PROGRESS REPORT 1985 - 1986
Instituto de Física Universidade Federal do Rio Grande do Sul
Ptril Mtffi • Imi mi FOREWORD
Despite difficulties arising fro» uncertainties in the scientific policy and economic situation of the country, the scientific activity and production of the Institute regained at the level of previous years. During the present period the Institute of Physics Moved to the new University Campus thereby having access to ample new installations and waking possible the expansion of its activities. Although expected to be beneficial in the long range, numerous difficulties had to be «et particularly by experimental groups, slowing down temporarily their production, until all the equip- ments were again operational. A new COBRA 1400 computer (equivalent to a Eclipse Data General MV 8000 II one'; has been acquired. This acquisition nade possible for the first tine in many years, an adequate level of computational support for our work. During this period discussions were started on the need for new research and technological facilities for our Institute, in particular laboratories for thin films and electronic microscopy, and expansion of the existing ones, like the ion implantation. The scientific achievements of the Institute were made possible by the financial support of FINEP (Financiadora de Estudos e Projetos), CNPq (Conselho Nacional de Desenvolvimento Científico e Tecnológico), CAPES (Coordenação de Aperfeiçoamento de Pessoal de NTvel Superior) anó the University Administration. The continuous support of the University Administration to secure outside funding is also acknowledged. The effort in editing this report,due to Professor Walter K. Iheumann with the expert assistance of Mrs. Ivone H. Schunck, who also did part of the typing together with Mrs. Manda Aurélio Knebel, Mrs. Ana Neri Juliano Nunes, Mrs. Maria Cecilia do Ama- ral, Mrs. Mara N. C, Friedrich and Mrs. Denise A. R. Cauiuro are gratefully acknowledged.
Edemundo da Rocha Vieira, Director, Institute of Physics. TABLE OP CO8TEKTS Peat I. RESEARCH 19 EXPEKIMBKTAL PHYSICS
I.a) Perturbed Angular Correlation
-Magnetic Hyperf ine Fields in Beusler Alloys Co ?YZ ft • Ti.Zr; Z » Al,Ca,So) 3 - The Effect of Pressure and Temperature on the Electric Fi«*ld Gradient in the Indium Sites in Compounds of the In-Bi System 1 I.b) MOssbauer Spectroscopy
- Spin Reoricntation in (Er,Gd)Fe3 Compounds 5
-Magnetic Properties of the Hydride Pd FeHQ 7 5
-Spin Reorientation Phenomena in KJe.4» (RE = Ce, Dy» Et ) Alloys from "Fe and Dy Mttssbauer Spectroscopies 6 - Hyperf inc Fields at sr Sites in the Heusler Alloys Rh.Mr.Z Ú - Ce,Sn,Pb) 6 - MBssbauer Measurement of the Hyperfine Magnetic Field at p ite in Heusler Alloys Rh~MnZ (Z * In and Sb) 7 -Magnetism and Crystal Field Properties of the (RE - Y, Ce, Dy. Er) from MBssbauer Spectroscopy -Electrical Transport Properties of B13NÍ under Helium and Hydrogen Implantation 8 -Spin Reorientation Phenomena in (Er Gd ),Fe ,B Alloys ê - TDPAC and MBssbauer Measurements of Hyperfine Fields in Chroeium- Based Chalcogenide Spinels 9
I.c) Ion Implantation InPd Interactions in Defect Ca^cr.des in AgPd and CuFd 1 1 -Distributions of Light Ions and Foil Destruction after Irradiation of Organic Polymers -Depth Profile and Thermal Annealing Behaviour of Bi Implanted into an Al/Ti Bilayer Structure 12 -Range Profiles of Implanted Bi and Au in Amorphous Silicon M -Range Profiles of 10 to 380 keV i20Sn and '33Cs in Amorphous Silicon 13 - Secondary Electron Emission from the Entrance and Exit Surfaces of Thin Carbon Foils under Fast Ion Bombardment 't 3 -Two Types of HeV Ion Beam Enhanced Adhesion for Au Films on SiO_ 14 - Adhesion Enhancement Induced by MeV Ion Beams 1 b -Measurement of the Carbon Content of Silicate Glasses by Use of 12 13 the C(d,p0) C Reaction 16 -Electrical Contact and Adhesion