.S. Lackner, C.H. Wendt, Devanathan, R., N. Yu, et al., dislocations, grain boundaries, and et al., "Kinetics of Thermal Dehy- "Electron Diffraction Analysis of a interfaces in a wide variety of droxylation and Carbonation of Metastable State in Ion-Irradiated materials from superconductors to Magnesium Hydroxide," /. Am. MgAl O Spinel," Microscopy and structural ceramics. We have used the 2 4 Ceram. Soc. 78, 1892 (1996). Microanalysis Proc. 53, 160 (1995). new HRTEM to image such defects with much greater accuracy at the Chen, C.L., T.T. Tsong, et al., Devanathan, R., N. Yu, et al., atomic level, making it possible to "Surface Diffusion and Surface "Relationship between Structure and compare them with modeling predic- Atomic Roughness on Ir (001) Mechanical Properties of Ion- tions and improve interatomic Surface and Terraces," Appl. Surf. Sci. Irradiated MgAl2O4 Spinel," potentials. 94/95, 224-230 (1996). Microscopy and Microanalysis Proc. 53, 358 (1995).

Competency Development Projects—Materials Science 163 Devanathan, R., N. Yu, et al., Kotula, P.G., I.M. Anderson, F. Chu, Reimanis, I.E., M.E. Hawley, et al., "Structure of the Metastable State in et al., "ALCHEMI of NbCr/V CIS- "The Fracture Characteristics of Ion-Irradiated Magnesio-Aluminate Structured Laves Phase," Microscopy Czochralski-grown Y3A15O12," /. Spinel," Phil. Mag. Lett. 72,155-161 and Microanalysis Proc. 54, 554-555 Amer. Ceram. Soc, 78, 2282-2286 (1995). (1996). (1995). Griffin, A.J., M.F. Hundley, T.R. Kung, H., R.G. Castro, et al., "The Reimanis, I.E., JJ. Petrovic, et al., "A Jervis, et al., "Residual Stress, Structure of Plasma Sprayed MoSi2- Crystalline Si3N4 /Amorphous Si3N4 Mechanical Behavior and Electrical A12O3 Microlaminate Tubes," Scr. Composite," J. Amer. Ceram. Soc. 79, Properties of Cu/Nb Thin Film Metall. Mater. 32, 179 (1995). 395_400 (1996). Multilayers," Mater. Res. Soc. Symp. Kung, H., J. Griffin, et al., "The Reimanis, I.E., J J. Petrovic, et al., Proc. 382, 309-314 (1995). Stabilization of B.C.C. Cu in Cu/Nb "The Fracture Behavior of a CVD Hirvonen, J-R, I. Suni, H. Kattelus, et Nanolayered Composites," Crystalline Si3N4/Amorphous Si3N4 al., "Crystallization and Oxidation Microscopy and Microanalysis Proc. Composite," Ceram. Trans. 42, 277- Behavior of Mo-Si-N Coatings," 54, 228-229 (1996). 283 (1995). Surface Coatings Technol. 74/75,981 Kung, H., T.R. Jervis, et al., "High Reimanis, I.E., J.J. Petrovic, et al., (1995). Temperature Structural Stability of "The Mechanical Properties of Single Hirvonen, J-R, P. Torri, R. MoSi2-Based Nanolayer Composites," Crystal a-Si3N4" Ceram. Trans. 42, Lappalainen, et al., "Tribological J. Vac. Sci. Tech. A13, 1126-1129 229-236 (1995). Characteristics of MoSi /SiC (1995). 2 Reimanis, I.E., H. Suematsu, et al., Nanocomposites," Nanostruct. Mater. Kung, H., T.R. Jervis, et al., "The Properties of Single Crystal 6, 881 (1995). "Structure and Mechanical Properties Si3N4," /. Amer. Ceram. Soc. 79, Jervis, T.R., J-R Hirvonen, et al., of MoSi2-SiC Nanolayer 2065-2073 (1996). "Tribology and Mechanical Properties Composites," Phil. Mag. A. 71,759- Safar, H., S. Foltyn, H. Kung, et al., of Excimer Laser Processed Ti-Si N 779 (1995). 3 4 "ab-Plane Aniostropy of the Critical Surfaces," /. Mater. Res. 10,1857 Kung, H., T.R. Jervis, et al., Currents in Twinned YBa Cu O (1995). 2 3 7 d "Synthesis, Structure and Mechanical Superconductors," Appl. Phys. Lett. Jia, Q., F. Chu, CD. Adams, et al., Properties of Nanostructured 68, 25 (1996). "Characteristics of Conductive MoSi N ," Nanostruct. Mater. 7, 2 x Sickafus, K.E., N. Yu, and M. Nastasi, SrRuO Thin Films with Different 81-88 (1996). 3 "Radiation Resistance of the Oxide Microstructures," /. Mater. Res. 11, Mitchell, T.E., M. Nastasi, et al., Spinel: The Role of Stoichiometry on 2263-2268 (1996). "Synthesis, Structure and Mechanical Damage Response," Nucl. Instr. Meth. Jia, Q., S.G. Song, X.D. Wu, et al., Properties of Nanolayered B 116, 85 (1996). "Epitaxial Growth of Highly Composites of Mo, MoSi , MoSi N 2 2 x Sickafus, K.E., N. Yu, et al., "The Conductive Oxide RuO Thin Films and SiC," in Novel Techniques in 2 Irradiation Damage Response of on (001) Si," Appl. Phys. Lett. 68, Synthesis and Processing of Advanced MgO-3Al O Spinel Single Crystals 1069 (1996). Materials, J. Singh and S. Copley, 2 3 Under High-Fluence Ion-Irradiation," Eds. (The Metals, Materials, and Jia, Q.X., X.D. Wu, et al., "Deposition Nucl. Instr. Meth. B 106, 573-578 Minerals Society, Warrendale, Pa., of Epitaxial YSZ on Single-Crystal Si (1995). 1995) p. 271-281. and Subsequent Growth of an Song, S.G., C.L. Chen, et al., Amorphpous SiO Interlayer," Phil. Maloy, S.A., and T.E. Mitchell, 2 "Observation of Nano-scale Epitaxial Mag. Lett. 72, 385-391 (1995). "Dislocation Decomposition, Growth of Diamond on the Si (100) Dissociation, and Deformation in Jia, Q.X., X.D. Wu, S.R. Foltyn, et al., Surface," /. Appl. Phys. 79,1813 MoSi and a-Al O Single Crystals," "Fabrication and Characterization of 2 2 3 (1996). in Plastic Deformation of Ceramics, High Temperature Superconductor R.C. Bradt, and C.A. Brookes, Eds. Song, S.G., R. Vaidya, et al., Josephson Junctions with A Novel (Plenum Press, New York, 1996), "Stacking Faults in SiC Particles and Design," IEEE Trans. Appl. pp. 53-62. Their Effect on the Fracture Behavior Supercond. 5, 2103-2106 (1995). of a 15 Vol % SiC/6061-Al Matrix Ormeci, A., F. Chu, et al., "A Total- Jia, Q.X., D.S. Zhou, et al., Composite," Met. Mater. Trans. 27A, Energy Study of Electronic Structure "Characterization of Ba Sr TiO 459 (1996). 0 5 0 5 3 and Mechanical Behavior of C15 Thin Film Capacitors Produced by Laves Phase Compounds: NbCr and Pulsed Laser Deposition," Integrated 2 HfV ," Phys. Rev. B 54,12753 (1996). Ferroelectrics 10, 73-79 (1995). 2

164 Los Alamos FY1996 LDRD Progress Report Suematsu, H., JJ. Petrovic, and T.E. Vaidya, R.U., A.K. Zurek, and A. Yu, N., Q. Wen, D.R. Clarke, et al., Mitchell, "Plastic Deformation of Wolfenden, "Effect of Plasma "Formation of Fe or Cr Doped Silicon Nitride Single Crystals," Sprayed A12O3 Coating on the Epitaxial Sapphire Thin Films on Mater. Sci. Eng. A 209, 97-102 Strength, Elastic Modulus and Sapphire Substrates," /. Appl. Phys. (1996). Damping of Ti-25 Al-lONb 78,5412 (1995). Intermetalric," /. Mater. Eng. Perf. 4, Thoma, D.J., E.M. Schwartz, S.R. 3 (1995). Bingert, et al., "Microsegregation Zhou, D.S., C.L. Chen, T.E. Mitchell, During Melt-Spinning of Dilute Walter, K.C., H. Kung, J.T. Tesmer, et al., "Thin Films of Cubic Boron Palladium Alloys," Melt Spinning, et al., "Characterization and Nitride on Silicon," Phil. Mag. Lett. Strip Casting and Slab Casting, E.F. Performance of DLC Films 72, 163-166 (1995). Matthys and W.G. Truckner, Eds. Synthesized by Plasma and Ion Beam (The Metals, Materials, and Minerals Techniques," Surface and Coatings Zhou, D.S., and T.E. Mitchell, Society, Warrendale, Pa., 1996). Technol. 74/75, 734-738 (1995). "Atomic Structures of a Stacking Fault and a Domain Boundary in a- Tiwari, P., X.D. Wu, et al., "High- Walter, K.C., M. Nastasi, H. Kung, Silicon Nitride," /. Microsc. Soc. quality Epitaxial YBCO Thin Films et al., "Diamond-Like Carbon Amer. 1,263-266 (1995). Directly on LiNbO3" Phil. Mag. B 71, Deposition for Tribological 903-912 (1995). Applications at Los Alamos National Zhou, D.S., and T.E. Mitchell, Laboratory," Mater. Res. Soc. Symp. "Dislocations in as-Grown CVD a- Tiwari, P., X.D. Wu, et al., "Study of Proc. 383,411(1995). Silicon Nitride," J. Amer. Ceram. Soc. High Quality YBCO Thin Films 78,3133-3136(1995). Grown Directly on Y-cut LiNbO3," J. Yan, M., S.P. Chen, et al., "Atomistic Electron. Mater. 25, 131-135 (1996). Study of Energy and Structure of Zhou, D.S., and T. E. Mitchell, Surfaces in NiO," Phil. Mag. A 72, "Rotation Domains in a-Silicon Tiwari, P., X.D. Wu, et al., "Synthesis 121-138 (1995). Nitride," Phil. Mag. A 72, 1131-1140 of Low Resistivity Complex Oxides (1995). on MgO Using Pt as Buffer Layer," J. Yan, M., S.P. Chen, et al., "Atomistic Electronic Mater. 25, 51-55 (1966). Study of Energy and Structure of Zurek, A.K., W.R. Thissell, and D.L. Surfaces in NiO," in Structure and Tonks, "Spall Behavior and Damage Vaidya, R.U., D.P. Butt, et al., "Effect Properties of Interfaces in Ceramics, Evolution in Tantalum" (Assoc. for of Microbial Corrosion on the Tensile D. Bonnell, M. Ruhle and U. the Advancement of High Pressure Stress-Strain Response of Aluminum Chowdhry, Eds. (Materials Research Science and Technology International. and A1 O Particle Reinforced 2 3 Society, Pittsburgh, Pa., 1995) Conf., Warsaw, Poland, Sept. 10-15, Aluminum Composite" (to be pp. 441^46. 1995). published in Corrosion Prevention and Control). Yano, T., M. Ikari, et al., "Effect of Neutron Irradiation on Knoop Vaidya, R.U., L.E. Hersman, et al., Hardness Anisotropy in MgO- Al O "Microbiologically Influenced 3 2 3 Single Crystal," /. Amer. Ceram. Soc. Corrosion of Aluminum 6061 and 78 (6), 1469-74 (1995). A12O3 Particle Reinforced Aluminum 6061 Composite under Anaerobic Yu, N., P.C. Mclntyre, et al., "High- Conditions and Elevated Temper- Quality Epitaxial Growth of Gamma- atures: Effect on the UTS and Strain Alumina Films on Sapphire Induced to Failure" (to be published in by Ion Beam Bombardment," Phys. Corrosion Prevention and Control). Rev. 5 52,17518(1995). Vaidya, R.U., S.G. Song, et al., "The Yu, N., K.E. Sickafus, and M. Nastasi, Effect of Structural Defects in SiC "Temperature Effects on Ion Particles on the Static and Dynamic Irradiation Damage in MgAl2O4 Response of a 15 Percent SiC/6061- Spinel Single Crystals," Mater. Res. Al Matrix Composite" (APS Topical Soc. Symp. Proc. 373, 401 (1995). Conference, Seattle, Wash., August 1995). Vaidya, R.U., and A.K. Zurek, "Effect of Aging Treatment on the Com- pression Behavior of a B4C/A16061 Composite," /. Mater. Sci. Lett. 15, 385-387 (1996).

~~Competency Development Projects—Materials Science 165~~

~~Engineering and Base Technologies~~

Molten Salt and Molten Lead Bowman, CD., "Current Status and Recommended Future Studies of Systems Studies Underground Supercriticality" (ICENES '96, Eighth International Conference on Emerging Nuclear Gary Doolen Energy Systems, Obninsk, Russia, June 24-28,1996). Accelerator-driven transmutation of develop a thorium-uranium breeder nuclear waste (ATW) is a technology reactor. We believe that key features Bowman, CD., "Optimization of that can essentially eliminate the of our system—the accelerator drive, Accelerator-Driven Technology for plutonium, higher actinides, and the robust fuel cycle, the low power Light-Water Reactor Waste environmentally hazardous fission density, the absence of breeding Transmutation" (Second International products in the spent fuel from requirements, and the use of trivalent Conference on Accelerator-Driven nuclear reactors. This project ad- actinides—should make our ATW Transmutation Technologies and dresses key systems and programmatic system considerably simpler than the Applications, Kalmar, Sweden, June issues related to ATW—specifically, Oak Ridge reactor. 3-7,1996). how molten salt and liquid lead Finally, development of effective technologies developed for ATW fit tools for neutronics calculations, Bowman, CD., and F. Venneri, into the waste management infrastruc- including the coupling of neutron "Underground Supercriticality from ture. We have focused our efforts on transport, depletion, and kinetic Plutonium and Other Fissile modeling and analyzing the physics codes, has enabled us to develop Material," Science and Global of the ATW target and blanket to innovative designs involving liquid Security 5, 279 (1996). optimize transmutation performance. fuels in previously unexplored Doolen, G., F. Venneri, M.A. First, we defined the active part of neutron flux and spectrum regimes. Williamson, et al., "The Los Alamos the system as consisting of a graphite- These designs are now feasible Accelerator-Driven Transmutation of reflected, molten salt subcritical blanket through the use of our accelerator Nuclear Waste Concept (ATW)," in assembly coupled to an appropriate drive, which enables us to use Proceedings of the International liquid lead/bismuth neutron production subcritical fuel levels for improved Workshop on Nuclear Methods for target. Our system does not have an control and efficiency. We are Transmutation of Nuclear Waste, internal graphite moderator. continuing to explore the use of a fast M.K. Khankhasayev, H.S. Plendl, and Then, we performed preliminary neutron spectrum to enhance the Z.B. Kurmanov, Eds. (World calculations that coupled the neutron efficiency of transmutation. Scientific, Singapore, 1997), transport codes LAHET and MCNP pp. 26-28. with the depletion codes ORIGEN Publications and DYNA. These calculations Venneri, F., N. Li, and M.A. Williamson, "Physics and Chemistry showed that our system maintains low Bowman, CD., "Accelerator-Driven actinide inventories while efficiently Transmutation Technologies for of Accelerator-Driven Transmutation burning fuel (by fission), two impor- Resolution of Long-Term Nuclear Systems" (Second International tant features. We have also introduced Waste Concerns," in Proceedings of Conference on Accelerator-Driven significant passive safety features the International Workshop on Nuclear Transmutation Technologies and such as a massive heat sink of liquid Methods for Transmutation of Nuclear Applications, Kalmar, Sweden, June salt around the exterior of the reactor Waste, M.K. Khankhasayev, H.S. 3-7, 1996). vessel. Plendl, and Z.B. Kurmanov, Eds. In addition, we initiated a study to (World Scientific, Singapore, 1997), compare our new ATW system with pp. 257-270. the 8-MW molten salt reactor operated at Oak Ridge National Laboratory during the 1970s to

Competency Development Projects—Engineering and Base Technologies 167 Advanced Measurements and Techniques In our study of semiconductors, a variety of optical measurements in High Magnetic Fields revealed the behavior of semiconductor heterostructures in high magnetic fields. These included measurements Laurence Campbell of magneto-photoluminescence (MPL) intensity, energy oscillations, The objective of our project was to which suggested the possibility of and optical Shubnikov-de Haas use advanced measurement technol- having metamagnetic transitions in (OSdH) oscillations in a modulation- ogy in order to better understand the magnetic fields to 100 T. We also doped, GaAs/AlGaAs single fundamental properties of materials looked at unconventional semicon- heterojunction. The MPL and OSdH subjected to high magnetic fields. ductors in high magnetic fields, measurements showed energy and Properties of interest included the examining the energy-gap formations intensity oscillations caused by the materials' electrical conductivity, of Kondo insulator compounds. In interaction (crossing) between the microscopic structure, and thermal particular, we studied the effect that second sub-band Landau levels characteristics. We had two main very high magnetic fields have on the (occupied by photo-generated tasks: a study of correlated electrons energy-gap formation in SmB6 electrons) and the Fermi level. We and optical measurements on semi- compounds. Magnetoresistance also looked at MPL measurement of conductors. experiments were performed in GaAs/AlGaAs double-well structures In our correlated-electron study, we magnetic fields to 50 T and at that included (1) a modulation-doped, looked at ground-state properties of temperatures down to 40 mK. For the coupled double quantum well and heavy fermion compounds in high first time, we observed that the low (2) an asymmetric, coupled double magnetic fields, with a focus on excitation gap closes in a magnetic quantum well. We further looked at compounds that exhibit magnetic- field of 35 T at 40 mK. Studies were undoped GaAs/AlGaAs multiple field-induced transitions. In particular, also carried out to verify that the quantum wells and CdTe single- we looked at YbNi2B2C, a new heavy observed effects were not sample- crystal thin films. fermion compound presenting dependent and to obtain a theoretical extremely high magnetic anisotropy, understanding of the phenomena.

Dynamic High-Strain Deformation of Our major accomplishments reflect the coordinated nature of this project. Materials: Experiments, Advanced We performed MD simulations of extended-dislocation intersection in Constitutive Modeling, and Computational face-centered-cubic metals to improve Implementation our understanding of plastic deformation at strain rates of 10V1 to 10V1. We successfully applied the Tonks Dean Preston ductile damage model to spallation data of ultrapure tantalum. We Science-based stockpile steward- selected a set of coordinated experi- measured and analyzed the texture ship requires the capability to predict mental, mathematical-modeling, and and plastic constitutive properties the implosion dynamics of primaries code-implementation tasks that we are induced by upset forging high-purity and the subsequent expansion of using to (1) improve the calibration of bar stock. By reloading prestrained warhead components, for which the the mechanical threshold stress (MTS) samples over a wide range of tem- properties of material under extreme and Preston-Tonks-Wallace (PTW) peratures and strain rates to about conditions (large strain, high strain strength models with new Hopkinson 10V1, we obtained data required for rates, and high temperatures) are bar data at elevated temperatures and accurate determination of PTW and critically important. The thrust of this at very large strains; (2) extend the MTS model parameters. We modeled project is directed at providing the models to include texture evolution; the nonequilibrium, shock-induced Laboratory with the ability to perform (3) employ the methods of molecular transformation from the body- predictive numerical simulations of dynamics (MD) to improve the centered cubic phase to the hexagonal large-strain dynamical behavior by models at intermediate strain rates; close-packed phase of iron. To date synthesizing material strength and (4) develop an advanced model of we have focused the texture evolution texture data with condensed matter ductile damage growth and spall; and modeling on implementating an theory and mesoscale physics to (5) analyze and model solid-solid analytical anisotropic elastoplastic construct advanced constitutive phase transformations. strength model into the CHAD code. models. For this project we have

168 Los Alamos FYI996 LDRD Progress Report Publications Tonks, D.L., "Application of the Zurek, A.K., W. Richards Thissell, D.L. Tonks Ductile Damage Model to Boettger, J., and D. Wallace, Tonks, et al., "Spall Behavior and Spallation in High-Purity Tantalum," "Metastability and Dynamics of the Damage Evolution in Tantalum," in Los Alamos National Laboratory Shock-Induced Phase Transtion in Proceedings of AIRAPT International report LACP-95-416 (1995). 1ion,"Phys. Rev. B 55, 2840 (1997). Conference, W.A. Trzeciakowski, Ed. Zurek, A.K., W. Richards Thissell, (World Science Publishing, Singapore, Johnson, J.N., R.S. Hixson, D.L. D.L. Tonks, et al., "Micromechanics 1995) pp. 941-3. Tonks, et al., "Rate-Dependent of Spall and Damage in Tantalum," J. Spallation of Tantalum," in Shock Mater. Process. Technol. 60, 261 Compression of Condensed Matter, (1996). S.C. Schmidt and W.C. Tao, Eds. (American Institute of Physics, New York, 1995) p. 523.

Ultrasensitive Sensors for Weak devices and increased the production yield. We fabricated and tested Electromagnetic Fields Using HTS SQUIDs with both large-area (1 mm2) pickup loops for magnetometer SQUIDs for Biomagnetism, NDE, and applications and those with small-area Corrosion Currents (100 urn2) pickup loops for SQUID microscope applications.

Edward Flynn Publications This project centers on developing We have developed and published Flynn, E.R., R. Bracht, R.H. Kraus Jr., ultrasensitive sensors for detection of the results of a low-performance, et al., "A Digital-Signal-Processor weak magnetic fields and has three prototype electronics system that (DSP) Flux-Locked Loop for Bio- task areas: (1) a new concept in eliminates 99.5% of a simulated magnetic Applications of SQUIDs" superconducting weak-field sensor background field in a system inte- (to be published in the 1996 Inter. arrays, (2) introduction of digital grated with a Los Alamos HTS Biomagnetics Conf. Proc). signal processors (DSPs) into the SQUID. Thus we have improved the superconducting quantum interference background rejection and developed a Jia, Q.X., X.D. Wu, D.W. Reagor, device (SQUID) circuit, and (3) im- SQUID sensor system for unshielded et al., "Edge-Geometry SNS DC proved high-temperature supercon- applications. We also successfully SQUIDs Using Ag-doped ducting (HTS) Josephson junctions tested a similar low-Tc system Yba2Cy3O? x Electrodes," Electron. for HTS SQUIDs. (superconducting at liquid helium Lett. 32, 499 (1996). We have focused on developing temperatures, 4 K). Kraus, R.H. Jr., R. Bracht, E.R. Flynn, HTS (superconducting at liquid In addition, we developed better et al., "High Temperature SQUID nitrogen temperature, 77 K) SQUID superconducting-normal-supercon- Magnetometer and Gradiometer sensors and systems, and on back- ducting (SNS) junctions to improve Systems with Digital-Signal- ground noise rejection using a DSP- both SQUID performance and the Processor (DSP) Flux-Locked Loop controlled flux-locked loop to enable mechanics of wire bonding and for Biomagnetic Applications" (to be direct cancellation of the noise SQUID circuit layout. A silver-doping published in the 1996 Inter. Biomag- magnetic field at the SQUID sensor. technique has significantly improved netics Conf. Proc). These efforts have yielded SQUID the performance of the SQUID sensors for applications that require unshielded environments.

Competency Development Projects—Engineering and Base Technologies 169 Short-Pulsed Electric-Discharge a medium-voltage, repetitive, short- pulsed discharge. The accompanying Degradation of Toxic and Sludge Wastes plot shows the data for DCP. The technique provides relatively high electrical efficiency for applications Louis A. Rosocha, Los Alamos National Laboratory involving waterborne pollutants. The Frank J. Wessel and Vitaly M. Bystritskii, University of California, Irvine specific energy input for the degradation of one pollutant molecule is in To overcome the drawbacks of aerosol-injection geometry, electrode the range of 40-100 eV and depends conventional pollutant-degradation geometry, and pulse-discharge on both the operational parameters of technologies, we are developing a circuitry. the discharge and the concentration. short-pulsed electric-discharge We have successfully demonstrated We plan to conduct future studies to chemical reactor (see accompanying an innovative technique for degrading identify intermediate by-products and diagram) to ionize and degrade an aerosol mixture of various to optimize the operating parameters aqueous-based pollutants, particularly organics—pNP, dichlorophenol that lead to a higher degree of organic compounds such as chlori- (DCP), and perchloroethylene—using mineralization. nated solvents and biphenyls. Such compounds are hazardous air and atomizer water pollutants that are harmful to human health. They are not decom- posed by natural microorganisms and are, therefore, persistent in the environment. An ideal degradation method would convert these pollutants into harmless or easily handled "mineralized compounds" such as carbon dioxide and simple acids. Our reactor offers several advantages over current degradation technologies: it has the potential to produce higher levels of degradation Cross section of the cell of the and less secondary waste, and it can short-pulsed electric-discharge handle aqueous-based wastes that are chemical reactor. difficult to incinerate. Our degradation process could have widespread use for the treatment of industrial I Pyrex tube wastes such as those from chemical plants, the petrochemical and pharmaceutical industries, painting operations, and manufacturing. During the first year of the project, we commissioned the reactor, t \J established its operating parameters (such as voltage and current), and 60 - assessed its ability to decompose an 50- aqueous solution of a model organic T3 9 40 - pollutant, paranitrophenol (pNP). o During this second year, we opti- 30 - mized the operating parameters for o 20 - voltage, pulse duration, pulse- 6 ; ^ repetition frequency, flow density, and 10 - _ droplet dimension. In addition, we 0 - extended the reactor studies to include i chlorinated compounds and assembled a new reactor incorporating Number of treatment cycles beneficial design modifications in the chamber-material construction, Plot of the amount of chlorine that the pulsed-discharge reactor removed from a 1000-ppm aqueous solution of dichlorophenol over repeated treatments.

170 Los Alamos FY1996 LDRD Progress Report Laser-Sheet Imaging of HE-Driven For our experiments, we used a fluorescein-loaded layer embedded in Interfaces water as the test object, and we successfully observed the optical signal from the fluorescein dye. A Robert Benjamin 10-gal. aquarium contained the experiments. Interfacial instability of a thin, incorporate MILSI at a Laboratory Other experiments compared two high-density fluid layer that lies firing site, enhancing diagnostic framing methods: pulsed laser versus between two less-dense fluids is a capability. This work is supported in pulsed camera. The pulsed camera fundamental research problem in both design and data analysis by flow method, which puts an image intensi- weapons and inertial confinement simulations with computer codes used fier on the front end of a charge- fusion (ICF). Experimental observa- in weapons and ICF work. coupled-device camera, proved better. tions of highly distorted, preturbulent, Several HE-driven experiments this We intend to use this method for shock-accelerated gas flows motivate past year demonstrated the feasibility future HE experiments. Finally, two- the study of such flows in liquids. of producing a useful laser sheet with dimensional design calculations Our project studies thin liquid a 10-W, air-cooled argon laser. The indicate that diagnostic time will layers driven by a high explosive laser beam becomes in effect a thin probably be limited by lateral (HE). We are using multiple imaging sheet that illuminates a two-dimen- rarefaction waves and that the denser, of laser-sheet illumination (MILSI) to sional slice through the liquid thin fluid layer should be only 1-2 cm diagnose the transient flow patterns. interfaces. The resulting image is then from the HE. The objective of our work is to detected with a high-speed camera.

A Neural-Network-Based System for adapt these algorithms into a general- purpose computer code that will be Damage Identification and Location in used to detect damage in structural Structural and Mechanical Systems and mechanical systems. We have completed a comprehensive literature survey of the damage identification Charles R. Farrar field, and we sponsored a workshop on damage identification from There are many large structures and structural dynamics, neural networks, changes in vibration characteristics. mechanical systems for which it and pattern recognition to develop a Researchers from the United States would be desirable to monitor their comprehensive, self-diagnosing, and many foreign countries attended "health" and to identify damage as structural-monitoring and damage- the workshop and helped to define the early as possible. The objective of this detection system. state of the art. project is to develop a computer- Our primary technical achievement based system that can remotely this year is the development of Publications monitor and detect damage in nonlinear time-frequency-analysis structural and mechanical systems. algorithms that can be applied to Doebling, S.W., "Minimum-Rank Clearly, such development would be measured vibration data for global Optimal Update of Elemental of high value and wide application. damage detection in structures and Stiffness Parameters for Structural We have begun to integrate new mechanical systems. We have verified Damage Identification," AIAA J. 34, damage identification algorithms (that these algorithms by applying them to 2615-2621 (1996). monitor the vibration response of a simple test specimens in which the physical structure or system) with damage produces a nonlinear vibra- adaptive computing strategies. Our tion response not present in undam- research will couple expertise in aged specimens. We are beginning to

Competency Development Projects—Engineering and Base Technologies 171 Development of Inexpensive Continuous-Ennission Monitors for Feedback Control of Combustion Devices to Minimize Greenhouse Gases, Toxic Emissions, and Ozone-Damaging Products

David J. Funk Sample/Reference IR Chamber There is little doubt that combus- Source Polarizer Dispersing/ tion is the major cause of poor urban Combining air quality and depletion of the ozone 000^7 Prisms Detectors layer and a major source of the Lens greenhouse gas carbon dioxide. Furthermore, there is little doubt that global combustion activity is increasing. We are addressing these concerns through research and development of sensitive, inexpensive, continuous- emission monitors (CEMs) based on the optical properties of expected, gas-phase, hazardous materials. To date we have begun work on three Frequency Computer DSP Board specific tasks: (1) proof-of-principle Generator experiments for an inexpensive, solid- state NOX detector; (2) proof-of- Schematic of the solid-state Fourier transform spectrometer. principle experiments of a solid-state, Fourier transform (FT) spectrometer (see the first figure), which has led to a disclosure and pursuit of a patent; and (3) infrared HeNe detection of hydrocarbons. Our preliminary experiments indicate high sensitivity for absorption of the infrared HeNe wavelengths by hydrocarbons found •8 commonly in fuels. We are presently c8 quantifying these results. CO c We have conducted studies of the o solid-state FT spectrometer using a broad-band light source, dispersing the radiation, modulating four bands 0.5 0.6 0.8 of light at four different frequencies, Time (s) recombining the light, and recording the time output in single-shot mode, Raw output of the phototubes (light detectors) as a function of time. The top as shown in the second figure. We trace is the time-dependent signal transmitted through a red filter; only one of applied a Fourier transform to the data the stripes in the mask (the focal plane of an optical system) is transmitting and observed the four frequency light and only a signal frequency is detected. The bottom trace is the time- peaks corresponding to the four dependent signal of the full output from the mask (no filters); the four carriers bands, as shown in the third figure. exhibit the expected beating behavior. We expect that these inexpensive optical sensors will assist in providing direct feedback of turbine power systems and assure the public and operators of facilities that facility emissions lie within accepted bounds.

172 Los Alamos FY1996 LDRD Progress Report 3.5 - 3.0 ! y \ / ; 2.5 ( i 2.0 i t i 1.5 i / v/ N \l \ \ ( 1.0 / v 'V V1 1 / ' X ^ A A \ i 0.5 / ••/\ ' A- A \ i nn 700 650 600 550 500 450 Wavelength (nm) (A)

Data from studies of the solid-state FT spectrometer. (A) Solid lines are Gaussian fits to the transmission of each of the striped elements. The dashed and dotted-dashed lines are the absorption of each of the filters studied. (B) Transmission spectra of the filters. The solid line is with no 55 60 65 70 75 80 85 90Hz filter in place. (B) Frequency

Distortion, Residual Stress, and Thermal During the year we developed a computational model that predicts the Gradient Issues for Plutonium Gravity distortion and residual stresses in a final cast plutonium part. By numeri- Casting in Ambient-Temperature Molds cally tracking the temperature history at different locations in the part, we S. Dale Soderquist can estimate the final metallurgical condition of the part. We made several The goal of this one-year project process is that it will minimize the castings to develop information for was to begin development of the amount of waste generated during the the model and to develop the mold process of casting plutonium alloys in casting operation. The numerical design. Five of the castings were of thin-walled, ambient-temperature methods that were developed to surrogate material (four depleted molds and to develop the methods model the process increased under- uranium and one bismuth). We made necessary to numerically simulate the standing and could lead to optimiza- one casting of a plutonium alloy and process. The new casting technique tion of the process. Numerical performed metallurgy on the final part decreases equipment complexity and prediction of fluid flow, heat transfer, to determine the as-cast material state. increases cooling rates after casting. thermal gradients, stresses, and Use of a thin-walled mold greatly These effects simplify heat-treating distortion aids in process design and simplified the casting process, and we requirements for the plutonium alloys. will eventually allow fabrication of a expect the metallurgy of the as-cast An additional benefit of the new higher quality product. part to be superior to that of castings made by traditional methods.

Competency Development Projects—Engineering and Base Technologies 173 Radiation Resistance Measurements of After exposure, the relative magnetic moment of each sample was Rare-Earth Permanent Magnet Material found to be within one standard deviation (0.5%) of its preirradiation for High-Intensity Linac Applications value. These results indicate no measurable change in the strength of David Barlow each sample's magnetization. We determined the neutron dose for each The objective of this project is to During this reporting period, we exposure by integrating the proton characterize the radiation resistance of exposed samples of samarium cobalt, beam on the target and the neutron rare-earth permanent magnet materi- a rare-earth permanent magnet energy spectrum by analyzing the als in an accelerator environment by material, to neutron radiation at the results of a set of activation foils from irradiating samples with neutrons. Los Alamos Neutron Science Center a companion experiment at the same High-strength, rare-earth permanent A-6 target facility. A total of 20 facility. magnet materials can be used in samples from 4 different sources were These results indicate that perma- various compact magnets for steering exposed to 5 different dose levels nent magnet assemblies can survive 19 2 and focusing high-energy particle ranging from 1.0 x 1017 to 1.0 x doses of 1.0 x 10 n/cm or more beams. Such permanent magnet 1019 n/cm2. We then retrieved the with little or no degradation in their assemblies take considerably less samples from the neutron source and magnetic-field strength. However, in space than comparable electromag- stored them to allow the short-lived an actual assembly, the permanent nets and are extremely attractive if activation products to decay. Ten magnet material will be exposed to space is at a premium. In addition, months later, we took the samples out external demagnetizing fields, which permanent magnets offer a level of of storage just long enough to have been shown to greatly increase reliability that far surpasses that of measure their relative magnetic the rate of radiation damage. The real electromagnets—an important ad- moment before returning them to test of a permanent magnet's radiation vantage for applications that require storage. resistance will require exposing the high reliability. assembly to the expected radiation field.

Molten Salt and Separations Technologies considered by Brookhaven National Laboratory in the past and extending Evaluation our analysis to lead-based fuels. Molten salt and bismuth-based fuels are especially well suited for the Francesco Venneri pyrochemical processes under investigation, and these solvents are Accelerator-driven transmutation of for these processes. Building on the reusable. Finally, we have modeled nuclear waste (ATW) offers great Integral Fast Reactor (IFR) fuel and analyzed the thermodynamics of promise as a method to essentially technology processes developed at these fuels in state-of-the-art three- eliminate plutonium, higher actinides, Argonne National Laboratory and the dimensional simulations. and environmentally hazardous fission plutonium pyrotechnology developed This project steadily continues to products in the spent fuel waste from at Los Alamos, we have refined the attract increasing interest from other nuclear reactors. The goal of this molten salt/liquid metal pyrochemical U.S. national laboratories, industry, project has been to evaluate the processes and identified the individual and universities. potential of existing technologies and process steps for particular applica- adapt them for use in ATW, focusing on tion for ATW. Moreover, we have heat generation, fluid motion, and established a universal process for Publications chemical separations for molten salt treating pyrochemical fuel that is Li, N., "Performance Estimates for and lead-based systems. applicable to many different types of Waste Treatment Pyroprocesses in We have identified significant new spent fuel elements and other nuclear ATW" (Second International methods for preparing spent fuel for waste products. Conference on Accelerator-Driven ATW treatment and post-transmutation In addition to molten salt fuels, we Transmutation Technologies and separations and have submitted an have worked on liquid metal fuels, Applications, Kalmar, Sweden, June application for an international patent revisiting the bismuth-based fuels 3-7,1996).

174 Los Alamos FY1996 LDRD Progress Report Neutron Metrology for Stockpile Publications Stewardship at LANSCE Morris, C, V. Armijo, L.G. Atencio, "An Integrating Image Detector for Energy Neutron Radiography" (Fifth Chris Morris International Conf. on Applications of Nuclear Techniques: "Neutrons in The goal of this project is to fast, two-dimensional, delay-line- Research and Industry," Crete, develop neutron-detector technology readout, position-sensitive detector for Greece, June 1996). to advance research in support of the thermal and cold neutrons. Because Laboratory's stockpile stewardship readout speed is important for mission. In particular, the emphasis is ultimate performance, we built a PC- on higher-resolution imaging detec- based system aimed at 20 Mbytes/s. tors for both high-energy and cold We have built two 3He-doped, wire- neutrons. An additional task is to chamber systems and have success- evaluate new technology for position- fully used them for detecting the first sensitive detection of thermal, cold, ultracold neutrons produced at Los and ultracold neutrons. Alamos. We also developed a new We have made progress in several concept of a velocity-matched areas. For example, we have devel- detector for epithermal neutrons and oped and implemented new technol- will test it next year. ogy for imaging with high-energy neutrons. We designed and are putting together a detector with an active area of 20 x 20 cm2 and a pixel size of 1.8 x 1.8 mm2 for neutron radiography. We have coupled converters to image plates and have begun investigating these for fast-neutron imaging. We have designed and are building a

~~Competency Development Projects—Engineering and Base Technologies 175~~

~~Plasmas, Fluids, and Particle Beams~~

High-Energy Test of Proton produced proton radiographs of a suitably dense, unclassified test Radiography Concepts object. The experiment tested capabilities in data collection, image Chris Morris reconstruction, and hydro-code simulation and validated models of Proton radiography offers the beam generation and available test- high-energy proton radiography. promise of outstanding performance recording technology for data We designed a lens using existing in terms of position-resolution and acquisition. Proton radiography offers quadrupole magnets, constructed it on sensitivity to density variations. potential advantages over current and the Al beam line of the AGS, and Proton radiography is also very well proposed x-ray radiography technolo- used it to image 10-GeV protons. The suited to provide a complete history gies and could be an alternative or results include (1) images made with of explosive-driven compressions of combined technology for the Ad- an integrating detector, (2) measure- heavy-metal systems. In addition, vanced Hydrotest Facility (AHF) ments of the background and mea- through the use of multiple beams and initiative. surements of the resolution functions, detector systems, we may be able to We completed a proof-of-principle and (3) forward-model fits to the reconstruct tomographic images of the experiment for proton radiography transmission data. In all cases the object under test. We can also using 3- to 9-GeV proton beams results agree with initial estimates and implement proton radiography using available at Brookhaven National provide strong support for the utility established accelerator technology for Laboratory's Alternating Gradient of proton radiography as a new Synchrotron (AGS). The experiment hydrotest diagnostic.

Comparison of Cyclotrons and Linacs for We have been looking at the fundamental limits that might restrict High-Intensity-Beam Applications the operation of cylcotrons. In particular, we have begun to formulate a halo-formation model analo- Tarlochan S. Bhatia gous to that used by Gluckstern for the treatment of halo in linacs but Two types of high-intensity sub- cyclotrons versus linacs. We find that with the addition of larger external GeV ion accelerators are in use as for applications requiring beam power nonlinear terms introduced by the drivers for neutron sources. The first in the range of 10-20 MW, a cyclo- edge focusing in the cyclotron sector of these is the linear accelerator, tron of high efficiency is probably magnets. The model formulation is which accelerates up to ~1 mA of cheaper than a similar linac of high very similar to that in Gluckstern's 800-MeV protons as operated at Los efficiency because of both the distri- linac model. The beam-dynamics Alamos. The second class of driver is buted nature of the power feeds in model of Ryne and Wangler should a cyclotron such as the one at the Paul linacs and the significantly lower allow us to simulate halo formation Scherer Institute in Switzerland, radio frequency at which a cyclotron for a high-intensity beam that where a beam of ~1 mA of 600-MeV operates. In addition, the pulse format compares favorably with the linac protons is available. The aim of this of the cyclotron (continuous wave) is model. project is to develop a better under- naturally better suited to target standing of the capabilities and requirements than a room-temperature Finally, we have started to set up limitations of circular machines in linac of high efficiency, which would detailed simulations for cyclic-ion comparison with linear accelerators. have to be pulsed to achieve high accelerators with a view toward estimating beam losses not only at We have conducted a preliminary beam loading. We plan a detailed cost extraction but also during acceleration. investigation of the cost benefits of comparison.

Competency Development Projects—Plasmas, Fluids, and Particle Beams 177 A I -kW-Power Demonstration from the Publications Goldstein, J.C., et al., "Theoretical Advanced Free-Electron Laser Study of the Design and Performance of a High-Gain, High-Extraction- Richard Sheffield Efficiency FEL" (submitted Nucl. Instrum. Methods Phys. Res.). Free-electron lasers (FELs) are not 1-kW optical beam power and that Nguyen, D.C., "Synchronously widely used because of two principal would require only minor modifica- Injected Amplifiers, a Novel drawbacks: (1) they tend to be large, tions to the Advanced FEL. complex, and thus costly, and (2) the The additional objectives of this Approach to High-Average Power average power they can deliver in the project then became to engineer and FELs" (submitted to Nucl. Instrum. optical beam is generally low com- procure an electron beam line com- Methods Phys. Res.). pared with that of other laser sources. patible with the proposed operation of Sheffield, R.L., et al., "Electron As a result, credible use of FELs for a 1-kW optical beam. An associated Beamline Design for LANL 1 kW high-power applications still requires major task was the physics design of FEL" (submitted to Nucl. Instrum. a demonstration that they can deliver the electron beam line from the end of Methods Phys. Res.). such power. In fact, the highest the wiggler to the electron beam average power achieved to date with dump. This task was made especially any FEL is only 10 W. difficult because the beam was This project was initiated to address expected to have 20 kW of average the issue of FEL size, which was power and a 25% energy spread. answered by building the Advanced We accomplished all project FEL, a table-top device that demon- goals—the high-power electron beam strated reliable operation at modest design was completed (see figure), but significant power levels (a few and the hardware necessary for high- watts). During its operation, we power operation was designed and developed a new idea in FEL design procured. The next step is to test the that, based on computer simulations, Advanced FEL at the full 1-kW showed would generate as much as optical beam power.

Engineering layout of the high-power FEL beam line at the Advanced Free-Electron Laser facility. The 1.3-GHz linear accelerator is on the left. The optical table is actually a 6-ft-high x 10-ft-long "wall" on which beam line components, such as the 6-ft-long wiggler, are mounted. The beam line is now fully installed and operational.

178 Los Alamos FY1996 LDRD Progress Report Advanced Techniques for Producing, We have written a computer code to calculate the UCN production rate for Polarizing, and Storing Ultracold Neutrons a solid deuterium superthermal source and compared the results with data taken at the Petersburg Nuclear Susan Seestrom Physics Institute reactor in Gathchina, Russia. We identified uncertainties in Project objectives are modeling We have designed and are assem- the cross-section databases available ultracold neutron (UCN) production bling a UCN transport system and an as well as the need for better normal- in cryogenic materials and develop- experimental storage bottle for UCNs. ization of benchmark data. ment of techniques for storing and This bottle incorporates a novel polarizing ultra-cold neutrons. This shutter design that will allow us to activity is centered around developing study the spectrum of UCNs produced Publications techniques and experimental appara- by the source at the Manuel Lujan Jr. Bowles, T.J., R. Hill, et al., "Ultra tus to make use of an UCN source at Neutron Scattering Center. The bottle Cold Neutrons at a Spallation Source" Los Alamos as well as to study the will allow us to study the UCN (Int. Symp. on Neutrons Optics and design and performance of a second- storage time as a function of different Related Research, Kumatori, Japan, generation UCN source. Such a neutron velocity. We have identified March 1996). source is the planned long-pulse and obtained a superconducting spallation source that would provide magnet suitable for initial attempts to Seestrom, S.J., TJ. Bowles, et al., UCNs of parameters unmatched polarize UCNs. "Plans for an Ultra Cold Neutron anywhere else. The techniques being We have designed and are assem- Source at Los Alamos" (Japan Hadron developed will open up a range of bling two separate experimental UCN Project Workshop, Tskuba, Japan, fundamental physics studies as well detectors; one is a helium-3 gas March 1996). as novel experiments in materials scintillator and the other is a helium-3 Seestrom, S.J., T.J. Bowles, R. Hill, science. Fundamental physics proportional counter. We have also et al., "Development of an Ultra Cold experiments include improved designed and acquired the compo- neutron Source at MLNSC" (Int. measurement of the neutron lifetime nents for a data acquisition system Conf. on Applications of Nuclear and decay parameters; such measure- that will be used to take and analyze Techniques, Crete, Greece, ments provide a sensitive and unique data from these detectors to determine June 1996). test of the Standard Model for the UCN production rate and the elementary particle interactions. bottle-storage lifetime.