Modification Produced by High Energy Heavy Ion Bombardment of Au Film on GaAs 1 7 -Comparative Study oft Interactsilie F&atas Foraeã t/ direct .ao Implantation and Radiation Enhanced Diffusion of Tin in Two Kinds of Steel 18 -Mass and Energy Dependence of I*tp I an ted Ion Profiles in the AZIlt Photoresist 19 -Energy. Mass and Dose Dependence of Implanted lot. Distribution into Polymer Layers 1? - Large Z -Range Effect for Eu, Yb sad Au lens laplanted la Aax>rphit£d Silicon 20 - Implantation and Thermal Annealing Behaviour of Bi Implante* into Al/Ti and Ai/V Bilayer Structures 20 -Energy Dependence of the Z -Range Oscillation Effects in Si'icon 2 1 -Range Prcfiles of Ions in Double-Layer Structures 2' - Range Distributions and Thermal Behaviour of Bi laplaraei . to KC1 and Al/KCI Bilayer Structure 2. - Comparison of Several Nuclear Reactions Techniques for Hyaiogen Depth Profiling in Sclids 2. -Measurement of Eolian Sand Ripple Cross-Sectional Shapes 2 3 - Llectrical Transport Properties of Bi-Ki under Heiiua Irradiation and Hydrogen Implantation 24 -Evidence for che Metal-Insulator Transition in a Pure 3D Metal 2 5 - Direct Ion Implantation and Radiation Enhanced Diffusion of Tin into Iron 2 3 - Ion Inplantation Metallurgy 26 - Influence of He-Vacancy Complexes on the Thermal Behavior of Nitrogen Precipitates in Fe 26 -Modification of the Mechanisms of High Teasperature Oxidation of Steels by Tin Ion Inplantation and Radiation Enhanced Diffusion Par I - High Cr bon Steel 2 7 - Projected Ranges and Range Stragglings of Au and Bi Implapted into Carbon Films and into 5iO~ 28 - Hydrogen Depth Profiling in Solids: A Comparison of Several Res. nant Nuclear Reaction Techniques 26 - Interdiffusion and Reaction in the Iron-Aluminum Bilayer. I - Rutherford Backscattering Analysis of Furnace Annealed Samples 29 -Concentration-Depth Profile of RBS Spectra with Poor Mass Rose i it ion 30 - lor. Implantation and Radiation Enhanced Diffusion of Tin into Iron and Steels 30 -Dopants Redistribution During Titsnium-Disilicide Forsation by Rapid Thermal Processing 31 l.d) Microelectronics -Recoil Implantation of Antimony into Silicon by Argon Ion Bombardment 3 3 Page - The Suppression of Residual Defects in Silicon Implanted vith Arsenic by Rapid Isothermal Annealing 13 -Residual Defects in Implanted Silicon Submited to RTA: Evidence of a Chemical Effect 34 -A Channelling and Conversion Electron MBssbauer Spectroscopy Study of Annealing Behaviour of Tin Implanted Silicon 34 -Dopants Redistribution During Titanium-Disilicide Formation by Rapid Thermal Processing 35 -The Suppression of Residual Defects of Silicon Implanted vith Group III, IV and V Elements 35 -Rapid Thermal Annealing of Silicon Amorphized by Ionic Implantation 36 - Sb Recoil Implantation in Si by Ar and Ge Ion Bombardment 36 -Formation of Niquel and Titanium Suicides by Rapid Thermal Process 3 7
I.e) Electronic Transport and Magnetism
-Magnetic Ordering in YGd Alloys 40 -Magnetostriction of Single Crystals of Yttriun Doped with Rare Earths Impurities <*0 - Helimagnetic Structure in Diluted Y-Gd Alloys u ' -Hall Effect in Ce^ Y Pd. Mixed-Valence Alloys 4i -Spin-Disorder Resistivity in Ni-MniSn. In ) Heasler Alloys 42 - Anisotropic Thermal Expansion of Yttrium Metal and Yttrium-Based Rare Earth Alloys at Low Temperature 4 2 - Specific Heat Measurements in Scandium - Rare Earth Anisotropic Spin Glasses 4 2 -Comparative Study of Isothermal and Isochronous Crystallization of Metallic Glasses 4 3
-Crystallization of Feon Ni BOA Glasses 43 DU—X X £\J -Chemical Short Range Order in Fe20N*60B2Q Amorphous Alloys 4 4
-Electrical Resistivity of Amorphous Fen m-Zr- na 44 -Electrical Resistivity Near the Critical Point in Pd-Based Heusler Alloys 4 3 -Critical Coeficients for the Ferro-Param&gnetic Phase Transition in Metallic Glasses at High Temperatures 46 -Ion Bombardemetit of Metallic Glasses 46 -Study of the Crystallization and Thermal Stability of Amorphous Alloys Type (Pe1x»ix)80B20 4 7 - Seoiclassical Theory of the Electronic Transport in Metals 48
I.f) Laser -Tuning of a tfarroy Linewidth Pulsed Dye Laser with a Fabryperot and Diffration Grating Over a Large Wavelength Range 50 P«ge Microstracture and sone of its Optical Effects in Thin Films SO Measurement of the Principal Refractive Indices of Thin Films 30 FECO-Based Observations of Birefringence at Normal Incidence in Optical Coatings 5? Computer Simulation of Thin Film Growth: Applying the Results to Optical Coatings 52 Pirani Pressure Sensor Built with the Filament of Incandescent Lamp 3 2 + The 337 nm Nitrogen Laser Resonances with the f 0 ( Po)-B Transitions in Molecular Iodine (I_) 88 5 3 -Deterministic Chaos in a Glow O.C. Helium Discharge 5 3 -Accidental Resonances of the 337 ran Nitrogen Laser with the f-B Transitions in Molecular Iodine 5- - Light Scattered by a Microscopic Sphere 3 5 -CARS Studies of Energy-Transfer Processes in Na-H., System -Õ -A Variable-Angle Ellipsometer for Refractive-Index Measurements 3b
II. RESEARCH IN THEORETICAL PHYSICS
II.a) Condensed Matter Theory - Effect of the d-f Correlation on the Electronic Structure of Intermediate Valence Systems 5 9 -Real Space Renormalization of a Mixed Valence Haroiltonian on a Bethe Lattice 3 9 - Effect of the d-f Coulomb Correlation on the Valence Transition of Intermediate Valence Systems 59 - Effect of the Spatial Correlation on the Alloy Analogy Approxi- mation to the Hubbard Hamiltonian 60 -Critical Exponents for 4> -Field Models with Long-Range Interactions 60 - A New Approach to the Study of an Anderson Impurity in a Linear Chain 6! -The Spherical-Model Limit in a Random Field 6' -Effects of Trilinear Symmetry Breaking on the Potts-Model Transition of Uniaxially Stressed SrTiO. 62 J 3 -Renormalization and Phase Transitions in Potts <•> -Field Theory with Quadratic and Trilinear Symmetry Breaking 62 -Conductivity of a Random Electron Chain Renormalization Group Approach 6 3 -Quantum Spin Glass: A Repiica-Synmetric Theory with Positive Entropy 6 3 - Superalgebra and the Spherical Model of a Spin Glass 64 - Simple Approximation for the Bethe-Ansatz Solution of Che One- Dimensional Fermi Cas 64 Page - Non-Universality of Ratios of Critical and Tricritical Parameters in the Three-State Potts Model with Symmetry Breaking Perturba- tions 65 - The Spherical Model as the Limiting n-Vector in a Random Field 65 -Phase Transitions in Asymmetric Potts Models: Breakdown of the Classical Mean-Field Picture 66 -The Statistical Interference Approach to Generalised Thermodynamics: I. Statistics 66 -The Statistical Interference Approach to Generalized Thermodynamics: II. Thermodynamics 67 - Statistical Inference in Equilibrium and Nonequilibrium Thermodynamics 67 -A Diagrammatic Solution of the Kondo Lattice 67 -Localization Properties in Binary Alloys Described by a Bethe Lattice 68 - Critical and Tricritical Points in the Three-State Potts Model with Symmetry-Breaking Perturbations 68 - A Study of the Hubbard Hamiltonian and Intermediate Valence Systems on the Bethe Lattice 70 - Diagrammatic Solution of an Intermediate Valence Hamiltonian and of the Kondo Lattice 70 II.b) Quantum Field Theory -Quantization of QED and QCD in a Fully Fixed Temporal Gauge 7 3 -Excitation Rates of Heavy Quarks 7 3 -Dynamics of Gauge Systems and Dirac's Conjecture 73 -Operator Quantization of Non-Abelian Gauge Theories in a Completely Fixed Axial Gauge 7 4 -Canonical Quantization of a Two-Dimensional Model with Anomalous Breaking of Gauge Invariance 7 4 -Canonical Derivation of the Gluon Propagator in the Temporal Gauge 7 5 -Quantum Dynamics of Chiral Fermions in -i Model with Anomalous Breaking of Gauge Invariance 75 -Excitation of Heavy Quarks and DilepconB Production by Neutrinos 76