Development of Ion-Beam Techniques for We also evaluated the detection methods required to distinguish the Study of Special-Nuclear-Materials- between the ions used to probe actinides from the alpha particles Related Problems produced by natural decay. We have measured the limitations of solid-state Carl Maggiore detectors for analyzing alpha-active materials and have identified alternative The objective of this project is to actinides in engineered systems and resonance and nuclear reaction develop ion-beam techniques for under conditions of temperature, methods with time-of-flight detection characterizing actinides and their pressure, and residual gas composition as preferable when extreme sensitivity effects on other materials. The project that correspond to those in the field. We is needed for such problems as is designed to enhance our ability have measured the radiolytic break- submonolayer surface contamination. measure the oxidation, corrosion, down products of the polymers by When masking and the use of absorber diffusion, and stability of actinides mounting a quadrupole mass spectrom- foils cannot be used to minimize the and the materials with which they eter to the scattering chamber at the inherent alpha activity from actinide may come in contact. IBML. We have also determined the materials, we have identified particle Using ion beams at the Los Alamos depth distribution of hydrogen and identification methods for near-surface Ion Beam Materials Laboratory helium isotopes in actinides and in analysis. We have also measured the (IBML) to simulate alpha particles, surrogates such as the gold/silver alloys sensitivity, spatial and depth resolution, we have accelerated the aging of used to simulate actinides. and precision of elastic recoil detection polymeric materials in contact with and nuclear reaction analysis in studying actinides.

Competency Development Projects—Plasmas, Fluids, and Particle Beams 179 Generation and Compression of a Target Kirkpatrick, R., and D. Smifherman, "Energetic Alpha Transport in a Plasma for Magnetized Target Fusion Magnetized Fusion Target" (to be published in Fusion Technol). Ronald Kirkpatrick Kirkpatrick, R., P. Sheehey, et al., "Proposed Generation and Com- The goal of this project is to The second graph shows the three- pression of a Target Plasma for MTF" develop a computational capability dimensional trajectory of a single DT (to be published in Proc. Tenth IEEE for the design and interpretation of an fusion alpha particle through a Int. Pulsed Power Conf.). experiment on magnetized target magnetized target plasma. We are fusion (MTF). MTF relies on developing a charged particle trans- Lindemuth, I., R. Reinovsky, V.K. magnetoinsulation to allow slow, port method intended to efficiently Chernychev, et al., "Target Plasma near-adiabatic compression of a hot and accurately treat energy deposition Formation for Magnetic target plasma to fusion conditions. by the DT alphas in an MTF plasma Compression/Magnetized Target This year we employed our during fusion ignition and burn. Fusion," Phys. Rev. Lett. 75, computational tools to assess the The third graph represents the 1953(1995). impact of experimental compromises temperature history inferred by analysis Sheehey, P., R. Faehl, et al., such as a necessary design change in of filtered silicon diode data from the "Computational Modeling of the region near one electrode. We MAGO II experiment conducted at Los Magnetically Driven Liner-on-Plasma developed a capability to simulate the Alamos in October 1994. It suggests Fusion Experiments" (to be published emission from a hot, magnetized that the magnetized plasma reached in the Proc. 7th Int. Conf. Megagauss plasma in order to be prepared to over 300 eV and remained above Magn. Fields). interpret pending experimental data in 100 eV from 2.5 to 7.5 us, after which terms of density and temperature, and the diagnostic failed. Sheehey P., J. Guzik, et al., we tested its effectiveness on the data "Calculations of Proposed Mag- from related MAGO experiments. For netized Target Fusion Experiments" MTF we need to achieve temperatures Publications (to be published in Proc. I Oth Bienn. Nucl. Explos. Des. Phys. Conf. 1995). above 50 eV and magnetic fields Idzorek, G., and R. Kirkpatrick, above 5 T. In addition, it is necessary "Analysis of Filtered Silicon Diode Sheehey, P., J. Guzik, R. Kirkpatrick, to keep impurities at a sufficiently low Data from the MAGO 2 and MAGO 3 et al., "Computational and level to avoid significant radiation Experiments" (to be published in the Experimental Investigation of losses during the compression phase. Proc. 7th Int. Conf. Megagauss Field Magnetized Target Fusion" (to be We made significant progress on a Generation, MegaGauss VII). published in Fusion Technol.). new transport method for the computation of alpha-particle energy deposition in the magnetized deuterium-tritium (DT) fusion target Temperature and Density Profiles plasma. This method will allow 100000 efficient computation for the dynamic problems that we must handle for MTF target design. We established informal interactions with the French CEA laboratory, Limeil; Advanced Laser and Fusion Technology, a Canadian company; and General Atomics in La Jolla, California. We are also developing the potential applications of this research to science-based stockpile stewardship. The first accompanying graph shows a computed Kadomtsev stable profile for a plasma produced by a 0.02 discharge through a cryogenic deuterium fiber in a 2-cm-high by 2- cm-radius cylindrical container. The Computed Kadomtsev stable profile for a plasma produced by a discharge calculations indicate that a plasma through a cryogenic deuterium fiber in a 2-cm high by 2-cm radius cylindrical suitable for MTF can be produced. container.

~~180 Los Alamos FY1996 LDRD Progress Report The trajectory of a single DTfusion alpha particle through a magnetized target plasma.~~

~~Effective Plasma Temperature~~

~~1.E+3 -~~

~~I1 \ . 1.E+2 - V 1 t 1.E+1 - 1 1~~

~~I 3 » noise level * % 1 1.E+0 - I \~~

~~» » 1.E-1 - 0.0 2.0 4.0 6.0 8.0 10.0 time (us)~~

~~The temperature history inferred by analysis of filtered silicon diode data from the MAGO II experiment conducted at Los Alamos in October 1994.~~

Competency Development Projects—Plasmas, Fluids, and Particle Beams 181 Advanced Modeling of High-Intensity A third area in which we have made significant progress is in Accelerators effectively dealing with very large amounts of data. For example, the memory required to store 100 million Robert Ryne particles in a 3-D simulation is nearly 10 Gbytes. To handle this volume, we The goal of this project is to and radial motion in ion linear perform "data pruning" inside a code develop an advanced modeling accelerators). A major accomplish- before the data is written to disk. In capability for the design of future ment in our project has been to some cases this process has enabled high-intensity accelerators that can be develop a version of PARMILA that us to visualize the beam halo while used for waste transmutation, pluto- runs on parallel computers, currently concurrently reducing the size of the nium conversion, spallation-neutron the most powerful computers avail- data set by more than three orders of production, tritium production, etc. able. The parallel version of magnitude. Our goal is to develop a suite of codes PARMILA has significantly improved that can model the beam through performance over the original (scalar) kilometers of complex accelerating version and has been run with up to structures, including radio-frequency 30 million particles. In addition, it is quadrupoles, drift-tube linacs, more accurate than the scalar version coupled-cavity drift-tube linacs, because of the development of a coupled-cavity linacs, and high- three-dimensional (3-D), as opposed energy, beam-transport sections. to two-dimensional, parallel space- In prior years' work, we developed charge routine. a family of codes to perform simula- In another area, we applied split- tions of simple test systems. Now our operator, symplectic techniques to emphasis has been placed on model- efficiently compute the dynamics of ing realistic accelerator systems. intense beams in radio-frequency Realistic linacs are usually designed accelerating gaps, including compli- and optimized using complex simula- cated z-dependent fields in the gaps. tion codes. The most widely used linac simulation code in the United States is called PARMILA (for phase

~~182 Los Alamos FY1996 LDRD Progress Report Chemistry~~

Binding Carbon Dioxide in Mineral Form: Publications A Critical Step toward a Zero-Emission Butt, D.P., K.S. Lackner, C.H. Wendt, et al., "Kinetics of Thermal Dehy- Coal Power Plant droxylation & Carbonation of Magnesium Hydroxide," /. Am. Ceram. Soc. 19, 1892-1898 (1996). Klaus Lackner Lackner, K.S., D.P. Butt, and C.H. Fossil fuels are a large and estab- have tested a wide variety of common Wendt, "Progress on Binding CO2 in lished energy resource, and coal minerals for the direct gas-solid Mineral Substrates" (Third Inter- reserves will last for centuries. How- reaction with carbon dioxide. We national Conference on Carbon ever, for fossil fuels to remain an found that either pretreatment or some Dioxide Removal, Cambridge, Mass., important energy source, the environ- sort of elevated pressures are neces- September 9-11, 1996). mental impact of their carbon dioxide sary to obtain sufficient reaction rates. Lackner, K.S., D.P. Butt, et al., emissions must be eliminated. To that By developing this technology, we "Carbon Dioxide Disposal in Solid end, we are working to develop will provide the fossil power industry Form," Proc. of 21st Int. Tech. Conf. disposal processes that permanently with the means to remain competitive, on Coal Utilization & Fuel Sys. 21, bind carbon dioxide into environmen- even if greenhouse gases need to be 133-134 (1996). tally safe, solid waste products, such eliminated. Fossil fuels could satisfy a as carbonate rock. The reason these growing world energy demand for Lackner, K.S., C.H. Wendt, D.P. Butt, processes are potentially economi- many more centuries. et al. "Carbon Dioxide Disposal in cally viable is that the underlying Carbonate Minerals," Energy, Int. J. chemical reactions are energetically 20, 1153-1170(1995). and thermodynamically favored. Last year we published a paper that outlined the basic concepts and Foreign Nuclear Test Radiochemical sketched out several approaches based on different readily available calcium- Diagnostics or magnesium-bearing minerals and different chemical reaction paths. We Michael Macinnes are continuing to refine our processing schemes. We are focusing some of For this project, one of our goals is data through manipulating actual our attention on the basic chemistry to develop a capability to interpret radiochemical data. Last year we in an effort to speed up the chemical radiochemical data from foreign focused our efforts on a survey of reaction, thereby making it more cost- nuclear tests. This ability would be early tests of nuclear weapons states, effective. an obvious benefit in non- and concentrating on the technology used This year we developed several counterproliferation and would by most states in their initial nuclear viable processes, selected the most support the draft language of the devices. We revived two computer promising candidate processing Comprehensive Test Ban Treaty. We codes that evaluate nuclear test debris scheme, and experimentally verified are also working to develop methods on-line, and we trained three analysts all of the steps in the laboratory. For to enhance our ability to extract to use these and other evaluation our candidate process we have information from the early nuclear tools. This year we used these improved the reaction rate of the weapons tests of other countries. We analysts and tools to evaluate alterna- central solid-gas reaction, the carbon- are evaluating alternative weapons tive technologies that weapons states ation of magnesium hydroxide. We technologies and improvements to might be employing as they expand can now achieve rates of carbonation interpretation techniques because their technology base and as they ten times faster than our first experi- these capabilities will be useful in incorporate elements of thermo- ment appeared to indicate. With assessing potential proliferant nuclear technology. To date, we have regard to alternative processes, we designs. reevaluated 10 nuclear events, We can best gain expertise in the including those that we selected as evaluation of atmospheric nuclear test benchmarks.

Competency Development Projects—Chemistry 183 The Characterization of Atmospheric as a function of temperature, pressure, and surface coverage. Aerosols: Applications to Heterogeneous Publications Gas-Particle Reactions Henson, B.F., K.R. Wilson, and J.M. Robinson, "Quantitative Measure- Jeanne M. Robinson, Los Alamos National Laboratory ments of Multilayer Physical Kimberly A. Prather, University of California, Riverside Adsorption on Ice from Nonlinear Light Scattering" (1996 International We have continued the development different environments in which Symposium on Physics and of aerosol time-of-flight mass different chemical processes are Chemistry of Ice, Hanover, N.H., spectrometry for the analysis of the expected. We will also use these August 1996). size and chemical composition of instruments as on-line probes for Noble, C.A., and K.A. Prather, "Real- individual aerosol particles in real monitoring controlled, heterogeneous, Time Measurement of Correlated Size time. We characterized the particles chemistry processes important in the and Composition Profiles of produced directly from various stratosphere and troposphere at the Individual Atmospheric Aerosols," combustion sources such as wood single-particle level. Env. Sci. Tech. 30, 2667 (1996). smoke and diesel and gasoline In addition, we have investigated exhaust. The goal of these source- the thermodynamics of model polar Wilson, K.R., B.F. Henson, and J.M. characterization studies is to establish stratospheric aerosols. Using second Robinson, "Physical Adsorption unique size and composition profiles harmonic generation, we monitored Measurements of HCl on Water Ice," for particles from various sources, the adsorption and phase behavior of EOS Trans., Am. Geophys. Union 76 which will allow for more-accurate HCl on water ice films. We identified (1995). source allocation. Information at the quasi-liquid/solid transition Wilson, K.R., B.F. Henson, et al., this level of detail is necessary for postulated by theorists. We are "Equilibrium Thermodynamics of establishing more-directed controls of presently using mass spectrometry to HCl Adsorption on Water Ice" (211th particulate emissions. measure vapor pressures over the American Chemical Society National hydrate ice films in conjunction with We also built two field-portable Meeting, New Orleans, La., March optical measurements, as shown in the instruments for establishing regional 1996). variations in aerosol particles, which figure. Our goal is to map out the will add to our understanding of phase diagram of the HC1/H2O system atmospheric processes by probing

~~Rate= 4.22 x 10"7 moles/sec~~

~~Rate= 4.76 x 10~8 moles/sec~~

~~2 3 Coverage (monolayers)~~

Adsorption spectra for HCl on water ice at 180 K. The HCl vapor was introduced at two different rates. Our preliminary data analysis using classical physical adsorption suggests that different hydrates are formed in these experiments.

184 Los Alamos FY1996 LDRD Progress Report Kinetic Studies of Competitive Adsorption Publications Processes Related to Automobile Catalytic Liu, J., M. Xu, and F. Zaera, "Determination of the Rate Limiting Converters Step in the Oxidation of CO on Pt(III) Surfaces," Catal. Lett. 37,9-13 (1996). Mark Paffett, Los Alamos National Laboratory Liu, J., M. Xu, et al., "Sticking Francisco Zaera, Unversity of California, Riverside Probabilities for CO Adsorption of This project focuses on the study The behavior observed in that latter Pt(III) Surfaces Revisited," J. Phys. of the reaction kinetics in catalytic regime suggests that the reactivity of Chem. 99, 6167-6175 (1995). conversion processes for exhaust the adsorbed oxygen depends on the Xu, M., J. Liu, and F. Zaera, "Kinetic gases by using the method devised by local coverage of neighboring sites. Evidence for the Dependence of King and Wells. We have investigated Beams with CO + O2 mixtures were Surface Reaction Rates on the both the oxidation of CO and the also used to better mimic realistic Distribution of Reactants on the reaction between NO and propene on catalytic conditions. We found that at Surface," /. Chem. Phys. 104, 8825- Pt(ffl) surfaces. high temperatures, the rate of CO 8828 (1996). We found that in the first case, the oxidation is equally determined by the presence of preadsorbed atomic CO incoming flux as long as the Zaera, F., J. Liu, and M. Zu, "Isothermal Study of the Kinetics of oxygen does not significantly affect CO:O2 ratio is kept low. For high Carbon Monoxide Oxidation on the initial sticking coefficient of CO, CO:O2 ratios, however, the CO but preferentially blocks the bridge steady-state coverage increases, Pt(III): Rate Dependence on Surface sites. No reaction takes place below poisoning the adsorption of oxygen Coverage" (submitted to J. Chem. Phys.). 300 K, and above 400 K, CO2 and slowing down the overall CO2 production is controlled by the production. impinging frequency of the incoming Finally, preliminary data has now CO. However, between 300 and 400 been acquired for the second system K, the rate of surface recombination (NO and propene) and is being of CO with oxygen competes with analyzed. that of CO adsorption, and not all of the surface oxygen is reactive.

Investigations of Biomimetic attributed to an excited-state conformational change that enhances the Light-Energy-Harvesting Pigments conjugation between the p-electron systems of the porphyrin ring and Robert Donohoe bridging diarylethyne group. The intensity of the aryl and ethyne-bridge The design of materials for con- absorption spectroscopies to charac- vibrations monotonically decreases as trolled photophysical response, such terize the ground-state structures of the degree of steric constraint as energy conversion or destruction of the neutral and oxidized porphyrin increase. This trend parallels that pollutants, can be approached from a arrays. The electrochemical and observed for the rates of energy molecular level. The goal of this spectral properties of the arrays transfer in these arrays and indicates project is construction of extended indicate that the electronic communi- that the excited-state electronic arrays of molecular pigments with cation between the macrocycles is communication can be tuned via predictable and controllable light- relatively weak in the ground and structural modification of the initiated responses. excited electronic states. This commu- diarylethyne linker. We have approached the investiga- nication is through-bond, rather than We are about to begin the investigation of the excited-state dynamics in through-space, and is mediated by the tion of new arrays that incorporate porphyrin oligomeric arrays by diarylethyne linker. redox switches to mediate energy acquiring transient absorption and In the case of the torsionally transfer. These switches may include time-resolved fluorescence measure- unconstrained dimers, we observed pigments capable of selective oxida- ments. The present effort serves as a extremely large resonance Raman tion or, possibly, chromophores that complement to these excited-state intensity enhancements for aryl ring can be photo-oxidized, thereby methods by using resonance Raman, and ethyne-bridge stretching modes. providing a light switch of the electron paramagnetic resonance, and These intensity enhancements are excited-state energy transfer.

~~Competency Development Projects—Chemistry 185~~

~~Mathmatics and Computational Sciences~~

Nuclear Futures Analysis and Arthur, E.D., and R.L. Wagner, "The Los Alamos National Laboratory Scenario Building Nuclear Vision Project" (Global Foundation Energy Conf.; Technology for the Global Economic and Edward D. Arthur Environmental Survival and Prosperity, Miami Beach, Ha., Nov. 8-10,1996). In this project we have begun with the civilian nuclear-fuel cycle and examination of future nuclear-energy began testing plutonium management Krakowski, R.A., "Global Nuclear scenarios and assessed the size of the strategies. (3) We modeled three Energy/Materials Modeling in Support resulting inventories of plutonium and technologies for management of global of Los Alamos Nuclear Vision Project" other nuclear materials. We also plutonium inventories—mixed-oxide- (Global Foundation Energy Conf. modeled various technological fueled light-water reactors, liquid-metal Technology for the Global Economic approaches and their impacts on the reactors, and accelerator systems—via and Environmental Survival and management of such inventories. The the code system of item 1 and assessed Prosperity, Miami Beach, Fla., Nov. 8- effort emphasizes establishing quantita- the impacts in terms of residual- 10,1996). tive metrics to assess proliferation risk plutonium inventories, time period to Krakowski, R.A., "Long-Term from projected material accumulations achieve results, and the system Tradeoffs between Nuclear-Fossil-Fuel during civilian nuclear-power use. deployments required. Principal focuses of these analyses are Burning" (Global Foundation Energy identification and testing of technolo- Conf.; Technology for the Global gies and materials management Publications Economic, Environmental and Survival and Prosperity, Miami Beach, Ha., strategies that contribute positively to Arthur, E.D., "Impact of ADTT Nov. 8-10,1996). future security, nonproliferation, and Concepts on the Management of robust-energy scenarios. Global Plutonium Inventories" (Second We accomplished the following Int. Conf. on Accelerator-Driven objectives in FY 1996. (1) A robust Transmutation Technologies and nuclear-fuel-cycle model was added Applications, Kalmar, Sweden, June 3- to a major global energy, economics, 7,1996). energy-projection model (i.e., the Pacific Northwest National Laborato- ries' Edmunds, Reilley, and Barnes model) and the results tested. These results provide unique capabilities for assessing and testing nuclear materials-management strategies for nine major world regions. The accompanying figure provides an example of Results for projected projected growth in global plutonium plutonium inven- inventories (arising from spent nuclear tories in spent reactor fuel) along with regional reactor fuel arising contributions to the total. We also from use of the developed a more detailed nuclear-fuel- energy-projection cycle model to be used separately that and nuclear-fuel- provides a platform for testing the cycle model energy model results and for technol- discussed in the text. ogy impact assessment (see item 3). (2) We developed a model to determine proliferation-risk metrics associated 2070

Competency Development Projects—Mathematics and Computational Sciences 187 New Numerical Models for reduced cost of computer time and memory. We believe this is the first Global Ocean Modeling application of SSA and POD, which were designed for experimental data Len Margolin analysis, to compare the accuracy of different numerical realizations of We have developed new numerical method of averaging for multiple-time- stochastic flows. methods that improve the accuracy scale problems; and we implemented We have presented our results at and efficiency of models of geophysi- a semi-Lagrangian formulation of the professional meetings in the fields of cal flows, especially models of the dispersive shallow-water equations. applied mathematics, computational global circulations of the ocean over We constructed numerical models for physics, and meteorology and have climate time scales. We adapted Burgers' equations in one and two published these results in appropriate analytical techniques from nonlinear dimensions and for a 1.5-layer model peer-reviewed journals. dynamics and nonequilibrium of shallow and dispersive shallow water (to simulate ocean basin statistical mechanics to develop these Publications methods. We developed new algo- circulations). rithms based on these methods in a After formulating and implement- Nadiga, B.T., L.G. Margolin, and P.K. format compatible with the current ing our new algorithms, we tested Smolarkiewicz, "Different Approxi- generation of ocean models, and we them on problems representative of mations of Shallow Fluid Flow over implemented these algorithms on a large-scale ocean dynamics. We an Obstacle," Phys. Fluids 8, 2066 variety of platforms, including applied singular spectrum analysis (1996). workstations and the massively (SSA) to compare the time spectra of Nadiga, B.T., M.W. Hecht, et al., "On parallel Connection Machine, CM-5. the numerical solutions of the two Simulating Flows with Multiple Time 1.5-layer models. Similarly, we used Specifically, we constructed an Scales" (submitted to Theor. and the principal orthogonal decomposi- approximate inertial manifold Comput. Fluid Dyn.). methodology for finite-difference and tion (POD) to compare the spatial finite-volume approximations, and accuracy of these different approxi- Poje, A.C., D.A. Jones, and L.G. generalized the underlying theory to mations. We demonstrated that the Margolin, "Enslaved Finite Difference include both dissipative and quasi- new models would reproduce the Approximations for Quasi- geostrophic flows; we developed a accuracy (in space and time) of more Geostrophic Flow," Physica D 98, 559 finely resolved simulations, but at a (1996).

Lie Group Applications to the which describes the spherical blast wave produced by a point explosion, Solution of Differential Equations for the case in which the ambient gas has an initial density gradient in a given direction. This provides a two- Charles W. Cranfill dimensional generalization of the usual one-dimensional solution. This project applies Lie Group This year we developed a general techniques to the solution of partial procedure for finding analytic differential equations (PDEs) describ- solutions to the hydrodynamic Publications ing physical systems important to Los equations for fluids having more Alamos National Laboratory's realistic equations of state than that of Axford, R.A., "Group Theory of scientific mission. There are two main an ideal gas. The procedure was used Invariant Flux and Slope Limiters" objectives: (1) to construct analytic or to construct analytic solutions to the (Ninth Nuclear Explosives Code quasi-analytic solutions for use as one-dimensional Noh test problem, Developers Conf., San Diego, Calif., benchmark test problems and (2) to which describes an imploding fluid Oct. 22-25, 1996). develop improved numerical solution whose stagnation against a symmetry Axford, R.A., "Lie Group Symmetry algorithms that possess the same surface produces an outward-moving Properties of the Besnard-Harlow- symmetries (e.g., rotational, transla- shock, for both the stiff-gas and Mie- Rauenzahn-Zemach Spectral tional, and scaling invariance) as the Gruneisen equations of state. Turbulence Transport Model" PDEs. We also constructed an analytic (JOWOG-32M Mtg. on Mix solution to the Sedov test problem, Research, Los Alamos, N.Mex., July 22-26, 1996).

188 Los Alamos FY1996 LDRD Progress Report Lithospheric Processes Sims, K.W., W, DePaolo, DJ. Murrell, et al., "Mechanisms of Magma Generation beneath Hawaii W. Scott Baldridge and Mid-Ocean Ridges: U-Th and Sm-Nd Isotopic Evidence," Science Our objective was to improve our depths. We determined the extent and 267,508-512(1995). understanding of the origin and evo- style of fluid infiltration and trace- Slack, P.D., P.M. Davis, W.S. lution of the lithosphere by studying element distribution in natural Baldridge, et al., "The Upper-Mantle selected processes such as deformation magmatic systems, and we investi- Structure of the Central Rio-Grande and magmatic intrusion during crustal gated neon-21 as a tool for dating Rift Region from Teleseismic P-Wave extension, formation and extraction of surficial materials. and S-Wave Travel-Time Delays and mantle melts, fluid transport of heat Attenuation," /. Geophys. Res., Solid and mass, and surface processes that Publications Earth 101,16003-16023 (1996). respond to deep-seated events. Addi- tional objectives were to promote and Ferguson, J.F., W.S. Baldridge, L. Wendlandt, E., D.J. DePaolo, and develop innovative techniques and Braile, et al., "Structure of the W.S. Baldridge, "Thermal History of support relevant educational endeavors. Espanola Basin, Rio Grande Rift, Colorado Plateau Lower Crust from Our seismic studies suggest three New Mexico, from SAGE Seismic Sm-Nd Mineral Geochronology of central points: (1) that underplating of and Gravity Data," New Mex. Geol. Xenoliths," Geol. Soc. Am. Bull. 108, crust by mantle melts is an important Soc. Guidebook 46, 105-110 (1995). 757-767 (1996). crustal-growth mechanism, (2) that Jiracek, G.R., C.L. Kinn, C.L. Scott, White, T.D., G. Suwa, and B. Asfaw, low-angle faults can be seismogenic, et al., "Tracing Crustal Isotherms "Australopithecus Ramidus, a New and (3) that shear deformation creates under the Western Margin of the Species of Early Hominid from mantle anisotropy near plate bound- Jemez Mountains Using SAGE and Aramis, Ethiopia," Nature 375, 88 aries. Results of geochemical work Industry Magnetotelluric Data," New (1995). determined that magmas from oceanic Mex. Geol. Soc. Guidebook 47', 129- intraplate islands derive from a WoldeGabriel, G., et al., in "Scientific 133 (1996). uniform depth in the upper mantle, Correspondence," reply to "Age of whereas melts erupted at mid-ocean Olsen, K.H., "Continental Rifts: Early Hominids," Nature 376, 559 ridges are mixed from a range of Evolution, Structure, and Tectonics," (1995). in Developments in Geotectonics (Elsevier, Amsterdam, 1995), vol. 25, pp. 453^60.

Geometrically Compatible 3-D Monte cost of the code by modeling neutron- based oil-well logging tools; and Carlo and Discrete-Ordinates Methods generated adjoint solutions used in the testing of a new Monte Carlo variance reduction technique called the local Jim Morel importance function transform. The The first objective of this project provides us with a unique capability latter technique was developed by our was to develop a discrete-ordinates for efficiently and accurately perform- collaborators at the University of Michigan. (Sn) radiation transport code for ing calculations in complex 3-D calculating three-dimensional (3-D), geometries. In addition, this Sn code unstructured, tetrahedral meshes. The can generate adjoint solutions which second objective was to develop can be used by the MCNP code to variance reduction techniques for the dramatically reduce the statistical general-geometry Monte Carlo variance obtained in difficult Neutron and Photon (MCNP) calculations. transport code that would utilize In the past year, we investigated adjoint solutions from the unstruc- new iterative acceleration techniques tured-mesh Sn code. Our Sn code was for our Sn code; investigated auto- the first 3-D unstructured-mesh Sn matic mesh refinement techniques for code ever developed. As such, it our Sn code; tested the accuracy and

Competency Development Projects—Mathematics and Computational Sciences 189 Adaptive Monte Carlo Methods for Publications Radiation Transport Booth, T.E., "Adaptive Monte Carlo Attempts on a Continuous Transport Problem" (The Adaptive Monte Carlo Thomas E. Booth Workshop, August 14-16, 1996, Los Alamos, N.Mex.). For discrete-transport problems, known, the local characteristics of the Booth, T.E., "Exponential Conver- exponential convergence can be solution are known, and the global gence on a Continuous Monte Carlo obtained either by learning the zero solution must be locally consistent. Transport Problem" (submitted to variance biasing (adaptive Monte The reduced-source method Nucl. Sci. Engin.). Carlo) or by repeatedly solving for the produced exponential convergence for difference between the true solution a unidirectional problem with pure Kong, R., and G. McKinney, "Error and the current estimate of the solution absorption, as shown in the second Reduction Using Adaptive Monte (reduced-source Monte Carlo). This figure. Expressing the reduced source Carlo: The Reduced Source Method" project seeks to generalize these known as an expansion of continuous-basis (The Adaptive Monte Carlo exponential-convergence methods from functions seems to offer the best hope Workshop, August 14-16, 1996, Los discrete-transport problems to continu- for extending the exponential conver- Alamos, N.Mex.). ous-transport problems. The ultimate gence to multidimensional problems Lichtenstein, H., "Investigation of goal is to apply these methods to with scattering. problems that currently cannot be False Learning in Adaptive Monte solved. Carlo Transport" (The Adaptive Monte Carlo Workshop, August 14— The project sought to produce the 16,1996, Los Alamos, N.Mex.). first exponential-convergence results for continuous Monte Carlo problems, either by adaptive or reduced-source Monte Carlo. Additionally, we sought to understand and protect against false Exponential Convergence by Taylor Expansion convergence. We successfully showed 1mfp (expansion order 50) adaptive Monte Carlo to produce exponential convergence (with erderl .f computer time) on a bidirectional, sigt=1 sigs-5 f=.5 b=.5 thick=1 delta=.1 continuous-transport problem with 2 surfaces arbitrary scattering, as shown in the 1000 particles per iteration first figure. We extended the results to K-directional problems and tested for K=10. The solution method used the differential transport equation to constrain the possible solutions to a 2K-parameter family. Statisticians have proved exponential convergence for such families on discrete problems. The false convergence problem was ameliorated by enforcing local constraints on the biasing. That is, 4 5 6 10 although the global solution is not iteration number

~~Plot of the relative error of the penetration probability through a slab with bidirectional scattering as a function of iteration number (1000 particles per iteration).~~

~~190 Los Alamos FY1996 LDRD Progress Report 1.00E+QQ~~

~~1.00E-Q1~~

~~l.OQE-02 ^ 1~~

~~1.00E-03~~

i K=50C zones 1.00E-04 W-1O ,GO0mer. k^vS Plot of the relative error 1.DOE-05 versus iteration number for 1.00E-06 penetration through a 5-mean-free-path, purely I.OOE-07 i K=| 000 zones | absorbing slab, using the |yNiQQ,OQP/iter.[ reduced-source method. I.OQE-08 : Different values of the 1.00E-09 particles per iteration (W) ; and number of slab zones LOOE-tO

~~(K) are shown. 1 2 3 4 5 6 7 B 9 10 11 12 13 14 15 16 Namber of Iterations~~

High-Performance Computing of Response" (to be published in Phys. Rev. B). Electron Microstructures Birnir, B., V. Gudmundsson, and K. Johnson, "Floquet States and Electron Alan Bishop Interactions for Laser-Driven Quantum Wells" (submitted to Phys. The purpose of this project, a bifurcation sequence in a quantum Lett. A). collaboration with scientists at the well. Our simulation agrees with Galdrikian, B., and B. Birnir, "Period University of California at Santa preliminary experimental measure- Doubling and Strange Attractors in Barbara (UCSB), is to model novel ments and points the way to designing Quantum Wells," Phys. Rev. Lett. 76, quantum properties of optically optical devices with technologically 3308 (1996). driven, electronic nanostructures important frequency-mixing and (quantum wells). These structures are subharmonic responses. Finally, we Kenkre, V.M., S. Raghavan, et al., fabricated and measured at UCSB developed a theory of nonequilibrium "Memory Function Approach to using dedicated molecular-beam transport in a double quantum-dot Interacting Quasiparticle Boson epitaxy and free-electron laser system. Systems," Phys. Rev. B 53, 5407 facilities. We have developed a new Our project draws on the (1996). time-dependent density-functional Laboratory's core competency in Wang, L., W.Z. Wang, and A.R. model that is being implemented in theory, modeling, and high-perfor- large-scale parallel computations and Bishop, "Theory of Quantized mance computing. It is relevant to Dynamic Capacitance Charging that can systematically handle all the programs in nanotechnology, semi- relevant physical interactions in Spectroscopy in Nanostructures," conductor modeling, information and Phys. Rev. Lett. 74, 4710 (1995). nonequilibrium properties. This sensor technology, and multiscale model is helping us understand the nonlinear and nonequilibrium Zang, J., A.R. Bishop, et al., nanostructures' response to optical processes. "Nonequilibrium Transport and excitation. Population Inversion in Double We extended our model with a Quantum Dot Systems" (to be density matrix formalism that Publications published in Int. J. Mod. Phys.). incorporates dephasing and energy Bewley, W.W., C.L. Felix, J.J. relaxation processes. We also general- Plombon, et al., "Far-Infrared Second- ized the formalism and numerical Harmonic Generation in GaAs/ implementation to include multiple AlGaAs Heterostructures: quantum-level processes. We then Perturbative and Nonperturbative used this robust model to simulate a

Competency Development Projects—Mathematics and Computational Sciences 191 Modeling Complex Phenomena: • dislocation generation from crack fronts in ductile materials; Multiple Length and Time Scales in • the smoothing of rough surfaces in solid-on-solid models; Extended Dynamical Systems • ordering and melting of moving flux lattices in three-dimensional Peter Lomdahl Josephson junction arrays with disorder and external magnetic This research combines competen- topical problems in materials science field and current; cies in high-performance computing, and condensed matter. The meso- • filamentary and plastic vortex flow theory of complex systems, and scopic scale provides a fundamental in disordered thin-film supercon- materials science in a new way that bridge between microscopic and ductors; has great potential for applications to macroscopic modeling approaches • magnetic vortices in Heisenberg multiple length- and time-scale and, ultimately, is the link between spin layers; and phenomena in condensed matter and (1) synthesis and processing and • hierarchical twinning and tweed materials science. We are developing (2) functionality. texture in elastic models. (1) analytical techniques in non- Using nonlinear techniques and equilibrium and nonlinear science and large-scale simulations, we have Publications (2) numerical algorithm and simula- systematically studied mesoscale tion techniques using massively pattern formation and dynamics in Cirillo, M., A.R. Bishop, et al., "High- parallel computation and advanced nonlinear, nonequilibrium systems Frequency Pumping of Josephson visualization. We then apply the exhibiting topological excitations Soliton Oscillators," Phys. Rev. B 52, developed techniques to the study of (i.e., dislocations, vortices, vortex 506 (1995). mesoscopic textures and their lines, and domain walls). Specifically, Dominguez, D., N.G. Jensen, and associated dynamics for a number of we have focused our research efforts A.R. Bishop, "Resistive Hysteresis on the following: and Nonlinear J-V Characteristics," Phys. Rev. Lett. 75,4670 (1995). Dominguez, D., N.G. Jensen, et al., Continuing Benchmarking of "Transformer Configuration in 3- Ocean-Circulation Models Dimensional Josephson Lattices," Phys. Rev. Lett. 75, 717 (1995).

David Poling Jensen, N.G., A.R. Bishop, and D. Dominguez, "Metastable Filamen- Our objectives in this project were atmosphere simulations for years to tary Vortex Flow in Thin Film to (1) become proficient at running come. Analysis of this run will Superconductors," Phys. Rev. Lett. 76, ocean- and climate-related simulation provide insight into the strengths and 2985 (1996). codes and analyzing their outputs, weaknesses of such simulations and Sanchez, A., A.R. Bishop, and N.G. (2) use this proficiency to follow the better understanding of the subgrid Jensen, "Smoothing of Rough migration of simulation to massively processes that will always be neces- Surfaces," Phys. Rev. B 52, 5433 parallel computers, and (3) communi- sary in such calculations. The (1995). cate the lessons we learn to our ensemble runs should provide one of colleagues and coworkers. the first attempts to study the variabil- Zhou, S.J., B.M. Beazley, et al., This year we completed a series of ity of this kind of simulation and thus "Large-Scale Molecular Dynamics ensemble runs using two computer a means of evaluating the predictive Simulations of Three-Dimensional codes: one that simulates the atmo- capability of any such simulation. Fracture" (submitted to Phys. Rev- sphere, the other the ocean (ECHO). Lett). These runs of the ECHO-coupled, Publications Zhou, S.J., D.M. Beazley, P.S. ocean-atmosphere model should Lomdahl, et al., "Dislocation provide insight into using computer "Preliminary Results from Ensemble Emission from a Three-Dimensional models to predict climate changes. Runs of the ECHO-Coupled, Ocean- Crack" (submitted to Proc. 9th Int. The resulting amount of data will be Atmosphere Model" (Cooperative Conf. Fracture). immense and take some time to Antarctic Research Center, University analyze. of Tasmania, Hobart, Australia, Zhou, S.J., P.S. Lomdahl, et al., The 100-year run will provide a July 29, 1996). "Dynamic Crack Processes via baseline for comparisons of ocean and Molecular Dynamics," Phys. Rev. Lett. 76,2318 (1996).

192 Los Alamos FY1996 LDRD Progress Report Simulation Methods for In addition, we developed a stochastic model of the bacterial Advanced Scientific Computing flagellar molecular motor and applied our numerical methods to the direct simulation of stochastic differential James Gubernatis equations. The rapid increase in raw computa- Langevin methods for stochastic tional power has created exciting differential equations. We also try to Publications opportunities for scientific computa- improve current algorithms used to Brandow, B., "The Exotic tion. The complexity and realism of simulate problems with disparate time Superconductors: Characteristic the problems that can be simulated and/or space scales. Features and a Possible Explanation" promise to greatly advance many This year we developed and applied (submitted to Adv. Phys.). scientific and technological fields. a different algorithmic approach to the Accordingly, scientific computing is problem of quantum-mechanical Castillo, J., et al., "A Generalized enjoying considerable worldwide simulations of hydrogen diffusing on Length Strategy for Direct popularity. Yet many challenging and into the surface of a metal. Optimization in Planar Grid- scientific problems remain unsolved Instead of performing a real-time Generation" (submitted to /. Comput. because of inadequate algorithms, simulation, we performed the simula- Phys.). especially algorithms that are suitable tion in imaginary time and then used Castillo, J., et al., "A Practical Guide for massively parallel architectures. Bayesian statistical inference methods to Direct Optimization for Planar In this project, our objective is to to analytically continue the simulation Grid-Generation" (submitted to SIAM create effective new algorithms for data into real time. This method Rev). solving these problems, giving the resulted in improved accuracy of Laboratory the initiative in key predicted spectral properties of the Davis, K., "PERs from Projections for technical areas by combining the diffusing hydrogen. Our most Binding-Time Analysis," J. Lisp talents and efforts of our physical dramatic finding was a significant Symbolic Comput. 8, 249 (1995). scientists and applied mathematicians. shift in vibrational frequencies from Zhang, S., et al., "A Constrained Path We concentrate on developing those predicted by normal-mode Monte Carlo Method for Fermion advanced N-body simulation tech- theory, underscoring both the quan- Ground States" (submitted to Phys. niques, including classical and tum and the anharmonic nature of the Rev. B). quantum Monte Carlo techniques, hydrogen diffusion. molecular dynamics techniques, and

Adaptive Mesh Refinement Algorithm and parabolic systems because the operator is cast in divergence gradient Development and Dissemination form. We have begun designing C++ sparse data structures that can be used not only for our methods but for any Jeffrey S. Saltzman work that needs to be performed on data of codimension one. Our objective is to develop and During this fiscal year, we have disseminate adaptive mesh refinement concentrated on developing algo- (AMR) algorithms for structured rithms that are conservative for Publications meshes. Areas of development include adaptive overset grids. We have also Brislawn, K., D. Brown, et al., algorithms for parallel architectures, supported some development work for "Adaptively-Refined Overlapping techniques for the solution of partial an AMR library written in C++ called Grids for the Numerical Solution of differential equations on adaptive AMR++. This library is a collection Hyperbolic Systems," Proc. ICASE/ meshes, mesh generation, and of routines that facilitate the manipu- LaRC Workshop Adaptive Grid algorithms for nontraditional or lation and generation of adaptive grids generic applications of AMR. AMR and data. Efforts for conservation Methods 3316, 95 (1995). algorithms are perceived as difficult to include using both algebraic and meld to current algorithms. Therefore, Cartesian techniques to solve elliptic we are developing tools that diminish equations on overset adaptive meshes. this perception and will allow more Algebraic and Cartesian methods can computational scientists to use AMR possibly be extended to hyperbolic within their own work.

Competency Development Projects—Mathematics and Computational Sciences 193 Neutron Transport Methods for have changed the focus of the effort in this direction. To formulate a 3-D, 3-D Cartesian Adaptive Meshes adaptive-mesh-refinement solver for the transport equation, we have gone to Raymond E. Alcouffe a more object-oriented paradigm, which is being done through FOR- The mesh representation of complex mesh, which allows internal mesh TRAN^. Using the features of this three-dimensional (3-D) geometries is refinement in areas where gradients in language, we have explored the concept currently accomplished using Cartesian physical quantities (such as pressure, of solving the equations for the grids that are very regular or arbitrary density, temperature, and neutron flux) inversion of the transport operator cell meshes that are accurate but do not are large. We are developing efficient by cell and in a block-of-cells method. have any regular connectivity. Methods numerical methods for the solution of Our results show that the cell-by-cell that use regular grids are computa- the discrete-ordinates transport method as implemented on the Cray tionally efficient because the con- equation on such meshes. T3D is about a factor of 3 slower than nectivity of the mesh is regular and Building upon the two-dimensional, our regular parallel sweeper. In going well characterized. Arbitrary grids can adaptive-mesh solver that we devel- to the block sweeper, we hope to accurately represent complex geom- oped last year, we have investigated recoup much of the inefficiency of the etries, but the complex structure of the 3-D solvers this year. The thrust of this cell-by-cell method in the parallel resulting matrices makes them difficult development is to use parallel architec- environment. We do not yet have to solve efficiently. An efficient ture in our 3-D calculations, and so we results for the block-parallel sweeper. compromise is the adaptive Cartesian

Applications of Nonlinear and method for controlling front dynamics in reaction-diffusion systems with Stochastic Dynamics nonuniform external fields; and (6) derivation of rigorous bounds on heat transport by turbulent convection. Charles Doering

This project supported research in organized, spatial structures in Publications applications of nonlinear and stochas- nonequilibrium models; and (4) nonlin- Cai, D., A.R. Bishop, and N. Gronbech- tic dynamics systems with the aim of ear wave and soliton applications in Jensen, "Discrete Lattice Effects on exploiting the last decade's progress optics and ocean modeling. Breathers in a Spatially Linear in understanding the dynamics of Last year's accomplishments Potential," Phys. Rev. £53,1202-1205 nonlinear, or noisy, systems related to included (1) development of new, (1996). problems in theoretical physics, nonlinear, evolution equations for chemistry, and biology. The common weakly nonlinear internal waves in a Cai, D., A.R. Bishop, and N. Gronbech- denominator is the fundamental roles two-fluid system; (2) establishment of Jensen, "Perturbation Theories of a that nonlinearity, noise, and disorder a framework for comparison of Discreet Integrable Nonlinear play in the dynamics of both simple century-long simulations of the wind- Schrodinger Equation," Phys. Rev. E 53, and complex systems. We also studied driven double-gyre; (3) asymptotic 4131^136(1996). the underlying theoretical problems solution of a model problem explain- Cai, D., A.R. Bishop, and N. Gronbech- that have much in common within the ing the deflection of laser beams in Jensen, "Spatially Localized Temporally paradigms of nonlinear science. The plasma flows; (4) development of a Quasi-Periodic, Discrete Nonlinear major areas of research included scheme for stable pulse transmissions Excitations," Phys. Rev. E52, R5784- (1) stochastic models of molecular in optical fibers and investigation of R5787 (1995). motors; (2) turbulent diffusion and the nonadiabatic dynamics of dark convective heat transport; (3) self- solitons; (5) demonstration of a

194 Los Alamos FY1996 LDRD Progress Report Choi, W., and R. Camassa, "Long Konotop, V.V., D. Cai, et al., Salkola, M.I., A.R. Bishop, et al., Internal Waves of Finite-Amplitude," "Interaction of a Soliton with Point "Coupled Spin-Boson Systems Far Phys. Rev. Lett. 77,1759-1762 (1996). Impurities in an Inhomogeneous, from Equilibrium," Phys. Rev. B 54 Discrete, Nonlinear, Schrodinger (18), 12645 (1996). Constantin, P., and C. Doering, "Heat- System," Phys. Rev. E 53, 6476-6485 Transfer in Convective Turbulence," Wang, W.Z., J.T. Gammel, et al., (1996). Nonlinearity 9,1049-1060 (1996). "Quantum Breathers in a Nonlinear Reimann, P., and T.C. Elston, Lattice," Phys. Rev. Lett. 76, 3598 Doering, C, et al., "Random Walks, "Karmer's Rate for Thermal Plus (1996). Resonance, and Ratchets," in Non- Dichotomous Noise Applied to equilibrium Statistical Mechanics in Ratchets," Phys. Rev. Lett. 11, 5328- One Dimension, V. Privman, Ed. 5331 (1996). (Cambridge University Press, New York, 1996).