-Operator Quantization of Non-Abttian Gauge Theories in a Completely Fixed Axial Gauge 76
II.c) Plasma Physics -Electron Cyclotron Wave Absorption by the Fast Tail Generated by the DC Electric Fiel^ in Tokamak Plasmas 78 - Disaipative Instabilities at the Edge of Reversed-Field Pinches Driven by a Combination of Plasma Gradients and a Parallel Current 78 •Electron Cyclotron Heating of a Tokamak Plasma st Down-Shiftcj Frequencies 7 9 -Ex»ct Invariants in Resonance Form for Time-Dependent Potentials 7 9 Page - Angular and Moatentuss Distribution Dependence of Electron Cyclotron Absorption «ad Amplification in Mirror-Confined Planas 80 - Electron-Cyclotron Heating of a Tokamak Reactor with the Extraor- dinary Mode 81 - Electron Cyclotron Damping for Large Wave Power in Tokamak Plasmas 81 -Power Dependence of Electron Cyclotron Wave Damping in Tokaamk Plasmas 82 - Cross Effects on Electron-Cyclotron and Lower-Hybrid Current Drive in Tokamak Plasmas 82 - Electron Cyclotron Wave Damping for Oblique Propagation in Hot Plasma* 83 -Temperature Effects on Ion Acoustic Soli tons in Plasmas with Near Critical Density of Negative Ions 83 -Rational Functions of Momentum as Invariants for One-Dimensional, Time-Dependent Potentials: Basic Theory 64 -Rational Functions of Momentum as Invariants for One-Dimensional, Time-Dependent Potentials: Two- and Three-Resonance Cases 8** - Quasilinear Equation for Oscillations in Magnetoplasmas in a Weakly Relativistic Approximations 85
II.d) Nuclear Physics -Bags in the Shell Model 87 -Recent Developments in Quasi-Free Nucleon-Nucleon Scattering 67 - S-Wave Meson-Nucleon Scattering in an SU(3) Cloudy Bag Model 88 - KN Scattering in the Cloudy Bag Model: s, p, and d Waves 88 - Pion-Nucleon Scattering in the Cloudy Bag Model 89 -Hybrid Quark Models and Unitary Theory of Pion-Nucleon Scattering 89 -Lifetime of a Nuclear Hole State in a Relativistic Model 9'
III. Astronomy and Astrophysics -The Cancellation of Magnetic Flux. I on the Quiet Sun ?5 - The Cancellation of Magnetic Flux. II in a Decaying Active Region 96 -G Band and H Photometry of LMC and SMC Red Clusters 97 -The Primeval Hadron and the Regge Law 97 -The Average Density of the Universe and the Regge Law 97 - HII Region Age Indicators 98
-Photometric Measurements of WHQ and [0III]/Hft of HTI Regions in M83 6 » 98 -A Comparative Study of the Stellar Content in Normal and Active Nuclei of Spiral Galaxies 99 - Spectrophoeonetry of the Nucleus of NGC 7552 99 - BV Surface Photometry of Southern Galaxies. I. NGC 4507 1 00 - BV Surface Photometry of the Southern Galaxies NGC 6769, 6770 1 00 and 6771 Faga -Colour Gradients in Globular Clusters 101 -Ages and Metallicities of LMC and SMC Red Clusters Through MB and G Band Photometry 102 -The Distribution of Interstellar Extinction Near Sun 102 -Strip Photometry of Comet Halley 103 -Galaxies with Strong Nitrogen Lines t03 -Nuclear Stellar Population of NGC7/Í (ARP 78) 104 - BV Surface Photometry of the Southern Galaxies NGC 2855 and NGC 4507 104 -Morphology of LMC Clusters 105 -NGC 2209: The Nature of the Dark Patch 106 - Cosmo logical Mass Density and the Regge Law 106 -Evolution of HI I Regions 107 -Age Determination of the Magellanic Clouds ano Isolated Extragalactic HII Regions 107 - A Search for Periodicities in the Light Variation of Some Seyfert Galaxies 108 -Strip Photometry of Comet Halley 108 -Photometric Studies of Southern Open Clusters, II NGC 3766 and NGC 5460 109 -Multicolor Photometry of Three Southern Open Clusters 109 - Spectrophotometry of the Nuclei of NGC 772 and NGC 5325 1 10 -Galaxies with Strong Nitrogen Lines 1 10 - Halley's Comet 112 -A Measurement of Secular Evolution in the Pre-White Dwarf Star PG 1159-035 1 13 -The Most Recent Value for the Rate of Period Change in the ZZ Ceti Star G117-B15A 1 13 -A Comparison Between Optical and X-Ray Simultaneous Observations of the Variable Pre-White Dwarf Star PG1159-035 1 14 IV. PHYSICS EDUCATION
-Theses on Physics Teaching in Braz.il 1 16 -Teaching at the University: Suggestions to the Teacher 116 -Collage Teaching: Instructional Alternatives 117 -Teaching and Learning: Theoretical Approaches II7 -Student Evaluation of Tetcher's Performance: New Evidences of Validity of an instrument t f 7 -Concept Mapping: An Altevnative Strategy for Evaluation 1 18 -Reseach Methodology and Teaching Methodology: A Practical Application lie •Beta Coefficient: Estimate of the Reliability Coefficient of a Composite Variable 118 Soma Characteristics of Porto Alegre High School Physics teachers 119 -Cognitive Mapping in Thermodynamics Through Multidimensional Scaling 1i9 Intuitive Concepts in Objetive Items Applied in Entrance Exs nations at the Universidade Federal do Rio Grande do Sul 1 19 Concept Maps 1 20 Concept Maps in Physics Teaching 1 20 Curriculum Emphases and Science Teacher Preparation 12 1 • The Entrance Examination of the Federal University of Rio Grande do Sul (UFSGS) 122 An Epistenological Analysis of Curriculum 122 Validation of a Test to Detect Whether the Student Possesses the Newtonian Conception on Force and Motion 1 2 3 Concept Mapping in tie Investigation of Student's Conceptual Knowledge Structures *n Physics 123 Physics Laboratory: Learning Measuring Instruments !23 •Physics Laboratory: An Analysis of Curriculum '24 - Concept Maps 1 2 4 •An Enpirical Study About the Relation Between the Period and the Amplitude of a Simple Pendulum 124 •Detection of Intuitive Concepts in Electricity Using Clinical Interviews 12 5 •The Influence of the Instrument of Evaluation on the Kind of Evidence Gathered About Learning From Laboratory Physics 125 •The Attitude Toward Physics: Does Laboratory Physics Matter? 125 •Evidence of Learning Produced by Laboratory Physics Teaching: Inf*uence of the Evaluation Instrument 126 •Textbooks as Vehicles of Curriculum Emphases in Physic? Teaching 126 •Frameworks for Curriculum Analysis and Design in Science Teaching 126 •Laboratory Teaching Materials for Secondary Schools 127 • Studies Concerned with Physics Laboratory in Porto Alegre High Schools 129 •Physics Laboratory: Cuniculum and Actual Learning Outcomes Analysis 129 • Intuitive Concepts on Electricity Detected Through Clinical Interviews 130 Spontaneous Conceptions on Termodynamics; A Study at College Level Using Clinical Interview i 30 V. INSTRUMENTATIOR Page - Superisolated Liquid Helium Dewarc and Valves for Rigid Transfer Tubes 133 -A Practical Conductance Meter for Low Temperature Resistance Thernometry and Control 133 -Synchronous Detection of Small Changes in the Resistance of Amorphous Metals 133
Jl. APPENDIX
-List of Publications 135 -Papers Accepted for Publication 145 - Papers Presented at Meetings and Conferences 1 48 -M.Sc. Theses 160 -Ph.O. Theses 16 1 -Staff Members of the Department of Physics 182 -Staff Members of the Department of Astronomy 164 -Engineering Staff of the Institute of Physics 165 -Graduate Students of the Institute of Physics: 166 -Ph.D. Students 166 -M.Sc. Students 167 RESEARCH IN EXPERIMENTAL PHYSICS I.a) PERTURBED ANGULAR CORRELATION -3-
MAGNETIC HYPERFINE FIELDS IN HEDSLER ALLOYS COgYZ (Y - Ti.Zr; Z • Al,Ga,Sn)* S.D. de Sousa**, R.N. Saxena , W. Schreiner and F.C. Zawislak Magnetic hyperfine fields (ahf) acting on Ta at the Ti and Zr sites have been measured in Heusler alloys Co.TiAl(G,Sn) and Co.ZrAl(Sn) by the TDPAC techniques utilising the 133-482 keV gamma cascade in 181Hf. Curie temperatures of all the alloys have also been measured using a vibrating sample magnetometer. Present data together with the existing results on the Co.HfAl(Ga,Sn) are discussed and compared with the ahf systerna tics in Heusler alloys.