Theoretical Foundation for Publications Baggerly, K., "Part III: Interfacing Adaptive Monte Carlo Theory and Practice" (Adaptive Monte Carlo Methods, Los Alamos, Richard Picard N.Mex., August 14-16, 1996). Cox, D., "Part II: Continuous State The Monte Carlo method is a key We overcame this requirement Spaces" (Adaptive Monte Carlo tool for analysis of many complex through the use of interpolating Methods, Los Alamos, N.Mex., problems, especially in the nuclear smoothing functions. When the August 14-16, 1996). fields. This project is one of several expected score conforms to a model that are aimed at significantly linear in its parameters (such as a Kollman, C, K. Baggerly, D. Cox, extending the effectiveness of the polynomial in several variables, for and R. Picard, "Adaptive Importance method. example), use of results from a full Sampling on Discrete Markov The standard central limit theorem, rank experimental design is sufficient Chains" (submitted to Ann. Appl. applicable to Monte Carlo work to obtain exponential convergence. Probability). where N simulation runs are statisti- We discussed this work as part of an cally independent, provides for the extensive workshop involving Picard, R., "Part I: Discrete State standard deviation to converge to zero participants from across the interna- Problems and Interpolated at the rate of the square root of N. tional Monte Carlo community. Smoothing" (Adaptive Monte Carlo Methods, Los Alamos, N.Mex., Under restrictive conditions, the We also obtained simulation August 14-16, 1996). replacement of independent sampling evidence of exponential convergence with adaptive learning algorithms has for Halton's sequential Monte Carlo recently been shown to provide method when applied to large, sparse exponential convergence. The goal of matrices. Use of path information and this project is to obtain exponential splitting/roulette techniques acceler- convergence under less restrictive ated this convergence. conditions. In addition, our efforts in statistical In the first year of the effort, we mechanics focused on improving successfully generalized the existing convergence properties of multi- theory, which required the simulation canonical recursion algorithms, which to visit all process states—a burden- overcome the long correlation times some requirement for large problems. of the standard Metropolis algorithm.

Competency Development Projects—Mathematics and Computational Sciences 195 Advanced Three-Dimensional Eulerian Publications Rider, W.J., "Filtering Nonsolenoidal Hydrodynamic Algorithm Development Modes in Numerical Solutions of Incompressible Flows" (submitted to William Rider Int. J. Numer. Methods Fluids). Rider, W.J., "Robust Formulation of The purpose of this project is to We achieved another important Approximate Projection Methods for investigate, implement, and evaluate advance in interfacial closure of Incompressible Flows" (submitted to algorithms that have high potential for multifluid equations in both com- /. Comput. Phys.). improving the fidelity and efficiency pressible and incompressible regimes of large-scale, three-dimensional, by including relevant physical Rider, W.J., and D.B. Kothe, Eulerian hydrodynamic simulations. phenomena in a physical manner (the "Reconstructing Volume Tracking" This project combines core strengths fourth figure shows two potential (submitted to J. Comput. Phys.). of several Laboratory divisions. The types of interface topologies). project is of high potential institutional benefit given the renewed emphasis on numerical simulations in y///////// science-based stockpile stewardship W3/ and the Accelerated Strategic Com- puting Initiative. We used data generated in other projects, such as Telluride (a molding \ and casting simulation tool), as active platforms for testing our algorithms. Examples of algorithms we implemented are interface-tracking methods, multidimensional advection methods, interfacial physics, and \ parallel communication libraries. (a) A v-direction pass of the operator (b) An x-direction pass of the Chief among the improvements we split method. operator split method. made is the application of fully multidimensional methods for advection in the form of both interface-tracking and shock-capturing techniques. The first figure provides a graphical depiction of both standard and modified multidimensional interface-tracking methods. We found that these methods reduce the magnitude of grid-dependent effects and improve solution accuracy. These grid dependencies are most acute for converging coordinate frames. Our implementation of interface tracking uses systematic techniques volumes fluxed twice from computational geometry. The second and third figures show several (c) The naive unsplit method. (d) The unsplit method. fundamental aspects of this algorithmic approach. A comparison of three multidimensional advection schemes we investigated. For the operator split integration (a and b), the x-pass follows the y-pass. We do not recommend the naive unsplit method (c) because of its inability to advect volumes in a conservative, monotonic manner. We obtained the best results with the corner-coupled geometrically unsplit method (d).

196 Los Alamos FY1996 LDRD Progress Report The method we implemented for computing the flux volume involves fundamental geometric steps (represented here as polygons). We formed these polygons by sweeping out areas with a positive velocity field. (a) Edge volume flux polygon. (b) Comer volume flux polygon. 1 [ \ - *

I : X _ (a) IThe initial normal and interface (b) A new guess at the normal, (c) The method applied to a curved in the loca•l stencil. interface. The interface reconstruction step is the function of several fundamental geometric steps.

~~(a) A simple unmixed cell. (b) A complex well-mixed cell.~~

The algorithm for the interfacial physics treats unmixed or well-mixed cells self-consistently. This includes processes such as surface tension or solidification for low-speed casting applications or pressure and volume relaxation for high- speed hydrodynamics.

Competency Development Projects—Mathematics and Computational Sciences 197 Phase Transitions, Nonequilibrium Publications Cooper, F, S. Habib, et al., Dynamics, and Critical Behavior of "Nonequilibrium Dynamics of Strongly Interacting Systems Symmetry Breaking in Lambda Phi4 Field Theory" (submitted to Phys. Rev D). Emil Mottola Cooper, F., Y. Kluger, E. Mottola, In this project, we performed large- applications to spinodal decomposition "Anomalous Transverse Distribution scale simulations of strongly interacting and structural phase transitions in a of Pions as a Signal for the Pro- systems and investigated a variety of variety of systems such as spin chains duction of DCCs," Phys. Rev C 54, approaches to the nonequilibrium and shape-memory alloys. 3298 (1996). dynamics of phase transitions and In FY 1996 we extended non- Cooper, R, Y. Kluger, et al., critical behavior. Focus areas included equilibrium field theory beyond "Nonequilibrium Quantum Dynamics (1) the finite-temperature, quantum mean-field techniques and studied of Disoriented Chiral Condensates," chromodynamics (QCD) phase- rare B particle decays. We also Phys. Rev. D 51, 2377 (1995). transition and nonequilibrium dynam- performed a kink calculation for a ics of a new phase of matter (the sixth-order-polynomial strain-field Gupta, R., and T. Bhattacharya, quark-gluon plasma) above the critical theory that describes shape-memory "Light Quark Masses from Lattice temperature, (2) nonequilibrium alloys. Finally, we computed correla- QCD" (submitted to Phys Rev. D). dynamics of quantum fields using tion functions, structure factors, and Gupta, R., and P. Tamayo, "Critical mean-field theory and, (3) stochastic thermodynamic quantities like the Exponents of the 3-D Ising Model," classical field theoretic models with specific heat for the alloys. Int. J. Mod. Phys. C. 7, 305 (1996). Habib, S., E. Mottola, and P.G. Tinyakov, "Winding Transitions at Finite Energy and Temperature: An 0(3) Model" (to be published in Phys. Rev.).

Numerical Simulations of transverse flux-line wandering, we determined the critical ratio of Disordered Superconductors columnar-to-point disorder strength needed to localize the bosons. James Gubernatis Publications The objectives of this project We also addressed the localization Devereaux, T.P., R.T. Scalettar, G.T. included studying (1) the interplay of of flux lines caused by splayed Zimanyi, et al., "Phase Diagram for disorder and interactions in quantum columnar pins. Using a Sine-Gordon Splay Glass Superconductivity," Phys. systems with applications to mobility type of renormalization-group study, Rev. Lett 75, 4768 (1995). problems, the onset of superfluidity, we obtained an analytic form for the disordered superconductors, and critical temperature. We also deter- Moon, K., and S. Girvin, "Critical quantum phase transitions, (2) the mined the critical temperature from Behaviour of Superfluid 4He in problem of flux-line motion in current-voltage characteristics Aerogel," Phys. Rev. Lett. 75, 1328 superconducting materials with high obtained from a molecular dynamics (1995). critical currents, and (3) the develop- simulation. The combined studies Moon, K., R.T. Scalettar, and ment of software and computational enabled us to construct the phase G.T. Zimanyi, "Dynamical Phases of algorithms for these classes of diagram as a function of interaction Driven Vortex Systems," Phys. Rev. problems. Specifically, we carried out strength, temperature, and disorder. Lett. 11,2778 (1996). Monte Carlo studies of the critical Finally, we employed the recently 4 behavior of superfluid He in aerogel. developed mapping between boson Sandvik, A.W., and M. Vekic, We found that the superfluid density world-lines and the flux motion in "Quantum Phase Transitions in 2D exponent increases in the presence of quantum Monte Carlo simulations to Antiferromagnets," J. Low Temp. fractal disorder with a value roughly analyze localization in the presence of Phys. 99, 367 (1995). consistent with experimental results. disorder. From measurements of the

198 Los Alamos FY 1996 LDRD Progress Report Transactional Memories: A New conflict-resolution scheme by establishing an order on conflicting Abstraction for Parallel Programming transactions when a conflict is detected (called the "required commit order"). So long as this order is Joseph Fasel acyclic, no transaction need be aborted. Current distributed-memory locking. This transaction approach multiprocessor computers make the permits the underlying system to Unfortunately, our parallel virtual development of parallel programs exploit the potential parallelism in machine (PVM) implementation of difficult. From a programmer's transaction processing. We are explor- transactional memory was not able to perspective, it would be most desir- ing the feasibility of designing parallel demonstrate a performance improve- able if the underlying hardware and programs using the transaction ment over traditional approaches to software could provide the program- paradigm for data consistency and a parallel programming. As this ming abstraction commonly referred barrier type of thread synchronization. situation probably results from PVM's to as sequential consistency—a single We experimented with alternative high overhead and latency, we address space and multiple threads. implementations of transactional directed our efforts toward imple- But enforcement of sequential memories, specifically a pessimistic menting a low-latency implementa- consistency limits opportunities to approach, appropriate for low tion of the message-passing interface optimize architectural and operating communication latency, and an (MPI is another standard parallel- system performance and leads to poor optimistic approach for higher programming library) on the Meiko performance. A new abstraction called latency. The optimistic approach CS/2 massively parallel super- "transactional memories" may minimizes communication but computer and a cluster of work- provide a solution to this problem. increases the probability of a conflict stations on a high-speed switch. We The programming model is shared being detected at transaction commit- completed this implementation in the memory with multiple threads. ment. When such a conflict occurs, summer of 1996. At the end of FY However, we obtain data consistency low-priority transactions may need to 1996, we had not yet ported the through the use of transactions rather abort in favor of high-priority transactional memory implementation than mutual exclusion based on transactions. We improved on one to this new framework.

Development of an Integrated System for We validated the initial system at a professional society meeting in Estimating Human Error Probabilities and September 1996. We guided HRA practitioners through a hands-on Modeling Their Effects demonstration and had them complete a survey on system utility. We will use Heidi Hahn the data gathered at the meeting to guide further system development. This project is aimed at developing from a weighted average across the Final validation will occur in the next an expert system that will allow in- matches, with weights being deter- phase of the project. tegrated error estimation using input mined by the "goodness of fit" for from many different sources with each match. Publications differing quantitative bases. The So far, we have completed two resulting knowledge-based system tasks: we built a prototype system Hahn, H.A., J.L. Auflick, and J.A. will allow analysts to find appropriate with limited data incorporated, and Morzinski, "Demonstration of a human error probabilities (HEPs) for we validated system design with HRA Prototype Knowledge-Based System use in probabilistic risk assessment practitioners. The prototype system for Estimating Human Error and human reliability analysis (HRA). now contains all but one of the major Probabilities," Proc. Human Factors Our system will (1) allow analysts to HRA methodologies used to generate Ergonom. Soc. 40th Annual Meet. 2, input relevant information; (2) com- HEPs. We will incorporate the 869(1996). pare the analyst's situation with remaining method, along with data different approaches and identify one from several minor sources, into the or more "matches"; (3) provide valid final system during the next project estimates based on selected matches; year. and (4) provide an estimate drawn

Competency Development Projects—Mathematics and Computational Sciences 199 Novel Monte Carlo Algorithms for For the third problem area, we studied in detail a collection of new Statistical Mechanics algorithms to simulate first-order phase transitions, spin-glass problems, protein-folding problems, etc., James Gubernatis that adaptively construct an importance sampling function. We identi- The Monte Carlo method is a key In the second problem area, we fied three areas in which existing tool for analysis of many complex developed a novel algorithm to methods can be improved: the manner problems. This project is aimed at simulate micelle formation in ternary in which certain density functions are significantly extending the effective- fluid mixtures involving surfactants. estimated, the manner in which the ness of the method and specifically The base system being simulated is an learning process is executed, and the looks at novel methods applicable to Ising model, and the new algorithm manner in which the Monte Carlo statistical mechanics. makes a special use of the Swendsen- samples the importance function. For We made progress on three problem Wang cluster algorithm to produce the first area, we developed codes to areas. In the first, we successfully statistically independent configura- permit the use of kernel estimation implemented the Gibbs ensemble tions at each Monte Carlo step. With methods to improve the density method for a mixture of hard disks of each new configuration, we used the function estimation. For the second, vastly different radii. This implemen- inversely restricted sampling tech- we identified several other learning tation required devising special rules nique to grow the micelles. We processes that might be more effective for moving large disks into regions of computed micelle density and size and have started to test them. Work on predominantly small disks, produced distributions as a function of surfac- the third area will occur in the coming a much more efficient algorithm than tant concentration. year. the standard implementation, and permitted an extensive study of phase separation in mixtures.

implement a unique database that will Advanced Computational Science provide researchers with validated influenza sequence data. We have Andrew White developed a model of influenza epidemiology that includes the For this project we used advanced Springs, Colorado) requires the implementation of antiviral drug modeling and simulation techniques integration of sophisticated turbulent treatment and the possibility that the (both classical and learning-based) to burn models and adaptive mesoscale virus will be drug resistant. try to predict the occurrence and weather models. We have used a self- Unusual periods of excessive heat course of various kinds of crisis predicting transport description of the can lead to increased mortality. For events. Because of their complex, relevant combustion and transport example, from July 11 to July 27, time-critical nature, these applications phenomena to successfully character- 1996, Chicago, Illinois, recorded 465 clearly emphasize the need for high- ize the bulk evolution of a wildfire. heat-related deaths. We are studying performance computing and commu- We then implemented this description improvements to the "effective nication technology. in a computer code and validated it temperature" index (comprising Accurately predicting the course of using data provided by the U.S. Forest temperature and humidity) that is wildfires (for example, in Yellowstone Service. commonly used. To that end, we are National Park and in Glenwood Influenza is a prime example of a studying historical weather data reemergent viral health threat, and it (1973-1993) from the National is a prototype for threats from natural Oceanographic and Atmospheric and artificial biological agents. We Administration (NOAA) and mortal- are working with the Center for ity data from the CDC through the use Disease Control (CDC) to define and of Expert Network modeling tools that combine the best features of rule- based systems and neural networks.

200 Los Alamos FYI996 LDRD Progress Report Development of an Automated benchmarking HELIOS with the new libraries, a task we previously Core Model for Nuclear Reactors performed with the old libraries. Finally, we also began writing the linkage code that will transform Russell Mosteller HELIOS output into NESTLE input. Completing that linkage code will be This project is aimed at developing developing a linkage code to trans- the next step in our project. an automated package of codes that form HELIOS output into NESTLE can model the steady-state behavior of input, developing additional steady- nuclear-reactor cores of various state thermal-hydraulics modules for Publications designs. As an added benefit, the data NESTLE, and benchmarking produced by the steady-state analysis HELIOS and NESTLE both individu- Mosteller, R.D., "Benchmarking of can also be used as input to the TRAC ally and in combination. NESTLE against Measured PWR Data at Beginning of Life," Trans. transient-analysis code for subsequent During this reporting period, we Am. Nucl. Soc. 73, 369 (1995). safety analysis of the reactor at any have completed the standalone point in its operating lifetime. benchmarking of NESTLE and Mosteller, R.D., "Comparison of The basic capability to perform performed extensive benchmarking of Doppler Coefficients from ENDF/B- steady-state reactor-core analysis HELIOS. We have also obtained a V and ENDF/B-VI," Trans. Am. Nucl. already exists in the combination of new version of HELIOS, along with Soc. 74, 331 (1996). the HELIOS lattice-physics code and several new cross-section libraries for Mosteller, R.D., "Validation of the NESTLE core-simulation code. it. These new libraries are based on NESTLE against Static Reactor Our purpose is to complete the ENDF/B-VI Release 3, whereas the Benchmark Problems," Trans. Am. automated package by obtaining old libraries were based on ENDF/B- Nucl. Soc. 74, 310(1996). cross-section libraries for HELIOS, VI Release 2. Currently, we are

Density Function Estimation for function. For the postsimulation analysis, we showed that although Monte Carlo Simulations advanced kernel estimation methods can improve the representation of the James Gubernatis density function, there is little advantage to using an estimator other Applying modern statistical densities of states in order to evaluate than a histogram because the estimate methods to experimental data can the free energies in phase equilibria. is subsequently used to compute dramatically enhance the information This is a long-standing problem in the average quantities. We are presently extracted, effectively increasing the application of the Monte Carlo investigating the use of these ad- efficiency of data collection. Most method. vanced methods to adaptively modern statistical methods for Presently, density function estima- construct the importance sampling estimating density functions begin tion is a key step in the Swendsen- function used in simulations. Here we with histograms as a crude estimate Ferrenberg histogram method for expect these new methods to offer a and then move on to a wide variety of postsimulation data analysis and in significant advantage. more sophisticated and powerful adaptively improving the importance methods such as kernel estimators, sampling in recently proposed orthogonal series, and maximum methods such as multicanonical and penalized likelihood methods. simulated tempering algorithms. In The goal of this project is to use each case, a simple histogram method modern statistical methods, such as is used to estimate the density advanced density function techniques, to analyze Monte Carlo data. Specifi- cally, we are adapting such methods to determine the configurational

Competency Development Projects—Mathematics and Computational Sciences 201 Self-Organization and Pattern Formation Camassa, R., et al., "Layer-Mean Quantities, Local Conservation Laws" (submitted to Phys. Rev. Lett). Robert Ecke Camassa, R., et al., "Long Internal Waves of Finite Amplitude," Phys. Rev. The formation of regular structures is calcium waves (as models of biological Lett. 11,1759 (1996). important in science and technology, self-organization). and recently there has been much Our successes include demonstrating Camassa, R., et al., "Long Time attention focused on self-organizing the nucleation mechanism for disloca- Evolution Equations for Shallow Water and self-assembling systems. Instead of tions with rotation and measuring the with a Varying Bottom" (to be building structures by hand, as in long-wavelength distortion angle. We published in Physica D). microelectronic lithography, one would have also extended the study of design or search for systems that put multivalued front speeds to the Camassa, R., et al., "A Melnikov themselves together. If successfully derivation of dynamical equations for Method for Homoclinic Orbits with developed, self-organizing and self- front transitions and correctly predicted Many Pulses" (to be published in assembling systems could have a major spontaneous transitions between Archive F, Archive for Rational impact on a wide range of technologi- counterpropagating fronts. We have Mechanics and Analysis). cally useful applications. further suggested a way to control Camassa, R., et al., "Nonlinear Internal One variety of such systems is domain patterns using a spatially Waves in a Two-Layer Fluid," J. Fluid pattern-forming systems that can nonuniform, external advective field. In Mech. 313, 83 (1996). produce simple regular and irregular the simulation area, we have written a structures. Two examples of pattern three-dimensional simulation code for Choi, W, "On the Fission of Algebraic formation are thermal convection and message-passing machines such as the Solitons" (submitted to Proc. R. Soc. reaction-diffusion systems, in which T3D machine to elucidate the role of London). various cell processes for Ca2+ dynam- two-dimensional patterns of stripes, Ecke, R., et al., "Spiral Defect Chaos in ics. We also demonstrated numerically spirals, targets, hexagons, squares, and Rayleigh-Benard Convection: Defect and analytically that a self-organization "self-replicating" spots have been Population Statistic" (to be published in process is intrinsic to the dynamics of observed and modeled. The elucidation Physica A). of types of patterns, their dynamics, microtubules. and the possible application of such Hagberg, A., et al., "Controlling mechanisms to problems of technologi- Domain Patterns Far from Equili- cal interest is a large part of our work. Publications brium," Phys. Rev. Lett. 76,427 (1996). Specific systems we have studied are Baras, R, et al., "Microscopic Hagberg, A., et al., "Order Parameter spatio-temporal patterns in cellular Simulation of Chemical Bistability in Equations for Front Transitions: Planar automata, defects in rotating thermal Homogenous Systems," J. Chem. Phys. and Circular Fronts" (to be published in convection (shown in accompanying 105, 8257 (1996). Phys. Rev. E). figure), replicating spot dynamics in reaction-diffusion Haim D., et al., "Breathing Spots in a systems, and spatio- Reaction-Diffusion System," Phys. Rev. temporal dynamics of Lett. 11,190 (1996). Hu, Y., et al., "Convection Under Rotation for Prandtl Numbers near Optical One: Part I. Linear Stability" shadowgraph (submitted to Phys. Rev. E). image of spiral Liu, Y, et al., "Dynamics of Surface defect chaos in Patterning in Salt Crystal Dissolution," thermal con- Phys. Rev. E 53,5572 (1996). vection. This state was totally Oron, A., et al., "Evolution and Forma- unexpected, and tion of Dispersive-Dissipative Patterns" its discovery and (to be published in Phys. Rev. E). subsequent Reynolds, W.N., et al., "Self- exploration have Replicating Spots" (to be published in changed dramatically Phys. Rev E). the way researchers think about the system of thermal convection.

202 Los Alamos FY1996 LDRD Progress Report Sullivan, T., et al., "Turbulent Solutal Zharnitsky, V., "Breakdown of Stability Convection and Surface Patterning in of Motion in Superquadratic Potentials" Solid Dissolution," Phys. Rev. £54, (submitted to Phys. Rev. E). 486 (1996).

Application of Discrete Mathematics Krumke, S.O., H. Noltemeier, et al., "Compact Location Problems with Budget and Communication Vance Faber Constraints," in 1st Intl. Conf. on Computing and Combinatorics This project in combinatorial In computational finance we have (Springer Verlag, Berlin, 1995), Vol. analysis is aimed at studying and applied innovative computational 959, pp. 510-519. quantifying the properties of discrete methods to pricing various derivatives objects and their operations. The and options. In computational Krumke, S.O., H.-Noltemeier, et al., knowledge gained is applicable to all geometry we have found efficient "Complexity and Approximability of areas of science and engineering. Our methods for point location and Certain Bicriteria Location Prob- goal is to extend the combinatorial Delaunay triangulations as well as lems," in 21st Workshop in Graph method as a viable and useful tool to efficient computational methods for Theoretic Concepts in Computer help in solving Laboratory problems. geometric problems arising in pattern Science 1017, 73 (1995). Since this project was conceived, we matching and cartography. We Krumke, S.O., H. Noltemeier, H.U. have used the methods of combinato- continue to develop methods for Drangmeister, et al., "Network rics to solve problems in numerical efficient cluster analysis. The algo- Improvement Problems," in 22nd analysis, computer networks, cluster rithms, some of which have been Workshop in Graph Theoretic Concepts analysis, learning theory, DNA patented, are now being extensively in Computer Science (in press). mapping, group testing for biology, used at the Laboratory. evolutionary trees, quantum physics, Marathe, M.V., and S.S. Ravi, and wavelet analysis. The basic "Approximation Algorithms for the approach of the researchers participat- Publications Minimum Satisfiability Problem," ing in this project is to gain a deep Arikati, S.R., A. Dessmark, et al., Information Processing Letters 58 (1), understanding of problems arising in "Approximation Algorithms for 23 (1996). laboratory research and to use their Maximum Two-Dimensional Pattern Marathe, M.V., R. Ravi, and R. skills in combinatorial methods to Matching," in 7th Annual Symposium solve them. Sundaram, "Service Constrained on Combinatorial Pattern Matching Network Design Problems," in 5th In the field of quantum computing, (Springer Verlag, Berlin, 1996), Vol. Scandinavian Workshop on Algorithm we have designed several new and 1075, pp. 348-360. Theory (SWAT) (Springer Verlag, efficient algorithms for quantum error Chalasani, P., and S. Jha, "A Berlin, 1996), Vol. 1097, pp. 28-30. correction and fault-tolerant comput- Topological Study of Concurrent ing. As a result of this and other work, Marathe, M.V., H.B. Hunt III, et al., quantum computing has been proven Processes" (submitted to Science of "Approximation Schemes for to be physically realizable. In Programming). PSPACE-Complete Problems for communication networks we have Chalasani, P., A. Blum, and S. Succinct Specifications" (to be developed new approximation Vempala, "A Constant Factor published in SIAM J. Computing). algorithms for several basic problems Approximation for the k-MST Marathe, M.V., H.B. Hunt III, et al., that arise in network design and Problem in the Plane" (Annual "Complexity of Hierarchically and 1- analysis. These algorithms will Symposium on Theory of Dimensional Periodically Specified potentially be useful in upgrading Computation, Las Vegas, Nev., 1995). Problems" (to be published in AMS network performance and especially Proc). in finding efficient routing methods. Chalasani, P., S. Jha, and I. Saias, "Approximate Option Pricing" Marathe, M.V., R. Ravi, R. Sundaram, (Conference on Foundations of et al., "Bicriteria Network Design Computer Science, Burlington, Vt, Problems," in Proc. 22nd Int'l. 1996). Colloquium on Automata, Languages Chalasani, P., R. Motwani, and A.S. and Programming (Springer Verlag, Rao, "Algorithms for Robot Grasp Berlin, 1995), Vol. 944, pp. 487-498. and Delivery" (submitted to SIAM J. Computing).

Competency Development Projects—Mathematics and Computational Sciences 203 Theory and Modeling of Correlated- Systems," Phys. Rev. B 53,5407 (1996). Electron Materials Louca, D., T. Egami, et al., "Local Jahn-Teller Distortion in Alan Bishop La j xSrMnO3 Observed by Pulsed Neutron Diffraction" (submitted to There is today a significant oppor- nonadiabatic and inelastic quantum Phys. Rev. Lett.). tunity for exploiting complex elec- transport, including multiple spatial- Matveenko, S., A. Bishop, and A.V. tronic materials based on properties and temporal-scale effects. We have Balatsky, "Superconductivity totally beyond those of traditional modeled the origins of non-Fermi- Fluctuations in 1-D 2-Band Electron- solid-state materials. The new liquid and pseudogap behavior in Phonon Model with Strong Repulsive materials are characterized by strong perovskites and heavy-fermion competitions between coupled Electron-Electron Interactions" (to be compounds, including intrinsic and published in Phys. Rev. B). electronic, structural, and magnetic extrinsic disorder, d-wave symme- degrees of freedom and by sensitivi- tries, and multiphonon bound states. Rabson, D.A., and S.A. Trugman, "A ties to dimensionality and geometry. Finally, we have established regular Spin Model for Investigating This project provides theory and discussion and seminar sessions for Chirality," /. Phys. Condensed Matter modeling of correlated electronic communication between and among 7,9005 (1995). materials for three major tasks: experimentalists and theorists. Roder, H., A.F. Voter, et al., (1) isolation of novel phenomena; "Chebyshev Moment Problems: (2) integration of synthesis and Publications Maximum Entropy and Kernal characterization with theoretical Polynomial" in Maximum Entropy modeling of phenomena in specific Abrahams, E., A.V. Balatsky, et al., and Bayesian Methods, K.M. Hanson classes of materials; and (3) develop- "Properties of Odd Gap Super- and R.N. Silver, Eds. (Kluwer ment of scientific control of synthesis- conductors," Phys. Rev. B 52, 1271 Academic Press, New York, 1996), microstructure-property relationships. (1995). These tasks in turn address three pp. 187-194. Balatsky, A.V., and E. Abrahams, critical science issues at the cutting Roder, H., J. Zang, and A.R. Bishop, "Odd Time Magnetic Correlations and edge of research in correlated "Lattice Effects in the CMR Chiral Spin Nematic," Phys. Rev. Lett. electronic materials: What are the Manganites," Phys. Rev. Lett. 76, 74, 1004 (1995.) roles of electron-electron and elec- 1456 (1996). tron-lattice interactions, disorder, Balatsky, A.V., and M. Salkola, Salkola, M., A.R. Bishop, and V. chemical doping, magnetic field, "Impurity Induced States and the pressure, and temperature in control- Kenkre, "Coupled Quasiparticle- Absence of Quasiparticle Localization Boson Systems: The Semiclassical ling metal-insulator transitions? What in Disordered D-Wave Super- conditions induce non-Fermi-liquid Approximation and Nonlinear conductors," Phys. Rev. Lett. 76, 23 Schrodinger Equation," Phys. Rev. B metallic behavior and what are their (1996). experimental signatures? How can the 52 (R), 3824 (1995). local structure of these materials be Bishop, A.R., "Tuning Ground States Salkola, M., A.R. Bishop, and V. probed? and Excitation in Complex Electronic Kenkre, "Quantum Complexity in We have worked closely with Materials" (to be published in Coupled Spin-Boson Systems" (to be experimentalists to study the origin Synthetic Metals). published in Phys Rev B: Rapid and detection of intrinsic fine-scale Bonca, J., and S.A. Trugman, "The Communication). structure in strongly correlated Effect of Inelastic Processes on Salkola, M.I., A.R. Bishop, et al., electronic materials, including Tunneling," Phys. Rev. Lett. 75, 2566 "Correlation-Function Analysis of double-exchange and Jahn-Teller (1995). Nonadiabatic and Nonlinear Systems: effects in perovskite oxides, that leads Polaron Tunneling," Phys. Rev. B 51, to the polaronic and elastic short- Engelbrecht, J.R., M. Randeria, and 8878 (1995). range textures recently observed C.A.R.S. de Melo, "BCS-Bose Crossover: Broken Symmetry State" through neutron, x-ray, and resonant Scalapino, D.J., and S.A. Trugman, (to be published in Phys. Rev. B: ultrasound probes. We have begun "Local Antiferromagnetic Correlation Rapid Communication). pair-distribution function analysis of and D-Wave Pairing" (to be published models with local and long-range Kenkre. V., S. Raghavan, et al., in Philos. Mag. B). order. We have developed new "Memory-Function Approach to nonperturbative methods for, and Interacting Quasiparticle-Boson increased our understanding of,

204 Los Alamos FYI996 LDRD Progress Report Schmeltzer, D., and A.R. Bishop, Silver, R.N., H. Roder, et al., "Spin Zang, J., A.R. Bishop, and H. Roder, "Bosonization of the Continuum Correlation Functions in Random- "Double Degeneracy and Jahn-Teller Version of t-J Model Coupled to a Exchange S=l/2 XXZ Chains," /. Effects in CMR Perovskites," Phys. Dissipative Guage Field in 2- Appl. Phys. 79, 4632 (1996). Rev.BR53,l (1996). Dimensions," Phys. Rev. B 54, 4293 Trugman, S.A., "Complex Scattering (1996). Zang, J., A.R. Bishop, and D. Dynamics and the Quantum Hall Schmeltzer, "Frustrated Spin-Peierls Silver, R.N., A.F. Voter, and J.D. Effect," Physica D 83, 271 (1995). Chains," Phys. Rev. B 52, 6723 Kress, "Linear-Scaling Tight Tyson, T.A., S. Conradson, A.R. (1996). Binding from a Truncated Moments Bishop, et al., "Evidence for a Local Approach," Phys. Rev. B 53,12733 Zang, J., H. Roder, et al., "Low Lattice Distortion in Ca-doped (1996). Temperature Magnetic Properties of LaMnO3" (to be published in Phys. the Double Exchange Model" (to be Silver, R.N., B. Bauml, et al, Rev. B). published in J. Phys. C Lett.). "Spectral Properties of the 2-D Wang, W.Z., J.T. Gammel, et al., Holstein t-J Model" (High- "Quantum Breathers in a Nonlinear Temperature Superconducting Lattice," Phys. Rev. Lett. 73, 3598 Conference, Beijing, China, February (1996). 1997). Wang, W.Z., Y. Lu, A.R. Bishop, et Silver, R.N., H. Roder, et al., "Kernal al., "Dynamic Jahn-Teller Effect in Polynomial Approximations for Fullerene C " (to be published in Densities of States and Spectral 60 Phys. Rev. B). Functions," J. Comp. Phys. 124, 115-130(1996). Silver, R.N., H. Roder, et al., "The Kernal Polynomial Method Applied to the Non-Orthogonal Electronic Structures" (to be published in Phys. Rev. B, Brief Reports).

~~Competency Development Projects—Mathematics and Computational Sciences 205~~

~~Geoscience, Space Science, and Astrophysics~~

Modeling the Heat Flow and Resulting Publications Bunge, H.-R, M.A. Richards, and J.R. Dynamics in Earth's Interior Baumgardner, "Effect of Depth- Dependent Viscosity on the Planform Gary Glatzmaier of Mantle Convection," Nature 379, 436 (1996). We have used computer simulations We have also conducted several and laboratory experiments to study laboratory experiments of convection Jarvis, G.T., G.A. Glatzmaier, and V.I. the dynamics of Earth's deep interior. in viscous fluids to complement our Vangelov, "Effects of Curvature, Our computer models have simulated computer modeling studies and Aspect Ratio and Planform in Two- the flow in Earth's mantle on rela- provide further insight into convective and Three-Dimensional Spherical tively small scales such as within mixing. In addition, we are using Models of Thermal Convection," magma chambers, below volcanoes, geochemical observations of Earth to Geophys. Astrophys. Fluid Dyn. 79, and beneath midocean ridges. These constrain the dynamics of our 147 (1995). three-dimensional models of localized computer models by estimating the Kincaid, C, G. Ito, and C.W. Gable, features have demonstrated the effects amount of mixing that has occurred in "Laboratory Investigation of the of the highly temperature-dependent Earth's mantle. Interaction of Off-Axis Mantle viscosity of mantle material on the Plumes," Nature 376,758 (1995). structure of the fluid flow and on the transport and mixing of different Kincaid, C, J.-G. Schilling, and C.W. minerals within the mantle. Gable, "The Dynamics of Off-Axis Our global three-dimensional Plume-Ridge Interaction in the models of mantle convection have Uppermost Mantle," Earth Planet. also uncovered how sensitive the Sci. Lett. 137, 29 (1996). global-scale flow structure is to the Olson, P., and G.A. Glatzmaier, variation of the viscosity throughout "Magnetoconvection in a Rotating the mantle. In particular, we have Spherical Shell: Structure of Flow in found that it is very likely that the the Outer Core," Phys. Earth Planet. lower part of Earth's mantle has a Inter. 92,109 (1995). much higher viscosity than the upper part; our simulations that have this Van Keken, P.E., and C.W. Gable, same variation in viscosity produce "The Interaction of a Plume with a subduction-like downflows at the Rheological Boundary: A Com- surface that are very much like those parison," /. Geophys. Res. 100,20291 seen on Earth at the boundaries (1995). A snapshot of our global simulation of between tectonic plates (see accompa- convection in Earth's mantle. The nying figure). image shows cold (dense) material as a dark shade and warm (buoyant) material as a light shade. A cutaway of the mantle shows the structure down to the core. The long and narrow dark regions on the surface resemble subduction zones on Earth.

Competency Development Projects—Geoscience, Space Science, and Astrophysics 207 Remote Sensing ScienceThrust: simulated remote measurements of a canopy from 10-km altitude on two New Concepts different vertical leaf distributions with the same leaf area index. Based on these encouraging results, we are Siegfried Gerstl initiating collaborations with experts outside Los Alamos to develop laser The primary objective of this canopy. Our model simulations and remote sensing altimeters. project is to evaluate the feasibility of information retrieval algorithms show new research ideas that are based on that EnVI cannot only measure the extrapolations of science and technol- total leaf area index (LAI) but also the ogy that are already at the forefront of vertical distribution of the LAI. The remote sensing science. These studies second figure shows the results of have provided timely input for NASA's future civilian research, the New Millenium Program, and the U.S. Air Force Scientific Advisory Board. We have looked at a promising Hot-Spot Search-Light (HSSL) Satellite Cluster concept for measuring vegetation canopy hot-spot characteristics from • Detector distances space. The concept involves active L = 10 to 200 km illumination and bistatic detection that Detector 3 would allow angular distribution • Command and Control by Microwave measurements from space in a searchlight mode, which is equivalent to measuring a localized bidirectional reflectance distribution function (BRDF). The concept comprises a pointable illumination source, such as a laser operating at an atmospheric- window wavelength, coupled with a number of high-spatial-resolution detectors (clustered around the illumination source in space) that receive photons nearly coaxial with the retroreflection direction. Micro- wave control and command among the satellite cluster would allow simultaneous orientation of the direction of the laser beam and the telescope detectors so that the coupled system can function like a searchlight with almost unlimited pointing capabilities. The concept is called the hot-spot search-light (HSSL) satellite cluster and is shown in the first figure. S Gerstl. L.ANL. March 96 A nominal altitude of 600 km for the satellite cluster will allow hot-spot BRDF measurements out to about an The hot-spot search-light satellite concept, a free-flying constellation of a 18-deg phase angle. central laser source and a surrounding cluster of detector telescopes at distances of 10 to 200 km from the source, for an instantaneous field-of-view We have also demonstrated the (IFOV) of 200 m. feasibility of an environmental volumetric imaging (EnVI) concept that would use active remote sensing from space to measure the distribution and density of foliage in a vegetation

208 Los Alamos FY1996 LDRD Progress Report Publications flat LAI profile 0.050 r Gerstl, S.A.W., "Angular Signatures, and a Space-borne Measurement Concept," IGARRS'96 Symp. Proc. 3, 1642 (1996). Gerstl, S.A.W., "A Measurement Concept for Hot-Spot BRDFs from Space" (to be published in International Workshop on Multiangular Remote Sensing, Beijing, Proceedings). 100 200 300 400 500 Priedhorsky, W.C., R.C. Smith, and C. height (cm) Ho, "Laser Ranging and Mapping triangular LAI profile with a Photon-Counting Detector," 0.050 F Appl. Opt. 35, 3 (1996). 0.040 (pe r c m 0.030 LA I ia l 0.020 en t

~~diffe r 0.010~~

~~0.000 E 0 100 200 300 400 500 height (cm)~~

Simulated measurements of vertical leaf area index (LAI) distribution profiles with the environmental volumetric imaging (EnVI) concept. The leaves are distributed uniformly over 3 m in the top panel and in a triangular distribution shape in the lower panel. The thick lines show the timing profile of the singly reflected laser photons. The thin solid lines are the differential LAI distribution as derived from the photon counting; these match well with the input differential LAIs.

Subsurface Noble Gas Transport Our major accomplishment this year was to develop a three-dimen- at the Nevada Test Site sional model using the Los Alamos TRACR3D code that simulates the movement of tritium and krypton Joseph Thompson through the groundwater as it moves to the pumped well at the Cambric The objectives of our research are the carbonate rock around the nuclear site. The model showed that the to explain the results of a groundwater device contributed to the post- delayed arrival and loss of krypton pumping test done from 1975 to 1991 detonation migration of Kr-85 could indeed be explained but that at the location of the nuclear test throughout the rubble chimney above there was substantial uncertainty Cambric at the Nevada Test Site and, the collapsed crater. The distribution about initial radionuclide distribution, especially, to examine and understand of krypton was thus different from hydrologic parameters, and other the subsurface transport of noble gas. that of tritium, which was contained factors. In addition, we began to The elution data from the pumped in the immediate vicinity of the consider the influence of thermally well showed that the appearance of cavity. This initial distribution of induced convection currents on the krypton in the elution was delayed krypton resulted in some losses of distribution of radionuclides around relative to tritium and that only half of Kr-85 from the groundwater and in its the location of the nuclear test. We are the calculated Kr-85 source term was delayed arrival, relative to tritium, at using the TRACR3D code to simulate ever removed. We hypothesized that the pumped well. buoyancy-driven flow to determine its carbon dioxide gas that evolved from significance in the Cambric study.

Competency Development Projects—Geoscience, Space Science, and Astrophysics 209 Analysis and Visualization of Global Hudson, M.K., A.D. Kotelnikov, X. Li, et al., "Modeling Formation of Magnetospheric Processes New Radiation Belts and Response to ULF Waves," in Proc. Taos Workshop on Energetic Particles (AIP, New Dan Winske York, N.Y., in press).

The purpose of this project is to Publications Hudson, M.K., W. Lotko, C. Cattell, develop new computational and et al., "Modeling of Mesoscale Cattell, C, I. Roth, and M. Linton, visualization tools to analyze particle Processes in the Global Geospace "Effects of Low-Frequency Waves on dynamics in Earth's magnetosphere. System," Space Sci. Rev. 71, 623 These tools will allow us to construct Ion Trajectories in the Magnetotail," (1995). an efficient global picture of particle Geophys. Res. Lett. 23, 3445 (1995). fluxes that requires only a small number of satellite measurements as input parameters. The visualization tools developed have led to a better understanding of particle dynamics in Earth's magnetotail in the presence of turbulent wave fields (see first figure). They have also demonstrated how large electromagnetic pulses in the solar wind can interact with the magnetosphere to increase the population of energetic particles and even form new radiation belts (see second figure). The work performed in this project has application to auroral, iono- spheric, and magnetospheric phenom- TICK HARKS EVERY 18 RE ena, to plasma kinetics, transport, and impurities, and to plasma waves, oscillations, and instabilities.

Effect of a turbulent wave on the trajectory of a 100-eVproton with an initial pitch angle of 10° in the magnetotail. The upper two plots show the proton's trajectory in the absence of turbulence in (a) the x-z and (b) x-y planes (x corresponds to the sun-Earth direction and is the horizontal axis in each panel, z points to the north, and y is the cross-tail direction). The small figures to the left show the orientation of the magnetic field. In these two plots, the proton's motion is essentially adiabatic, combining gyration, bounce, and magnetic-field-gradient drift motion. The lower two plots show how a single monochromatic wave with an amplitude of 10 mV/m affects the proton's trajectory: the proton is (c) chaotically scattered in the current sheet region (near z = 0) and (d) drifts much farther in the direction of the cross- tail electric field, increasing its energy.

~~210 Los Alamos FY1996 LDRD Progress Report Proton flux~~

Energy (MeV) Calculation of the proton flux that results from a large solar wind storm. The plot shows the flux intensity (white is most intense, dark is less intense) as a function of energy and of the L shell (a ratio given in Earth radii). Such plots can be compared with data obtained directly from spacecraft, such as NASA's CRRES satellite.

Neutron Star Evolution and Emission Publications Abney, M., and R.I. Epstein, "Ekman Pumping in Astrophysical Bodies," /. Richard Epstein Fluid Mech. 312, 327 (1996). We have studied the physics of The second focus was the interac- Abney, M., R.I. Epstein, and A. V. compact stellar objects. Our research tions among stars in crowded regions Olinto, "Observational Constraints on has focused on three areas: the of galaxies, such as near galactic the Structure and Dynamics of Vela," internal dynamics of neutron stars, centers. We discovered that high- Astrophys. J. 466, 91 (1996). their interactions with other stars, and velocity collisions between red-giant Epstein, R.I., B.C. Edwards, M.I. the development of new techniques stars and compact objects led to Buchwald, et al., "Observations of for observing them. The first focus of significant mass loss. These results our research has been the anomalous appear to explain the puzzling dearth Laser-Induced Fluorescent Cooling of behavior of pulsars—spinning, of red supergiants near the center of a Solid," Nature 377, 500 (1995). strongly magnetized neutron stars. our galaxy and may provide an Link, B., and R.I. Epstein, "Statistics We found that the observed sudden explanation for the source of mass of Gamma Ray Burst Temporal changes in the star's spin rate, so- that falls into the massive black holes Asymmetry," Astrophys. J. 466, 764 called "glitches," may be due to in quasars. (1996). cracking of the star's hard crust that The third focus was the develop- Link, B., and R.I. Epstein, produces heat, thereby altering the ment of a laser-powered cryogenic "Thermally-Driven Neutron Star spin rate of the star's superfluid cooler for spaceborne astronomical Glitches," Astrophys. J. 457, 844 interior. Additionally, we found that observations. Such reliable and long- (1996). the star's behavior after a glitch lived devices would facilitate sensitive reveals that the crust and liquid gamma-ray spectral observations of Van Riper, K.A., B. Link, and R.I. interior are threaded by a magnetic gravitationally shifted nuclear lines Epstein, "Vortex Creep and Thermal field of at least a trillion gauss. from the surface of neutron stars. Evolution of Neutron Stars," Astrophys. J. 448, 294 (1995).