*To be published in Hyperfine Interactions. **Departamento de Física, UFSCAR, SP, Brasil. ++In»tituto de Pesquisas Energéticas e Nucleares, IPEN-CNEN/SP, Brasil.
THE EFFECT OF PRESSURE AND TEMPERATURE ON THE ELECTRIC FIELD GRADIENT IN THE INDIUM SITES IN COMPOUNDS OF THE *.n-Bi SYSTEM* S.G. Fries, A. Maciel and J.A.H. da Jornada By using the time dependent perturbed angular correlation (TDPAC) technique the electric field gradient (EFG) was measured as a function of pressure, for the compounds InBi, In.Bi and In.Bi., and as a function of temperature for In.Bi, using 111Cd as probe in the Indium sites. It was possible to identify the phase transition induced by pressure in the compound In.Bi a» a transformation to the structure of the compound In.Bi. with defects. Estimates were made of the volumetric and thermal contributions to the EFC for the compounds In.Bi and In.Bi.. The high value of the volumetric contribution obtained for In.Bi is comparable to the known values for pure metals. For In.Bi. the importance of anharmonic effects in the EFG shows up.
•Submitted to J. Fays. F: Metal Physics, 1986. I.b) MOSSBAUER SPECTROSCOPY -5-
SPIH REOMINTATlOiJ IH (Er,Gd)Pe3 COMPOUNDS* J.B.M. da Cunha» P.J. Viccaro and A. Vasquez The MBssbauer effect ha» been used to study the magnetic properties of pseudobinary (Er.Gd)Fe. compounds. The spectra show that the spin-reorientation temperature, T , decreases with increasing Gd concentration. This decrease is explained by the concentration dependence of the average crystal field anisotropy at the (Er,Gd) sites. A simple single-ion model for the free energy was used to describe the magnetoerystalline anisotropy. The model adequately describes the concentration dependence of the reorientation temperature.
«Published in J. Phys. F: Net. Phys. IS (1985) 709.
MAGKFTTC PROPERTIES OF THE HYDRIDE Pd3FeHQ ?* M.H. Preis Corri», W.H. Schreiner, J.E. Schmidt, P.J. Viccaro and A. Vasquez Results of magnetisation and Fe MOssbauer measurements show that the strong ferromagnetic coupling in Pd-Fe is markedly altered in the hydride
Pd.FeÜQ j. The magnetic moment of (4.59±0.03)uB is reduced by the presence of hydrogen to (O.83±0.03)y_, This reduction is accompanied by a decrease of approximately 46Z in the magnetic transition temperature of the hydride compared with that of Pd-Fe (499 K). In addition MBssbauer spectra at 4.2 K in external magnetic fields indicate that anisotropic antiferromagnetic coupling dominates in the hydride. Results are compared with those for where similar effects are observed. «Published in J. Phys. F: Met. Phys. 15 (1985) 1779. -6-
SPIV UOsUORATiai FHflNMttà IV K^F*,^ (BE H Co, Dy, Br) ALLOTS FROH 5?Fe ATO i6iDy MDSSBAOIB SFECTROSCOPIES* A. Vasques*. J.M. Fricdt, J.P. Saaches, Pt. L'Bcritier**, 1. Fruchart** Centre de Recherches lluclcaires, 67037 Strasbourg Ceder, France
Magnetically aligned polycrystalline samples of Er2Fe .B, Ce^*^* and Dy.Fe^B have been studied by Mdssbauer spectroscopy Fe and Dy) in the teaperature range between 4.2 K and 350 K. The results demonstrate a constant collinear spin structure for Ce-Fe.JI and Oy^Fe.JI xn this temperature range. A spin reorientatioa from the basal c-plane to the c-axis is observed for Er.Fe ,B when temperature is increased above 328±3 K. «Published in Solid State Coma. 55 (1985) 753. •On leave from IF-UFRGS, Brazil. **ENSIEG, UA 1109 CNRS, 38402 Saint Martin d'Heres, France.