Competency Development Projects—Geoscience, Space Science, and Astrophysics 21 Remote Sensing ScienceThrust: Publications Laser Remote Sensing Cooper, D., W. Eichinger, R. Ecke, et al., "Initial Investigations of Micro- Scale Cellular Convection in an Siegfried Gerstl Equatorial Marine Boundary Layer Revealed by Lidar," Geophys. Res. The focus of our work is to length scales, the large-scale structure Lett. 25 (1), 45 (1997). extend a Raman lidar system to the may have length and time scales Jacobson, A.R., and R. Sramek, "A measurement of atmospheric similar to those from linear stability Method for Improved Microwave- constituents such as aerosols and analysis of thermal convection in a Interferometer Remote Sensing of water vapor with unprecedented bounded thermal layer. Analysis Convective-Boundary-Layer- accuracy and range resolution. suggests that the large-scale motions Turbulence, Using Water Vapor as a This work will be applied to non- of the equatorial MABL are consis- Passive Tracer" (to be published in proliferation and environmental tent with weakly turbulent, small- Radio ScL). boundary-layer science. Upgrades scale Rayleigh-Benard-like convective to the system included the addition processes. To address these important of a line-narrowed Nd: YAG laser issues, we will perform future lidar for temperature measurements and experiments capable of resolving the improving the command and temporal behavior of the equatorial control software. To understand MABL. the measurements, we are develop- In a further complementary effort, ing a microscale boundary-layer we developed an innovative method model with 2-m resolution. We for determining water-vapor-column fielded the upgraded lidar system irregularities by microwave interfer- in a central Pacific experiment, ometry. This new method exploits and we are using the data to archival radioastronomical data from validate the high-resolution the Very Large Array. microscale boundary-layer model. In March 1996, we used the advanced scanning Raman lidar to quantify processes associated with the ocean-atmosphere interface, including intermittency and coherent atmospheric features in the "warm pool" of the tropical western Pacific near Manus Island. The data shows excellent vertical and horizontal, microscale spatial and temporal structure in the equatorial Marine Atmospheric Boundary Layer (MABL). The data included, for the first time, an observation of microscale cellular convective structures with hexagonal patterns associated with Rayleigh-Benard-like cells (see the accompanying figure). To characterize the structures involved with the mass-energy -540 -S30 -6S0 -soo exchange at the ocean-atmosphere Range (m) interface, we used the scanning Raman lidar to image the three- A horizontal Raman lidar scan of water vapor acquired 10 m above the ocean dimensional structures found in surface on March 26, 1996, in the tropical western Pacific near Manus Island. the surface layer of the MABL. Although the atmospheric boundary layer is turbulent on small

212 Los Alamos FY1996 LDRD Progress Report Development of the First Nonhydrostatic, ing an IBM R-6000 workstation, a Cray Y-MP, and a highly parallel CM- Nested-Grid, Grid-Point Global 5. All of the necessary physical algorithms have been developed, Atmospheric Modeling System on including cloud and radiation Parallel Machines parameterizations, boundary layer treatment, and a soil module.

Chih-Yue J. Kao Publications All of the existing global atmo- modeling system (GAMS) with state- Kao, C.-Y.J., A. Quintanar, MJ. spheric models suffer from one or of-the-science physics and chemistry. Newman, et al., "Climate Simulations more of the following shortcomings: This highly modularized, self- with NCAR CCM2 Forced by Global (1) lack of an interactive nested-grid calibratable system will also provide a Sea Surface Temperature in 1950- capability, which makes it difficult to unique testbed for high-performance 1989," J. Climate 9, No. 12 (1996;. evaluate the regional impact; computing architecture. (2) spherical spectral representation We have successfully tested a Reisner, J., and C.-YJ. Kao, (as opposed to grid-point finite- global reduced-grid system in GAMS "Efficiency of a Forward-in-Time difference) of model variables, which and the lower boundary conditions in Shallow Water Code on a Sphere" (to hinders model performance on terms of sea surface temperature and be published in Parallel Computation parallel machines; and (3) use of the orography in the model. We have also Fluid Dynamics). hydrostatic approximation, which studied the intrinsic difference Smith, W.S., and C.-Y.J. Kao, makes the models potentially ill- between the hydrostatic and non- "Numerical Simulations of Observed posed. As a result, no atmospheric hydrostatic global models and are Arctic Stratus Clouds Using a Second- model is capable of simulating the full preparing a manuscript on this work. Order Turbulence Closure Model," /. range of spatial scales of atmospheric We have tested many three-dimen- Appl. Meteorol. 1,47-59 (1996). circulations from global-scale wave sional elliptical equation solvers to disturbances to microscale plume find a fast convergence rate of the Smith, W.S., and C.-Y.J. Kao, dispersion. pressure solution and decided to use "Stratocumulus-Capped Boundary The goal of this work is to develop the Conjugate Gradient method. Layer and its Diurnal Variation," Monthly Weather Review 8,1803-1816 a nested-grid, global atmospheric Our prototype model runs on a wide range of computer platforms, includ- (1996).

Production and Application of the calibration methods, we analyzed data collected during the 1995 Coastal High-Specific-Activity Si-32 Ocean Processes research cruise in Monterey Bay (sponsored in part by the National Science Foundation and Dennis R. Phillips the Monterey Bay Aquatic Research Institute). We completed and submit- In this project we have worked to carbon dioxide. By correlating the ted for publication two papers that produce the radionuclide Si-32 with data from our silicate-uptake studies describe the methods and the results unusually high specific activity and to with data from studies on the uptake of our experiments. develop methods for using Si-32 in of other essential nutrients, such as oceanographic field research on bicarbonate, inorganic nitrogen, and factors affecting the global climate. inorganic phosphorus, we can provide Publications In collaboration with researchers important information on the role of Brzezinski, M.A., and D.R. Phillips, from the University of California at diatoms in the global climate. Fur- "Evaluation of Si-32 as a Tracer for Santa Barbara, we developed biologi- thermore, current theories indicate Measuring Silica Production Rates in cal oceanographic experiments using that silicate may be the limiting Marine Waters" (to be published in Si-32 as a tracer to measure silicate nutrient in some important ocean Limnology and Oceanography). uptake by diatoms, siliceous phy- bodies, and our data from this project toplankton that require silicate as a can be used to test such models. Brzezinski, M.A., and D.R. Phillips, nutrient. Because of their sheer This year we refined our radio- "Silica Production in the Monterey, volume, the diatoms sequester analytical techniques, focusing on California, Upwelling System" significant amounts of atmospheric calibration methods. After validating (submitted to Limnology and Oceanography).

~~Competency Development Projects—Geoscience, Space Science, and Astrophysics 213 Remote Sensing Science Thrust: Hyperspectral Sensing~~

~~Siegfried Gerstl~~

Our goal is to develop detector technologies using hundreds of 0.12- Plume against sky narrow spectral bands for remote Clean sky at same elevation sensing. We are concentrating on the i 278 K blackbody spectrum infrared portion of the solar spectrum at hyperspectral resolution. We have made proof-of-concept measurements with a modified Fourier transform infrared (FTIR) spectrometer, identifying gaseous species in plumes from passively degassing volcanoes. We used a combination of (1) passive remote sensing with the FTIR spectrometer for multiple species concentrations and/or ratios and (2) active remote sensing with the elastic lidar data to remotely quantify (10% error) plume species fluxes. We are 4=5 20x10 - using these methods in parallel with o traditional COSPEC, a correlation O) spectrometer operating in the solar CM ultraviolet (for SO2 flux), and direct sampling methods (for total chemical composition) to obtain ground-truth I measurements of the new techniques. O c We successfully field-tested these .S techniques at the White Island and ca Ruapehu volcanoes in New Zealand. DC We detected the White Island plume at a distance of 50 km and made 800 1000 1200 1400 routine measurements at 6 km from Wavenumber (cm"1) Ruapehu. We easily identified both H2O and SO2 in the plumes of both Passive FTIR spectra of the Mt. Ruapehu plume on May 10, 1996, obtained volcanoes from distances up to 6 km. from a distance of 6 km. (Top) Radiometrically calibrated long-wave infrared The first figure shows the SO2 and H2O spectrum of the volcanic plume viewed against clear sky (heavy line) compared spectra obtained at Ruapehu. While the with a spectrum of a segment of sky at the same elevation angle but without any standard HgCdTe detector provides plume (fine line). For reference, the dashed line shows a blackbody spectrum at optimum performance in the long-wave the ambient air temperature of 278 K. The most prominent divergence of the 1 infrared region (8-12 |jm), the addition two spectra, the broad double-peaked feature extending from 1100 to 1200 cmr of an InSb detector allowed us to obtain (9 to 8.3 jim), is due to SO2 in the plume. The bottom figure shows the high-quality spectra in the 3-5 |jm difference between the two spectra in the top figure. The many sharp lines 1 region, thus permitting the detection of throughout the 800-1000 cm' region are due to water vapor. HC1 in the White Island plume from a distance of 1 km (see the second figure). All FTIR measurements were completely passive, i.e., they did not rely on artificial infrared sources or

214 Los Alamos FY1996 LDRD Progress Report known emissions of radiation from hot rocks or lava. Our detection and quantification of volcanic HC1 by completely passive means is a first and opens up a much greater range of volcanoes for study. The incorporation of absolute radiometric calibration by means of specially constructed, portable, blackbody reference sources is HCI another first performed in our project. 0.3- Radiometrically calibrated measure- White Island Plume ments, combined with simultaneous (Plume minus Sky) u 4/26/96 H COSPEC measurements of SO2 path densities, allow plume temperature measurement. This, in turn, allows accurate determination of the concen- 0.2- SO trations of the other gases from the infrared spectra. We found SO2/H2O ratios determined in this manner to be (0 in good agreement with those (0 obtained from direct sampling of the fumerole gases. 0.1 -I

Publications HCI Reference Spectrum 200 ppm.m in 1 atm N Christenson, B., J. Lindsay, F. Goff, et 2 al., "Direct Sampling and COSPEC Results Supporting FTIR and LIDAR 0.0- Measurements of Volcanic Emission at White Island and Ruapehu SO2 Reference Spectrum Volcanoes," EOS Trans. Amer. 800 ppm.m in 1 atm N2 Geophys. Union 77, F830 (1996). Cottingame, W, D. Pettit, S. Love, et I I al, "Integrated LIDAR/UV/IR Remote 2500 2600 2700 2800 2900 3000 Sensing of Volcanic Emissions at Wavenumber (cm-U ) White Island and Mt. Ruapehu, New Zealand," EOS Trans. Amer. Geophys. Passive FTIR of the White Island plume, midwave infrared region, illustrating Union 11, F801 (1996). the first completely passive quantification of the ratio of HCI to SO2 in a volcanic plume. Upper curve shows the plume-sky difference, as in the first Love, S., D. Pettit, W. Cottingame, et figure, converted to emissivity using an estimated plume temperature of 310 K. al, "Integrated Infrared/UV/Lidar The lower two curves show laboratory reference spectra of HCI and SO2. Both Remote Sensing of Volcanic the broad SO2 feature and the regularly spaced sharp lines of HCI are clearly Emissions at White Island and Mt. evident in the plume spectrum. Ruapehu, New Zealand," EOS Trans. Amer. Geophys. Union 11, F802 (1996).

~~Competency Development Projects—Geoscience, Space Science, and Astrophysics 215 Studies of Dynamical Processes Affecting Global Climate~~

~~Charles Keller~~

The objective of this project is to polar stratospheric cloud interactions gain a fundamental understanding of with nitric acid trihydrate, a major the interactions between Earth's component in ozone depletion. atmosphere and its oceans. We are focusing on improving models of processes in four main areas: numerical physics, cloud representation, 500 mb Standing Waves (Cold Years) water vapor observations, and the heterogeneous chemistry of aerosols. 90N- We have made advances in applying approximate inertial manifolds (AIMs), a method of dealing with subgrid-scale physics, to numerical computations of ocean models. We have developed a finite-difference version of AIMs for the shallow-water model equation, resulting in a large decrease in computing time with no loss in accuracy. I I I I I |1 I I ! F | I I | I I | I I | I I | I I | I I Our implementation of the now 0 30E 60E 90E 130E 150E 180 150W 120W 90W 60W 30W 0 fully developed cloud parameteriza- CONTOUR FROM -250 to 150 by 50 I I 1 I I I I I I I I ! L tion package, SUNAS, into a global circulation climate model, CCM2, is showing remarkable improvement in simulating the hydrologic cycle (see first figure). Other parameters improved include the following: zonally averaged precipitation; overall cloudiness and precipitation patterns, particularly in the Amazon basin and the western Pacific; and persistent stratiform cloud decks observed in the ~| I I ] i I | I f|l i | I 1 | eastern ocean basins. 0 30E 60E 90E 120E 150E 180 150W 120W 90W 60W 30W 0 CONTOUR PROM -150 to 150 by 50 We have used our shipboard lidar observations of water vapor in the equatorial Pacific to develop the first horizontal, two-dimensional maps of evaporative features in the ocean/ atmosphere boundary layer. These maps show alternating patterns of dry and moist air indicative of rising and descending currents seen in laboratory convection experiments (see second figure). I I | I I | I I | I I | I We have used advanced laser 0 30E 60E 90E 120E 150E 180 150W 120W 90W 60W 30W 0 techniques to study heterogeneous CONTOUR FROM -200 to 150 by 50 processes on thin films that simulate These simulations show departure of 500 mbfrom the zonally averaged stratospheric and tropospheric aerosol geopotential height (analogous to pressure) for cold years. These simulations surfaces. In addition, we are quantify- were made using global circulation models (a) SUNAS and (b) CCM2 and are ing adsorption processes mimicking compared with data from (c) observations.

216 Los Alamos FY1996 LDRD Progress Report This plan view of water vapor concentrations 10 m above the equatorial Pacific Ocean shows patterns of dry and moist columns reminiscent of classic convection.

~~i85F -SSO -5S0 -5*0 -&5O -650 -640 -830 -620 -610 -600 Range (m)~~

Publications Elliott, S., X. Zhao, R.P. Turco, et al., Shao, Z., and E.S. Titi, "Photochemical Numerics for Global "Parameterizing the Global Attractor Chen, F., and M. Ghil, "Interdecadal Scale Modeling: Fidelity and GCM of the Navier-Stokes Equations by Variability in a Hybrid Coupled Testing" (to be published in Mon. Nodal Values" (to be published in Ocean-Atmosphere Model" 'Weather Rev. A). Numerical Functional Analysis and (submitted to /. Phys. Optimization). Oceanography). Henson, B.F., K.R. Wilson, and J.M. Robinson, "A Physical Adsorption Smith, W.S., and C.-Y.J. Kao, Chen, E, and M. Ghil, "Interdecadal Model of the Dependence of C1ONO "Numerical Simulations of Arctic Variability of the Thermohaline 2 Heterogeneous Reactions," Geophys. Stratus Clouds Using a Second Order Circulation and High-Latitude Res. Lett. 23, 1021 (1996). Turbulence Closure Model," J. Appl. Surface Fluxes" (submitted to J. Phys. Meteorol. 1,47(1996). Oceanography). Jones, D., and E.S. Titi, "Cl Approximating Inertial Manifolds for Smith, W.S., and C.-Y.J. Kao, "Using Cooper, D.I., W.E. Eichinger, S. Barr, Dissipative Nonlinear Equations" a Turbulence Radiative-Convective et al., "High-Resolution Properties of (submitted to J. Diff. Eqns.). Model to Study the Cloud/Radiation the Equatorial Pacific Marine Interaction with the FIRE Data," Mon. Atmospheric Boundary," /. Atmos. Jones, D., L. Margolin, and E.S. Titi, Weather Rev. 8, 1803 (1996). Sci. 53,2054(1996). "On the Effectiveness of the Approximate Inertial Manifolds— Zhao, X., and R.P. Turco, Elliott, S., and F.S. Rowland, "Methyl Computational Study" (to be "Parameterization of Halide Hydrolysis Rates in Natural published in Theor. Comput. Fluid Photodissociation Rate for Waters" (submitted to J. Atmos. Dynamics). Stratospheric Three Dimensional Chem.). Modeling" (submitted to /. Geophys. Kao, C.-Y.J., A. Quintanar, M.J. Elliott, S., R.J. Cicerone, and R.P. Res.). Newman, et al., "Climate Simulations Turco, "Influence of the Hetero- with NCAR CCM2 Forced by Global Zhao, X.-R, R.P. Turco, et al., geneous Reaction HC1 + HOC1 on an Sea Surface Temperatures 1950- "Numerical Simulation of the Ozone Hole Model with Hydrocarbon 1989" (to be published in /. Climate). Dynamical Response of an Arctic Additions" (to be published in J. Vortex to Aerosol Associated Geophys. Res.). Noble, C.A., and K.A. Prather, "Real- Chemical Perturbations in the Lower time Measurement of Correlated Size Elliott, S., R.P. Turco, X.P. Zhao, et Stratosphere," Geophys. Res. Lett. 12, and Composition Profiles of al., "Photochemical Numerics for 1525 (1996). Individual Atmospheric Aerosol Global Scale Modeling: Fidelity and Particles," Environ. Sci. Technol. 30, GCM Testing," /. Appl. Meteorol. 34, 2667 (1996). 694 (1995).

Competency Development Projects—Geoscience, Space Science, and Astrophysics 217 Transport Processes in Space Plasmas Publications Birn, J., "Magnetotail Stability and Dynamics: Progress 1991-1993," Joachim Birn Surveys in Geophys. 16, 299 (1995). In this project we combined efforts Birn, J., and M. Hesse, "Details of in space-data analysis with theory and Current Disruption and Diversion in laboratory and computer simulations 1000 Simulations of Magnetotail to advance the fundamental under- Dynamics," /. Geophys. Res. 101, standing of solar-terrestrial interaction 15345 (1996). through space-plasma processes. Birn, J., S.P. Gary, and M. Hesse, Two-dimensional simulations of the "Microscale Anisotropy Reduction magnetopause have shed further light and Macroscale Dynamics of the on the nature of surface waves and Magnetotail," J. Geophys. Res. 100, their contribution to ion diffusion in 19211(1995). this boundary region. In these simulations a curved bow shock, its Birn, J., M. Hesse, and S.P. Gary, associated foreshock, and a turbulent "The Role of Microprocesses in magnetosheath are formed as shown Macroscale Magnetotail Dynamics," in the first figure. These simulations in Cross-Scale Coupling in Space combine proper accounting for the Plasmas, J.L. Horwitz et al., Eds. microphysics with the provision of a (Geophys. Monogr. Ser., American global perspective of the boundary Geophysical Union, Washington, DC, region. 1995), Vol. 93, pp. 275-285. We have also performed the first Birn, J., M. Hesse, and K. Schindler, high-resolution, full-particle (implicit) "MHD Simulations of Magnetotail simulations of the guide field tearing Dynamics," /. Geophys. Res. 101, at the magnetopause, using large ion- 100 200 300 12939 (1996). to-electron mass ratios. We found that, in sharp contrast to previous X (c/cop) nonlinear theories, the multimode Bow shock structure in a large-scale, tearing islands can grow to large two-dimensional simulation of solar amplitudes, resulting in large trans- wind-magnetosphere interaction. The port of magnetic flux and mixing of figure shows the intensity of the the magnetosheath and magneto- magnetic field component By (as spheric plasmas as seen in the second indicated by the color bar) in the figure. We developed a new nonlinear coordinate frame x, y. The y-axis theory of the tearing mode at the units (c/copj represent the ion inertial magnetopause. scale length. We have further studied the consequences of the electromagnetic proton anisotropy instability in the terrestrial magnetosphere. We used one-dimensional hybrid computer simulations to examine the velocity distribution response of both hot (~10-keV) and warm (~10-eV) protons. Results are that the enhanced fluctuations from this instability not only preserve the initially bi-Maxwellian character of a hot- proton distribution, but also drive an initially nongyrotropic hot distribution Y (c/

218 Los Alamos FY1996 LDRD Progress Report Chow, V.W., and M. Rosenberg, Krauss-Varban, D., H. Karimabadi, Rosenberg, M., and N.A. Krall, "Low "Electrostatic Ion Cyclotron and N. Omidi, "Kinetic Structure of Frequency Drift Instabilities in a Instability in Dusty Plasmas," Planet. Rotational Discontinuities: Impli- Dusty Plasma" (submitted to Phys. Space Sci. 43, 613(1995). cations for the Magnetopause," /. Plasmas). Geophys. Res. 100, 11981 (1995). Chow, V.W., and M. Rosenberg, Rosenberg, M., and D.A. Mendis, "Electrostatic Ion Cyclotron Kuo, H., C.T. Russell, and G. Le, "UV-Induced Coulomb Crystal- Instabilities in Negative Ion Plasmas" "Statistical Studies of Flux Transfer lization in a Dusty Gas," IEEE Trans. (submitted to Phys. Plasmas). Events,"/. Geophys. Res. 100, 3513 Plasma Sci. 23, 177 (1995). (1995). Convery, P.D. and S.P. Gary, Russell, C.T., "The Structure of the "Electromagnetic Proton Cyclotron Le, G., C.T. Russell, et al., "ISEE Magnetopause," in Physics of the Ring Instability: Threshold and Observations of the Low Latitude Magnetopause, P. Song et al., Eds. Saturation" (to be published in J. Boundary Layer for Northward (American Geophysical Union, Geophys. Res.). Interplanetary Magnetic Field: Washington, DC, 1995), pp. 81-98. Implications for Cusp Reconnection" Elphic, R.C., "Observations of Flux Russell, C.T., "A Study of Flux (submitted to J. Geophys. Res.). Transfer Events: A Review," in Transfer Events at Different Planets," Physics of the Magnetopause, P. Song Lindsay, G.M., J.G. Luhmann, et al., Adv. Space Res. 16, 4159 (1995). et al., Eds. (American Geophysical "CME Characteristics in the Inner Winske, D., and N. Omidi, "Diffusion Union, Washington, DC, 1995), pp. Heliosphere: Relationship to Corona at the Magnetopause: Hybrid 225-233. Velocity" (submitted to /. Geophys. Simulations," J. Geophys. Res. 100, Res.). Gary, S.P., V.M. Vazquez, and D. 11923(1995). Winske, "Electromagnetic Proton Maravilla, D., K.R. Flammer, and Winske, D., V.A. Thomas, and N. Cyclotron Instability: Proton Velocity D.A. Mendis, "On the Injection of Omidi, "Diffusion at the Distributions," /. Geophys. Res. 101, Fine Dust from the Jovian Magnetopause: A Theoretical 13327 (1996). Magnetosphere," Astrophys. J. 438, Perspective," in Physics of the 968 (1995). Gary, S.P., L. Yin, and D. Winske, Magnetopause, P. Song et al., Eds. "Electromagnetic Proton Cyclotron Maravilla, D., K.R. Flammer, and (American Geophysical Union, Instability: Heating of Cool D.A. Mendis, "The Nature of the Washington, DC, 1995), p. 321. Magnetospheric Helium Ions," Ann. Orbits of Charged Dust Injected into Winske, D., S.P. Gary, et al., "Ion Geophys. 14, 1 (1996). the Jovian Magnetosphere during the Heating in a Dusty Plasma Due to the Tidal Break-Up of Comet Shoemaker- Gary, S.P., M.F. Thomsen, et al., Dust/Ion Acoustic Instability," Levy 9" (submitted to Astrophys. "Electromagnetic Proton Cyclotron Geophys. Res. Lett. 21, 2069 (1995). Space Sci.). Instability: Interactions with Yur, G., H.U. Rahman, J. Birn, et al., Magnetospheric Protons," /. Geophys. McKean, M.E., N. Omidi, and D. "An Improved Simulation Facility for Res. 100, 21961 (1995). Krauss-Varban, "Wave and Ion Magnetospheric Modelling," /. Evolution Downstream of Quasi- Hesse, M., J. Birn, et al., "MHD Geophys. Res. 100, 23727 (1995). Perpendicular Bow Shocks," J. Simulations of the Transition of Geophys. Res. 100, 3427 (1995). Yur, G., H.U. Rahman, J. Birn, et al., Magnetic Reconnection from Closed "Magnetotail Structures in a to Open Field Lines," /. Geophys. Omidi, N., and D. Winske, "Kinetic Laboratory Magnetosphere" Res. 101, 10805 (1996). Structure of the Magnetopause as (submitted to /. Geophys. Res.). Inferred from 1-D Hybrid Hesse, M., D. Winske, et al., "Hybrid Simulations," /. Geophys. Res. 100, Modeling of the Formation of Thin 11935(1995). Current Sheets in Magnetotail Configurations," J. Geomagn. Rosenberg, M., and N.A. Krall, Geoelec. 120, 749 (1996). "Modified Two-Stream Instabilities in Dusty Space Plasmas," Planet. Space Karimabadi, H., D. Krauss-Varban, Sci. 43, 619 (1995). and N. Omidi, "Kinetic Structure of Intermediate Shocks: Implications for the Magnetopause," J. Geophys. Res. 100, 11957(1995).

Competency Development Projects—Geoscience, Space Science, and Astrophysics 219 Physical Properties and Mantle Dynamics Cyan, H., J.D. Carnes, and O.L. Anderson, "Thermal Properties of Forsterite, including Cv, Calculated Thomas Shankland from rxfcj. through the Entropy" (to be published in J. Phys. Chem. Solids). Understanding the physical Publications properties of minerals and rocks Guyer, R.A., and K.R. McCall, Abramson, E., J.M. Brown, and J. reveals processes in the earth and "Capillary Condensation, Invasion Zaug, "Elastic Constants of San events in its history. Because plan- Percolation, Hysteresis, and Discrete Carlos Olivine to 17 GPa" (submitted etary interiors are difficult to assess, Memory," Phys. Rev. B 54, 18 (1996). to /. Geophys. Res.). research methods that combine Guyer, R.A., and K.R. McCall, sophisticated techniques and associ- Anderson, O. L., "Anharmonicity of "Superfluid Avalanches" (submitted ated theory are essential for interpret- Forsterite and the Thermal Pressure of to Phys. Rev. Lett.). ing geophysical field measurements in Insulators" (to be published in terms we need for improving our Geophys. Res. Lett.). Guyer, R.A., K.R. McCall, G.N. understanding of Earth's temperature, Boitnott, et al., "Quantitative composition, stress state, history, and Blackman, D.K., J.M. Kendall, P.R. Implementation of Preisach- hazards. One objective of our project Dawson, et al., "Teleseismic Imaging Mayergoyz space to Find Static and is to study minerals and rocks using of Subaxial Flow at Mid-Ocean Dynamic Elastic Moduli in Rock" materials science methods; another is Ridges: Travel-Time Effects of (submitted to J. Geophys. Res.). to develop new research methods, Anisotropic Mineral Texture in the Hearn, I, G. Humphreys, K. Deuker, such as high-pressure techniques, Mantle" (to be published in Geophys. et al., "Effect of Anisotropy on the rock physics computational codes, J. Int.). Development of Oceanic and nuclear-based analyses. Brown, J.M., and LJ. Slutsky, Lithosphere" (submitted to /. In the past year, we continued to "Thermoelastic Behavior of Olivine Geophys. Res.). refine our transient optical-grating under Upper Mantle Conditions of apparatus, which we have used to Pressure and Temperature" (submitted Kadish, A., P.A. Johnson, and B. determine sound velocities in fluids to /. Geophys. Res.). Zinszner, "Evaluating Hysteresis in and water ice at high pressures, and to Earth Materials Under Dynamic Chai, M., and J.M. Brown, "Effects of fine-tune our single-crystal x-ray Resonance" (to be published in J. Static Non-hydrostatic Stress on the R diffraction apparatus, which can be Geophys. Res.). used to analyze materials at extremely Lines of Ruby Single Crystals" (to be published in Geophys. Res. Lett). Lutterotti, L., S. Matthies, H.R. Wenk, high pressures and temperatures. et al., "Combined Texture and In addition, we have designed Chai, M., and J.M. Brown, "Elastic Structure Analysis of Deformed computational tools for forward and Constants of a Pyrope-Grossular- Limestone from Time-of-Flight inverse modeling of complex stress- Almandine Garnet to 20 GPa" Neutron Diffraction Spectra" (to be strain histories of rocks. Furthermore, (submitted to Geophys. Res. Lett.). published in J. Appl. Phys.). by analyzing the ratio of tungsten to thorium in samples of bulk silicate Chai, M., J.M. Brown, and L.J. McCall, K.R., and R.A. Guyer, "A rocks, we determined that tungsten Slutsky, "Elastic Constants of New Theoretical Paradigm to depletion is of the same order as Kilbourne Hole Orthopyroxene to Describe Hysteresis, Discrete depletion of the iron and nickel that 12.5 GPa" (submitted to J. Geophys. Memory and Nonlinear Elastic Wave form Earth's metallic core. This result Res.). Propagation in Rock," Nonlinear agrees with the hypothesis that Earth Chai, M., J.M. Brown, and L.J. Processes in Geophysics 3, 89 (1996). formed heterogeneously, that is, with Slutsky, "Thermal Diffusivity of McCall, K.R., R.A. Guyer, L. Zhu, et dense materials accreting ahead of Mantle Minerals" (to be published in al., "Experimental Determination of lighter ones. And finally, we have Phys. Chem. Minerals). Dynamic Elastic Properties of Rock obtained pressure-volume-tempera- Chai, M., J.M. Brown, and Y. Wang, from Quasistatic Measurements," in ture equation-of-state measurements Rock Mechanics: Tools and on single crystals and seismic velocity "Yield Strength, Slip Systems and Deformation Induced Phase Techniques, M. Aubertin, F. Hassani, measurements on several dense and H. Mitri, Eds. (Balkema, minerals, which enables us to better Transition of San Carlos Olivine up to Transition Zone Pressure at Room Rotterdam, the Netherlands, 1996), p. understand the composition of Earth's 147. outer 1000 km. Temperature" (submitted to US-Japan Research at High Pressure).

220 Los Alamos FY1996 LDRD Progress Report Newsom, H.E., K.W.W. Sims, P.D. Shankland, T.J., A.G. Duba, E.A. Zhao, Y, D. Schiferl, and T.J. Noll Jr., et al., "The Abundance of W Mathez, et al., "Increase of Electrical Shankland, "Thermoelasticity of in the Bulk Silicate Earth: Constraints Conductivity with Pressure as an MgSiO3 Orthoenstatite," Phys. Chem. on Core Formation," Geochim. Indicator of Conduction through a Minerals 22,393 (1996). Cosmochim. Acta 60, 1155 (1996). Solid Phase in Mid-Crustal Rocks" Zhao, Y, D. Schiferl and J.M. Zaug, (to be published in /. Geophys. Res.). Pearson, A., and H. R. Wenk, "EBSP "RSCU-SOS: A Rapid Intensity Orientation Imaging of Quartz in a Wang, Y., M. Chai, and J.M. Brown, Searching and Centering Routine for Granodiorite Mylonite from the Santa "Deformation Induced Phase Single Crystal Diffraction Studies at Rosa Mylonite Zone, Southern Transformation in San Carlos Olivine Simultaneous High Pressures and California" (submitted to Texture and at Room Temperature" (submitted to Temperatures," /. Appl. Cryst. 29, 71 Microstructure). Geophys. Res. Lett.). (1996). Ragan, D.D., D. Schiferl, and D. Wenk, H.R., G. Canova, Y. Brechet, et Zhao, Y., R.B. VonDreele, TJ. Clarke, "Silicone Fluid as a Pressure al., "A Deformation-based Model for Shankland, et al., "Thermoelastic Medium in Diamond-Anvil Cells" Recrystallization" (to be published in Equation of State of Jadeite (submitted to Rev. Sci. lustrum.). Acta Metall. Mater.). NaAlSi2O6: An Energy-Dispersive Study" (to be published in Geophys. Schiferl, D. and Y. Zhao, High- Res. Lett.). Pressure/High-Temperature Diamond- Anvil Cell System for Single-Crystal X-Ray Diffraction" (submitted to Rev. Sci. lustrum.).

~~Competency Development Projects—Geoscience, Space Science, and Astrophysics 221~~

~~Nuclear and Particle Physics~~

~~Advanced Research Capabilities for Neutron Science and Technology— Neutron Polarizers~~

~~Robert Robinson~~

The purpose of this work is to apply the spectrometers or diffractometers the expertise at both Los Alamos and at MLNSC, although such implemen- at the National Institute of Standards tation will not be covered by the and Technology (NIST) in polarized project. If successful, our work would gaseous 3He to research the develop- allow significant improvement in ment of new laser-driven 3He capability in neutron scattering to be polarizers suitable for condensed- implemented at Los Alamos. matter research at the Manuel Lujan So far, we have purchased all the Jr. Neutron Scattering Center instrumentation necessary to polarize (MLNSC) at Los Alamos. Helium-3 a cell and measure its polarization. polarizers are the technology of We now have three 16-W diode laser choice for broad-band applications at arrays and are collaborating with wavelengths below 2 A and for large- NIST, Princeton University, and the divergence applications at all neutron Tri-University-Meson Facility (British wavelengths. Columbia) for cell fabrication and This project involves developing the filling. Together we chose a cell experimental design, including the geometry suitable for condensed- laser, glass cell, magnetic shielding matter applications and assembled all and neutronics, then testing the cell the components for the neutron-beam both on the surface profile analysis experiment. We requested beam time reflectometer (SPEAR) and on a on the SPEAR at MLNSC in prepara- diffractometer. By the end of the tion for testing the polarizer early next project, we expect to know enough to year. implement this technology on any of

~~Competency Development Projects—Nuclear and Particle Physics 223~~

~~Biosciences~~

Solution Structure of the protein in deuterated form. We have also demonstrated that we can reconsti- cAMP-Dependent Protein Kinase tute a catalytically competent holoenzyme from the expressed components, and we have measured x-ray scattering //// Trewhella data from free C and R subunits as well as reconstituted holoenzyme with Understanding the molecular basis Protein kinase is a dimer of dimers deuterated and nondeuterated R. for biochemical regulation is a (R C ), where C and R designate the 2 2 We are preparing for a neutron fundamental problem in human catalytic and regulatory subunits, contrast-variation study on the medicine. Unregulated or uncoordi- respectively. Free C is fully competent holoenzyme with deuterated R. This nated activities generally lead to to catalyze the phosphorylation of experiment will yield the shapes and pathological conditions and, if not proteins. The catalytically inactive disposition of the R and C compo- corrected, to uncontrolled prolifera- holoenzyme is activated when cAMP nents in the complex, giving the first tion or cell death. In this project, we binds to R, which exposes the structural insights into the nature of are addressing this fundamental catalytic site on C, allowing access to the interactions between R and C. question by studying the cAMP- protein substrates. dependent protein kinase, which has The three-dimensional crystal served as the central model for structures of free C and R have been Publications modulation of cell function by protein solved, providing a basis for modeling Mitchell, R., G.A. Olah, W. Gu, et al., phosphorylation, one of the most the holoenzyme using scattering data. "The Solution Structure of cGMP- We have succeeded in cloning and important mechanisms of cell Dependent Protein Kinase (PKG) and expressing both C and R and, in the regulation. Its Alteration," Biophys. J. 70, 432 case of R, have produced the expressed (1996).

Development of Biosensors and Bioprobes reactions with ligands in the glasses and the spectroscopy and kinetics of relevant Based on Spectroscopic Monitoring of myoglobin reactions in solution. Enzymes and Other Proteins Encapsulated Techniques were developed for observing the kinetics of reactions at elevated in Sol-Gel Glasses pressures of gaseous ligands.

William Woodruff Publications Bailey, J. C. James, and W. Woodruff, This project sought to explore and Our specific objectives were (1) to "Flow-Flash Kinetics of O2 Binding to develop new types of biosensors and characterize encapsulated biomolecules Cytochrome c Oxidase at Elevated bioprobes in biotechnology. Biosensors and their interactions with a porous [O2]: Observations Using High- detect and measure analytes using the glass matrix and monitor the effect of Pressure Stopped-Flow for Gaseous encapsulated biomolecules, while different processing conditions using Reactants," Biochem. Biophys. Res. bioprobes examine the encapsulated spectroscopy and kinetics, (2) to Commun. 220 (3), 1055-60 (1996). biomolecules to elucidate their similarly characterize interactions of physiological/biochemical functions or the encapsulated biomolecules with Decatur, S., S. Franzen, G. DePillis, et structures. Our goal was to apply potential substrates or ligands, and al., "Trans Effects in Nitric Oxide advanced spectroscopic methods to (3) to apply the above information in Binding to Myoglobin Cavity Mutant biosensors and bioprobes whose developing sensing elements for use in H93G," Biochem. 35 (15), 4939^-4 sensing elements consist of enzymes biosensors and bioprobes. Major results (1996). and other proteins encapsulated in included the characterization of optically transparent sol-gel glasses. encapsulated myoglobin and its

Competency Development Projects—Biosciences 225 Molecular Characterization of We hypothesize that spermine and spermidine (two components of the Flow-Sorted Mammalian Centromeres buffers) exchanged for proteins, resulting in compact chromosomal structures. L. Scott Cram, Los Alamos National Laboratory Utilizing a 10-mM MgSO4,10-mM Barbara Hamkalo, University of California, Irvine KC1,5-mM HEPES buffer (pH 8), the flow cytometer can sort chromosomes To better understand the fundamental Initial chromosome sorts, utilizing without any apparent loss of proteins. mechanisms underlying such cellular buffers developed by Los Alamos Inclusion of the reducing agent processes as the regulation of gene researchers for genomic cloning, dithiothreitol in the sorting buffer expression, differential condensation, resulted in samples devoid of detectable improves the resolution of chromo- and chromosome segregation, we are amounts of protein, although they somes during sorting without protein interested in isolating and identifying contained measurable amounts of loss. We can reproducibly observe a the proteins from the centromere region DNA. Based on a series of control large number of polypeptides, in of mammalian chromosomes. experiments, we determined that addition to the histones, by SDS-PAGE The goal of our project is to employ chromosomal proteins were being (sodium dodecyl sulfate-polyacryla- flow cytometry to isolate large quanti- displaced from the DNA into the mide gel electrophoresis) and by silver ties of both intact mouse chromosomes supernatant before sorting. An exten- staining gels containing proteins and a chromosome fragment derived sive analysis of each component in the released from approximately 200,000 from centromere regions to biochemi- sorting buffers showed that three chromosomes per lane. cally compare the protein composition components—EDTA, EGTA, and of the two fractions. This is a novel mercaptoethanol—were responsible for With the results of this study approach to identify proteins preferen- extracting all but a few chromosomal complete, we will now characterize tially associated with centromeres that scaffold proteins. This displacement these proteins and extend our methods could play a role in centromere higher- occurred despite the fact that by to recovering and characterizing order structure and/or function. fluorescence microscopy, the chromo- proteins from other chromosome types somes appeared to retain their structure. and regions.

Advanced Biomolecular Materials experiments. First we constructed a simple humidity oven with neutron- Based on Membrane-Protein/Polymer transparent windows for reflectivity studies. We prepared thin-film samples Complexation by spinning protein mixtures onto silicon wafers. To hydrate the films, we Gregory Smith placed each in this sealed oven with a reservoir of D2O (heavy water) and measured the room-temperature, The goal of this work has been to (2-D) self-assembly of the membrane neutron reflectivity at the High-Flux (1) develop a fundamentally new class protein bacteriorhodopsin. At high Beam Reactor at Brookhaven National of bioactive molecular films composed humidity, the ordered phase of this Laboratory. In each case, the of reconstituted and native, self- highly complex self-assembly exhibits reflectivity measurement was consis- assembled, membrane proteins scattering characteristics of a 2-D solid tent with a bare silicon surface. Upon combined with polymers and (2) apply with power-law decay of positional optical examination of the samples, we synchrotron-based, small- and wide- correlations. Two results of the x-ray found that the multibilayers had angle x-ray scattering to characterize scattering measurements are (1) the delaminated from the silicon substrate, the structure and phase behavior, the first measurements of a protein-lattice leaving droplets of sample on the interlayer and macromolecular forces, elastic rigidity, which is directly related surface. and the stability of the protein-shape of to the protein-protein interactions, and these new materials. These materials (2) an experimental demonstration of While the spinning technique shows can be used as biosensors, selective the limits on the resolution of the promise in preparing the films neces- filters, and light-to-chemical energy protein structure in 2-D protein crystal- sary for the reflectometry experiments, converters. lography (an expanding field because these results suggest that the films must We have completed the first series of of the recent success of techniques for be deposited on etched silicon, very high-resolution, synchrotron, x-ray preparing 2-D protein crystals). clean quartz, or surfaces that have been scattering studies of the purple mem- To enhance the structural work, we altered with silane to produce a high brane composed of a two-dimensional initiated a series of neutron degree of hydrophobicity.

226 Los Alamos FYI996 LDRD Progress Report Similarity Landscapes: An Improved at the RNA level. We have used our capabilities for rapid searches of the Method for Scientific Visualization of entire database in GenBank to examine the properties of microsatellites, Information from Protein and DNA regions of DNA that consist of multiple Database Searches repeats of a short (usually 2- to 6-base) sequence, in lower organisms. We have discovered that microsatellites are far Norman Doggett more prevalent in lower organisms, even prokaryotes, than had previously The focus of this project is to study separation of closely related viruses, been realized, that many of these the evolution of human and simian particularly HIV-1. This directional microsatellites occur in reading frames, immunodeficiency viruses (HTV). As evolutionary change is concentrated in and that a large fraction of them are the viral genomes diverge, it is possible short tripeptide motifs called sequons. polymorphic. Ten out of ten of the in- to monitor the ratio of meaningful to These sequons are sites of n- frame microsatellites examined in the silent changes at the RNA level and glycosylation, and the proteins of yeast Saccharomyces cerevisiae were determine the intensity of the selection retroviruses have unusually large polymorphic. that is operating on them. numbers of sequons. We have found This year we have developed a that sequons have evolved more rapidly method for distinguishing transitional in the more virulent HTV-1 than in the Publications and transversional changes of these two less virulent HTV-2, and calculation of Wills, C, A. Farmer, and G. Myers, types and find that both types of change the relative rates indicates that they "Rapid Sequon Evolution in HIV-1" often show a pattern of intense di- have evolved three times as rapidly (to be published in AIDS Res. Hum. rectional selection that has driven the compared with the rate of substitutions Retroviruses).

Formation of Drug-Bearing Vesicles interaction in improving oral drug efficacy. in Mixed Colloids of Bile Salts and Phosphatidylcholine Publications Hjelm, R.P., C. Schteingart, et al., Rex Hjelm "Form and Structure of Self- Assembling Particles of Monoolein- We are examining novel methods of interactions could be responsible for Bile Salt Mixtures," /. Phys. Chem. 99, forming drug-bearing liposomes. the bioavailability of oral drug formula- 16395 (1995). Liposomes have proven to be effective tions. Therefore, we are also studying Hjelm, R.P., P. Thiyagarajan, C. as intravenous delivery systems for the particle structure in simulations of Schteingart, et al., "Probing Self- insoluble drugs. We are studying the intestinal mixture to test whether Assembly in Biological Mixed systems that could potentially form the bile salt/phosphatidylcholine Colloids by SANS, Deuteration, and liposomes spontaneously, such as systems are good models of drug-bile Molecular Manipulation," in Neutrons biological mixed colloids, as a better interactions in the intestine. We are in Biology, B. Schoenborn and R. alternative to the presently used studying these systems using small- Knott, Eds. (Plenum Press, New York, mechanical means of liposome angle neutron scattering, supplemented 1996), pp. 175-190. production. Because liposomes are by light scattering. formed spontaneously in these systems, We have shown that the inclusion of Hjelm, R.P., P. Thiyagarajan, C. the formulations could be stored in dry therapeutic levels of the steroidal drugs, Schteingart, et al., "Structure of Mixed form and reconstituted by the addition cholesterol, progesterone, hydrocorti- Micelles Present in Bile and Intestinal of appropriate buffers, thus reducing sone, and deoxycorticosterone, does Content Based on Studies of Model the need for costly equipment and not affect liposome morphology. These Systems," Falk Symposium on Bile procedures and improving shelf life results support our theory that mixed Acids in Gastroenterology: Basic and considerably. We need to show the colloids have a valuable role in drug Clinical Advances 80,41 (1995). conditions and drugs that do not delivery. Further, we have shown that interfere with the spontaneous forma- particle morphology in bile salt/ Mang, J., and R.P. Hjelm, "SANS tion of liposomes. The study of these phosphatidylcholine particles is the Investigation of the Pressure and colloids also relates to the efficacy of same as that found in the intestine, Temperature-Dependent Structure of oral formulations, because drug-bile allowing us to test models of bile-drug the Salt Lecithin System" (to be published in Mol. Cryst. Liq. Cryst).

Competency Development Projects—Biosciences 227 Structural Biology of Disease-Associated Publications Chen, X., S.V.S. Mariappan, P. Catasti, DNA Repeats and Protein-DNA et al., "Hairpins Are Formed by the Complexes Involved in the Repair of Single DNA Strands of the Fragile X Triplet Repeats: Structure and DNA Damage Biological Implications," Proc. Natl. Acad. Sci. U.S.A. 92,5199 (1995). Goutam Gupta Chen, X., S.V.S. Mariappan, S. Smith, et al., "Hairpin Induced Slippage and This work focused on examining complementary strand) under physi- Methylation of the Fragile X Repeats" the structural biology of the DNA ological solution conditions. We have (submitted to /. Biomol. Struct. Dyn.). triplet repeats associated with also demonstrated that the same hairpin genetically inherited neurological structures are formed during replica- Mariappan, S.V.S., X. Chen, X., P. disorders such as fragile X, Myotonic tion, leading to slippage, which in turn Catasti, et al. "Hairpin and Junction Dystrophy, and Huntington's disease. contributes to the observed length Structures of Fragile X Triplets," (The accompanying schematic polymorphism. Proceedings of the Ninth Conversation demonstrates how the number of such Furthermore, we have carried out in Biomolecular Stereodynamics, repeats is related to the expression of biochemical assays with human R.H. Sarma and M.H. Sarma, Eds. fragile X syndrome.) methyltransferase that demonstrate that (Adenine Press, 1995), pp. 105-19. We have used two-dimensional the same hairpin structure that causes Mariappan, S.V.S., X. Chen, X., P. nuclear magnetic resonance spectros- slippage and length polymorphism is Catasti, et al. "Solution Structure of copy, nondenaturing gel electrophore- also an excellent substrate for methyla- the Individual Strands of the Fragile sis, and digestion by single-strand- tion, and we found that the fragile X X Repeat," Nucleic Acids Res. 24, 784 specific PI or SI nuclease to demon- triplet repeats are more sensitive to (1996). strate that the triplet repeats found in methylation than many other DNA the genes causing these neurological regions, especially when they have Mariappan, S.V.S., L.A. Silks, P.A. disorders adopt hairpin structures (i.e., been expanded. The accompanying Springer, et al., "Solution Structure of a single strand of DNA loops back to sketch shows a possible mechanism of the DNA Triplet CAG Associated base-pair with itself rather than with its expansion and methylation. with Huntington's Disease" (submitted to /. Biomol. Struct. Dyn.).

~~Transcription Start~~

~~i'MR-I~~

Transcription of FMR-1 j j Strong methyl Control X^^^^^X binding pratetn Methylation j region / \^ SuppressiunofEMR-l f ~\ Weakmethyi Normal ^..^«.«.i v" binding protein \ Expanded Y methylated CpG i_ ; f unmethylated CpG CpG islands

A schematic representation of the FMR-1 gene. The location of the fragile. X repeat, (GCC)n'(GGC)n> is shown in the 5' untranslated region, although the exact location and the interrelationship of the promoter and the enhancer are not yet known. The ranges of repeat numbers, n, are shown for normal, transmitting, and affected males.

228 Los Alamos FYI996 LDRD Progress Report A sketch of how the presence of a transient and mobile three-way junction can cause both expansion and methylation. The intrinsic preference of hairpin formation by the GCC strand leads to a three-way junction with a Watson-Crick anchor. Hairpin When the GGC strand acts as the template, such a three-way junction leads to expansion if the GCC hairpin escapes repair. In the GCC hairpin of the three-way junction, the Cs are C*C paired, rather than C*G paired Substrate Transition as in the Watson-Crick duplex. One of Intermediate the Csfrom a C'Cpair is more susceptible to being "flipped out" of the duplex and methylated than a C -BB- from a C*G pair. The GCC hairpin at Watson-Crick a three-way junction is also capable Duplex of slipping and sliding, which can make the C*Gpair in a hairpin "slip" one notch to create a C*C pair.

Applications of Optical Trapping to 30 dB, we trapped and measured particles in flow streams that had Single-Molecule DNA Sequencing velocities of up to 12 mm/s. We showed that samples can be noninvasively positioned either Richard Keller upstream or downstream from the detection probe volume, a feature We are investigating whether we forces associated with a highly integral to SMD implementation. In a can use optical laser trapping (i.e., focused laser beam for this task. stationary fluid, we demonstrated optical tweezers) for single-molecule We successfully demonstrated trapping of 2.8-|jm paramagnetic DNA sequencing and single-molecule optical trapping in laminar flow beads that were coated with lambda detection (SMD). Single-molecule streams and completely characterized DNA. However, because of significant DNA sequencing involves selecting the trapping process as a function of variations in the optical and magnetic the fragment to be sequenced, fluid flow velocity, chamber dimen- properties of these substrates, we synthesizing the complementary sion, trapping depth, incident laser could not trap DNA-coated beads strand using fluorescently labeled power, and fluorescence measurement consistently and reliably in the nucleotides, attaching DNA fragments geometry. In particular, we integrated present system. to host substrates (microspheres) an optical laser trap with fluorescence anchored in a flow stream, sequen- excitation/emission capability in a tially cleaving the end nucleotide with flow cytometric geometry so that we Publications an exonuclease to release the labeled could study microparticle confine- nucleotide into the flow stream, and ment and off-axis fluorescence Wang, W, Y. Liu, G.J. Sonek, et al., using laser-induced fluorescence to detection. At the trapping wavelength "Optical Trapping and Fluorescence detect and identify the dye-tagged of 1064 nm, we simultaneously Detection in Laminar Flow Streams," nucleotides. We are currently using a trapped and displaced 2-um-diam Appl. Phys. Lett. 67, 1057 (1995). pipette to hold the microsphere fluorescent latex microspheres by up containing DNA in the flow stream. to ±20 um; we did this by scanning This project involves investigating the the trapping beam in directions applicability of optical laser trapping parallel and perpendicular to the flow as an alternative method of holding stream, while we measured particle the microsphere in the flow stream. fluorescence. With fluorescence We can use the radiation trapping signal-to-noise ratios in excess of

Competency Development Projects—Biosciences 229 Microbial Acquisition of Iron from acquire iron from hematite. To our knowledge, such a process is unique Iron-Bearing Minerals and previously unreported in the literature. Larry Hersman Publications Iron is a universal nutrient require- compounds, or peaks, were of interest ment for all life forms. Although the because with increased incubation Forsythe, J., P. Maurice, et al., fourth most-abundant element in the time (of the microorganisms in the "Imaging the Results of geosphere, iron is virtually insoluble presence of hematite), these peaks Biogeochemical Reactions with under environmental conditions became larger. In other words, Tapping Mode Atomic" (to be (neutral pH, oxic), where it exists exposure to hematite appeared to published in Goldsmidt Geochem. mainly as very insoluble oxides, induce the production of these Conf. Proc). hydroxides, and oxyhydroxides. We metabolic products. Hersman, L., M. Harrington, M. do not completely understand how We performed a series of assays to Martinez, et al., "Dissolution of iron is solubilized and made available determine the role of HPLC com- Hematite by an Aerobic Pseudomonas for biological use. The overall pounds in hematite dissolution. Sp." (Gordon Conf.: Environmental objective of this research was to Specifically we investigated the Sciences, June 23-29, New Hampton, determine, in part, some of the potential of these HPLC compounds N.H., 1996). mechanisms used by microorganisms to reduce iron or to serve as electron- to acquire iron-form hematite. transport molecules (i.e., ligand Hersman, L., P. Maurice, and G. In the past we have reported on the bridges) between a reductant and iron. Sposito, "Iron Acquisition from dissolution of hematite by microbially Results of these reduction assays Hydrous Fe(III) Oxides by an Aerobic produced, iron-binding ligands called suggest that these compounds are Pseudomonas Sp" Chem. Geol. 132, siderophores. During this past year we capable of serving as ligand bridges 25-31 (1996). investigated the role of other meta- between a reductant nicotinamide Maurice, P., L. Hersman, and G. bolic products on the dissolution of adenine dinucleotide (NADH) and Sposito, "Application of Atomic- hematite. Of particular interest were iron. Although strictly an aerobic Force Microscopy to Studies of high-performance liquid chromatogra- species, this particular species of Organic and Microbial Interactions of phy (HPLC) compounds that eluted Pseudomonas appears to use a special Hydrous Fe(IH)-Oxides," Chem. from a C-4 column before the form of reductive dissolution to Geol. 132, 33^3 (1996). siderophores. These pre-siderophore

The Biology of Novel Animal Genes: Mouse Despite extensive biochemical analysis, the biological significance of APEX Gene Knockout the multiple enzymatic functions of APE in vivo has not been determined. The goals of this project are to Mark Macinnes conduct preliminary genetic, biological, and cellular characterizations of Apurinic/apyrimidinic (AP) repair of AP sites is essential for mice containing a nonfunctional endonuclease (APE), sometimes preventing such mutations from version of the APE gene—mice known as APEX, is involved in a key becoming stably incorporated into the whose APE genes have effectively step in the repair of spontaneous and cellular genome, which can cause the been "knocked out." induced AP sites in DNA, in which an cell to die or become cancerous. Loss information-containing base is lost or or modulation of repair enzymes such Using gene targeting strategies, we damaged, essentially breaking the as APE may elevate the spontaneous have generated mouse embryonic rungs of a cell's DNA ladder. APE mutation rate in cells and may lead to stem (ES) cells that are heterozygous removes the damaged part of the a substantial increase in the incidence for a deletion mutation in the APE ladder so that another repair enzyme of cancer. gene (that is, they contain one normal can rebuild it correctly. Efficient

230 Los Alamos FY1996 LDR.D Progress Report and one nonfunctional APE gene). We We have shown, through genetic development, although embryo have subsequently produced whole and histological analyses of early remnants have been identified at day animals, derived directly from the stage embryos (days 3.5 to 11.5 of a 9.5 of gestation. APE-/- embryos were heterozygous ES cells, containing this 20-day mouse gestation period), that not found later than this period, and APE mutation. These animals are loss of the APE gene product does not preliminary evidence suggests that the overtly normal and do not display any affect blastocyst formation or implant- developmental failure in these animals adverse effects of the mutant APE ation. However, at or around day 7.5, induces apoptosis, or programmed allele. However, by inbreeding these during a period of substantial cellular cell death (essentially cell suicide), mice, we have determined that differentiation and expansion, APE-/- which results in complete embryonic animals which are genetically embryos begin to fail in normal death between 7.5 and 9.5 days of homozygous for the APE null development. These embryos display gestation. These results underscore mutation (designated APE-/-) die a variety of abnormalities and do not the essential functional significance of early in gestation. progress further than day 7.5 of this DNA repair gene during normal embryonic development.

Competency Development in Antibody Park, M.S., J.A. Knauf, S.H. Pendergrass, et al., " Ultraviolet- Production for Cancer Cell Biology Induced Movement of the Human DNA Repair Protein, Xeroderma pigmentosum Type G, in the Min S. Park Nucleus," Proc. Natl. Acad. Sci. USA 93, 8368-8373 (1996). Investigating the roles that proteins In the past year we continued to play in complex biological processes produce antigens and antibodies Park, M.S., D. Ludwig, et al., requires the use of antibodies against critical to identifying and monitoring "Physical Interaction between Human specific cellular proteins. The the expression of crucial proteins RAD52 and RPA Is Required for objective of this project is to develop involved in cell-cycle checkpoints, the Homologous Recombination in the technical capabilities, including regulation of cell division, and the Mammalian Cells," /. Biol. Chem. the use of recombinant technology, rate-limiting steps of DNA repair. 271, 18996-19000 (1996). for producing high-quality antibodies Specifically, we produced three more Shen, Z., K.G. Cloud, et al., "Specific that can be available for research on antigens (total now is eight over the Interactions between the Human cancer development. entire project period), two more RAD51 and RAD52 Proteins," /. Our work includes both conven- antibodies (total now is five over the Biol. Chem. 271,148-152 (1996). tional and recombinant antibody- entire project period), using conven- producing technology. The con- tional approaches. We also produced a ventional method involves purifying library of antibody genes that encode cellular proteins, or antigens, and recombinant antibodies. injecting them into an animal, which in turn produces antibodies to the antigen. Recombinant techniques Publications involve isolating the genes that code Knauf, J.A., S.H. Pendergrass, B.L. for the desired antigen or antibody Marrone, et al., "Multiple Nuclear and inserting the genes into an Localization Signals in XPG expression vector. Recombinant Nuclease," Mutat. Res. 363, 67-75 technology enables us to make large (1996). quantities of high-quality antibodies. Controlled expression of an antibody gene that is specific to tumor antigen provides another novel approach for immunocancer therapy.

Competency Development Projects—Biosciences 23 I Covariation of Mutations: A into our structure prediction software during the next year. Computational Approach for Finally, we have continued our work on neural-net-based scoring Determination of Function and functions to quantify the matches Structure from Sequence between sequence and structure in inverse folding investigations by increasing the spatial resolution and Alan Lapedes, Los Alamos National Laboratory accuracy of our models. Melissa Cline, University of California, Santa Cruz David Haussler, University of California, Santa Cruz Publications One of the foremost problems in two cases, as part of the CASP-2 Barrett, C, R. Hughey, and K. molecular biology is understanding structure prediction contest, we Karplus, "Scoring Hidden Markov protein folding—what processes predicted the folding of a sequence Models" (to be published in transform proteins from simple linear before its structure was determined, CABIOS). sequences to elaborate structures of and in both cases, our predictions helices, sheets, and turns. Many were experimentally verified. Grate, L., R. Hughey, K. Karplus, et researchers use Newtonian-mechan- We have also enhanced our tool al., "Tutorial: Stochastic Modeling ics-based molecular dynamics to suite to include a graphical, Techniques: Understanding and convert amino acid sequences into RASMOL-based alignment viewer Using" (Third International Con- three-dimensional forms, but this and scoring options so we can ference on Intelligent Systems for approach is cumbersome and is not as accommodate different model lengths. Molecular Biology, St. Louis, Mo., accurate as desired. In this project, we Upcoming features include a weight- June 12-15,1996). take a different approach in our study ing scheme that builds on phyloge- Hughey, R., and A. Krogh, "Hidden of inverse protein folding. Inverse netic relationships and emphasizes the Markov Models for Sequence folding approaches attempt to match alignment columns most critical to the Analysis," CABIOS 12 (2), 95-107 an amino acid sequence to a library of structure or function of a protein. (1996). known structures. "Inverse," therefore, We have also continued to develop refers to the process of working a neural net method for modeling beta "backward," using many known sheet interactions. Based on a pro- structures to determine the folding tein's amino acid sequence, as well as endpoints of a new sequence. (In other physical properties including contrast, most conventional ap- chain separation and beta strand proaches start with amino acid membership, we can estimate the sequences and little, if any, reference likelihood that two beta strands will to known structures.) We expect our be in contact. We plan to incorporate work on inverse protein folding to this beta sheet modeling capability bring to light enough new knowledge on the relationship between structure and sequence to facilitate great progress on better understanding protein folding in general. hi the past year, we expanded the linear Hidden Markov Model software, a probabilistic pattern recognition program originally designed for speech recognition, into a functioning protein structure predictor. To test the software, we built a model library that contains models for approximately 1000 protein families, and we used this library to predict the structure of most of the proteins in one family. In

~~232 Los Alamos FY1996 LDRD Progress Report Structure, Dynamics, and Function Nobel Prize winners) have given presentations at this series of discus- of Biomolecules sions.~~

Hans Frauenfelder Publications Olah, G.A., and R.P. Hjelm, "Analysis Our project is aimed at enhancing • the T chopper, which minimizes o and Simulation of a Small-Angle Los Alamos' core competency in unwanted background; and Neutron Scattering Instrument on a experimental techniques, theory, high- • the variable detector position, 1 MW Long Pulse Spallation Source" performance computing, and model- which allows for better optimiza- (Workshop on Neutron Scattering ing. Our main focus is on simulating tion of resolution and neutron flux Opportunities at Long Pulse and understanding biomolecular for individual experiments. Spallation Sources, HMI Berlin, structure, dynamics, and function. In We will implement and test these Germany, June 24-27, 1996). particular, we are developing scatter- upgrades in the next project year. ing techniques to study the structures We have also designed an LQD for Olah, G.A., R.P. Hjelm, and P.A. of biomolecular complexes in a next-generation long-pulse spalla- Seeger, "Small-Angle Scattering solution. tion source. In the area of structural Instruments on a 1 MW Long Pulse One of our primary goals has been biology applications, we have used Spallation Source" (ICANS-XIII, to increase—by a factor of 10—the neutron scattering to complete work 13th Meeting of the International intensity of the existing low-Q on a receptor/ligand complex as well Collaboration on Advanced Neutron neutron diffractometer (LQD) at the as a protein/DNA complex important Sources, 5232 Villigen PSI, Manuel Lujan Jr. Neutron Scattering in DNA damage repair. Switzerland, October 11-14, 1995). Center at Los Alamos. This increase To strengthen interactions between Olah, G.A., and J. Trewhella, "The would result in a dramatic improve- theory and experiment and between Structure of the Muscle Protein ment in its application to structural the biological and physical sciences, Complex 4Ca2+*Troponin C'Troponin biology studies. we have communicated our work and I: A Monte Carlo Modeling Analysis We used Monte Carlo modeling goals at regular meetings of research- of Small-Angle Neutron Scattering methods to design and test a number ers from all interested Laboratory Data" in Neutrons in Biology, B. of upgrades to the LQD that would organizations. In addition, we are Schoenborn and R. Knott, Eds. increase the flux of neutrons on our conducting a distinguished lecture (Plenum Press, New York, 1997). biological samples (see accompanying series on Issues in Modern Biology figure). Specifically, we designed the and are using the forum to discuss the following: directions of the field and, in particu- • a five-hole multiaperture collima- lar, our work. In total, 17 distin- tor, which allows a sample to "see" guished lecturers (7 of whom were a larger area of the neutron source (moderator) and, hence, to capture Movable 2-D Detector more total neutrons; (64 x 64 cm2)

~~Single or 5-Hole Multi- Aperture Coliimation~~

~~Liquid 2H Moderator Detector Rail~~

Gravity Focuser Schematic showing the designed upgrades to the low-Q neutron diffractometer (LQD) at the Manuel Lujan Jr. Neutron Scattering Center. To date, structural biology applications using LQD To Chopper have been limited by the neutron flux on this instrument. The designed improvements will result in a dramatic increase in its application to structural biology studies.

Competency Development Projects—Biosciences 233 Advanced NMRTechnology for Publications Hammel, P.C., Z. Zhang, et al., "Sub- Bioscience and Biotechnology Surface Imaging with the Magnetic Resonance Force Microscope," /. Low Jill Trewhella Temp. Phys. 101, 59 (1995). Hernandez, G., S.E. Rokop, P.A. Nuclear magnetic resonance imaging capabilities. We have also Springer, et al., "NMR Studies of (NMR) technologies play critical made advances in the miniaturization Troponin 1(96-115): Free in Solution roles in bioscience and biotechnology of two critical magnetic resonance and Bound to Troponin C," in both imaging and structure deter- force microscope components: the Biophysics J. 70, 384 (1996). mination. The major issues limiting micromechanical resonator and the the application of NMR to many micromagnetic tip. In the area of Hoyt, D.W., J. Zhao, et al., important problems are the inherent high-field NMR and isotope labeling, "Comparison of Small-Angle X-ray low sensitivity of the NMR experi- studies have been completed on the Scattering and Gradient Encoded ment and the spectral resolution muscle protein troponin C complexed NMR Diffusion Experiments for required to study biological mol- with segments of its regulatory target Assaying the Aggregation State of ecules. This project addresses both of troponin I. This complex is respon- Proteins in Solution" (submitted to J. these issues by working on the sible for the regulation of muscle Magn. Reson.). development of (1) magnetic reso- contraction and is too large for study nance force microscopy with the Trewhella, J., G. Hernandez, S.E. using conventional NMR approaches. Rokop, et al., "High-Field NMR & long-term goal of imaging individual As is the case for the vast majority of 2+ biological molecules and (2) high- Stable Isotopes for Studying Ca - biomolecular complexes, the complex Binding Proteins and Their magnetic-field NMR with isotope has limited solubility, resulting in labeling to overcome current limita- Complexes," 27th Annual Southeast. even more demands on the NMR Magn. Reson. Conf. Proc. 1,4 (1995). tions on the size of biomolecules experiment. Using state-of-the-art, whose structures can be determined high-field NMR instrumentation at Zhang, Z., PC. Hammel, and G.J. using multidimensional NMR. Pacific Northwest National Labora- Moore, "Application of a Novel RF In the past year we have developed tory, we have measured NMR data Coil Design to the Magnetic a novel radio-frequency coil design from complexes of isotopically Resonance Force Microscope," Rev. for NMR force microscopy applica- labeled troponin C complexed with Sci. lustrum. 67, 3307 (1996). tions that are pushing the limits of key sequence segments of troponin I. sensitivity in magnetic resonance We have successfully interpreted detection for imaging, and we have these data in terms of structural demonstrated subsurface spatial information on the troponin I component.

Nonlinear Analysis of Biological Sequences most discriminatory, and use of these subsequences yielded a correct classification rate of 0.82 for both David Torney types of sequences—the best success rate yet reported for such short We have established the usefulness The purpose of this project is to sequences. We have begun to develop of parities of subsequences for develop effective new computational sophisticated statistical methods for classifying binary sequences. To use and mathematical techniques and combining the parities from many this approach for DNA sequences, we apply them to analysis of the structure subsequences, since we employed first converted these subsequences to of biological sequences. We are several thousand, as a classification binary sequences. We determined the currently focusing on the detection technique. We explored cumulants, average parities for subsequences of and characterization of functional which yield an expected parity for a 54-base-long coding sequences, for domains. We are also modeling subsequence based upon its subse- which the frame and strand were multigenic human diseases with the quences, and thus enable the winnow- known, and for noncoding sequences. goal of designing more effective ing of "key" subsequences. These We found that the subsequences with experiments that will discover the simplest cumulants revealed novel genetic components of these diseases. the smallest number of letters were

234 Los Alamos FYI996 LDRD Progress Report statistical features of coding and Publications Huynen, M.A., et al., "Rate of Killing noncoding sequences. of HIV-Infected T-Cells and Disease Bruno, W.J., "Modeling Residue Our characterization of protein- Progression," Science 272,1962 Usage in Aligned Protein Sequences sequence motifs, conserved through (1996). via Maximum Likelihood," Mol. Biol. evolution, was made much more Evol. 10, 1368-1374 (1996). Huynen, M.A., et al., "Smoothness effective by employing maximum Within Ruggedness: The Role of likelihood techniques. By averaging Huynen, M.A., "Exploring Phenotype Neutrality in Adaptation," Proc. Nat. over possible evolutionary histories, Space through Neutral Evolution," /. Acad. Set U.S.A. 93, 397 (1996). we derived accurate profiles for Mol. Evol. 43, 165 (1996). amino acid usage. Furthermore, this Torney, D.C., "Group Tests for Huynen, M.A., et al., "Assessing the approach allows the quantification of Complex Biological Systems" Reliability of RNA Folding Using coevolution of pairs of amino acid (submitted to Nature). Statistical Mechanics," J. Mol. Biol. residues. Based on preliminary 43 (1996). models, we found many more statistically significant pairs of Huynen, M.A., et al., "Base Pair coevolving residues than are yielded Probabilities in a Complete HIV-1 by other approaches and have Genome," /. Comp. Biol. 3, 253 corroborated these interactions (1996). through studies of molecules with known structure.

Indigenous Bacteria as Hosts for (DCA) from which to isolate indigenous hosts for engineered and wild Proteins for Bioremediation type alkane dehalogenase genes. From one of these sites, we have begun enrichment cultures and direct plating James Brainard to isolate Type I fluorescent Pseudomo- nas and other indigenous species Successful application of engi- many contaminants, unmodified and capable of degrading DCA and neered proteins for in situ bio- engineered proteins and genes, and intermediates of DCA degradation. remediation requires efficient microbial isolates. mechanisms to introduce and distrib- During the first year of this project, ute the enhanced biological activity at we have made excellent progress in Publications the contaminated site. An attractive several areas: (1) isolating microor- Herrick, J.B., and J.R. Brainard, strategy to accomplish this process is ganisms into which to place genes for "Design of PCR Primers for the through the use of bacteria native to engineered Haloalkane dehalo- Amplification of Unknown, the site as hosts for the engineered genases, (2) developing the tools Homologous Catabolic Gene proteins. The goal of this project is to required to detect, track and measure Sequences from Environmental gain sufficient understanding of the genes in the environment, (3) devel- Samples," Abstracts of the 96th coupled biological, chemical, and oping methods to introduce and Annual Meeting of the American physical processes occurring at express broad-host-range plasmids Society for Microbiology N, 110 contaminated sites in order to containing engineered genes, and (1996). rationally design and test this strategy. (4) using numerical simulations to Although the project is primarily identify which parameters are most Herrick, J.B., K.S. Harris, and J.R. focused on a specific enzyme important in limiting bioremediation Brainard, "Rapid Fingerprinting of (Haloalkane dehalogenase) and effectiveness. Bacteria Using ERIC PCR Primers" specific Pseudomonas isolates, the We have selected three sites that are (to be published in PCR: Essential results will have broad applicability to contaminated with 1,2-dicholoethane Techniques, J. Burke, Ed., Bios. Sci. Publ., Oxford, England).

Competency Development Projects—Biosciences 235 Landscapes and Dynamics of Proteins Frauenfelder, H., "Proteins as Paradigms of Complex Systems" in Roentgen Centennial, E. Umbach, Ed. Hans Frauenfelder (World Scientific, Singapore, in press). The goal of the project is to In addition to the more formal understand the energy and affinity discussions with visitors and at the Frauenfelder, H., and P.G. Wolynes, landscapes in physics and biology. conference and workshops, many "Picturing the Working Protein," in Complex systems, such as biopoly- discussions on theoretical and Theoretical and Computational mers, glasses, and large martensitic experimental aspects were held at Genome Research, S. Suhai, Ed. crystals, have a highly degenerate CNLS. Partially as a result of these (Plenum Press, New York, in press). ground state and can assume a large interactions, we proposed a new core- Frauenfelder, H., et al, "Proteins and number of different structures. These competency development thrust area the Physics of Complexity," in Non- characteristics are typically described for the Laboratory on structural linear Excitations in Biomolecules, by a rugged energy landscape. The biology, which involves collaboration M. Peyrard, Ed. (Springer-Verlag, dynamics within such a landscape are among four divisions and is now Berlin, 1995), p. 177. far more intricate than dynamics in active as an integrated structural simple systems, displaying hysteresis biology resource. Johnson, J.B., D.C. Lamb, H. and sometimes showing the multi- Frauenfelder, et al., "Ligand Binding scale character of an avalanche or a to Heme Proteins VI. Interconversion quake. Our goal implies some new Publications of Taxonomic Substates In Carbon- directions in the study of nonlinear Frauenfelder, H., "The Complexity of monoxymyoglobin," Biophys. J., 71 systems and closer interactions with Proteins," in Physics of Biological 1563-1573 (1996). theorists, computer experts, and Systems—from Molecules to Species, experimentalists at Los Alamos H. Flyvbjerg, J. Hertz, et al., Eds. National Laboratory and in a number (Springer-Verlag, Berlin, 1997), of universities. pp. 29-60. The project objective for the first Frauenfelder, H., "Komplexitat in der year, which we met, was to learn belebten Materie," Schriftenreihe more about the field from visitors, Ernst-Abbe Kolloquium Jena 9, 1-26 seminars, and workshops. Many (1995). vrsitors were invited to give talks both at the Center for Nonlinear Studies Frauenfelder, H., "Proteins—A (CNLS) and also in the colloquium Challenging Many-Body Problem" (to series "Issues in Modern Biology." be published in Philos. Mag.), The 16th CNLS Annual Conference was called "Landscapes." The conference included reports on experimental, theoretical, and modeling studies in glasses, spin glasses, biopolymers, hierarchical materials, neural networks, and evolution, and it attracted the best researchers in this field. The conference was reported in Nature.

236 Los Alamos FYI996 LDRD Progress Report Engineering Haloalkane Dehalogenase dynamics of dehalogenating enzymes; (4) developing and validating experi- for Bioremediation mental models for understanding the effects of heme environment on enzyme dehalogenation functions; James Brainard and (5) using cryocrystallography to trap reaction intermediates of cyto- Although bioremediation is poten- These modified proteins have chrome P450 and characterize their tially one of the most cost-effective enhanced capabilities for degrading structure. environmental cleanup tools, present specific halogenated alkanes and may bioremediation practices have difficulty be optimized for in situ bioreme- achieving effective destruction of some diation strategies and waste stream Publications contaminants, notably halogenated treatment. Although our efforts are Oprea, T.I., G. Hummer, and A.E. hydrocarbons. Many microorganisms focused on engineering halocarbon- Garcia, "Identification of a Functional contain halocarbon degrading enzymes, degrading enzymes, the results have Water Channel in Cytochrome P450 but these enzymes are poor catalysts application to other contaminants, in Enzymes" (to be published in Proc. relative to other enzymes. Enzymes that particular, other recalcitrant organics Natl. Acad. Sci. U.S.A.). work on zenobiotic halogenated and both toxic and radioactive metals. contaminants suffer from poor affinity This year we have made excellent Travis, B.J., and N.D. Rosenberg, for the contaminant and slow turnover progress in (1) developing the "Modeling in situ Bioremediation of rates even when the contaminant is molecular biology tools to allow TCE at Savannah River" (submitted to bound, and sometimes generate toxic rational and directed-evolution Environ. Sci. Technol). intermediates. The goal of this project approaches to enzyme engineering; is to develop the tools and understand- (2) developing the microbiological, ing required to engineer enzymes with analytical, and spectroscopic tools to enhanced properties for bioremediation screen, select, and characterize of contaminants. To do this we design, improved enzymes; (3) theoretical construct, express, and test enzymes modeling of the chemical reactions, based on naturally occurring enzymes solvent interactions, and protein that degrade halocarbons.

Competency Development Projects—Biosciences 237 # * * Program Development Projects •%** Program Development (PD) projects support R&D aligned with future programmatic opportunities at the Laboratory as guided by the Laboratory's strategic planning process. PD projects are selected by the Laboratory program directors to explore and develop technologies needed for emerging mission objectives in nuclear weapons, nuclear materials and stockpile management, nonproliferation and international security, conventional defense, environmental management, industrial partnerships, and energy. This year, PD projects accounted for 24% of the LDRD budget and 21 % of all projects, and they supported research in all nine technical disciplines.

Examples of subjects investigated by PD projects include the effects of aging on nuclear materials, helium-3 targets for tritium production in fission systems, global nuclear material monitoring, sensors for detecting chemical and biological warfare agents, advanced oxidation technologies for chemical demilitarization, advanced nuclear fuel processing and radionuclide separations, integrated approaches to advanced machining, improved atmospheric transport in complex terrain, and subsurface directed-energy methods for groundwater treatment.

~~Materials Science~~

Fundamental and Applied Studies of more stable than free vacancies, providing incipient traps for the diffusion Helium Ingrowth in Plutonium of helium. Total-energy calculations have indicated that Pu3Ga compounds Michael Stevens may be the ground-state preferred phase in this system, which suggests The overall objective of this project have a functional system in place for that fine-scale precipitation of this is to begin development of new tools measuring, with high sensitivity, he- phase over time may be possible in and techniques for characterizing the lium release from small plutonium aged materials. This year, we have effect of radiolytic aging on the prop- coupons. Experiments will begin this also performed calculations to deter- erties of weapons-grade plutonium. coming year on coupons secured from mine local relaxations around a gal- To accomplish our goal, we must de- the Laboratory's Pit Surveillance Pro- lium atom in delta-phase plutonium, sign new techniques for directly mea- gram. In the area of "artificial" aging and next year we will refine these cal- suring helium transport in aged induced by ion-beam implantation, culations. Moreover, we have com- material; develop ion-beam tech- this year we succeeded in using radia- pleted measurements of charge niques for artificially aging plutonium tion damage codes to simulate alpha- densities and potentials for the Pu3Ga through combined helium/heavy-ion decay damage in plutonium. We phase. To predict spall in planar implantation as well as develop meso- selected and synthesized a gold-silver (layered) microstructures, we have scopic microstructure simulations to alloy simulant to begin the ion-beam developed a one-dimensional, finite- predict helium/point defect energetics implantation studies. Helium implan- difference code that will allow us to and segregation tendencies; conduct tation has been successful, but we en- study model alloys and, eventually, ab initio, total-energy calculations to countered problems with heavy-ion plutonium. Finally, this year we have develop a better understanding about implantation because, in this case, designed a special chamber for as- the way in which group IIIB elements surface sputtering occurred instead of sessing plutonium films under shock stabilize the delta phase; and develop implantation. conditions. spall codes and techniques for mea- Mesoscopic structure modeling ef- suring dynamic properties of materi- forts resulted in calculated energies Publications als under shock conditions by using for a variety of defects in delta pluto- the laser-driven miniflyer technique. nium, such as certain orientation grain Becker, J.D., J.M. Wills, et al., The thermal effusion work for mea- boundaries, faults, and vacancy and "Electronic Structure of Pu suring helium transport has success- interstitial-point defects. Further work Compounds with Group IIIB Metals: fully progressed this year. We now showed that certain clusters of five to Two Regimes of Behavior," Phys. Rev. six vacancies may be energetically B 54 (24), 17265-17268 (1996).

Cost-Effective Development of cess-control methods, and materials and device modeling for the films and Thin Films for Flat-Panel Displays their applications. We reached a number of significant Joysree Aubrey milestones during the course of the project: (1) deposition of oriented We have used an integrated Theoretical. These personnel worked films of zinc oxide, indium tin oxide, concept-to-prototype process for together to develop thin-film semicon- and silicon; (2) characterization of the modeling and fabricating thin films ductors and conductors with superior films; (3) mesh set-up and simulation for applications in flat-panel displays. qualities. of the ion-gun performance using the two-and-one-half dimensional code The approach for developing "thin We deposited films using a state-of- MERLIN; (4) evaluation of deposition films by design" has proved to be in- the-art, flow-through ion gun and parameters for use in the development valuable in materials research. The characterized the samples with an of adaptive-control techniques; and project included personnel from three extensive array of diagnostic equip- (5) initiation of materials and device divisions at Los Alamos: Applied ment. Theoretical support consisted of modeling and development of a de- Theoretical Physics, Materials simulation of the performance of the vice-modeling code, FEDPIX. Science and Technology, and ion gun, development of adaptive pro-

Program Development—Materials Science 241 Development of High Magnetic Fields tially different field dependencies of the charge and spin gaps in Kondo for Energy Research insulators at fields to 50 T. In addition, we have taken high-field thermo- Joe D. Thompson dynamic and transport measurements of Ceg7La03Pd3 to test theoretical pre- The goal of this project is to dem- This year we have designed (1) a dictions for Kondo-hole behavior. onstrate the feasibility of building a capacitor bank for a 50-T insert and 100-T magnet for high-magnetic-field (2) the signal sequencing patterns to Publications research. If successful, this project control a 50-T outer magnet of a com- would enable us to meet a longer-term bined 100-T magnet. We have also Boenig, H.J., LJ. Campbell, K.R. goal of establishing the technological made extensive electrical simulations Eberl, et al., "Design Status of the US and scientific bases upon which for a variety of 100-T magnet designs. 100-Tesla Non-Destructive Magnet DOE/Office of Basic Energy Sciences In parallel with the magnet work, System" (submitted to 7th Inter- will form a strategic alliance with the we have used molecular-beam epi- national Conference on Megagauss National Science Foundation to build taxial growth of GaAs to fabricate Magnetic Fields). a revolutionary 100-T, nondestructive large-area, very thin (100-nm thick) Harris, J.G.E., D.D. Awschalom, et magnet. This magnet will provide cantilevers that can be used for al., "Fabrication and Characterization high magnetic fields for furthering ultrasensitive micromagnetometry of 100 mm Thick GaAs Cantilevers" energy-related science and technology from room temperature to 30 mK in (submitted to Rev. Sci. Instrum.). important to the DOE mission. In arbitrarily high magnetic fields. We preparation for the 100-T magnet, we have also discovered what appears to Lawrence, J.M., T. Graf, M.F. have been developing diagnostics and be quantum oscillations in the magne- Hundley, et al., "Kondo-Hole have begun some high-field materials toresistance of "nonmagnetic" Behavior in Ce 97La 03Pd3," Phys. Rev. 5 53,12559(1996).' research measurements at 50 T. YbInCu4 and evidence for substan-

Advancing the Technology Base for 74% hydrogen, 25% carbon dioxide, and 1% carbon monoxide, we found High-Temperature Membranes that the membrane still performed well. Robert Dye We have applied for a patent on the composite metal membrane and have This project tackles major issues Sievert's law regime, permeation rate successfully licensed this metal mem- barring the implementation of high- is controlled by the diffusion of brane technology to industry. temperature membranes to separa- atomic hydrogen through the bulk tions and catalysis that might have a phase. In the surface-effects regime, Publications large impact for the DOE and for permeation rate is controlled by one industry. Advances made in this or more of several mechanisms for Peachey, N.M., R.C. Dye, P.D. Ries, project have moved the state-of-the- transporting gaseous hydrogen, as et al., "Pulsed Laser Deposition of art toward high-temperature mem- atomic hydrogen, into the bulk phase. Zeolitic Thin Films: Novel Structures brane viability and improved overall We have been very encouraged by for Molecular Recognition," J. Porous energy efficiency. tests of the multimetal membranes in Mater. 2, 331 (1996). We have accomplished modeling a reformed fuel mixture. Without opti- Peachey, N.M., R.C. Snow, and R.C. and data analysis of permeation rates mization, the membranes produced a 2 Dye, "Composite PdVTa Metal through composite metal membranes. hydrogen flux of 17 standard cmVcm Membranes for Hydrogen The model accounts not only for the at 286°C, with a partial pressure of Separation," J. Membrane Sci. Ill, well-understood Sievert's law regime 0.5 atm of hydrogen across the mem- 123 (1996). but also for the less-understood brane. After performing a 27-h life- "surface-effects" regime. In the time test using the gas mixture of

242 Los Alamos FY1996 LDRD Progress Report Giant Magnetoresistance Materials for 250 A and d-spacing corresponding to a highly strained material. Magnetic Recording Technology Publications Robert Hejfner Hawley, M.E., CD. Adams, P.N. This work focused on a class of materials. We are also exploring the Arendt, et al, "CMR Films' Structure transition-metal-oxide (TMO) materi- use of epitaxial strain to change the as a Function of Growth and Processing" (to be published in /. als (LaMnO3 doped with calcium, transport properties in thin-film barium, or strontium); these materials multilayers. Crystal Growth). exhibit an insulator-to-metal transi- Using thermogravimetric analysis Hawley, M.E., X.D. Wu, P.N. Arendt, tion near their ferromagnetic phase- on materials synthesized at different et al., "Microstructural Study of CMR transition temperatures. This oxygen pressures and temperatures, Films as a Function of Growth, transition from a paramagnetic insula- we have developed a phase diagram Temperature, as Deposited and tor to a ferromagnetic metal yields a for ideal growth conditions. We have Annealed," Mat. Res. Soc. Symp. very large magnetoresistance. Thus, studied the effects of lattice substrate Proc. 401, 531(1996). these materials may have important epitaxy by depositing (La,Ca)MnO3 uses as magnetic sensors in a variety materials on several lattice-matched Hundley, M.F., J.J. Neumeier, R.H. of applications, ranging from auto- isostructural substrates: lanthanum Heffner, et al., "Transport and mobiles to read heads for magnetic aluminate, strontium titanate, and Magnetism Correlations in Thin-Film storage. Practical use of these mate- neodymium gallate. X-ray diffraction Ferromagnetic Oxides," /. Appl. Phys. rials depends upon learning to control studies of these films indicate that 79, 4535 (1996). the synthesis parameters (principally large amounts of coherent interface Louca, D., EX. Brosha, and T. Egami, temperature, pressure, and composi- strain can be produced. We have "Observation of Polaronic Lattice tion) to achieve a specific carrier con- successfully adapted a semiconductor Distortion in Laj xSrxMnO3 by Pulsed centration and/or mobility. A second strain-layer approach and have fabri- Neutron Diffraction" (submitted to challenge is the high magnetic fields cated multilayer superlattices by Phys. Rev. Lett). (greater than 1 T) currently required depositing alternating layers of an Louca, D., W. Dmowski, T. Egami, et to achieve a large change in resis- Lao 67Cao 33MnO3 d strontium titan- tance. We conceived of two novel ate perovskites. These stacks exhibit al., "Evidence of Lattice Polarons in approaches to this field-sensitivity multiple x-ray satellite reflections that Lax xSrxMnO3 by Pulsed Neutron problem; these approaches involve are indicative of a highly ordered Diffraction" (submitted to Phys. Rev. developing multilayers of the TMO superlattice structure with a period of Lett.).

Characterizing Mechanical Effects of studies of polymeric systems and performed preliminary calculations of the Aging Damage elastic constants for the amorphous component of Estane; calculations for Philip M. Howe pure HMX are also underway. We will extend these studies to provide esti- Our goal is to use molecular-level During the reporting period, we mates of the adhesion strength between spectroscopic data and theoretical established shipping arrangements the HMX and binder. information from atomistic calcula- and experimental standard operating We computed micromechanics- tions in the parameterization of a procedures to allow studies of explo- based stress-strain curves as a func- micromechanical model designed to sive materials and made initial spec- tion of "binder" concentration for a assess aging effects on the properties troscopic measurements for fresh and model composite system that crudely of particle-filled composites. The aged samples of both the pure binder mimics an explosive formulation. We results will be used in the develop- and PBX-9501. Spectra for the fresh predicted reasonable behavior and are ment of a micromechanics-based and aged samples differed, indicating making refinements. Finally, we in- constitutive model for such materials. changes due to aging, and we con- corporated advances in a constitutive The main emphasis is on Plastic- cluded that spatially resolved data will theory for particle-filled composites Bonded Explosive 9501 (PBX-9501) be required for an improved under- into a computer model and predicted and its constituents, high-melting standing of the aging behavior. We much of the known characteristic explosive (HMX) and Estane binder. purchased software for atomistic behavior.

Program Development—Materials Science 243 High-Magnetic-Field Research Solem, J., "Overview and Introduction to Dirac" (Seventh Inter- Collaborations national Conference on Megagauss Magnetic Field Generation and Johndale Solem Related Topics, Sarov [Arzamas-16], Russia, August 5-10, 1996). The purpose of this project is to Clark, R., et al., "The Extreme Solem, J., and M. Sheppard, exploit the research potential of the Quantum Limit of Dilute 3D Electron "Experimental Quantum Chemistry at pulsed magnetic fields that might be Systems: Experimental Probe of Ultrahigh Magnetic Fields: Some possible with PEGASUS and Transport in Semiconductors and Opportunities" (submitted to Int. J. explosive-driven flux-compression Semimetals to 500 Tesla" (Seventh Quantum Chem.). generator sources to explore com- International Conference on Mega- pletely novel ideas in condensed- gauss Magnetic Field Generation and Solem, J., and M. Sheppard, matter physics and chemistry. The Related Topics, Sarov [Arzamas-16], "Quantum Chemistry at Ultrahigh project links the Laboratory to the Russia, August 5-10, 1996). Magnetic Fields" (Workshop on academic and industrial communities Properties of Molecules in Strong by involving those communities in Sheppard, M., et al., "Multi- Magnetic Fields, University of our research programs, which Megagauss Field Generation Using Florida, Gainesville, Fla., October enhances the technical vitality of the Capacitor Banks" (Seventh Inter- 24-27, 1996). Laboratory, benefits the broader national Conference on Megagauss Solem, J., et al., "DIRAC: a scientific community, and creates a Magnetic Field Generation and Campaign of Experiments to Study broader constituency for science- Related Topics, Sarov [Arzamas-16], Physics and Chemistry at Ultrahigh based stockpile stewardship. Russia, August 5-10, 1996). Magnetic Fields" (Seventh Inter- The initiative brought together Solem, J., "Basic Science at the national Conference on Megagauss American, Russian, Australian, and Extreme States of Matter," Bull. Am. Magnetic Field Generation and Japanese researchers from around the Phys. Soc. 41, 929 (1996). Related Topics, Sarov [Arzamas-16], world. We started with a campaign of Russia, August 5-10, 1996). experiments (Dirac series) using high- explosive-driven flux-compression generators. The Dirac series included four -150-T experiments using a linear explosive-driven flux-compression Ceramic/Polymer, Functionally Graded generator designed at Los Alamos and Material (FGM), Lightweight Armor System three -1000-T experiments using a cylindrically imploding, explosive- driven flux-compression generator John Petrovic designed at Arzamas-16. Our experiments explored quantum Significant improvement in body The critical step for developing limit phenomena in two- and three- armor has been listed as one of the ceramic/polymer FGM armor is devel- dimensional organic metals, semi- Department of Defense's (DoD's) "Top oping a graded-porosity, boron carbide metals, transition metals, and electron Ten Tough Problems." Required (B4C) ceramic that can then be liquid- gases; chemical-bond manipulation; advances in lightweight body armor to infiltrated with a polymer material or a and nonlinear Faraday rotation. These meet the DoD's needs can no longer be metal such as aluminum. We have experiments have been described in met through incremental advances in focused our efforts on developing a detail by other documents on the post-Vietnam-era armor systems based graded-porosity, B4C ceramic. Because LDRD program. We are still analyz- on Kevlar-type fabric vests and will we have chosen the B4C/A1 system as a ing much of the data. require the incorporation of lightweight benchmark to gauge the performance ceramics. The approach that provides of the B4C/polymer armor, our second- the most opportunity for improvement ary focus has been on establishing pro- Publications in performance is to employ FGMs in cedures for infiltrating aluminum into which the surface intercepting the bul- the B C ceramic. We have established Brooks, 1, et al., "Quest for the 4 let is made of a very hard ceramic that that gradients in carbon-induced B C Quantum Limit in Three Dimensional 4 can break up the bullet. This ceramic is densification and gradients in particle- Metals" (Seventh International then graded into an energy-absorbing size distribution are the two most prom- Conference on Megagauss Magnetic polymer or metal to absorb energy and ising approaches for developing FGM Field Generation and Related Topics, bullet fragments. armor. Sarov [Arzamas-16], Russia, August 5-10, 1996).