HYPERF1NE FIELDS AT sp SITES 111 THE HEUSLER ALLOYS Rh2MnZ (2«Ge,Sn,Pb)* S. Jha*, H.M. Seyoum*, CM. Julian**, R.A. Dunlap**, A.Vasquez, J.B.M. da Cunha and S.M.M. Raaos The Radial dependence of the Sn and Cd hyperfine fields in Rh-based Heusler alloys has been investigated with use of MSssbauer effect and time- differential perturbed-angular-correlation neasurenents. Result* indicate that the spatial variation of the conduction-electron, polarization is much more rapid than that predicted by present theoretical models. «Published in Phys. Rev. B 32 (1985) 3279. •Department of Physics, Univ. of Cincinnati, Cincinnati, Ohio 45221-0011, USA. "Department of Physics, Miami University, Oxford, Ohio 45056, USA. ••Department of Physics, Dalhousie Univ., Halifax, Nova Scotia, Canada B3H3J5. -7-
R MEASUREMENT OF THE BYPEIFIME MAGNETIC FIELD AT sp SITE IN REUSLER ALLOYS 9h£M. (Z - In AND Sb)*
S. Jha*, H.M. Seyotm*, Sherif Yehia*, Charilaos ilitros*, CM. Julian**, R.A. Du»l«p**, A. Vasqucz, J.B.H. da Cunha aod S.M.M. Raaos
We have Investigated Che systematic* of hyperfine aagnetic field on a fixed probe at the Z-site in Beusler alloys Rh JtaZ as the valence of Z (sp tt9 119 as been element) is varied. The hmf on Sn in Rh.Mnln „« Sn Q2 *' measured 1t9 12l at 293 K and 77 K. In Rh^, J2Sb w Sn Q2 the h»f or. Sb has been measured at 77 K, and on ^^Sn at 293 K and 77 K. The results are coapared 119 119 119 with the hat on So in Rh^ Ge>9g 'Sn>02, RhjMn Sn, and Rh^ Pb 98 Sr. Q2 *Published in Hyp. In. 28 (1986) 491. •iphys. Sept., Univ. of cTncinnaci, Cincinnati, Ohio, USA, 45221. **Phys. Dept., Miami university, Oxford, Ohio, USA 45056. ++Fhys. Dept., Dalhousie Univ., Halifax, Nova Scotia, Canada, B3K3J5.
MAGNETISM AND CRYSTAL FIELD PROPERTIES OF THE REjFe^B^ ALLC-7S (RE » Y, Ce, Dy, Er) FROM M0SS1AÜER SPECTROSCOPE*
J.M. Friedt, A. Vasquez+, J.P. Sanchez, P.L'Beritier** and R. Fruchart** Centre de Recherches Nucléaires, Université Louis Pasteur, 6703? Strasbourg, Cedex, France
Fe and Dy MBssbauer results are reported in the RE_Fe ,B (RE * Y, Ce, Dy, Er) alloys and some of the corresponding hydrides. An analysis of the Fe hyperfine parameters is performed consistently in the paramagnetic and ordered phases of the compounds, providing in particular the hyperfine fields (i.e. the local magnetic moments) at the various crystallographic site». The Dy hyperfine fields reveal fairly pur* jj » -x-> ground multiplets in 161 z £
Dv-Fe.-B and Dy2Fe.,BH- ~. The Dy quadrupole interactions are interpreted to provide empirical estimates for the second-order crystal field parameter &2 at the two Dy sites. Point charge calculations suggest highly anisotropic %2 tensors. A spin reorientation is observed in Er-Fe./B (and Er-Fe.-BH ) whereas in Dy.Fe.,B, YjFe.^B and Ce.Fe./B a col linear spin structure along -8-
the c axis is maintained down to 4.2 K. The directions of anisotropy along <-he series of compounds and the spin reorientation phenomena are discussed on the basis of the proposed crystal field parameters.
•Published iiè J. Phys. F; Met. Phys. JH& O9M») 651. «On leave frost IF-UFRCf. Brazil. **EKSIEG, UA 1109 CKRS, 38042 Saint-Martin-D'Heres, France.
ELECTRICAL TRANSPORT PROPERTIES OF Bi^i UNDER HELIUM IRRADIATION AND HYDROGEN IMPLANTATION*
L. Amaral , P. Nedellec, A. Traverse, H. Bern&s, L. Dumoulin** and J.P. Burger** Centre de Spectrometrie Nuclêaire et de Spectrometrie de Masse, B.P. n° 1, 91406 Orsay, France
We present data on the effects of a irradiation and H implantation on the electrical resistivity, p and the superconducting T of Bi.Ni. Two regimes of flux can be distinguished. At low doses, a large resistivity increase is due to atomic disorder, irrespective of the impinging (a or H); at the same time, only a slight T decrease is measured, ii. contrast with what is observed in At5 compounds. At high doses, specific effects due to H implantation are seen, probably implying significant modification of the electronic structure. There are indications that H enters the lattice as an interstitial, but that is also forms microbubbles.