244 Los Alamos FYI996 LDRD Progress Report NewAnion-Exchange Polymers for separated by a five-methylene spacer. The order of affinity for plutonium Improved Separations in Nuclear and from 1-M nitric acid was pyridinium > trimethylphosphonium > trimethyl- Industrial Applications ammonium. Replacing the central methylene group in a five-unit spacer Gordon Jarvinen with an ether oxygen further enhanced the sorption of plutonium. The objective of this work is to We designed and synthesized Compared with other separation improve our understanding of how the several new series of bifunctional, techniques, our new polymers offer structure of a new class of anion- anion-exchange polymers, and we the prospect of removing plutonium exchange polymers controls the bind- tested their ability to remove three more effectively from many nitrate ing of anionic actinide complexes actinides—plutonium(IV), process and waste solutions while from solution. This kind of fundamen- americium(III), and uranium(VI)— decreasing the volume of secondary tal data is needed to develop practical from nitric acid. The polymers waste generated. separation systems that will reduce contain a pyridinium site derived the cost of actinide-processing opera- from the host poly(4-vinylpyridine) Publications tions within the DOE complex. These and a second cationic site (either systems will separate actinides from trimethylammonium, pyridinium, or Marsh, S.F., G.D. Jarvinen, and R.A. both process and waste solutions. In trimethylphosphonium) attached Bartsch, "New Bifunctional Anion addition, anion exchange is widely through a chain of two to six methylene Exchange Resins for Nuclear Waste used in industry, and these new mate- groups. The new polymers removed Treatment" (to be published in React. rials may have much broader applica- plutonium 4-10 times more efficiently Polym.). tions in areas such as water treatment, than can the best commercial materials pollution-control technology, and presently available. The sorption kinet- purification of chemical products. ics and distribution coefficients for plutonium(iV) were generally best when the two cationic sites were

~~Program Development—Materials Science 245~~

~~Engineering and Base Technologies~~

Detection of Underground of deeply buried tunnels. We have successfully modeled critical aspects Structures and Tunnels of tunnel detection. Through another buried-wire experiment in which we used low-tem- Joseph Mack perature superconducting quantum interference devices (SQUIDs), we The primary objective of this and the Nevada Test Site (NTS), determined that more design and project is to assess electromagnetic respectively. hardware development is necessary (EM) and gravitational methods for It is believed that underground for successful gravity-gradiometry detecting underground structures. We communications using low-frequency detection of underground structures. also considered methods for detecting EM waves coupled to any longitudi- High-temperature SQUIDs show new land mines and improving under- nal conductor propagate as a surface promise as this new technology be- ground communications. guided wave with no cutoff frequency. comes interlaced with noise-control Using an improved means of elec- We successfully demonstrated this electronics. tromagnetic scattering, we obtained hypothesis at ~300-m depths at the We assessed other tunnel-detection excellent agreement between our Lyner Facility at the NTS. technologies in conjunction with the theoretical predictions and experimen- We have used resonant microstrip- experiments performed by other insti- tal results when sensing a grounded patch antennas to detect and image tutions. Of note was detecting tunnel #14-gauge wire buried 10 m. We also antipersonnel mine mockups in both presence with a magnetometer were able to detect the presence of an dry and wet soil, and we also estab- mounted on the unmanned, airborne ~30-m-deep, 7.3-m-diameter, lished clutter sensitivities. CYPHER vehicle, which was flown conductor-carrying tunnel. We per- In addition, emphasizing quasi- over the Yucca Mountain tunnel formed these experiments at Sandia analytic techniques, we developed a (7.3-m diameter, -30 m below the National Laboratories, New Mexico, computer code to model EM detection surface).

Active Noise and Vibration Control loop. We designed a mechanical demonstration fixture to hold the for Vehicular Applications damper/spring assembly, and we specified and procured a custom- made MR shock from MR Tech- Paul Lewis nologies. (MR shocks are still a developing technology and are not In this project we planned to We carried out background research readily available.) To characterize the develop a benchtop demonstration of and a literature search on semiactive performance of the MR shock, we a semiactive suspension system based suspensions and controllable shock took measurements, which were satis- on real-time nonlinear control of a absorbers, and we developed and factory. However, the device leaked magneto-rheological (MR) shock adapted numerical models and simula- MR fluid and had to be repaired by absorber. We embarked on this project tions of alternative nonlinear control MR Technologies; it subsequently because of the Laboratory's interac- algorithms for use with an MR shock. began to leak again. tions with General Motors (GM) (In an MR shock, friction is controlled Delphi in the area of active noise and rather than dampened.) We specified Because interests at both GM and vibration control and because of the and assembled the control system con- DARPA changed, we did not imple- Defense Advanced Research Project sisting of a 486-based personal com- ment the benchtop demonstration Agency's (DARPA's) interest in MR puter (PC) that has a special-purpose design. However, we have docu- technology for military applications. digital signal-processing board mented the design, simulation, and (TMS320C31) to handle the control measurements in the project's final report.

Program Development—Engineering and Base Technologies 247 Study of Possible Detector Geometries and depends on the size, spacing, and number of detectors in the monitor. for Detection of Radioactivity in Moving For a given detector configuration and vehicle, two of the dominant sensitiv- Vehicles ity factors are the occupancy background suppression and the shielding Robbie York provided by the components of the vehicle. The goal of this project is to The security plans for many DOE scintillators and decision-making evaluate different detector configura- facilities require monitoring of pedes- electronics. These automatic monitors tions as a means of improving the sen- trians and vehicles to control the determine the presence of SNM by sitivity of these instruments to achieve movement of special nuclear material comparing the gamma-ray and neu- a vehicle monitor that is economical, (SNM). Vehicle monitors often pro- tron intensities of the occupied practical to install, and sensitive vide the outermost barrier against the vehicle monitor to the background enough to be an effective barrier to theft of SNM. The standard SNM radiation level of the unoccupied illegal transportation of SNM. vehicle monitors consist of two pillars monitor. The most severe shielding locations that the vehicles drive through. The The sensitivity of these monitors in a vehicle are between the door two pillars contain both large plastic varies for different types of vehicles posts, above the engine block, and below the engine. By placing detectors above and below the vehicle (see Overhead detector figure), we minimized variations in Vertical pillars the sensitivity caused by gamma-ray shielding. With the source between the two door posts, the sensitivity of the side detectors was very poor, but the sensitivity of the lower detector was high. However, with the source above the engine block, the situation was reversed. We found that adding the overhead detector did not increase the worst-case sensitivity. Summing the count rates of the side and lower detectors decreased the minimum detectable mass by a factor of 3. However, when we summed all three detector groups, the sensitivity Lower detector improved by a factor of 5, while the nuisance-alarm rate remained A sketch showing the configuration of the four-pillar detector that we tested. constant.

Environmentally Conscious Coal possible engineered controls on those contaminants. Combustion: Development of Process Unlike utility-boiler combustion, home-coal combustion emits contami- Monitors and Improved Numerical Models nants cyclically. Only low levels of sulfur dioxide and other contaminants are Donald D. Hickmott produced, but they are potentially high enough to exceed Environmental Pro- Many inhabitants on the Navajo need on the Navajo reservation, and tection Agency standards for ambient reservation use free subbituminous potentially in the developing world, is air because of winter atmospheric coal in home-scale coal stoves for for a high-efficiency, smokeless stove inversions that occur in the neighboring their home heating. Coal is used for that burns diverse feedstocks (i.e., town of Shiprock, New Mexico. We similar small-scale combustion in coal, wood, biomass). In this project evaluated several engineering controls many developing nations, particularly we evaluated the contaminants pro- on home-coal-stove emissions, such as China. The principal coal-combustion duced during coal combustion in a small-scale scrubber systems and im- Navajo home-scale coal stove and the proved-efficiency stoves.

248 Los Alamos FY1996 LDRD Progress Report Establishing the Operational Durability device (polymer) thicknesses. We have identified that the dominant fail- of Polymer Light-Emitting Diodes ure mechanism of the PLEDs is delamination of the electron-injecting Ian Campbell metal contact, which occurs at less than 1000 hours of operation. This year we developed a new electro- Recently discovered polymer light- have all the device attributes (effi- absorption technique to measure the emitting diodes (PLEDs) have the ciency, emission colors, and operating electric field distribution inside the potential to revolutionize display tech- voltage) required to build a successful PLEDs. We used this technique to nology for defense and civilian appli- display technology. We initiated this assess relative device reliability. cations. Displays are expected to be project to establish meaningful device major drivers in both the computer operating lifetimes and to understand and the high-definition television PLED failure mechanisms with the Publications industries in the near future. At Los goal of controlling device reliability Alamos we are collaborating with and ultimately producing a viable Campbell, I.H., M. Joswick, et al., Hewlett-Packard Company, Uniax commercial product. "Measuring Internal Electric Fields in Corporation, the University of Texas We established a PLED lifetime Organic Electronic Devices Using at Dallas, and the University of testing facility to measure the change Electroabsorption Spectroscopy" (to California at Santa Barbara to develop in PLED light output and drive volt- be published in Polym. Adv. Technol). PLED technology. age at constant current bias as a func- Smith, D.L., S.M. Kogan, et al., Our ongoing collaborative research tion of time for different current bias "Acousto-Optic Modulation of III-V program has made it clear that PLEDs levels, operating temperatures, and Semiconductor Quantum Wells," Phys. Rev. B 53, 1421 (1996).

Helium-3 Targets for Tritium Production The special target design is an engineered, passive safety feature. in Fission Systems Our new concept for a reactor target was successfully tested in the solution high-energy burst assembly at Los Brian James Alamos. Targets of the type we

3 designed could be used for supple- Neutron irradiation of He is a the technical problems associated mental or contingency tritium pro- potentially attractive method for pro- with tritium production. duction in existing DOE reactors— ducing tritium. Should this method be We have invented a target that the advanced test reactor (ATR) at implemented, experimental, defense, reduces or eliminates the additional the Idaho National Engineering and power reactors could provide a reactivity resulting from a loss of 3He; Laboratory and the Fast Flux Test contingency supply of tritium. How- this target makes the use of 3He in 3 Facility (FFTF) at the Hanford Site— ever, the safety of putting He in a reactors a viable option for supple- or in commercial light-water reactors. reactor has always been questioned— mental or contingency production of 3 ISTs could also be used in flowing the loss of He would result in tritium. In the inherently safe target 3He systems at FFTF and ATR with increased reactivity. Moreover, con- (1ST), 3He normally "cloaks" an addi- on-line tritium extraction that allows tainment of the tritium produced is a tional strong solid absorber such as continuous removal of tritium from concern under both normal operating boron-10. If the 3He gas should leak 3He and thus lessens containment and accident conditions. The objective out of the target canister, the reactor problems. Such use would greatly re- of our project is to develop innovative flux will immediately "see" the solid duce the inventory of tritium at risk, designs of reactor targets for produc- absorber. The target canister can be and it would significantly reduce per- ing tritium by neutron irradiation of designed so that the reactivity shift on 3 meation of tritium into the reactor He. The new targets should overcome a loss of 3He is negligible or negative. coolant. Finally, it would also simplify shipment of tritium for use at Savannah River.

Program Development—Engineering and Base Technologies 249 Explosives Detector Using the Optical household dust. The optical signature from the gunpowder is short and in- Signature of Deflagrating Explosive tense, whereas the signatures from the engine oil and nonexplosives are dim Participates and long. Since the pulse magnitude and width are anticorrelated, the ratio of the magnitude to the width enables Herbert 0. Funsten a simple but extremely sensitive technique for differentiating explosives Because of the stickiness of explo- The accompanying figure shows sives, surfaces coming in contact with pulse signatures from 5-ug gunpow- from nonexplosives. Advantages of an explosive will become contami- der particulates (used in 45% of bombs this detection technology include nated with explosive particulates. and devices used or confiscated in the fewer false-alarm rates, faster sample These particulates, which will exist in United States), engine oil, and nonex- analysis, less costly instrumentation, possibly large amounts on the explo- plosive particulates such as paper and and higher sensitivity. sive packaging and environs, provide an important avenue for detecting the presence of explosives. Gunpowder In the past year, we developed a unique technique for detecting explo- Engine Oil sives residue. This technique detects Nonexplosives the rapid burn of explosives, which (Paper, vacuumed have a higher oxygen content and a paniculate) more rapid breakup of molecules in comparison with nonexplosives. The detection apparatus consists of (1) a sample surface, (2) a heat source that initiates deflagration, (3) a photomultiplier tube that detects the optical signature resulting from deflagration, and (4) a signal analyzer. Our tests of the explosives detector show that the 4 light output from the burning residue IO- io-3 io-2 lO"1 10° 101 of explosives is rapid and intense, which contrasts with the emberlike Time (s) burn of nonexplosives. A comparison of the optical output from explosive and nonexplosive materials.

Directed-Light Fabrication—A Laser five-axis capability allows true three- dimensional replication of metal com- Metal-Deposition Process for Fabrication ponents as designed on a computer; by contrast, the three-axis machine of Near-Net-Shape Components is capable of only two and one-half dimensions. Gary Lewis During the year we succeeded in assembling and testing the five-axis Directed-Light Fabrication (DLF) powder material that can be melted. system, including assembly and test is a direct metal-deposition process Our studies proved feasibility with of a support structure and powder- developed at Los Alamos National any metal that can be made into feed apparatus. The system has four Laboratory and is a revolution in powder form and with intermetallic powder feeders that can be run indi- manufacturing technology. The DLF compounds. vidually or simultaneously to provide materials to the focal zone of the process is the first rapid-prototyping, Our assembly work on a five-axis laser, where they are fused into the free-form fabrication process that DLF machine in this project was an desired component. This accomplish- deposits metals directly to near net extension of earlier efforts that had ment is a significant advance in shape. It is a material-independent been limited to the three-axis DLF capability. process capable of processing any manufacture. The transition to the

250 Los Alamos FYI996 LDRD Progress Report Modeling and Assessment of Concrete As part of our scoping activities, we produced an inexpensive and environ- and the Energy Infrastructure mentally friendly set of stains that can detect deleterious reaction products George Guthrie associated with ASR. This method is in contrast to the one currently used Concrete is an essential component The experimental and modeling by highway departments, which is of our energy infrastructure. It is the capabilities that we developed for based on uranyl acetate. The uranyl primary material used by the energy geological systems such as Yucca acetate method produces uranium- and transportation sectors (for ex- Mountain are useful in our work to contaminated wastes, exposes person- ample, in roads, bridges, runways, improve the design of next-generation nel unnecessarily to radioactivity, is dams, reactor containment vessels, concrete. Our first goal is to under- difficult to use, and may result in and radioactive- and metal-waste- stand the geochemical processes that ambiguous information about the disposal). The strength and durability lead to the alkali-silica reaction nature of ASR in a particular con- of concrete, which are the properties (ASR), which is one of the main crete. We also obtained promising that determine its effectiveness in any impediments to durable concrete results when we used nonlinear of these applications, result from worldwide. ASR is an interaction resonance ultrasound spectroscopy chemical and structural changes that between alkalis in the fluid and some to evaluate fractures in concrete. occur during the minutes to years that silica-rich components of the aggre- We are developing this work in follow the pouring of a particular con- gate. It results in the formation of a conjunction with the Alliance for crete structure. These chemical and gel that causes the concrete to frac- Transportation Research, which re- structural changes are controlled by a ture, greatly reducing the concrete's cently assembled a national expert variety of geochemical and mineral- strength and longevity. panel that conducted a successful ogical processes that also occur in independent, external review of our some geological environments. efforts.

Global Nuclear Material Monitoring be run in parallel with actual facility operations to improve the capability for detecting departures from standard Jo Ann Howell operating conditions. We also enhanced the computerized Local To facilitate the development of the pattern recognition, radiation sensor Area Network Material Accounting nuclear material monitoring system of design, portal monitor sensor design, System (LANMAS) to incorporate the future, we are working to design a digital video production, and facility access control and authorization. detailed plan for advanced integrated simulation. Some of the technologies facility monitoring. We will identify that we still need to develop include the necessary components, the appro- anomaly detection for particular safe- Publications priate demonstration facility, and the guards applications; integration of Howell, J.A., "Analysis of Facility- enabling technologies. databases with analysis systems, Monitoring Data" (to be published in We identified the following major alarm systems, and displays; and Nucl. Mater. Manage.). components: material-tracking sensor design and implementation of smart Howell, J.A., H.O. Menlove, P.E. systems, personnel-tracking sensor sensors, data-mining tools, and recon- Argo, et al., "Global Nuclear Material systems, information management ciliation tools. Monitoring with NDA and C/S Data systems, measurement systems to per- We have initiated a publication through International Facility form assay, analysis tools to process series about Los Alamos global Monitoring" (to be published in Nucl. the collected data, and software to tie nuclear-material-monitoring projects. Mater. Manage.). all of the above functions together The first document to be produced in into one system. the series will be about monitoring at Proceedings of The Facility We have identified several neces- the Japanese facility, Monju. We have Monitoring Workshop, J.A. Howell, sary technologies. Some of those that identified simulation as an area that is Ed., Los Alamos, N. Mex., September presently exist include interface build- not often exploited in facility monitor- 19-21, 1995, Los Alamos National ing, visualization, authentication, ing systems. Facility simulations can Laboratory document LA-CP-95-251.

Program Development—Engineering and Base Technologies 251 Frequency-Resolved Optical Gating: Publications A Diagnostic for the Characterization Taylor, A.J., G. Rodriguez, and T.S. Clement, "Determination of the n2 of Optoelectronic Materials and Devices through Direct Measurement of the Optical Phase," Opt. Lett. 21, 1812 (1996). Antoinette Taylor

Frequency-resolved optical gating (FROG) is an ultrafast diagnostic Normalized intensity and technique that measures the full elec- phase for a pulse with no tric field, both instantaneous ampli- sample in the beam. The tude and phase, of an arbitrary pulse width is 130 fs. The ultrashort pulse. Because FROG is a phase (§) varies almost general, broad-band optical diagnos- linearly with time over tic, it can be used in research areas for the pulse and hence which characterizing the full electric represents a nearly field of an optical pulse would pro- transform-limited pulse. vide critical insight into physical processes. One area in which FROG -200 -150 -100 -50 0 50 100 150 200 could have an enormous impact is in Time (fs) understanding the coherent interaction Normalized intensity and between optical pulses and optoelec- 1.0 - tronic materials and devices. The phase of the pulse after it objective of this research is to address traverses 0.95 cm of fused 0.8 - • - : sample. modulation by measuring the phase -200 -150 -100 -50 0 50 100 150 200 change of the optical pulse with Time (fs) FROG after the pulse traverses the material. The emphasis of this

research is to determine the types and 0.0 - iCt) accuracy of measurements possible with FROG. We have completed a -0.2 - thorough set of measurements of the ; n a nonlinear index, «2> i variety of -0.4 -- optical materials using FROG. The accompanying three figures exhibit -0.6 - typical intensity and phase data A derived from the FROG spectrograms -0.8 - used to determine n2. We have demonstrated that FROG accurately mea- -1.0 -200 -150 -100 -50 0 50 100 150 200 sures n2 in optical materials, with the error dominated by the uncertainty in Time (fs) the fluence measurement. We are cur- Phase change—A^(t)—is plotted for this data along with a fit (solid line) that rently completing a second set of involves simply scaling the measured normalized temporal intensity profile to fit measurements on cross-phase modu- A(f>(t). (To obtain A(])(t), the calculated value for linear dispersion in the sample lation in optical materials. is added to the phase data with no sample present before subtracting the phases measured with and without the sample in the beam.) This fit yields a constant that is proportional to A(|)(t)/I(t) and from which n2 can be determined. This set 16 2 of data yields n2 = 2.45 x 10~ cm /W for fused silica at 804 nm.

252 Los Alamos FYI996 LDRD Progress Report Neutron-Based, Land-Mine inert objects and explosive-containing mines. Our approach of using a con- Detection System Development trolled, high-flux neutron source increases the speed of detection and allows a longer standoff distance. A Thomas McDonald vehicle is still needed to transport the system, and we project that costs will The goal of this project was to diagram below) and the intense ion- be relatively high compared with examine the feasibility of developing beam source (see schematic diagram costs of metal-detection techniques a buried land-mine detection system on p. 26). The advantage of these currently in use. We believe that the by detecting and analyzing prompt sources is that they can be turned off neutron-based approach can be used gamma-rays induced by neutron inter- when not in use and can be used over most effectively in conjunction with rogation. This is a mature concept; a wide range of operating modes from other approaches in a suite of comple- however, it has not been successfully steady state to pulsed. We also mentary detection sensors. applied to the buried-mine detection reviewed alternative detection tech- problem because of lack of both a niques and carried out preliminary suitable neutron source and a detec- measurements using mock high- Publications tion system having a sufficiently high explosive material. Davis, H.A., G.E. Remnev, et al., signal-to-noise ratio. Most studies We found that the primary advan- "Intense Ion Beam Treatment of indicate that a source strength in the tage of the neutron-based detection Materials," Bull. Mater. Res. Soc. 21 range of 109-10n n/s would be neces- approach for nonmetallic mines is that (8), 58 (1996). sary to achieve a reliable detection the approach is a powerful discrimina- capability requiring interrogation tor. Other approaches, such as Davis, H.A., J.C. Olson, W.A. Reass, times of only a few seconds. ground-penetrating radar and infrared et al., "Progress Toward a Micro- We considered two neutron sources detection, can detect buried objects; second Duration, Repetitive, Intense that have the potential of neutron however, these objects may or may Ion Beam for Active Spectroscopic fluxes in the neighborhood of not be mines. The neutron-based Measurements on ITER," Rev. Sci. 10u n/s: the inertial electrostatic con- approach, on the other hand, detects lustrum. 68, 332 (1996). finement source (see schematic explosives and differentiates between

~~14 cm K2 (Emitter *2, Cathode) Shell (Grounded) X62 (Extractor Grid *2) 15 cm~~

Schematic of an inertial electrostatic neutron source design for supplying 10n n/s, pulsed or steady. The design is a series of spherical, concentric grids and an outer shell approximately 30 cm in diameter. We G2 estimate the power requirements to be approximately (Intermediate 20 kW. Grid)

~~XG1 (Extractor Grid *1) G1: (Outer Grid) K1 (Emitter*!, 600 V Cathode) G3 (Central Cathode) -50 KV, 300 ma~~

Program Development—Engineering and Base Technologies 253 Development of the Transient-Reactor TRAC, while GSE provided the expertise on real-time systems. Dis- Analysis Code (TRAC) for Real-Time cussions then expanded to (1) real- time software design techniques to Applications integrate TRAC into a real-time simulator and (2) ways to modify engi- G. Niederauer neering plant models for use in a simulator. Traditionally, nuclear-plant training The object of this project was to We also worked on the so-called simulators have employed simple investigate the feasibility of using Robinson plant model, modified it for thermal-hydraulics codes because of TRAC in a simulator. simulator use, and ran several tran- the demands to run in real time and We have worked extensively with sients cases to characterize TRAC's with limited computing power. There GSE Systems, Inc. to write an infor- performance in real time. We identi- has always been a desire to increase mal discussion paper on the real-time fied areas where run-time could be the flexibility of such training systems applications of TRAC. Together we improved and explored means for and to increase the fidelity of models outlined technical issues relating to modifying TRAC to achieve such in the simulators. Although TRAC is taking a batch code into real time and improvement. We investigated inter- the most advanced code for such a staged approach for developing faces between TRAC and a real-time applications, many issues need to be what we would call TRAC-RT, start- system, including data structures, addressed to take such a complex ing with a proof of concept. Los graphical user interfaces, and real- code from a batch engineering envi- Alamos provided the expertise on time executive control. ronment to real-time environments.

Rapid Prototyping of Hazardous steel as a surrogate, with the intent of applying the knowledge gained from Materials Using the Directed-Light the steel modeling and deposition experiments to fabricating a beryllium Fabrication Process component. We anticipate that it will be straightforward to assemble a Gary Lewis special system with the necessary engineered controls for handling In the past, fabricating components part with a laser beam that melts beryllium or other hazardous materials. from hazardous materials such as metal powder particles entering the Using DLF process parameters and beryllium has been difficult and ex- focal zone. Upon solidification, the information about the physical prop- pensive because of both the number metal forms a deposit representing a erties of stainless steel as input to a of processing steps necessary to get planar cross section of the part. heat-flow code, we modeled finite from the raw material to the finished Multiple cross-sectional layers are heat flow in steel. Unfortunately, be- product and the controls necessary to formed in succession until the part is cause we did not have a complete set process the materials safely without complete. The DLF system we cur- of beryllium thermophysical proper- contaminating the environment. Now, rently use has five axes of motion, ties, we were unable to apply the however, the directed-light fabrication allowing us to fabricate three- model to a beryllium component for (DLF) process that we developed at dimensional components and to comparison. From the steel models-, Los Alamos can produce, in a single deliver up to four different powders at we determined that we could control step, near-net-shape (within a few the same time or in succession. DLF the thickness of the deposited layers if thousandths of an inch) metal compo- can be used for depositing any metal we used heat-flow gradients to help nents that are fully dense. The process or intermetallic compound. optimize the DLF process parameters. We will correlate the theoretical data is nearly waste-free, and it eliminates The goal of this project has been to from these models with experimental or contains all contaminants produced apply DLF technology to fabricate results and will eventually incorporate with conventional methods. fully dense beryllium components the data into control loops for real- DLF uses tool paths generated from (that is, beryllium components having time process control. digitally designed solid models to full theoretical strength). To reduce accurately trace the cross section of a costs, we modeled the process using

254 Los Alamos FYI996 LDRD Progress Report designed for thermal-spectrum reac- Reactor-Based Tritium Production tors. We are currently applying for patents for both the fast-spectrum tar- Michael Houts get and the thermal-spectrum target. In addition, we assessed all aspects Los Alamos National Laboratory is been done related to that option, and it of the tritium production cycle, from responsible for stockpile stewardship. has the potential for providing signi- target fabrication to extraction of As part of its stockpile stewardship ficant amounts of defense-related tritium to getting the tritium into the responsibilities, Los Alamos must tritium. form required by the Department of assure that the United States has an A major accomplishment of the Defense. The use of flowing 3He adequate supply of tritium for defense project was our development of an loops (for which FFTF is well suited) purposes. In that context, the goal of inherently safe 3He-based tritium could greatly reduce the cost of our project was to evaluate options for production target designed for use in processing and shipping targets. The producing reactor-based tritium. fast-spectrum reactors (such as the use of static 3He targets rather than Much of our effort focused on evalu- FFTF). Although the basic operating flowing 3He would also reduce costs. ating the Fast Flux Test Facility premise is the same, the target is If the option for FFTF tritium produc- (FFTF). We selected the FFTF significantly different from the inher- tion is funded, Los Alamos is in an because little independent work had ently safe targets we had previously excellent technical position to participate in numerous aspects of this option.

Methods for the Rapid On-Line Detection 100 ppb by volume in air. The detection of these compounds satisfied the of Biological and Chemical Weapons deliverable of demonstrating the instrument for the detection of CW surrogates. Philip Hemberger In addition, we developed a technique for the rapid, direct detection— Our objective is to develop technol- trap mass spectrometry. We installed a ogy for the detection (using surro- membrane interface on the transport- with high sensitivity and gates) of chemical and biological able mass spectrometer and adapted the specificity—of pathogenic DNA. The warfare agents. The project consists instrument for the detection of surro- method consists of adding two DNA of three tasks: (1) to modify a trans- gates of chemical warfare agents. The probes to a sample containing the portable mass spectrometer for the instrument and sampling system are target DNA. The sample is then detection of chemical agents; (2) to mounted in a 20-in. x 20-in. x 36-in. analyzed by a laser-based, ultra- demonstrate the detection of specific transportable container. The instrument sensitive fluorescence system capable bacterial DNA sequences using a also requires a small cylinder of of detecting single molecules at two fluorescence-based, single-copy gene helium and a rotary vacuum pump, different wavelengths. If the target is detector; and (3) to upgrade a surface- which are mounted externally on the present, the two probes will bind to it, acoustic-wave measurement station. container. We also developed pre- and their signals will appear simulta- In the past year, we modified an liminary methods for detecting CW neously in time and space. Using the existing transportable mass spectrom- surrogates. The surrogates included system, we detected single copies of a eter for the field detection of chemical chlorobenzene, cyclohexanol, specific DNA sequence from Bacillus warfare (CW) agents. The detection dimethyl methyl phosphonate, and anthracis with a signal-to-noise ratio technology is based on the combina- dimethyl sulfoxide. These compounds of 20 in only 400 s in an excess of tion of membrane sampling and ion- were detected at approximately unrelated DNA material.

Program Development—Engineering and Base Technologies 255 Night-Vision Device Technology of view. For the bright-spot suppression, we have designed a segmented Development microchannel-plate scheme that suppresses the gain in only that segment illuminated by a bright light source, Herbert 0. Funsten while it retains full gain across all The U.S. military extensively uses aircraft. Bright-spot suppression is other segments. In this way, dim night-vision devices that utilize crucial to night missions in an urban objects within the field of view image-intensification tubes. These or other well-lighted environment remain visible. tubes have two significant problems (one with streetlights, flares, head- We finished a design and procured an that can critically compromise their lights). experimental, curved-microchannel- operation: (1) the field of view is re- In this project we are developing plate tube based on the wide-angle stricted due to aberrations introduced technology to overcome these prob- work in the first year. Currently we are by the flat-image plane and, (2) light- lems. First we are designing a curved- waiting for delivery of the fabricated sensitivity (gain) loss occurs when a image plane, using recently developed tube. We also finished a prototype for a bright-light source lies within the field detector technology that enables a segmented microchannel-plate design of view. A wide field of view is criti- wide field of view. We have per- and now are planning a laboratory cal to aviators who need peripheral formed optic and electro-optical simu- demonstration of the concept. vision for motion cues and detection lations to allow up to 80 degrees field of nearby obstacles, obstructions, or

Alamos Neutron Scattering Center. Integrated Approach to Advanced Machining These measurements revealed that the hoop stress increased with depth of cut; Robert D. Day however, the radial stress decreased with depth of cut. An elastic-plastic The goal of this project was to mea- for Ti-6A1-4V specimens. Kennemetal model provided a possible explanation sure the residual stresses induced by donated tools (both dull and sharp) for for this behavior. For small depths of machining as a function of the depth of this project. We measured the tools' cut, the tool makes multiple passes cut and the cutting tool's sharpness. sharpness radii at Los Alamos before through the damaged subsurface layer, The sample for these experiments con- machining, using interferometry, and which causes both residual stress com- sisted of a titanium alloy that contained determined them to be nominally 1 nm ponents to increase; however, the radial 6% aluminum and 4% vanadium. We for the sharp tools and 10 |am for the stress increases by a much greater performed cutting tests on this sample dull tools. amount than the hoop stress. The in the as-received condition and after a We measured the residual stresses second figure compares the calculated stress-relieving heat treatment. The first induced by x-ray diffraction using the residual stress with the measured figure shows cutting and thrust forces rotating anode located at the Los values.

~~1000 - 1— 1 1—1— 1 1 1 j i 1 !—1—111 1 1 1—1 Mil-~~

~~o Sharp tool thrust force per unit width N/mm E • Sharp tool cutting force per unit widtr , N/mm - E o Dull tool thrust force per unit width, N/mm X Dull tool cutting force per unit width, N/mm~~

~~100 - i * - Cutting and thrust forces for heat-treated $ Ti-6Al-4V specimens. The average is plotted. The uncertainty bars indicate the maximum and minimum measured force values.~~

~~1 0 - 1——1 1—i 1 1 1 1 | 1 1 1—h^-^-H 1 1 1—1 Mil-~~

~~0.1 1 10 100 Depth of cut,rrm~~

~~256 Los Alamos FY1996 LDRD Progress Report u- 1 : I 1 I lll| 1 1 1 1 1 I iii.- 0- 1 1 I I I lll| 1 1 I 1 Mll| H- i ij~~

~~-100- '-- -100- -200- -200- I J f :: -300- -.- -300- -i~~

-400- I -_- -400-i - i -500- -- -500- o Sharp tool radial residual stress, N/mm2 p Sharp tool calc radial stress N/mm2 -600 - o Sharp tool hoop residual stress, N/mm2 -- -600 - n Sharp tool calc hoop stress N/mm2 -700 - -700- - e- -800- , l -800- 1 1 1 1 1 1 H- 0.1 1 10 100 0.1 1 10 100 Depth of cut, (nm) Depth of cut, (|xm) a) b)

~~0- 1 1—i—i-r !• i | i 1 I I 1 1 IM| —h- \ 1—1 l-i-H- - 0-~~

-100- 100- u c i j -200- \ I 200- J [ -300- i f 300- -400- 400- I d> -500- 500- o Dull tool hoop residual stress, N/mm2 o Dull tool radial residual stress, N/mm2 J -600- 600- -+- o D Dull tool calc fioop stress N/mm2 o Dull too! calc radial stress N/mm2 S -700- 700- -800- 800- 0.1 1 10 100 0.1 1 10 100 Depth of cut, (jim) Depth of cut, (um) c) d)

Measured and calculated residual stresses. The average value is plotted. The uncertainty bars for the measured residual stresses are the combination of the variation in the measurements at four locations around each ring and the measurement uncertainty. The uncertainty bars for the calculated values come from the variation in the force measurements that were used in the data analyses: (a) sharp tool hoop stress, (b) sharp tool radial stress, (c) dull tool hoop stress, (d) dull tool radial stress.

~~Program Development—Engineering and Base Technologies 257~~

~~Plasmas, Fluids, and Particle Beams~~

Subsurface, Directed-Energy Methods for reaction rates over those found in simple fluids, the scaling to subsur- Groundwater Treatment face remediation is not promising, and the work will not continue. For the next fiscal year, we will John Coogan extend the research in enhanced transport under more controlled laboratory A critical issue in pump-and-treat higher ultrasound intensities to conditions to identify mechanisms, approaches to groundwater reme- destroy DNAPL surrogates in sand and we will use the knowledge gained diation is the limited mass transport of and soil. Although we discovered that to evaluate a field-ready prototype. subsurface organics, especially dense soil can act as a reaction fluidized nonaqueous-phase liquids (DNAPLs). bed, greatly enhancing sonochemical We are evaluating a novel concept using acoustic waves to enhance the transport and extraction of subsurface Effects of Ultrasound (US) on TCE Transport organics from leaking underground storage tanks. Until now the majority 10000 of research in this area has been focused on improving production in declining oil and gas reservoirs, and the underlying physical mechanisms -9/25 US vial for enhanced transport have not been _ 1000 O 9/25 control vial thoroughly investigated. Q. During the reporting period we •S -9/10 US transport vial explored two research paths. First we 9/10 control vial demonstrated that acoustic energy can 100 enhance the solubility of DNAPLs, Saturation specifically trichloroethylene (TCE), concentration in both sand and Pajarito tuff. Experi- mental work has clearly shown that the proposed process is real (see figure), with removal efficiencies 10 20 30 increased by orders of magnitude in Time (hours) both static and flowing systems. This work also suggests several potential TCE concentration measured as a function of time with and without ultrasonic mechanisms for the effect. Second, enhancement. Data for both controls and samples are shown. We applied we used cavitation and the resulting ultrasound to samples at time - 22 hours. The production of TCE levels above sonochemical reactions produced at the solubility limit suggests that emulsions may be formed.

Program Development—Plasmas, Fluids, and Particle Beams 259 Plasma Source Ion Implantation for capable of operation at 20 kV with a current capability of 2 kA. This modu- Advanced Manufacturing lator does not suffer from switching storage delay or temperature effects and permits system operation over Jay Scheuer large temperature extremes.

Plasma source ion implantation support of the industrial implants listed (PSII) and plasma immersion ion below. A new system dedicated to the Publications processing (PHP) can be used to development of PUP processes is now Reass, W.A., "Progress Toward a provide economical surface modifica- operational. We have performed dem- 20 kV, 2 kA PSH Modulator for tion to satisfy industrial and DOE onstration implants on actual industrial Automotive Production" (22nd Int. stockpile support needs. PSII is a non- components and are currently field test- Power Modulator Symposium, Boca line-of-sight ion implantation technique ing these components. We have con- Raton, Fla., June 24-27,1996). that reduces the complexity and cost of ducted implantation experiments at traditional ion implantation. PHP is a high temperature in collaboration with Walter, K.C., M. Nastasi, and C.P. logical extension of PSII that combines the Institute of Electrophysics and the Munson, "Adherent Diamond-like ion bombardment with plasma deposi- Institute of Metal Physics in Carbon Coatings on Metals via PSII" tion, thus allowing deposition of con- Ekaterinburg, Russia. A PSH/PUP (submitted to Surface Coatings and formal, adherent coatings with process for the deposition of adherent Technology). thicknesses of tens of microns. Our diamondlike carbon films on steels is Walter, K.C., K.T. Kern, J.R. Tesmer, project is dedicated to developing and almost fully developed. We have comet al., "Nitrogen and Boron Ion demonstrating PSD/PHP processes. pleted the design and fabrication of a Implantation into Electrodeposited We have performed process solid-state insulated-gate bipolar tran- Hard Chrome" (submitted to Surface development and characterization in sistor (IGBT) modulator that will be Coatings and Technology).

Magnet Design Concepts for the technical feasibility for delivering the required 100-MeV beam to the IP 100-MeV Isotope-Production Facility facility and still delivering the required beam to the proposed long- pulse spallation source (LPSS) facil- E. Wadlinger ity, the weapons neutron research facility, and the proton storage ring If an isotope-production (IP) facil- beam is directed to other areas of (PSR) at the Manual Lujan Jr. Neu- ity is to be viable at the 100-MeV LANSCE. Because of these con- tron Scattering Center. LPSS requires region of the Los Alamos Neutron straints, the magnet must be specifi- proton-beam macropulses of 60 pps Science Center (LANSCE) accelera- cally designed and built for this and PSR requires 20 to 30 pps of pro- tor, an efficient extraction system is intended application. Project objec- tons, leaving 30 to 40 pps for other required. The greatest uncertainties tives were to evaluate design concepts users. At the LPSS-proposed 21-mA are associated with the kicker magnet for the kicker magnet and its power peak proton-beam current and 1-ms needed to divert portions of the beam supply and to assess the feasibilities pulses, the IP facility would only need into any new beam line. This magnet of various design alternatives. 12 pps to get the required 250-uA must fit into a rigidly defined space We have developed a conceptual beam. The power supply design is within the transition region of the ac- design for a kicker magnet and power based on a proven and working design celerator and must operate in concert supply to be placed in the available for the RIKI (ring-injector kicker) with the current accelerator operations space in the transition region to pro- magnet that switches the 800-MeV systems. In addition, it must in no vide a proton beam for a proposed IP beam into the PSR. way degrade beam quality when the facility. Our design study shows the

~~260 Los Alamos FYI996 LDRD Progress Report Advanced Ignition of Jet Turbine Engines~~

~~James Early~~

During the past year we have demonstrated several innovative technologies for applying lasers as an alternative to capacitive discharge for the ignition of jet turbine engines. This s8 project focused primarily on two areas essential to the implementation of a practical laser igniter: (1) developing energy-efficient, laser-induced fuel-ignition methods that are effective and reliable, and (2) developing techniques to maintain the transparency of optical surfaces that isolate the laser from the hostile combustion- 0 chamber environment. Laser-based ignition concepts em- .10 -8 -6 4 -2 0 2 4 6 8 10 ploy many laser-wavelength and Radial Initiation Location in Fuel Cloud (mm) pulse-format mechanisms to increase With the same laser energy (144 mJ), the reliability of jet-fuel ignition is both the rate and duration of laser substantially improved by applying the dual laser pulse/plasma pumping energy delivery. We found that method (curve A) over that of conventional laser-spark ignition (curve B). increasing the time the laser light is applied to the fuel medium assists the growth of a stable flame kernel. At the same time, it reduces both laser peak- power requirements and inefficiency 120 # With Preheat in energy utilization. We used plasma pumping, direct • Without Preheat light absorption by fuel components and laser light/material surface inter- £ 80 - actions as energy-coupling mechanisms. We showed that these innovative ignition methods reliably ignited jet-fuel aerosols over a broad a range of fuel/air mixtures and at fuel e temperatures as low as -40°F. As 20 - shown by the jet-fuel ignition profiles in the accompanying figures, this kind 0 of ignition is superior to conventional -10-8 -6 -4-2 0 2 4 6 8 1012 laser-spark ignition. We also developed a laser-based method that effec- Radial Initiation Location in Fuel Cloud (mm) tively removes opaque deposits of fuel hydrocarbon combustion residues The laser-prevaporization method provides a significant enhancement to jet- from laser window surfaces. To date, fuel-aerosol ignition. Fuel droplets are vaporized by the direct absorption of this R&D effort has resulted in three low-peak-power (30 kW), 3-mm light provided by a free-running Er:YAG laser. pending patents, one provisional The fuel vapor is subsequently ignited by a laser spark produced by a focused, patent, and one invention disclosure. 91-mJ, Q-switched Nd:YAG laser pulse.

Program Development—Plasmas, Fluids, and Particle Beams 261 Removal of Transuranic Materials from would be used to volitalize and remove plutonium or uranium from contami- Contaminated Equipment Using Plasma nated surfaces. Decontamination Experiments with NF3 and tungsten (as the TRU surrogate) have demonstrated material-removal rates in a mild, Carter Munson reactive-ion-etching (RIE) mode. These rates are nearly an order of magnitude The primary goal of this project is to selection of NF3 as the plasma precur- faster than the material-removal rates develop and demonstrate the utility of sor gas because of the reduced potential we observed in the plasma-immersion plasma-based processes for the removal for particulate formation and nonvola- mode. We expect significant additional of transuranic (TRU) contamination tile material deposition. We conducted increases in removal rates when the from targets of interest to the DOE experiments to examine the removal of system operates in the combined RTF, complex. The first stage of the process various surrogate materials in a number and sputtering mode. has been to design, fabricate, and per- of different target geometries. form initial tests of a prototype plasma- We have also conducted a very large decontamination system using surro- scale test (~3-m2 target area) in another Publications gate materials. available facility. This test examined Munson, C, E.P. Chamberlin, et al., We have designed, fabricated, and the removal of a very hard, chemically "Development of Plasma-Based integrated a small system (-0.5 m3) resistant, amorphous carbon material Decontamination of Large Metallic with a two-stage, cryogenic trapping from the surface of an extremely com- Objects" (23rd International and recovery system. Examination of plex aluminum target. We used an oxy- Conference on Plasma Science, the etching characteristics of various gen plasma in this case as an analogue Boston, Mass., June 3-5, 1996). gases (CF4, NF3, SF6, etc.) led to the for the fluorine-based plasma that

Supporting Technologies for a Long-Pulse Several external review committees have examined the technical progress Spallation Source of our activities. Based on feedback from the committees, we began to Joey Donahue address some of the supporting engineering issues of the target-moderator- We are investigating the accelerator Our initial work was directed to- reflector system and target station in modifications, target-moderator- ward modeling the physics of target the latter half of the fiscal year. These reflector concepts, neutron-scattering system and neutron-scattering instru- include target thermohydraulics and instrumentation, and facility modifi- ment performance, which was needed the choppers that are used to shape cations necessary to design a long- to establish the scientific case for the the neutron pulses. The results of this pulse spallation source (LPSS) at Los LPSS. We also investigated the accel- work have been documented in publi- Alamos. We are building on last erator modifications necessary to cations, conference proceedings, and year's efforts and incorporating tech- achieve the 21-mA peak current internal Laboratory reports. nologies and ideas from synergistic required for a 1-MW LPSS. We had a activities at the Los Alamos Neutron successful 32-h accelerator develop- Publications Science Center (LANSCE), such as ment run at 800 kW of beam power the Accelerator Production of Tritium with the LPSS beam structure. This Fitzsimmons, M.R., "Reflectometry at Project, the LANSCE Reliability run demonstrated that the LANSCE Continuous Wave and Pulsed-Neutron Improvement Project, and Accelera- linac can already deliver 80% of the Sources" (to be published in Nucl. tor-Driven Transmutation Technolo- power needed for a 1-MW LPSS. lustrum. Methods). gies. Major emphasis is on evaluating These efforts supported the LPSS Fitzsimmons, M.R., and R. Pynn, concepts from an engineering per- proposal, its preliminary cost and "The Performance of Reflectometers spective to establish a basis for as- schedule estimates, and a preliminary at Continuous Wave and Pulsed- sessing the technical as well as cost engineering layout for the target Neutron Sources," ICANS-XIII: Proc. and schedule risks for the proposed station. 13th Meeting Int. Collaboration on LPSS facility. Advanced Neutron Sources (1995).

262 Los Alamos FY1996 LDRD Progress Report Olah, G.A., RA. Seeger, and R.P. Pynn, R., and D. Weinacht, "A Russell, G.J., E.J. Pitcher, et al., Hjelm, "Small-Angle Scattering Proposal for a Long-Pulse Spallation "Long-Pulse Spallation Source Instruments on a 1 MW Long Pulse Source at Los Alamos National Neutronic Performance" (Workshop Spallation Source," ICANS-XIII: Laboratory," ICANS-XIII: Proc. 13th on Neutron Scattering Opportunities Proc. 13th Meeting Int. Collaboration Meeting Int. Collaboration on at Long Pulse Spallation Sources, on Advanced Neutron Sources (1995). Advanced Neutron Sources (1995). Berlin, Germany, June 24-27, 1996). Pitcher, E.J., G.J. Russell, et al., Russell, G.J., E.J. Pitcher, and P.D. Waters, L.S., E.J. Pitcher, et al., "Performance of Long-Pulse Source Ferguson, "Coupled Moderator "Shielding Calculation for the Long- Reference Target-Moderator-Reflector Neutronics," ICANS-XIII: Proc. 13th Pulse Source Facility" (American Configuration," ICANS-XIII: Proc. Meeting Int. Collaboration on Nuclear Society 1996 Radiation 13th Meeting Int. Collaboration on Advanced Neutron Sources, 495-509 Protection and Shielding Division Advanced Neutron Sources, 323-329 (1995). Topical Meeting, No. Falmouth, (1995). Mass., April 22-25, 1996). Russell, G.J., E.J. Pitcher, and P.D. Pynn, R., and L.L. Daemen, "The Ferguson, "Neutronic Performance of Performance of Neutron a Benchmark 1-MW LPSS," in Spectrometers at a Long-Pulse Proceedings of the Workshop on Spallation Source," ICANS-XIII: Neutron Instrumentation for a Long- Proc. 13th Meeting Int. Collaboration Pulse Spallation Source (Lawrence on Advanced Neutron Sources (1995). Berkeley Laboratory report LBL- 37880, Berkely, Calif., 1995).

~~Program Development—Plasmas, Fluids, and Particle Beams 263~~

~~Chemistry~~

Advanced Oxidation Technologies for In preparing the apparatus and experiments, we established a projected Chemical Demilitarization mass balance for the two-stage unit (based on previous data related to Louis A. Rosocha phosphate esters) and compared this projection to incinerator-based pro- Safely demilitarizing chemical- system as a viable process for de- cessing. We evaluated various CW warfare (CW) agents is a high-priority stroying CW agents, thereby provid- surrogates and chose the pesticide problem for the Department of De- ing a basis for future program malathion as our primary simulant. fense (DoD). Historically, the DoD development. We focused on testing a We then designed and constructed a has preferred to destroy CW agents by system concept in which we first vola- lab-scale PBR/NTP reactor, consist- incinerating them. However, because tilize (and/or oxidize or pyrolize) a ing of a liquid-injection system, an incineration has many drawbacks surrogate liquid CW agent using a injection-rate meter, an electric fur- (such as leaks, hazardous air emis- thermal packed-bed reactor (PBR) nace, condensers, chemical traps, sions, and large secondary-waste and then further process the PBR off- plasma reactors, power supplies, and streams), the DoD is currently looking gas with a second-stage nonthermal chemical diagnostics. In addition, we for alternative methods that are highly plasma (NTP) reactor (see schematic carried out combined PBR/NTP pro- efficient at destroying these extremely diagram). We designed this two-stage cessing experiments and completed toxic chemicals. system for closed-loop operation to preliminary chemical-processing cal- Our main objective was to establish achieve extremely high degrees of culations on carbon dioxide traps, re- an innovative, advanced oxidation agent destruction and to collect and/or action chemistry, by-product control all by-products from the pro- distributions, and phase equilibria. cess.

~~Chemical - Feed~~

Schematic diagram of an advanced oxidation system for chemical demilitarization with a PBR and an NTP reactor that is based on silent- i discharge plasma (SDP). Our system atomizes liquid CW-agent surrogates and then injects them into the PBR, where they are oxidized or pyrolized. The PBR off-gas is then fed to the SDP cells (the NTP stage) for further r.^1 processing. Because we can operate the system in closed-loop mode, we can achieve an extremely high degree of destruction and can capture the by- products of the process. A particularly attractive feature of the system is its ability to operate with oxygen-free feed gases.

Program Development—Chemistry 265 Advanced Nuclear Fuel Processing actinides, performs a lanthanide/actinide separation, and recovers uranium from the other actinides as Larry Avens illustrated in the second figure. Initial experiments have shown that The goal of the project is to deter- (1) distillation-based separations; significant quantities of actinides, lan- mine unique approaches where Los (2) pyrochemical separations in metal thanides, and fission products can be Alamos' expertise in separations and alloy systems; (3) metal solvent sys- dissolved in a LiCl/KCl eutectic mix- nuclear materials operations can be tems for actinide/lanthanide separa- ture when heated. More importantly, applied to spent fuel reprocessing. tions; (4) salt-environment methods the chloride salts of many of these The first figure shows an overview of such as halide slagging; and (5) use of metals can be converted to their re- the technical goals of this proposal. ceramic materials that are constructed spective oxides by addition of sodium We intend to develop alternative pro- to selectively transport or capture ele- carbonate. We are also investigating cessing technologies and concepts ments. Our approach uses chloride the selective halogenation of the lan- necessary to understand critical ele- salt distillation and recycle methods thanides over the actinides. We have ments such as separation efficiencies, for plutonium electrorefining salts. begun investigating tungsten hexa- material and equipment requirements, Using selective transformations like chloride and other chloride melts to and waste generation. oxidation and distillation, we have determine their ability to maintain the This year we reviewed several sepa- designed a process that separates desired complex in a low-melting ration technologies. These were cesium and strontium from the medium.

~~Destiny of the actinides, fission products, and activation products from spent fuel processing.~~

~~I La/Ac/Fp + Na2CO3/LiCl J~~

~~Distillation~~

~~Ac = Th, U, Np, Pu, Am FP = Cs, Sr, Tc La = Ce, Eu, Yb, Lu Proposed chloride-based, molten-salt separation scheme.~~

266 Los Alamos FY1996 LDRD Progress Report Chemical-Biological Treatment of system. We applied these data to build and validate a numerical model to Heterogeneous Wastes simulate the coupled physical and biochemical processes in the James Brainard bioreactor. In addition, we demonstrated the applicability of HW treat- Heterogeneous wastes (HW)— Conventional chemical and physical ment strategies to the recycle/reuse of defined here as wastes containing oxidation technologies are not effec- Environstrip™ paint-stripper blast bulk solids contaminated with one or tive in treating these wastes because media. more components subject to Resource of problems with one or more of the Conservation and Recovery Act following: permitting, cost, public Publications (RCRA), Comprehensive Environ- perception, and performance. mental Response, Compensation, and Using integrated business and tech- Twary, L.V., R.K. Gmmbine, T.M. Liability Act (CERCLA), Toxic Sub- nical development activities, we are Foreman, et al., "Integrated Chemical/ stances Control Act (TOSCA) or working to develop, demonstrate, and Biological Treatment of Paint Stripper radiation restrictions—are difficult to implement chemical-biological tech- Mixed Waste," Proc. of the Third treat by any single conventional or nologies for the treatment of hazard- Biennial Mixed Waste Symposium developing technology. Included in ous HW. During the past year we (Cognizant Communication HW are decontamination and decom- obtained permits and treated actual Corporation, Elmsford, N.Y, 1995), missioning (D&D) wastes (for ex- plutonium-containing D&D waste p. 1171. ample, soil, clean-up debris, and obtained from storage at Technical Twary, L.V., K. Steenhoudt, B. Travis, paint-stripper waste); petroleum Area (TA)-54. We also obtained mass- et al., "Biodegradation of Paint wastes (hydrocarbons and contami- transfer kinetics equilibrium data and Stripper Solvents in a Modified Gas nated soils, metals, and sludges); biodegradation kinetics data for the Loop Bioreactor" (to be published in waste-treatment sludges and combus- destruction of organic paint-stripper Biotechnol. Bioeng.). tibles; and filter materials (paper, solvents in the modified gas-loop cloth, wood, solvents, and metals). bioreactor that is part of our treatment

Radionuclide Separations Using Pillared their strong affinity for strontium. The distribution coefficients (Kj values) Layered Materials for Ca2+, Sr2+, and Ba2+ onto the pillared TaWO6 compounds were determined as a function of ionic Norman Schweder strength, pH, surface area, and ionic radius. The objectives of this project are to titrations, surface area measurements, The data we obtained show a strong develop pillared layered materials pore size distributions, and capacity pH dependence and K values for the (PLMs) that can efficiently sorb measurements. The active sites in d three cations increasing to > 104 above radionuclides, such as strontium-90, these materials were probed with pH 12. Although PLMs removed from liquid nuclear wastes stored in electron paramagnetic resonance, >99.999% of the strontium from underground tanks at DOE facilities europium fluorescence, and infrared nuclear waste simulants, their sorp- and from mixed wastes stored at Los measurements conducted before and tion of strontium from actual waste Alamos; to characterize the most after the sorption of gases. was disappointing. Our analysis indi- promising of these PLMs and test A general conclusion obtained from cates that complexants in the actual them on actual wastes; and to investi- our data is that there are at least two waste compete effectively against gate their sorption mechanisms. active sites responsible for cation ex- PLMs for the strontium. Destruction change in these materials. A tentative PLMs are layered, inorganic ion of the complexants would make fea- interpretation of how these active sites exchangers propped apart by metal sible the application of PLMs to the function is that one is active at low pH oxide pillars. This year, we prepared Hanford waste. large batches of chromium-, and operates purely by an ion ex- titanium-, and silicon-pillared tanta- change process; the other site is active lum tungstate (TaWO6) materials. To at high pH, operates by a sorption characterize these materials, we used mechanism, and gives these materials

Program Development—Chemistry 267 Integration of Advanced, Nuclear Materials A second focus was on implementing a capability for hydrothermal Separations Processes R&D on plutonium-containing materials using small-batch reactors. We designed and built several hydrother- Gordon Jarvinen mal batch reactors (see accompanying diagram) that we will install in a We are investigating the fundamen- mal oxidation of plutonium-contain- glove box at the Plutonium Facility. tal chemistry issues that affect the in- ing combustible materials. To mea- We will conduct plutonium-speciation tegration of several promising new sure the solubility of Pu(VI) from experiments on 2- to 2.5-mL mixtures separations technologies into nuclear oversaturation in carbonate media, we of solution and solids at pressures of materials synthesis and processing. needed a well-characterized, solid- up to 6000 psi and temperatures of One of these technologies, hydrother- limiting phase. We prepared 500 mg 239 500°C-600°C in these reactors. When mal oxidation, uses water and an oxi- of PuO2(CO3) and characterized it we tested these batch reactors on non- dant at high temperature and pressure by powder x-ray diffraction, extended radioactive solutions, we found that to efficiently and safely destroy com- x-ray absorption spectroscopy, and hydrothermal processing conditions bustible materials. The water stream diffuse reflectance spectroscopy. We oxidized Ce(III) to Ce(IV) and Cr(III) that results can then be partitioned to initiated solubility experiments using to Cr(VI), supporting our expectation give optimal product or waste forms. this solid in 0.1- and 5.0-MNaCl so- that plutonium compounds will be The successful development of these lutions under 100% CO2. We col- oxidized to Pu(VI). new technologies will lead to greatly lected a set of spectrophotometric reduced generation of solid wastes titration data, some of which are from nuclear materials operations. shown in the accompanying plot. A One focus during this year was on preliminary fit gives formation con- the plutonium(VI) carbonate chemis- stants for the tris- and biscarbonato try (including solubility and specia- complexes to be log b130 = 17.7 and tion of plutonium) expected to control log b120 = 13.6, respectively. the fate of plutonium after hydrother-

~~0.6~~

~~0.5~~

~~0.4 pH 10.430~~

~~0.3 pH 10.430~~

~~Schematic drawing of a hydrothermal 0.2 - batch reactor that we constructed for this project. We will install it in a plutonium-handling glove box. 0.1 -~~

~~500 600 700 800 900 1000 Wavelength (nm)~~

A subset of absorption spectra used to determine the formation constants of Pu(VI) carbonate complexes. Experimental conditions were [PuO^] = 2 4.45 fflM, [CO3 ~] = 12.0 mM, ionic strength = 0.1-M NaClO4, temperature = 25°C, andpH = 7.059—10.430. The spectroscopic peaks clearly shift to higher wavelengths as the pH increases. To determine the formation constants, we fit these peak shifts to a model in which the formation constants and spectra of the individual complexes are free parameters.

268 Los Alamos FY1996 LDRD Progress Report Catalysis for Alternative Feedstocks Our work on the Heck reaction revealed supercritical carbon dioxide can be used as an alternative solvent William Tumas for the Heck reaction. We examined a number of catalysts for the reaction of In this project we focused on tech- processes utilizing carbon dioxide as iodobenzene with styrene in the pres- nical and program development work a solvent and a potential reagent. This ence of triethylamine. Perfluorinated in catalysis and supercritical fluid work focused on two classes of reac- phosphine catalysts dramatically in- chemistry to strengthen the tions that are industrially significant creased conversions to 99% after 12 Laboratory's capabilities and to posi- and could lead to extensive waste hours at 90°C and 5000 psi. We have tion Los Alamos for future programs. minimization/solvent replacement: found CO2 to be an effective cosol- The program development activities (1) palladium-catalyzed reductive vent for the direct cobalt-catalyzed air focused on working closely with in- carbon-carbon bond-forming reac- oxidation of cyclohexane and cyclo- dustry, DOE, and the EPA to launch tions (Heck reaction) to produce hexanone to adipic acid. Oxidation of new initiatives in catalysis for next pharmaceutical intermediates, as cyclohexane at 95°C produced adipic year and beyond. We expect the tech- shown in the first figure, and acid with selectivities higher than nical work on catalytic processes in (2) cobalt-catalyzed air oxidations of those of conventional solvents (>80%) supercritical carbon dioxide to yield cyclic hydrocarbons to produce poly- at low conversions (up to 4%). Direct innovative, environmentally benign mer intermediates, as shown in the air oxidation of cyclohexanone pro- second figure. ceeds at higher rates.

~~Pd(OAc)2,Et3N,L Ph Ph Phi Ph 5000 psi Ph~~

~~L = Ligand Time TfC) Conversion trans-Stilbene ds-Stilb*ne~~

~~none 12 h 90°C 19% >99% 4d 90°C 37% 93% 7%~~

~~12 h 90°C 14% >99%~~

~~12 h 90°C 99% 94%~~

~~24 h 40°C 51% 94% 6%~~

~~Summary of palladium-catalyzed carbon-carbon bond forming (Heck reaction), illustrating higher conversions using fluorinated phosphine ligands.~~

~~100 10~~

~~80 - - 8 ; Adipic acid selecti fity N~~

~~£T 60 - 6 ?~~

~~• o - 4~~

• 20 - - 2 • ; ws^ Conv ersion Oxidation of cyclohexane at 95°C in CO /HOAc, 2 • iii r^T i i • i i illustrating high selectivity for the formation of adipic acid at conversions up to 6%. 10 15 20 Time (hr)

Program Development—Chemistry 269 Separation Science and Technology: constants of the host polymers for a number of systems and successfully Membrane-Based Separations and fabricated optical-quality membranes from these polymers. Destruction Processes Our final goal was to develop in situ photocatalytic reactors for selec- Barbara F. Smith tive oxidation of organics. These systems may allow a valuable oxidized This project combines advanced removal from high-level waste surro- organic product to be synthesized separations and destruction technolo- gates using this new system. from an organic waste stream. We are gies with the objective of adapting We were also interested in develop- focusing our organic-oxidation studies them to industrial needs. Specifically, ing advanced electrochemical reactors on phenolic materials in aqueous our research focuses on the following that would improve our ability to streams and arenes in the gas phase. areas: synthesizing new extractants separate and treat waste. We success- Currently, we are collaborating with for removing valuable or hazardous fully demonstrated a new electro- Bechtel on applying species-selective metal ions from industrial waste and chemical-cell design in which the cell oxidation technology to its industrial process streams or from ground- voltage at a current density of symbiosis goals and on extrapolating waters, producing membranes that 300 mA/cm2 was just 1.7 V; the cell the technology to metal removal. will selectively separate industrial voltage in commercial units is 3.2 V. gases, and designing membrane or The resulting systems can provide Publications supported systems that will selec- more-energy-efficient organic de- tively oxidize or destroy hazardous struction than the commercial units Balaich, G.J., S.A. Fino, et al., organics. can. "Synthesis of an Organometallic Our first goal was to prepare water- Another area we studied was ad- Polyamide of Cobalt Dicarbollide" soluble, chelating polymers that could vanced membrane materials for sepa- (submitted to Inorg. Chem.). be used to remove or recover valuable ration of industrial gases such as Chamberlin, R.M., B.L. Scott, et al., or toxic metals from a variety of pro- hydrogen. We installed a polymer- "Butyllithium Deprotonation Versus cess or waste streams. Industry is in- spinning unit that produces hollow Alkali Metal Reduction of Cobalt terested in advanced, metal-ion fiber membranes, a favored membrane Dicarbollide" (submitted to Inorg. separations because these technolo- geometry for efficient separations. We Chem.). gies lead to lower operating and waste used this unit to spin membrane mate- treatment costs. This year, we pre- rials, such as polysulfone and Rais, J., D.V. Mason, and S.D. Abney, pared nine new, water-soluble, metal- polyaniline, into microporous and "Use of PVC Plasticized Membranes binding polymers, and some have ultraporous hollow fibers, and we for Uptake of Radioactive Cesium and shown selectivity for certain evaluated the spun systems for gas Strontium" (to be published in oxyanions (such as tungsten, molyb- separations. We also compared the Separation Sci. Technol). denum, arsenic, and selenium), even separation properties of these fibers Smith, B.F., T.W Robison, M.E. in the presence of a high salt concen- with the separation properties of Cournoyer, et al., "Polymer Filtration: tration (for example, 1-MNaCl). high-strength, highly conductive A New Technology for Selective (>50 S/cm), polyaniline solid fibers. Another goal was to separate fission Metals Recovery" (SUR-FIN95 In addition, we demonstrated the fea- products such as cesium and stron- Conference of the American sibility of producing ultraporous and tium from high-level radioactive Electroplaters and Surface Finishers microporous polyetheretherketone wastes or from contaminated ground- Society, Baltimore, Md., June 26-29, flat-sheet membranes. waters using a specific extractant, 1995). cobalt dicarbollide. As a soft anion, We are also developing "smart" fil- cobalt dicarbollide will selectively ters, which will selectively bind and, Winokur, M.D., J. Maron, and B.R. bind cesium and strontium and pull if designed properly, potentially de- Mattes, "Processing Induced Changes them from an aqueous phase into an stroy organic materials. We success- in the Local Structure of Amorphous organic phase. Current processes rely fully synthesized a number of host Polyaniline Using RDF Analysis," on hazardous solvents such as nitro- polymers for organic materials, and Macromolecules 28 (13), 4475 benzene; we modified the process to we demonstrated that these host poly- (1995). use diethylbenzene, an environmen- mers have the nanoporosity necessary tally benign organic solvent, in place to absorb organic contaminates from of nitrobenzene. We demonstrated water. We measured the equilibrium simultaneous cesium and strontium

270 Los Alamos FYI996 LDRD Progress Report Microwave Processing Improvements for can follow the rapid heating often encountered in a microwave processing Methane Conversion to Ethylene system. We studied the behavior of the microwave applicator system and developed theoretical models that Ray Stringfield yield insights about the stability and control of the system. The objective of this project was to their catalyst had not been prepared investigate microwave-enhanced properly, which led to anomalous, low catalysis. Published work by others selectivity for their conventional heat- Publications had demonstrated improved selectiv- ing runs. Even though we found no Nelson, E.M., "Enhancement of ity in microwave-driven catalytic con- improvement in selectivity with mi- Thermal Stability in Microwave version of 2-methylpentane to its crowaves, microwave processing still Applicators by Mismatching and isomers. offers the promise of rapid heating Detuning," 31st Microwave Power Our accomplishment was repro- adjustments and low thermal inertia— Symp. Proc. 31,108 (1996). ducing their experiment and discover- aids to quality manufacturing. ing that there is no improvement in We developed and characterized an selectivity using microwaves. The se- optical temperature diagnostic suit- lectivity at a given conversion was the able for use on a microwave applica- same for both microwave-heated and tor in this project. This pyrometer can conventionally heated catalyst beds. measure the temperature of small- Meetings with the authors of the ear- scale features on the catalyst bed. In lier work led to the conjecture that addition, it has a fast response that

~~Program Development—Chemistry 271~~

~~Mathematics and Computational Sciences~~

Data Resources and Sample Applications After reviewing the literature and talking with experts in the field, we for Information Analysis in Chemical and have determined that the greatest need in this area is for epidemiological Biological Warfare Defense models that account for spatial and transport aspects of disease spread. Kevin Buescher The Laboratory's simulation capabilities might help to address this need. The Laboratory has extensive infor- of infected individuals from a dy- For example, we could link transpor- mation analysis capabilities. Our goal namical systems viewpoint. We found tation and climate simulations to a in this project was to identify repre- that we could express a number of model of infection mechanisms to sentative applications for these in the disease models in a common form and better predict the evolution of an out- area of chemical and biological war- that we could transform these models break. fare defense. In particular, we focused in a way that allows us to perform on- In addition, the Laboratory's analy- on developing methods for detecting line estimates of their model param- sis capabilities could prove to be very the outbreak of diseases and for pre- eters in a computationally efficient useful in mining morbidity and dis- dicting their evolution. In particular, manner. Using this technique, we ease data to locate similar cases that we examined existing mathematical could track diseases in an automated could indicate the onset of an epi- models for the statistical progression and cost-effective manner. demic or an attack.

Information-Handling/Data-Fusion We researched commercially available databases containing export com- Technologies to Extract and Analyze modities information for application Export Information to our investigation and had extensive discussions with the Department of Commerce (and other organizations Harry Forehand involved in export-controls-data review). Yet it became clear that the Proliferant nations generally do not acquire such technology. Export data sources we needed did not con- have the technical capability and in- information, both dual-use, export- tain sufficient and necessary informa- dustrial infrastructure to produce controlled, and Schedule B {Statistical tion to derive indicators of proli- nuclear weapons without assistance Classification of Domestic and Foreign feration. In addition, none of the from nuclear weapons states or ad- Commodities Exported from the US) commercially available data contained vanced-technology countries. Hence are generally available electronically. sufficient detailed data to do the job they may procure the technology, both This project was intended to investi- adequately, nor was the data likely to material and hardware. We planned to gate automated data-handling and link- be available in the near future. The develop an information-handling/ analyses tools to develop techniques project was therefore terminated be- data-fusion tool to extract and analyze for rapid evaluation of technology- fore its normal term. export information to look for at- transfer mechanisms via export infor- tempts by proliferant countries to mation.

Program Development—Mathematics and Computational Sciences 273 Intelligent Controllers for Battlefield Reidys, C, "Mappings in Random Structures" (submitted to SIAM J. Simulations Discrete Math.). Stroud, P., "An Adaptive Airborne Chris Barrett Laser Flight Controller" (submitted to IEEE Trans. Systems, Man, and In this project we are developing, Nagel, K., C. Barrett, and M. Rickert, Cybernetics). testing, and demonstrating new meth- "Parallel Traffic Microsimulation of Stroud, P., "Simulation-Based ods for producing intelligent com- Traffic by Cellular Automata and Learning in Knowledge-Based puter-generated forces, battlefield Application" (submitted to Controllers" (1996 International simulations in which computer codes Transportation Res. C). Symposium on Intelligent Control, decide the behavior of military forces. Dearborn, Mich., September 1996). These battlefield simulations are an Rasmussen, S., C. Barrett, and M. area of growing importance and inter- Olesen, "Dynamical Hierarchies: A est to the Department of Defense Summary" (First International (DoD). Our new methods are based Conference on Artificial Life and on two advanced simulation technolo- Robotics, Oita, Japan, February 2-10, gies: intelligent control and adaptive 1996). systems. In intelligent control technology, we formally emulate the control process of the real system using a Visualization Capability for rule-based, expert systems approach that improves over time by adding Nonproliferation and Emergency Training: new rules. In adaptive systems tech- A "Poor Man V Virtual-Reality System nology, the adaptive systems software learns and adapts its tactics from synthetic battlefield experiences gener- George Papcun ated by the simulation. We have developed means to take Our system provides the operator The simulation environment we are an ordinary photograph or video im- with a set of computer programs that using is called JointSim; the Air age and rapidly transform it into a he or she can use to transform the Force, Army, and DoD have been de- three-dimensional virtual-reality envi- image into its three-dimensional rep- veloping this environment over the ronment of what is shown in the im- resentation. Included in the system is past few years, and it serves as an ex- age. This capability can be applied to a tutorial that teaches the operator cellent test bed and proving ground to nuclear nonproliferation, to emer- how to use the system. Because our introduce the Laboratory's research gency management, and to related system runs on an ordinary personal advances in battlefield simulations to situations. For example, if a photo- computer, it is relatively inexpensive the DoD. In FY96 we developed a graph can be obtained of some loca- and portable. command and control architecture tion that has dangerous chemicals that the joint U.S./U.K. working In the course of our research, we stored in it, a virtual-reality environ- group on command and control stan- have developed new means to make ment would let workers carry out dardization accepted as their standard measurements of complex shapes, practice runs for dealing with the reference model. We also developed a such as faces. This aspect of our work chemicals without exposure to the genetic algorithm that learns new tac- can be applied to recognizing images dangers of the actual environment. To tics for systems not yet in the DoD of people. take another example, let us suppose force structure. that a limited number of photographs are available of clandestine locations Publications where nuclear materials may be stored or manufactured. In such situa- Barrett, C, M. Wolinsky, and M. tions, a virtual-reality representation Olesen, "Emergent Local Control would allow inspectors to make mea- Properties in Particle Hopping Traffic surements, determine what additional Simulations" (Traffic and Granular information is needed, and so on. Flow, Julich, Germany, October 9-11, 1995).

274 Los Alamos FY1996 LDRD Progress Report Modeling for Environmentally Conscious Publications Manufacturing Charbon, Ch., and R. LeSar, "A2D Fully Coupled Model of Equiaxed Eutectic Solidification," in Richard LeSar Solidification and Processing, I. Ohnaka, and D.M. Stefanescu, Eds. This project focused on creating an tures of the microstructure, which en- (TMS, Warrendale, Pa., 1996). integrated approach for developing able us to analyze any microstructural simulation tools for environmentally parameters of interest as a function of Charbon, Ch., and R. LeSar, "A 2D benign manufacturing. We developed cooling rate and other processing con- Micro-Macro Model of Equiaxed casting simulations that would yield ditions. Eutectic Solidification" (to be an accurate prediction of materials' Modeling of Quiescent Crystalliza- published in Modeling and Simulation microstructures and properties, which, tion of Semicrystalline Polymers. We in Mater. Sci. Engin.). in turn, would enable development of developed a multiscale model for the Charbon Ch., and S. Swaminarayan, near-net-shape casting methods with crystallization of polymers that ac- "Modeling the Microstructure little waste. The specific objectives of counts for heat diffusion at the macro- Evolution of Thermoplastic this project were to develop method- scopic scale; grain nucleation, growth, Composites" (submitted to Mater. Sci. ology to couple microscopically based and impingement at the mesoscopic Engin.). solidification models to fluid flow and scale; and fibrils growth at the micro- to implement these techniques within scopic scale. Charbon Ch., and S. Swaminarayan, existing computational fluid dynamics Direct Modeling of Dendritic "A Multiscale Model of Polymer codes. Progress this year was made in Growth. We developed a model that Crystallization I: Growth of the following three areas. reproduces the growth of solutal den- Individual Spherulites" (submitted to Modeling of Equiaxed Eutectic drites, i.e., the destabilization of a Polymer Engin. Sci.). Solidification. We developed a model spherical nucleus into a dendritic Charbon Ch., and S. Swaminarayan, of equiaxed eutectic solidification that grain with primary, secondary, and "A Multiscale Model of Polymer couples the microstructural level tertiary dendrite arms. Crystallization II: Crystallization of a (nucleation, growth, and impingement We are planning to implement these Macroscopic Part" (submitted to of the grains) with the macroscopic successful microstructural models Polymer Engin. Sci.). level of heat flow. The principal out- within a new casting code being de- puts of the model are temperature and veloped under the Accelerated Strate- Thoma, D.J., Ch. Charbon, et al., solid fraction fields and detailed pic- gic Computing Initiative. "Directed Light Fabrication of Iron- Based Materials," Mat. Res. Soc. Symp. Proc. 397, 341 (1996). Low-Speed Flow Hydrodynamics foundries. We also performed heat transfer/solidification simulations of a gravity-poured, cast-uranium cylindri- John H. Cerutti cal shell; we were successful in reproducing experimental solidification This project has led to the develop- unique interfacial flow capability, as times. ment and application of a new tool, demonstrated by our simulations of a Because of our successes in this third called Telluride, for the simulation of drop splash and the filling of a box. In (and final) year of the project, the Ac- casting processes. Our efforts have al- addition, we implemented an interfa- celerated Strategic Computing Initiative lowed Telluride to model key processes cial-surface-tension model (essential Program has provided funding for fur- present in Los Alamos foundries. for mold-filling scenarios) and devised ther Telluride development. We formulated and implemented a and implemented a novel back- second-order-accurate algorithm for the diffusion model for alloy solidification. robust solution of the incompressible Efficient (>90%) parallelization of our Publications Euler equations. We incorporated a algorithms was demonstrated on sev- Brackbill, J.U., and D.B. Kothe, Runge-Kutta time-integration scheme eral multiprocessor platforms. "Dynamical Modeling of Surface (ideally suited for unstructured meshes) We performed isothermal "mold- Tension" (Third Microgravity Fluid into our volume-tracking algorithm. We filling" simulations (neglecting heat Physics Conference, Cleveland, Ohio, also devised and tested in two dimen- transfer) with conditions representative June 13-17,1996). sions a new "full remap" time-integra- of our foundries (e.g., a top fill of a box tion scheme. The volume-tracking and mold). We are presently simulating the Rider, W.J., and D.B. Kothe, "Volume fluid-flow algorithms give Telluride a fill of a copper chalice cast in our Tracking Reconstructed" (submitted to /. Comput. Phys.).

Program Development—Mathematics and Computational Sciences 275 A New Model to Estimate Regional our USC collaborators, we are also determining the optimum location and Emissions Inventories number of measurement sites needed to calculate an emissions inventory. As a prelude to the next step in developing our SITEOF model, we Michael Williams and Michael Brown coordinated an extensive volatile organic compounds (VOCs) canister With collaborators from the Univer- an entire city on 1-km2 grids (see first study as part of a larger field experi- sity of Southern California (USC), we figure). ment in the El Paso/Ciudad Juarez are optimizing a new model for com- Since emissions inventories are not region. The field experiment was a puting gridded air-pollution emissions known with any certainty in the real joint effort with the Texas Natural by integrating meteorological, photo- world, we have tested our new model Resource Conservation Commission chemical, and hybrid receptor models. with synthetic concentration fields and the US Environmental Protection At present, estimating gridded emis- (see second figure). These fields are Agency. Measurements show signifi- sions inventories is seen as the weak- produced by a Laboratory-developed cant correlation between carbon est link in air-quality evaluations. Our air-quality modeling system—the model, called SITEOF for Source higher-order turbulence model for at- monoxide and both acetylene and Identification through Empirical Or- mospheric circulation (HOTMAC) trans-2-butme (see third figure), indi- thogonal Functions, uses existing am- and the random particle transport and cating that routinely measured CO bient concentration measurements of dispersion (RAPTAD) model—with might be used as a surrogate for other pollutants and then runs "backwards" user-specified emissions inventories. VOCs and thus be used as an input to derive the pollutants' source loca- Using 30 days of model-computed parameter to the SITEOF model when tion and strength. By applying a sta- synthetic hourly concentration fields, studying reactive species. tistical empirical-orthogonal- we are investigating the most effective eigenfunction approach, SITEOF ways to construct gridded emissions produces emissions inventories over from the assumed inventories. With

1 - O 9° Example of gridded emissions fields generated with SITEOF from 2- synthetic concentration fields produced by a simple Gaussian 3- dispersion model. The gray box 0.0- represents an emissions source of 8 units strength; the contours depict the computed emissions inventory. Agreement is good for this simple case; we are using HOTMAC and RAPTAD data to optimize the SITEOF model for more realistic (complicated) scenarios.

~~I I I I I I I 1 1 0 1 2 3 4 5 6 7 8 grid no.~~

276 Los Alamos FY 1996 LDRD Progress Report Sept. 2, 0300 1st 3546 A one-hour average concentration field computed with the HOTMAC/ RAPTAD modeling system for a 1-km2 area source of a nonreactive pollutant (CO) in the El Paso/Ciudad Juarez region. Near the source, the plume travels close to the ground and is transported to the south-southeast by low-level winds; as the plume mixes upwards, it bends to the south- southwest and is carried along by upper-level winds. Thirty days of hourly synthetic concentration, wind, and boundary-layer-depth fields were produced and fed into the SITEOF statistical model. The computed 3498 emissions inventory was then 338 346 354 362 370 378 compared with the known emissions utmx, km inventory that was input into HOTMAC/RAPTAD. The white dots in the figure are monitoring stations. 1 I ' I ' I ' I ' I ' I ' I ' I ' 0 10 20 30 40 50 60 70 80 90 100 concentration, micrograms/m**3

~~GC measurements~~

Gas chromatograph measurements of carbon monoxide (a nonreactive air pollutant) and trans-2-butene (a highly reactive ozone precursor) taken in El Paso during an extensive field experiment this past summer. The high correlation between the two sets of measurements indicates that the routinely measured CO can be used as a surrogate for VOCs like trans-2- butene, which are seldom measured for thirty consecutive days at multiple locations. From the data collected, we will determine statistical relationships between CO and relevant VOCs.

~~I • I • I ' I • I • I • I~~

~~CO, ppm~~

Program Development—Mathematics and Computational Sciences 277 Improving Industrial Performance through Under program development accomplishments, we visited three steel Integrated Process Simulation, Control, companies (Inland, DOFASCO, and Bethlehem) and established a working and Optimization: Modeling Atoms to relationship with DOFASCO. We also Enterprise established a relationship with the Association of Iron and Steel Engi- neers (AISE), the steel industry pro- Anne D. Henriksen fessional organization, with the following outcomes: we (1) obtained The goals of this project were as ment. Technical accomplishments a prioritized list of three proposals follows: (1) develop an integrated, include the following. We developed that AISE was willing to fund for object-oriented system model of the an object-oriented system simulation joint work with Los Alamos; top three layers of the atoms-to-enter- of selected processes on the top two (2) hosted a meeting of over 30 AISE prise hierarchy; (2) develop process levels of the atoms-to-enterprise hier- members at Los Alamos to present the models of selected steel-production archy and integrated them with all the Laboratory's metals- and modeling- unit operations and molecular-level elements on the third (i.e., manufac- related work; and (3) obtained fund- models of selected steel-making pro- turing) level. We developed several ing from DOE for a follow-on project cesses for eventual integration into the models, including a blast-furnace, on blast-furnace stove control. model of the top three layers; (3) es- mass-balance process model (at the tablish relationships with members of unit-operations level) for integration the steel industry; and (4) generate with the system simulation; a basic Publication external funding from either DOE or oxygen-process (BOP), carbon-end- Henriksen, A.D., "A Framework for cooperative research and development point model (at the unit-operations Hierachical Object-Oriented agreements (CRADAs) for follow-on level) based on nonlinear-model, pre- Simulation Modeling of a Steel work. dictive control; and a BOP kinetics Manufacturing Enterprise," in The 1996 We have divided the accomplish- model (at the molecular level) for pre- Object-Oriented Simulation Conf. ments of this project into two catego- dicting carbon endpoint, which we Proc, C. Roberts and J. Wallace, Eds. ries: technical and program develop- will integrate with the nonlinear, pre- (Society for Computer Simulation, San dictive-control model. Diego, Calif., 1996), pp. 123-131.

National Environmental/Economic possible coordination of our organizations' efforts. Infrastructure System Model We investigated the development of an environmental technology evaluation tool that uses simulation science Robert Drake techniques. We experimented at making such a tool, trying out various ideas We are working to develop a new We have produced a new approach from other similar projects, such as our methodology for the macroeconomic for the macroeconomic modeling of Transportation Analysis and Simulation modeling of national environmental national environmental and economic System (TRANSEVIS) models. We and economic problems. We are doing problems. The concept is based on the demonstrated that the prospects for ap- this because the current suite of the integration of microsimulation method- plying simulation techniques to macro- nation's best macroeconomic forecast- ologies with the new microfoundations economic modeling are viable. DOE ing models is well known for its failure of macroeconomic theory. This year we Environmental Management to produce accurate analyses. In the completed the background analytical policymakers as well as Laboratory past, the computational complications research, and we briefed Laboratory environmental decision-makers have of simultaneously linking all of the program and division office leaders on expressed interest in further develop- nation's economic activities have pre- our project goals and technical pros- ment and use of the tool. They are invented researchers from designing ad- pects. We have generated significant terested in immediately applying it to equate policy analysis tools. This year internal technical support and program determine the most cost-effective we have explored, studied, and synthe- interest, and we have established exter- method of paying for the DOE com- sized the current literature concerning nal contacts with the U.S. intelligence plex cleanup within a competitive mar- the microbehavioral foundations of community and the Department of ket framework. We have already macroeconomic analysis; we focused State. We investigated a related project developed a very simplified model to especially on the linkages of natural that uses massively parallel processing simulate the Laboratory's transuranic resource markets and environmental at Sandia National Laboratories, and solid-waste stream. policy to the national economy. we negotiated with them concerning

278 Los Alamos FY1996 LDRD Progress Report Global Nuclear Material Flow Model Publications Dreicer, J.S., and D.A. Rutherford, "Fissile Material Disposition and Jared S. Dreicer Proliferation Risk" (International Spent Nuclear Fuel and Fissile The goals of this project are to assess future quantities and disposi- Material Management, Reno, Nev., (1) characterize the global inventory tion of nuclear material, estimate June 16-20,1996). of nuclear weapons material (pluto- future resource requirements for Dreicer, J.S., and D.A. Rutherford, nium and highly enriched uranium), nuclear material management and (2) characterize the safeguards ac- control, address material-transfer "Fissile Material Proliferation Risk," counting and management and control issues, and examine nuclear fuel- Nucl. Mater. Mgmt. XXV (1), 30 methodologies and enumerate the cycle, facility-specific issues. We can (1996). associated resource requirements, represent visually the global disposi- Dreicer, J.S., and D.A. Rutherford, (3) develop macro-system analytical tion of plutonium and highly enriched "Global Estimation of Unreported capabilities to estimate future quanti- uranium as well as facility-specific Plutonium Production in Thermal ties of nuclear material, estimate the data. Research Reactors," Nucl. Mater. impact on material inventory of dispo- We have completed two nuclear- Mgmt. Proc. XXX, 1050 (1996). sition options, and estimate future proliferation studies. The first study resource requirements for nuclear indicated potential areas that require Dreicer, J.S., and D.A. Rutherford, material management and control, strengthening in the International "Global Nuclear Material Control (4) develop a visual representation of Atomic Energy Agency's Safeguards Model" (International Spent Nuclear the information related to nuclear Criteria. We specifically showed that Fuel and Fissile Material Manage- facilities and sites and the nuclear there could be proliferation activity ment, Reno, Nev., June 16-20,1996). material flow among and within coun- that might go undetected under the tries, and support the development of current safeguards criteria. In the other pertinent algorithmic capabili- second study we estimated the ties necessary to undertake further amount of plutonium likely to have global nuclear material-related stud- been produced in a North Korean ies. research reactor during the entire Our results include the following: A period it operated. prototype analytical model has been developed to enable systems analysis of a variety of global, nuclear material management issues. The model can

~~Program Development—Mathematics and Computational Sciences 279 I Atomic and Molecular Physics~~

~~Measurement Criteria Analysis for Krypton, Xenon, and Hydrogen (Hydrogen/Deuterium/Tritium) Isotopes and Concentration Variability at Distance~~

~~Bryan Fearey~~

Our goal is to assess the feasibility noble-gas isotopic data. We also ana- of and technology for remotely sens- lyzed the effect of measurement un- ing noble-gas fission products emitted certainties on the estimated from reactors in order to determine parameters. The results of our work the reactors' operating parameters and indicate that noble-gas monitoring history. The importance of measuring should be experimentally feasible. xenon and krypton isotopic ratios has increased substantially as concerns about global nuclear proliferation Publications have grown in recent years. Nakhleh, C.W., W.D. Stanbro, L.N. We have modeled and performed a Hand, et al., "Noble-Gas Atmospheric systems analysis for the production Monitoring for International and atmospheric dilution of noble-gas Safeguards at Reprocessing Facilities" fission isotopic ratios, addressing such (to be published in Science and issues as the relative isotopic variation Global Security). as a function of nuclear fuel composition and reactor history and type. Of particular importance in our analysis was the question of how to back- calculate process parameters given

~~Program Development—Atomic and Molecular Physics 281~~

~~Geoscience, Space Science, and Astrophysics~~

The Carpinteria Reservoir Publications Redevelopment Project Kendall, R.P., M.B. Lee, A.G. Sgro, et al., "Tools for the Oil & Gas Virtual Enterprise" (SPE 72nd Annual Richard P. Kendall Technical Conference and Exhibition, San Antonio, Tex., October 5-8, The central goal of this project was We tested the reservoir manage- 1997). the development of a Web-based, res- ment system and actually used it to ervoir-management system that would evaluate new field-development plans Kendall, R.P., E. M. Whitney, R. Paul, allow multi-user access to large vol- for the Carpinteria offshore field. et al., "A Simulation-Based Reservoir umes of complex data and remote ac- Carpinteria was chosen as the location Management Program" (SPE 72nd cess to common user software tools. for first application of the manage- Annual Technical Conference and The objective was to greatly enhance ment system because the field has ex- Exhibition, San Antonio, Tex., the quality of analysis that could be perienced a production decline of October 5-8, 1997). done on complex systems such as an more than 10 years duration—typical Kendall, R.P, E. M.Whitney, R. oil field by a small team of profes- of some 20 offshore California fields. Webster, et al., "Advanced Reservoir sionals like those found in a typical The management system we designed Management for Independent Oil & independent oil- and gas-producing supports professionals (geoscientists Gas Producers" (SPE 72nd Annual company (there are about 8000 such and engineers) at five separate loca- Technical Conference and Exhibition, companies in the United States). tions (Long Beach, Carpinteria, San Antonio, Tex., October 5-8, We successfully developed a client- Ventura, Houston, and Los Alamos). 1997). server system that can support the use In effect, the system enabled these of best-of-class petrotechnical soft- professionals to form a "virtual enter- Kendall, R.P., E. M. Whitney, R. ware. A distributed-object data store prise" for the reservoir-management Webster, et al., "Improved Oil formed the "backplane" of this sys- study, and they have used the tools Recovery for Independent Oil & Gas tem. This data store (a data model and and approaches developed in the Producers" (SPE 72nd Annual a collection database) complies with project to formulate and evaluate al- Technical Conference and Exhibition, industry standards (Petrotechnical ternative oil recovery strategies for the San Antonio, Tex., October 5-8, Open Software Corporation), can be Carpinteria field. This project is a 1997). good example of the use of the rapidly queried from remote sites via the Sgro, A.G., R.P. Kendall, J.M. Kindel, evolving National Information Infra- Web, and can be maintained by the et al., "Improved Oil Recovery for structure to support a technical "owners" of the data at remote sites. Independent Oil and Gas Producers" project. (SPE Improved Oil Recovery Symposium, Tulsa, Okla., April 21, 1996). Voskanian, M.M., R.P. Kendall, E.M Whitney, et al., "A Simulation-Based Reservoir Management Program" (SPE Western Regional Meeting, Anchorage, Alaska, May 22-24, 1996).

Program Development—Geoscience, Space Science, and Astrophysics 283 Satellite-Based Laser Windsounder nology that has been used for all known incoherent Doppler lidar systems to date. During the course of the John Schultz study, however, it became apparent that much simpler optical systems Our objective for this project is to uses an interferometer to measure the based on Mach-Zehnder interferom- assess the technical feasibility of us- Doppler shift in near-ultraviolet laser eters promise equivalent performance ing satellite-based laser wind mea- light scattered from aerosols and par- with substantially reduced weight and surement systems to improve pro- ticulates entrained in the atmosphere. power consumption. At the conclusion liferation detection capabilities. At Our choice was based on the simplic- of the study, we built a breadboard present, much of the United States' ity and maturity of the required lasers Mach-Zehnder interferometer-based ability to detect proliferation depends and interferometers and on the poten- system and used it to qualitatively on physically sampling wind-borne tial for using the same system to mea- verify these predictions. To quantita- effluents from suspected facilities, but sure other atmospheric parameters of tively verify the benefits of systems the effectiveness of this technique is interest, such as water vapor content, based on Mach-Zehnder interferom- severely limited by inadequate knowl- temperatures, and various cloud eters, we have developed detailed edge of wind patterns. From our inter- properties. plans that include constructing and actions with the relevant operational We completed a conceptual design testing a fieldable ground-based wind proliferation detection organization, study to identify the technical chal- measurement system in collaboration we confirmed that better wind mea- lenges inherent in a relatively inex- with the University of Wisconsin and surements would contribute greatly to pensive, low-risk, proof-of-concept performing numerical data assimila- long-range and regional proliferation small-satellite mission appropriate to tion studies. detection. We also obtained enthusias- Los Alamos' technical capabilities. tic programmatic support and useful The major challenges that we identi- assessments of measurement require- fied were the system's weight, power Publications ments and priorities from the opera- consumption, laser scanning pattern Czuchlewski, S.J., MJ. Brown, G.H. tional users. and pointing knowledge, and tech- Nickel, et al., "Preliminary Analysis We evaluated four potential laser niques for assimilating measured data of Lidar Techniques for Regional wind-sensing techniques and selected into atmospheric transport models. Meteorological Studies," Proceedings the incoherent Doppler technique. It Our conceptual design was based on of the Gas Lasers Conference, SPIE the Fabry-Perot interferometer tech- 2702, 52-64 (1996).

Conditioning Geological Reservoir measurements (primarily well logs). These layers have the highest oil stor- Realizations with Time-Dependent Data age capacity and conductivity. The study also suggests that reservoir attributes correlate over distances of at Richard P. Kendall least 500 ft. Since the median distance from a well to its nearest neighbor is The goal of this project was to pro- can hope to stem only with the appli- about 250 ft, this means that improve- vide a preliminary geostatistical char- cation of the most advanced recovery ments in modeling can be expected if acterization of the Carpinteria off- techniques. One such technique is stochastic simulation methods are shore field in order to support the geostatistics to reduce the inherent used. future stochastic simulation of its geo- uncertainty in the geological descrip- logical attributes. This oil reservoir is tion of the field. typical of some twenty offshore fields The most important finding of this near the California coastline. Most of work was the identification of poten- these fields are experiencing a serious tial "pay" layers of the field, based on decline in oil production, which we the underlying statistics of the field

284 Los Alamos FY1996 LDRD Progress Report Improved Atmospheric Transport for Risk are very promising, including the ability to model 2- to 5-m structures in Assessment in Complex Terrain the surface layer of the atmosphere for the first time. Furthermore, the Daniel Cooper model appears to give the structural information observed by the lidar. Our objective is development of and ability to implement the estimates The biggest hurdle for the model is reliable and useful risk-assessment with available computing tools. the improved code development re- methods for problems involving the The development of a micro- and quired for the model to operate on release of atmospheric contaminants. mesoscale, convective, turbulent at- workstation computers, since the These methods require a combination mospheric model is well underway. present software requires extensive of quality and simplicity. Quality Some initial testing has been per- mainframe time. The next step is to means accurate and timely estimates formed with very promising results. improve the model and perform a of the likely transport trajectories and We used data acquired by the Raman complete evaluation of the model's the dilution, deposition, and transfor- water-vapor lidar showing plume ability to simulate complex plume mation of the material during travel. structure over the ocean as a test for dynamics in the surface-atmosphere Simplicity means user-friendliness validation of the model. Initial results interface.

Reservoir Enhancement on the and management needs, and developed work plans. Two of the collabo- Impermeable Margins of Productive rators accepted our invitation to participate in preparing a proposal for Geothermal Fields: Integrated Resource the evaluation of the technology. We Development and Management submitted this proposal to DOE in September 1996. In the past year, we also designed James Albright the seismic instrumentation package. We reassembled the package from The objective of our project for the with contemporary electronics and salvaged parts, machined and fabri- past year was three-fold. First, we sensors. This package would then be cated missing mechanical parts, wanted to identify, collaborate, and used to conduct assessments of the designed and fabricated improved partner with members of the geother- mapping hardware in producing electronics circuitry, and procured and mal industry in evaluating the applica- fields. installed state-of-the-art sensors. We tion of microseismic mapping In June 1996 in Santa Rosa, tested the entire package in a high- technology for assessing the role of California, we introduced the poten- temperature well and deemed the fracture permeability in developing tial for microseismic mapping to instrument fit for service. and managing geothermal production representatives of the geothermal in- fields. Second, we planned to prepare dustry at a DOE-sponsored workshop a proposal for submission to DOE for on "Subsurface Permeability Detec- the evaluation and assessment of tion and Mapping." Representatives microseismic mapping technology. from 80% of the major producers Third, we intended to reassemble a attended the workshop. We identified borehole seismic instrumentation three potential industrial collabora- package used in research at Los tors, visited their geothermal fields, Alamos 10 years ago and retrofit it assessed the reservoir development

~~Program Development—Geoscience, Space Science, and Astrophysics 285~~

~~Nuclear and Particle Physics~~

Disposition of Plutonium as Nonfertile Publications Fuel for Water Reactors Beard, C.A., J.J. Buksa, et al., "Development of Evolutionary Mixed Oxide Fuel," I996ANS/ENS Winter Kenneth Chidester Int. Meeting Trans. 75, TANSAO 75 1-490(1996). In this project, we are studying the of EMOX fuel (the other two-thirds potential for reducing global pluto- contains standard low-enriched ura- Buksa, J., S. Eaton, and J. Toevs, nium inventories by creating special nium fuel). Loading a core entirely "Disposition of Plutonium as Mixed fuels, especially nonfertile fuels, for with EMOX lowers the plutonium- Oxide Nuclear Fuel," Fourth Int. burning in conventional reactors. Our loading requirement to less than 3%. Conf. Nucl. Eng. (ICONE-4) 4, 453 project continued to build upon the Plutonium destruction rates increase (1996). initial investigations of nonfertile fu- with increasing plutonium loading els and concentrated on examining and an increasing core fraction of Eaton, S.L., C.A. Beard, and J.J. evolutionary mixed-oxide (EMOX) EMOX. Additionally, EMOX exhibits Buksa, "Evolutionary Mixed Oxide fuels consisting of the mixed oxides reactivity coefficients nearly identical Fuel Performance in Pressurized urania, plutonia, and a nonfertile com- to those of standard MOX. Water Reactors," 1996ANS/ENS ponent (currently, calcia-stabilized Winter Int. Meeting Trans. 75, We used the solid-state reaction TANSAO 75 1-490 (1996). zirconia). The nonfertile component method to fabricate a number of replaces some of the fertile uranium, nonfertile and EMOX fuel pellets of Ramsey, K.B., and H.T. Blair, lowering the amount of plutonium varying compositions. The source of "Fabrication of a Non-Fertile Fuel for produced through breeding and result- reactor fuel was PuO2 derived from the Disposition of Weapons ing in a net destruction—over the irra- the hydride-dehydride process for Plutonium," Fourth Int. Conf. Nucl. diation cycle—of plutonium in the converting weapons-grade plutonium Eng. (ICONE-4) 4, 499 (1996). fuel. We performed detailed reactor metal to oxide. Specifically, we fabri- physics calculations to determine the cated a nonfertile fuel with a compo- Ramsey, K.B., and K. Chidester, "Fabrication of Non-Fertile and behavior of the EMOX fuel under a sition of PuO2 (2.69 wt %), ZrO2 variety of parameters. We also con- (87.19 wt %), and CaO (10.12 wt %). Evolutionary Mixed Oxide Fuels," ducted fabrication experiments to de- The nonfertile fuel was sintered to 1996ANS/ENS Winter Int. Meeting termine the feasibility of using 89.7% of theoretical density. In addi- Trans. 75, TANSAO 75 1-490 (1996). standard, commercial processes for tion, we fabricated an EMOX fuel fabricating nuclear fuel to produce with a composition of PuO2 EMOX fuel with the desired composi- (10.97 wt %), UO2 (83.94 wt %), and tions. ZrO2 (4.63 wt %). The EMOX fuel The results of the calculations indi- was sintered to 96.8% of theoretical cate that net reduction of core-aver- density. No fabrication difficulties aged plutonium inventories can be were encountered. accomplished using plutonium loadings of greater than 6% (PuO2 in UO2- PuO2) with a nonfertile fraction of 30% (amount of fuel that is the nonfertile component). The nuclear reactor is loaded with a one-third core

Program Development—Nuclear and Particle Physics 287 An Ultracold Neutron Facility at the of the predicted UCN rate using measured parameters as input. These cal- Manual Lujan Jr. Neutron Scattering culations agree well with our analytical predictions of the UCN Center rates. More-detailed Monte Carlo and analytical calculations are now under Thomas Bowles way to better understand the microscopic production processes. Ultracold neutrons (UCNs) are neu- tube to the experiment. A UCN bottle We have also assembled the entire trons whose wavelengths are so long with filter plates at the ends has been system on the beam line. The system that they can undergo total internal constructed to allow a differential includes the source, monitoring reflection from a variety of materials. measurement of the UCN velocity equipment, shielding, and data acqui- This makes it possible to confine spectrum. sition electronics and the UCN guide, UCNs in a bottle for more than 100 s, Some of our accomplishments this bottle, filters, and detector. We are making a compact source for use in year were the installation and align- waiting for the new liquid hydrogen fundamental physics research. ment of the guide tube and shutter source to become available at the A UCN capability is seen as an es- assembly on Flight Path 11; detailed MLNSC to start the first experimental sential component if Los Alamos is to calculations of the shielding and the measurements. execute a strong and ongoing experi- shielding design, procurement, and mental program that would be among installation; tests of the algorithms for Publications the world's foremost in fundamental the phasing of the rotor-drive motor to neutron physics. This project is in- the 400-m/s cold neutrons from the Seestrom, S.J., TJ. Bowles, et al., tended to develop and demonstrate a MLNSC liquid hydrogen source; and "Plans for an Ultra Cold Neutron first experimental UCN source at the the assembly and testing of the rotor Source at Los Alamos" (Tsukuba, Manuel Lujan Jr. Neutron Scattering system, UCN guide tubes, and UCN Japan, Hadron Project Workshop— Center (MLNSC). This experimental bottle. Some small modifications to Nuclear Physics and Fundamental source will be based on a Doppler- the system to improve operations are Physics with Neutrons, March 1996). currently under way. shifted, Bragg-scattered source and Seestrom, S.J., T.J. Bowles, R. Hill, will use a rotor to select beam pulses Other accomplishments were the et al., "Development of an Ultra Cold from the accelerator. installation of the instrumentation for Neutron Source at the Los Alamos The UCN source uses Flight Path safe operation and monitoring of the Spallation Source" (to be published in 11 at MLNSC. A guide tube trans- system; measurements of the Proc. 14th Int. Conf. Appl. Accel. Res. ports the cold neutrons out to the reflectivity and mosaic spread of the Ind.). UCN converter, which is a set of mica mica crystals used in the UCN source; crystals on the end of a rotor that ro- design and building of the crystal Seestrom, S.J., T.J. Bowles, R. Hill, et tates in synchronism with the beam package using the parameters ob- al., "Development of an Ultra Cold pulse rate (20 Hz). UCNs are pro- tained from Monte Carlo calculations; Neutron Source at MLNSC" (to be duced at the rotor and pass through a and detailed Monte Carlo calculations published in Proc. Int. Conf. Appl. shutter to be transported by the guide Nucl. Tech.).

Measurement of Fissile Material in Spent sealers. Compared with conventional techniques, ours yields significantly Fuel and Alternate Nuclear Materials improved signal-to-noise ratios both from the interrogating neutrons and from the background radiation. Mark Pickrell Our new method can be applied to measuring the fissile content and the We investigate neutron interroga- The time control of the neutron reactivity of spent fuel for safeguards tion methods for measuring spent fuel signal and the data acquisition elec- and safety. Our project led directly to against high-radiation backgrounds. tronics that we have developed for a fully funded program to develop a Two applications of these methods are and used in the experiments are en- high-fluence neutron source as the the measurement of fissile content in tirely novel. Instead of using a short interrogating driver. The high-fluence spent fuel and the measurement of neutron pulse, as has been done con- source will also be used to further fissile material in alternate nuclear ventionally, we used a square-wave improve the signal-to-noise ratio of materials. In our experiments, we neutron signal and implemented a our measurements. used a deuterium-tritium neutron gen- digital lock-in amplifier by using a erator developed for borehole logging. personal computer and digital time

~~288 Los Alamos FYI996 LDRD Progress Report Biosciences~~

A Consortium for Biomedical Applications Goodwin, P.M., W.P. Ambrose, and R.A. Keller, "Single Molecule of Single-Molecule Detection Detection in Liquids by Laser- induced Fluorescence" (to be published in Acct. Chem. Res.). Richard Keller Goodwin, P.M., W.P. Ambrose, et al., Our goal is to perform basic re- to advancing single-molecule detec- "Spatial Dependence of the Optical search and explore applications in tion, Richard Keller received the Collection Efficiency in Flow ultrasensitive fluorescence detection Lester W. Strock Award from the Cytometry," Cytometry 21,133 technology in collaboration with the Society for Applied Spectroscopy. (1995). University of New Mexico (UNM) In addition to basic research, we Goodwin, P.M., R.L. Affleck, W.P. and private industry. The Laboratory developed secondary applications for Ambrose, et al., "Detection of Single leads the world in developing tech- laser and instrument manufacturers, Fluorescent Molecules in Flowing niques for ultrasensitive fluorescence chemical producers, and testing Sample Streams," in Computer detection in flowing streams. We have laboratories. Assisted Analytical Spectrometry, demonstrated the detection of indi- Steven D. Brown, Ed. (Wiley and vidual fluorescent molecules as they Sons, New York, 1996). are transported through a laser beam. Publications Applications include DNA sequenc- Affleck, R.L., W.P. Ambrose, Huang, Z., J.T. Petty, B. O'Quinn, ing, DNA fragment sizing, sensitive J.N. Demas, et al., "Reduction of et al., "Large DNA Fragment Sizing assays for randomly generated phar- Luminescent Background in Ultra- by Flow Cytometry: Application to maceuticals, and assays for ligands to sensitive Fluorescence Detection by the Characterization of PI Artificial orphan receptors. We anticipate addi- Photobleaching," Anal. Chem. 68, Chromosomes (PAC) Clones," tional applications in the areas of 2270 (1996). Nucleic Acids Res. 24, 4202 (1996). archeology and ecology. Ambrose, W.P., R.L. Affleck, Keller, R.A., W.P. Ambrose, We made significant progress in our P.M. Goodwin, et al., "Imaging P.M. Goodwin, et al., "Single approach to DNA sizing; we are now Biological Molecules with Single Molecule Fluorescence Analysis in using our flow cytometry approach to Molecule Sensitivity Using Near- Solution," Appl. Spectrosc. 50,12A size large PI artificial chromosome Field Scanning Optical Microscopy," (1996). clones and extended our sizing range Exp. Technol. Phys. 41, 237 (1995). down to 217 base pairs and up to Roslaniec, M.C., C.S. Bell-Prince, 167,000 base pairs. A small DNA- Ambrose, W.P., P.M. Goodwin, J. H.A. Crissman, et al., "New Flow sizin apparatus has been built and Enderlein, et al., "Fluorescence Cytometric Technologies for the 21st tested. We have developed much Photon Antibunching from Single Century" (submitted to Hum. Cell). faster, more accurate algorithms for Molecules on a Surface" (submitted to Wu, M., P.M. Goodwin, et al., single-molecule detection that provide Phys. Rev. Lett.). "Photochemistry and Fluorescence information not previously available. Emission Dynamics of Single We designed a pressure loading sys- Enderlein, J., and R.A. Keller, Molecules in Solution: B- tem that reduced sample loading time "Comparison of One and Two Focus Phycoerythrin?' /. Phys. Chem. 100 by a factor of 20. We also refined our Set-up in Single Molecule Detection (1996). measurements on the photobleaching Experiments" (submitted to Appl. of single molecules of phycoerythrin Spectrosc). and submitted the data for publication. In related work, we have developed an assay to find different ligands to promote cell growth in chemotherapy patients. For his contributions

Program Development—Biosciences 289 Cancer Risk Assessment This year, we have successfully correlated nuclear regulating factors with cell-cycle checkpoints; we have Bruce Lehnert proved that alpha particles, such as those emitted by radon and radon Creating new, mechanistically genes and gene products that render progeny, cause Gl and G2 cell-cycle based biotechnological methods for individuals more susceptible to expo- delays in normal cells; we have found assessing the risk of cancer develop- sures to carcinogens, especially ioniz- that alpha particles can induce the ment in individuals who have been or ing radiations. The initial specific generation of DNA-damaging extra- may be exposed to environmental car- aims of our mechanistically based cellular factors that may be exploited cinogens is the objective of this effort have been to identify and char- as biomarkers of exposure; we have project. Extensive evidence indicates acterize potential cancer-susceptibility demonstrated that wild-type and mu- that cancer risk is related to the exist- genes that are involved in cell-cycle tant p53 differentially alter the cell- ence of specific "susceptibility genes" regulation and DNA repair and to de- cycle and apoptotic responses to DNA that are heterogeneously distributed velop advanced flow-cytometry as- damage; and we have demonstrated among humans. However, an indi- says for those genes that are that poly (ADP-ribose) polymerase is vidualized assessment of cancer risk candidates for cancer susceptibility. associated with the products of some has not been previously possible be- Longer-term goals of the project are DNA-repair proteins. Finally, we have cause of major gaps in understanding to establish relationships between sus- demonstrated that phase-sensitive the basic mechanisms involved in car- ceptibility gene products and cancer flow cytometry can distinguish cinogenesis. risk and to develop bioassays for as- between immunofluorochrome- The scientific focus of this project sessing the risk posed by the suscepti- labeled antigens and cellular has been to identify those critical bility genes and gene products. autofluorescence.

Human Brain Mapping: Experimental and ware for constrained modeling and integration of anatomical MRI, fMRI, Computational Approaches and MEG. These same techniques will be extended to integration with other functional imaging modalities. Charles Wood Finally, we continued trade-off Our project combines novel sen- brain activation under comparable studies between boundary element sors, data acquisition techniques, and experimental conditions. These ex- models for the electromagnetic in- high-performance computing to ad- perimental comparisons used pat- verse problem and the widely used vance noninvasive brain imaging. The terned visual stimulation for and simpler spherical and spherical- experimental component emphasizes activation of striate and extra-striate shell models. Boundary element mod- optimization of spatial and temporal visual cortex in the two functional els can, in principle, provide greater resolution of functional brain imaging imaging modalities. In both fMRI and accuracy at the cost of increased com- by combining structural magnetic MEG, we observed multiple foci of putational complexity. However, nei- resonance imaging (MRI) of brain activation, which is consistent with ther the extent of the theoretical gains anatomy; functional MRI of blood predictions of brain activation for in accuracy nor the associated degree flow, oxygenation, and volume; and nonhuman primates. We are perform- of additional computational cost have magnetoencephalography (MEG) of ing additional analyses to determine been thoroughly explored. neuronal population currents. The the precise degree of correspondence computational component emphasizes between the two activation measures. Publications development of a high-resolution, Second, we completed and pub- three-dimensional volumetric model lished the results of our MEG studies Aine, C.J., et al. "Retinotopic of the brain based on anatomical of retinotopic organization of the Organization of Human Visual MRI; this model integrates structural human visual cortex. This analysis Cortex: Departures from the Classical and functional information from mul- demonstrated small but systematic Model," Cerebral Cortex 6, 354 tiple forms of brain images. departures from the conventional (1996). In the past year, we made four ma- "cruciform" model. These data will George, I.S., et al., "Mapping jor accomplishments. First, we com- form the base for further comparisons Function in the Human Brain with pleted and published the results of our of fMRI and MEG. MEG, Anatomical MRI, and initial experiments using functional Third, we made significant progress Functional MRI," /. Clin. MRI (fMRI) and MEG to compare on developing algorithms and soft- Neurophysiol. 12, 406 (1995).

290 Los Alamos FYI996 LDRD Progress Report Universal Biological-Agent Point-Sensor solid-state laser, a microchannel flow chamber, and a photon-counting de- Program Development tector. We obtained DNA fragments using restriction enzymes and stained Gary Salzman the fragments with POPO-3, a dye that is stoichiometric for DNA con- The three objectives for this project bacteria can be identified by the mass tent. We then analyzed the fragment were (1) to upgrade our biology labo- spectrum of a DNA fragment obtained sample with the microflow cytometer. ratory to Biosafety Level 2 (BL2) and using a set of restriction enzymes, and The response was linearly propor- to provide organisms and toxins to (3) to develop flow-cytometric meth- tional to DNA content from 384 to investigators in the Life Sciences Di- ods for identifying toxins. 167,000 base pairs. We obtained vision and other Laboratory organiza- This year we completed the BL2 DNA-fragment spectra from A,-phage tions, (2) to help develop and then to upgrade and obtained 25 microorgan- DNA and from bacteria artificial use a DNA-fragment-sizing flow isms. We also developed a microflow chromosomes. We also developed cytometer (here called a microflow cytometer for DNA-fragment sizing. bead-based sandwich assays for cytometer) to determine whether The flow cytometer uses a 532-nm, botulinum toxins A and B, ricin, and anthrax.

Sensors for Point Detection of layers resulted in an approximately 25% improvement in the density of Chemical and Biological Warfare Agents reagent molecules. This higher density led to increased sensitivity and Thomas Zawodzinski more stable films. We also used these new linker layers as reference films in SAW measurements. Second, we de- The goal, of this project was to with an organometallic complex that veloped a new polyelectrolyte deposi- develop sensors that detect airborne mimics the enzyme function. This tion method to quickly prepare chemical warfare (CW) agents. Dur- approach adds considerable robust- multilayer thin films with control at ing this year we progressed in demon- ness to our sensor while retaining the the molecular level. So far, we have strating electrochemical sensors for amplification from electrocatalytic tested this approach on CA and nickel CW agents and in developing surface reactions. The HCN sensors are also phalocyanine thin-film reagents and coatings for surface acoustic wave reversible. We are preparing several will soon test it on CD reagents. (SAW) and optical sensors for CW patent applications stemming from These thin films are quite stable and agents. In addition to sensing CW this work. reproducible. We also developed a agents, we can also chemically Our specific goals for the SAW and new sol-gel approach to prepare mul- modify, and thus destroy, CW agents optical sensors were to (1) develop tilayer films with excellent control of using either our electrochemical or new self-assembled linker layers to the reagent chemistry. New multilayer our SAW and optical technologies. enhance thin-film densities and films prepared in this manner have We demonstrated electrochemical stabilities, (2) develop new ap- shown excellent sensitivity and stabil- sensors for quantifying HCN (a blood proaches to multilayer thin films for ity. Third, we began testing CD and agent) and have also demonstrated a enhanced sensitivity, and (3) measure CA monolayer films against CW- possible electrochemical approach for the SAW response of cyclodextrin agent simulants. We also developed a quantifying sulfur mustards. Using (CD) and calixarene (CA) thin films test bed for Zeeman interferometry both enzymatic and enzyme-mimicking to CW-agent simulants. and initiated tests using our CD and catalytic sensors, we could sense First, we developed and tested new, CA thin films. HCN in the part-per-billion range. high-density, well-ordered linker The enzyme-mimicking catalytic ap- layers based on bifunctional self- proach involves replacing the enzyme assembled thin films. These linker

Program Development—Biosciences 291 Molecular Medicine for the 21 st Century: Publications A Computational Basis for Design and Perelson, A.S., A.U. Neumann, M. Markowitz, et al., "HIV-1 Dynamics Critique of Vaccines and Therapeutics In Vivo: Virion Clearance Rate, Infected Cell Lifespan, and Viral Generation Time," Science 271, 1582 Alan Lapedes (1996).

The kissing-loop RNA motif, in different positions in model se- which the loops of two stem-loop quences. (A correlated mutation is a structures base-pair with each other, is mutation at one site that affects a mu- thought to modulate steps in the life tation at another site.) Our evolution- cycle of retroviruses such as HIV (see ary model takes into account how the accompanying diagram). Using an phylogenetic tree affects the analysis RNA-folding protocol developed for of mutations, and it shows a higher this project, which takes into account correspondence of correlated posi- 5' information on possible base pairings tions with structurally adjacent posi- C: G^ and structural constraints resulting tions in the model than do previous helix 1 U: A C: G hairpin 1 from connectivity requirements, we analyses. G: C are studying the folding of a potential Furthermore, using patient data and G: C kissing-loop motif in HIV. Specifi- simple models, we have begun ana- A""~ cally, we are modeling the structure lyzing and have published the first \ \ G G G U C and the flexibility of this motif, and quantitative estimates of the dynamics helix 2 • • we have worked out three possible of HIV in vivo. We found that 10 bil- C C (- A G structures with low conformational lion viral particles are produced and energies (see accompanying figure cleared each day in a typical mid- -U :/ showing molecular models). stage AIDS patient and that the vast G :C Following on our earlier work, in majority (99%) of virus is produced helix 3 U :A hairpin 2 which we analyzed correlated muta- by cells that live only about 1.5 days. C :G G :C tions (also known as nonindependent These estimates suggest that if HIV mutations) in the V3 loop of HIV, we replication can be completely stopped 5' have developed an evolutionary model by potent drug combinations, then all that incorporates these mutations at HIV and infected cells might be The sequence and secondary structure eliminated from the body after two to of HIV TAR-TAR* kissing-loop motif. three years of treatment.

~~*"• " • •**~~

Three predicted structures of the HIV TAR-TAR* kissing-loop motif. Helices 1 and 2 are shown in light gray, and helix 3 is in medium gray. The two single-stranded loops (p-A-p, p-U-p) are plotted in dark gray.

292 Los Alamos FY1996 LDRD Progress Report Distributed Telemedicine for the National potential commercial partner, and the United States Army has given us Information InfrastructureTestbed funding to deploy TeleMed in its various testbeds. We have also worked successfully with Northern New David Forslund Mexico Community College to find ways of making TeleMed available for TeleMed is an advanced data man- This year we began the transition rural healthcare, including the award agement tool that uses object-based from the Gain Momentum client to a of a two-year grant by the National computing, distributed data reposito- Java-based client, extended the infra- Telecommunications & Information ries, advanced graphical user inter- structure to support relational data- Administration of the Department of faces, visualization tools, and bases, and worked with industry to Commerce. innovative concept extraction of im- begin the process of deploying tech- age information for storing and ac- nologies similar to TeleMed through- cessing medical records. More than a out the nation. We coordinated the Publications standard client/server application, work of several organizations to Forslund, D.W., "What CORBA Can TeleMed has a multitiered architec- collaboratively sponsor two work- Do: an Example of a New System ture in which there are multiple serv- shops on the Master Patient Index for Developed with Object Technology," ers between the persistent storage of use throughout the healthcare indus- Proceedings: Toward an Electronic databases and the clients. try. The system was also deployed and Patient Record^ (II), 255 (1996). In the original deployment of tested at the National Jewish Center TeleMed, we used a Sybase product for Immunology and Respiratory Forslund, D.W., and D. Kilman, "The called Gain Momentum for the client Medicine in Denver, Colorado, and at Virtual Patient Record: A Key to because of its powerful multimedia the National Institutes of Health in Distributed Healthcare and Tele- user-interface capabilities. Because Bethesda, Maryland. Our proposal to medicine," First Class Magazine VI the Java programming language was work with the National Information (II), 14 (1996). so widely and rapidly accepted on the Infrastructure Testbed was rejected by Forslund, D.W., R.L. Phillips, et al., basis of its portability and its usability that organization, which is now called "Experiences with a Distributed on the Internet, we have elected to the InfoTest. However, our work in Virtual Patient Record System," J. move away from Gain Momentum. this area has caught the interest of a Am. Medical Informatics Association Proceedings Symp. Supple., 483 (1996).

Deformable Human Body Model and costovertebral joints of the rib cage are gliding synovial joints, ex- Development cept for the first sternocostal joint, which is cartilaginous. The cartilaginous joints of the cervical, thoracic, William Wray and lumbar vertebrae are of a type called symphysis. Our goal is to develop a realistic, require representation in the deform- We have developed methods of rep- fully accessible, deformable human able human body model include the resenting the three types of synovial body model that is applicable to auto- major synovial joints of the upper and joints (gliding, hinged, and ball-and- mobile design by integrating existing lower limbs, the synovial joints of the socket) and one type of cartilaginous anthropomorphic dummy models with rib cage, and the cartilaginous joints joint (symphysis) in finite-element existing detailed biomechanical com- of the vertebral column. codes. These joint representation ponent models. The major synovial joints of the methods will provide a means for We have conducted extensive study appendicular skeleton include the linking detailed biomechanical mod- of human body anatomy and mechan- ball-and-socket joints of the shoulders els to the baseline anthropomorphic ics and determined that the critical and hips and the hinge joints of the dummy models. joints that are sufficiently movable to elbows and knees. The sternocostal

Program Development—Biosciences 293 Detection and Characterization of the detection system that produced the highest-quality data. Biological-Weapons Agents by Matrix- During this year we constructed instrumentation to perform MALDI- Assisted Laser Desorption/lonization TOF mass spectrometry on proteins. Mass Spectrometry In addition, we wrote and tested data acquisition and analysis software. We successfully detected the proteins Charles Wilkerson gramicidin S (-1150 Da) and bovine insulin (-5300 Da), but technical ob- The objective of this project was to (2) characterize the MALDI source stacles prevented us from observing develop and demonstrate a field- from instrumental and application larger species, such as anthrax toxins deployable point sensor, based on perspectives, (3) implement method- (80,000-90,000 Da) and botulinum matrix-assisted laser desorption/ion- ologies for identifying biological tox- toxin A (-150,000 Da). Over the ization (MALDI) mass spectrometry, ins and verifying their structures, (4) course of the year, we modified the to unambiguously identify biological critically compare experimental re- instrument, continually improving its toxins. Specifically, our goals were to sults obtained when the MALDI capabilities. We also modeled the (1) develop a MALDI source capable source is used in combination with a behavior of ions in the spectrometer of coupling with either a time-of- TOF or IT mass spectrometer, and to help extend our high-mass capabili- flight (TOF) mass spectrometer or an (5) design a field instrument based on ties. ion-trap (IT) mass spectrometer,

~~Novel Gene Complex Structure Determination by Neutron and X-Ray Scattering~~

~~Joe Gatewood~~

There are in excess of 200,000 We have successfully isolated "op- genes in each cell in the human body. erative" chromatin containing exclu- Most of these genes are inactivated sively the minor histone variants. while specific genes remain func- Histone HI is quantitatively missing tional. The packaging of genes into from operative chromatin. One of the higher-order chromatin is a funda- aims of this project was to determine mental factor in determining gene the proteins responsible for stabilizing activity. The basic unit of chromatin is operative chromatin. This chromatin the core particle, which consists of is stabilized by the microtubule pro- DNA wrapped around a protein as- teins tau and tubulin. Another goal of sembly of the four core histones. Two this project was to characterize the copies of each of the four core his- structure of operative chromatin nu- tones combine to form a protein cleosomes. Using solution scattering, octamer, which binds 146 base pairs we examined nucleosomes containing of DNA. A fifth linker histone (his- the minor variants and demonstrated tone HI) interacts with DNA extend- that these particles are structurally ing from the core particle to form the distinct from nucleosomes containing nucleosome. The proteins in this com- the major variants. The unusual struc- plex are similar in organisms ranging ture and stabilization of operative from mouse to man. The core histones chromatin by microtubule proteins consist of "major" and "minor" vari- provides a possible mechanism for ants. The minor variants constitute direct interaction of transcription less than 15% of the histones in machinery with specific chromatin somatic cells. domains.

294 Los Alamos FY1996 LDRD Progress Report In Situ Bioremediation of modify the flow field, and thus it can strongly affect the chemical environ- Trichloroethylene-Contaminated ment of the microbial population. Our model removes part of this source of Groundwater error through application of homogenization theory. Homogenization Nina Rosenberg theory determines an equivalent tensor to represent subgrid-scale proper- Results of bioremediation efforts have a significant impact on the effec- ties. Computational experiments are typically variable and difficult to tiveness of microbial degradation of indicate this is a significant improve- predict. An incomplete understanding contaminants. Next, we created a ment over the former use of single of the effects of variable site charac- computer code that can be used to scalar quantities within grid boxes. teristics (notably, soil heterogeneity, characterize microbial metabolism in Finally, we have prepared several indigenous microbial ecology, and laboratory-scale bioreactors. manuscripts for submission to profes- contaminant speciation) and the lack We conducted sensitivity analyses sional journals and have submitted a of adequate tools that would allow of key biokinetic parameters in a field proposal to the Environmental Man- specialists to predict results and mea- experiment aimed at the bioreme- agement Science Program (EMSP) sure successful bioremediation strate- diation of TCE contamination, and competition. Our proposal was gies have made the implementation of then we ranked the parameters. It is closely tied to a project on the genetic bioremediation more empirical than known that the degradation of TCE engineering of bacteria to more effi- desired. Our main objective for this generates by-products that are toxic to ciently degrade TCE. Although our project is to develop practical compu- the degrading microbes. Our analyses proposal made it to the last round, it tational tools that will enable us to indicated that TCE toxicity was, in was not funded. However, reviews work with site owners and providers fact, the most important parameter. were favorable, and we plan to resub- of remediation services in order to We also analyzed soil heterogeneity mit an improved proposal for the next solve problems in site-specific design through homogenization theory. The round of the EMSP competition, as and in performance assessment and naturally occurring heterogeneity in well as for the upcoming Natural implementation of bioremedation soils has not been included adequately Accelerated Bioremediation call. strategies for chlorinated solvents, in previous modeling studies of such as trichloroethylene (TCE), in bioremediation; that is one major rea- Publications groundwater. son for such studies not to have been This year, we have accomplished a sufficiently accurate. In computational Travis, B.J., and N.D. Rosenberg, number of tasks. First, we have con- models, the total volume of soil en- "Modeling In Situ Bioremediation of ducted an extensive literature review compassed by a field site is repre- TCE at Savannah River" (submitted to of previous experiments on competi- sented by a grid of small boxes, and a Environ. Sci. Technol.). tion between different types of mi- single value is used for soil properties Vanderberg-Twary, L., K. Steenhoudt, crobes present in soil and on preda- within each box. As a result, subgrid- B. Travis, et al., "Biodegradation of tion in soil microbe systems. It has scale variability is completely Paint Stripper Solvents in a Modified become clear not only that predation smoothed away. However, in reality, Gas Lift Loop Bioreactor" (to be and competition are present at con- subgrid-scale heterogeneity can published in Biotechnol. Bioeng.). taminated sites, but that they also

~~Program Development—Biosciences 295~~

~~Index of Principal Investigators~~

Abdallah, J. Jr. 72 Camassa, R. 65 EarLW. 51 Albers, R. 157 Campbell,! 159,249 Early, J. 261 Albright, J. 285 Campbell, L. 168 Ecke, R. 202 Alcouffe, R.E. 194 Carlson, J. 105 Eckert, J. 148 Altherr, M. 119 Carlsten, B. 43 Elling, J.W. 23 Arthur, E.D. 187 Casperson, D.E. 94 Elliott, S. 98 Aubrey, J. 241 Cerutti, J.H. 275 Epstein, R. 15,211 Avens, L. 266 Chamberlin, R.M. 59 Chen,D. 118 B Chen, S. 67 Chen,W. 66 Chidester, K. 287 Faber, V. 203 Balatsky,A. 156 Clark, T. 41 Faehl, RJ. 41 Baldridge, W.S. 189 Clements, B.E. 155 Farnum, E. 29 Barlow, D. 174 Cline, M. 232 Farrar, C.R. 31, 171 Barrett, C. 274 Cobble, J.A. 44 Fasel, J. 199 Benage, J. 40 Collins, L. 71 Fazio M., 37 Benjamin, R. 171 Coogan, J. 259 Fearey,B. 281 Berendzen, J.R. 129 Cooke, D.W. 9 Federspiel, F. 108 Bhatia,T.S. 177 Cooper, D. 285 Fenimore, E. 83 Bhattacharya, T. 111 Fitzsimmons, M. 154 Bigio, I. 25,127, 129 Cort, B. 140 Cram,L.S. 118,226 Flynn, E. 169 Birn, J. 92,218 Forehand, H. 273 Bishop, A. 70,161, 191,204 Cranfill, C.W. 188 Cremers, D. 23 Forslund, D. 293 Booth, T.E. 190 Frauenfelder, H. 233, 236 Borovsky, J. 99 Freyer, J.P. 123 Bourke, M.A.M. 147, 152 Funk, DJ. 73, 172 Bowles, T. 288 Funsten, H.O. 75, 250, 256 Bowman, J.D. 103 Davis, H.A. 26 Bradbury, E.M. 126 Day,R.D. 256 Brainard, J. 235,237,267 Devlin, D. 146 Breshears, D.D. 93 Doering, C. 194 Brown, D.L. 61 Doggett, N. 227 Garcia, A. 122 Brown, M. 276 Donahue, J. 262 Gary, S.P. 81 Buescher, K. 273 Donohoe, R. 21, 185 Garzon, F. 35 Burns, C. 47 Doolen, G. 167 Gatewood, J. 294 Bystritskii, V.M. 170 Drake, 278 Gavrilov, E. 68 Dreicer, J.S. 279 Gerstl, S. 208,212,214 Dunand, D.C. 152 Glatzmaier, G. 82,207 Dye,R. 14,242 Goff,F. 88 Dyer, R.B. 121 Goodwin, E. 116 Gosling, J. 85

Index of Principal Investigators 299 Gosnell,T.R. 33,74 K N Gottesfeld, S. 25 Gubernatis, J. 193, 198, 200, 201 Kao,C.-YJ. 80,213 Nguyen, D.C. 40 Gupta, G. 120,228 Kapustinsky, J. 27 Niederauer, G. 254 Gupta, R. 114 Keller, C. 216 Guthrie, G. 251 Keller, R. 229, 289 Guzik, J. 86 Kendall, R.P. 283,284 Kinnison,W. 104 Ott, K. 57 H Kirkpatrick, R. 180 Kocks,U.F. 143 Hahn, H. 199 Koskelo,A. 79 P Haight,R. 108 Kraus, R. 36 Hamkalo,B. 226 Kubas, G. 54 Paffett,M. 185 Hammel, P.C. 27, 151 Papcun, G. 274 Haschke, J. 60 Park, M.S. 119,231 Hasslacher, B. 62 Parkin, D. 149 Haussler, D. 232 Pearson, J. 130 Lackner, K. 34,183 Hawley, M. 144 Peng, J.-C. 109 Laflamme,R. 99 Hayden,F.G. 127 Perelson,A. 127 Lai, C.-C. 91 Heffner,R. 147,243 Perry, F. 95 Lamartine, B. 36 Hemberger.P. 255 Petrovic, J. 244 Lapedes,A. 232,292 Henriksen, A.D. 278 Phillips, D.R. 213 Lehnert, B. 290 Henson, B. 58 Picard, R. 195 LeSar, R. 275 Hermes R., 59 Pickrell,M. 288 Lewis, G. 250,254 Hersman, L. 230 Poling, D. 192 Lewis, P. 247 Hickmott, D.D. 78,248 Prather, K.A. 184 Li,D. 20,53 Hills, J. 95 Pratt, L. 117 LomdahLP. 192 Hime,A. 110 Preston, D. 168 Hixson, R. 11 Lowe,T.C. 146 Hjelm, R. 140,227 Hoffbauer, M. 14 M Q Hoffman, C. 108 Holm, D.D. 30,62,63 Quinlan, D. 67 Houts,M. 255 Machines, M. 183,230 Howe, P.M. 243 Mack,J. 247 HowelU.A. 251 Madland, D. 111 R Huang, J. 155 Maggiore, C. 179 Hubbard,K. 18 Mainieri, R. 35 Rider, W. 196 Hughes, R. 31,34 Maley, M. 160 Roberts, J. 135,145 Hyman, J. 64,66 Margolin, L. 188 Roberts, R.S. 35 McBranch, D. 45,159 Robinson, B.A. 80 McComas, DJ. 75 Robinson, J.M. 84,184 McDonald, T. 253 Robinson, R. 142,223 McNaughton, M.W. 109 Rosenberg, N. 295 Migliori, A. 19 Jacobson, A. 91 Rosocha,L.A. 170,265 Miller, W. 100,102 Ryne, R. 182 James, B. 249 Milonni, P. 74 Jarvinen, G. 245,268 Mitchell, T. 163 Jen,E. 69 Morel, J. 61, 189 Jia,Q. 153 Morris, C. 175,177 Johnson, P. 83 Mosteller,R. 201 Johnston, R. 30 Mottola,E. 112,198 Jones, E. 76 Munson, C. 262

~~300 Los Alamos FY1996 LDRD Progress Report u~~

Saltzman, J.S. 65,193 Ullmann, J. 108 Salzman, G. 291 Unkefer,C. 128 Sauer, N. 52 Scheuer, J. 260 Schiferl,D. 90 Schiferl, S. 18 Schmidt, D. 24 Venneri, F. 174 Schmidt, S.C. 56 Vieira, D. 106 Schoenborn, B. 120 Voter, A. 50 Schroeder, N. 267 Schultz, J. 284 w Schwarz, R.B. 138 Scovel, J. 63 Wadlinger, E. 260 Scripsick, R. 137 Warren, M. 85 Seestrom, S. 179 Watkin, J. 55 Shankland, T. 220 Wesse,F.J. 170 Shashkov, M. 69 West, G. 104 Sheffield, R. 178 White, A. 200 Shi,N. 136 Wilkerson, C. 294 Sickafus, K.E. 10 Williams, M. 276 Silks, L.A. 46, 116 Wills, J. 142 Sinnis, C. 113 Winske, D. 102,210 Smith, B.R 57, 270 Wood, C. 117,290 Smith, D. 19 Woodruff, W. 52,60,225 Smith, G. 137, 149, 226 Wray,W. 293 Soderquist, S.D. 173 Wysocki, F. 42 Solem, J. 244 Sparks, W. 81 Steckle,W.P. 15 Stevens, M. 154,241 Strauss, C.E.M. 71 York,R. 248 Stringfield, R. 271 Suszcynsky, D. 78 z Swanson, B. 150 Sze,R. 32 Zaera, F. 185 Zawodzinski, T. 51,291 Zhu,Y.T. 16 T Zurek,W. 96,98 Taylor, A. 28, 38, 252 Zweig, G. 64 Terwilliger, T. 121,122 Thode, L.E. 39 Thoma,D. 12 Thompson, J. 209 Thompson, J.D. 139, 158, 242 Tolmie, D. 68 Torney, D. 124,234 Trewhella, J. 115, 225, 234 Tumas, W 48, 269

~~USGPO 1997 573-236/33199 Index of Principal Investigators 301 This report has been reproduced directly from the best available copy.~~

~~It is available to DOE and DOE contractors from the Office of Scientific and Technical Information, P.O. Box 62, Oak Ridge, TN 37831. Prices are available from (615)576-8401.~~

~~It is available to the public from the National Technical Information Service, US Department of Commerce, 5285 Port Royal Rd. Springfield, VA 22616. BACK COVER~~

Clockwise from upper right: • Accretion disk around a rotating black hole (W. Miller, "Accretion onto Black Holes: The Power-Generating Mechanism"). • Diffusion image of helium-3 gas at thermal equilibrium (D. Schmidt, "Nuclear Magnetic Resonance Imaging with Hyperpolarized Noble Gases"). • Optical shadowgraph of the spiral defect chaos state in thermal convection (R. Ecke, "Self-Organization and Pattern Formation"). • Plasmid for expressing fusion proteins (J. Trewella, "Biotechnol- ogy Approaches to Stable-Isotope Labeling for Biomolecular Structure/Function Studies"). i s> *