•Published in J. Phys. F: Metal Vhys. J6» (1986) 1239. •On leave from IF-UFRGS, Brazil. **Laboratoire de Physique des Solides, Bat, 510, University Paris-Sud, 91405 Orsay, France.
SPIN REORIENTATION PHENOMENA IN (Er^Gd^Fe^B ALLOYS*
A. Vasquez and J.P. Sanchez Centre de Recherches Nucléaires, 67037 Strasbourg Cedex, France.
Fe Müssbauer spectroscopy measurements have been used to study the spin reorientation effect in the pseudo-ternary (Er. Gd ).Fe.,B alloys. A simple -9-
single-ion Model for the free energy explains the aagnetocrystalline anisotropy of the alloys and describes quantitatively the concentration dependence of the spin reorientatioa temperature. The Er crystal field parameters and the exchange fields are inferred from this model. *To be published in J. Less Common Metals. +0n leave froa IF-UFRGS, Brasil.
TDPAC AND MtJSSBAUER MEASUREMENTS OF HYPERFINE FIELDS IN CHROMIUM-BASED CHALCOCEN1DE SPINELS* S. Jha, Mohamed Elfazani, Sherif Yehia, C. Micros, Sanjeev Kumar*, Glenn M. Julian**, R.A. Dunlap , A. Vasquez, J.B.M. da Cunha and S.M.M. Ramos Hyperfine magnetic fields are measured at Cd— til and Sn-119 in CdCr.Se, and CuCr.Se,, as well as at Cd-111 in CdCr.S, and CuCr-S,. Quadrupole fre- quencies are measured for Cd-111 in CdCr.Se, above T . *To be published in Nyperfine Interactions. -«•University of Cincinnati, Cincinnati, Ohio, USA 45221. **Miami University, Oxford, Ohio, USA 45056. •+Dalhousie University, Halifax, Nova Scotia, Canada B3H3J5. I.c) ION IMPLANTATION -n-
lUInW INTERACTIONS IK DEFECT CASCADES IN AgPd AND CuPd*
M. Deicher, G. Grflbel, E. Racknagel, Th. Wichert and M. Eehar* Fakuldt fur Physik, Universitlt Konstanz, Wast Germany
AgPd and CuPd alloys, containing solute concentration of I at.Z or less, have be«n implanted vith radioactive In atoas below and above the temperature of stage III recovery in order to create defect cascades and to study their influence on solute atom clustering. The experiments show enhanced clustering at the projectile atom as soon as vacancies becoae mobile, whereas at 100 K the clustering just corresponds to that expected for a random distribution of Pc atoms.
*?ubished in Jiucl. Instr. and Meth. in Phys. Res. B _7/jJ (1985) 119. *un leave iron 1F-UFRGS, Brazil.
DISTRIBUTIONS OF LIGHT IONS AND FOIL DESTRUCTION AFTER IRRADIATION OF ORGANIC POLYMERS*
D. Fink*. J.P. 3iersack+, J.T. Chen*, M. StHdele**, K. Tjan**, X. Behar, C.A. Oliv eri and F.C. Zawislak
It ii found that light ions (Li, B) distribute neither according to their calculated range nor to their nuclear distributions but according to their ionizations after implantation into organic polymers. Also, the profile of chemical destruction after low dose light ion implantation (typically 10 -10 ions/cm ) into organic foils obeys the ionization distribution rather than the range or nuclear damage distributions. After annealing, or at higher implanted doses, a slight of the implantation or destruction profiles towards the nuclear damage distribution is found. The reason for this implantation behaviour may be partly understood is terms of diffusion and subsequent recombination with the created radicals. Li and B distributions in carbon (which Bay be regarded as the final product of polymer destruction,» show a shape which can be described by range profiles with subsequent diffusion and trapping at homogeneously distributed defects. In contrast Co light ion», implanted heavy ions distribute in polymers essential according -12-
to th* ir range profiles, due to negligible diffusion after implantation.
«Published in J. Appl. Phys. 58 (1985) 668. •Hahr.-Meitner-Institut ffir Kernforschung GmbH, Glienickerstr. 100. D-1000 Berlin 39, Germany. **Freie OniversitKt Berlin, Inst. f. Kernphysik Glienickerstr. 100, D-1000 Berlin 39, Germany.
DEPTH PROFILE AND THERMAL AilNEALIHG BEHAVIOR OF Bi IMPLANTED IKTO All Al/Ti BILATER STRUCTURE*
C.A. Olivieri , M. Behar, P.F.P. Fichtner, F.C. Zawislak, D. Fink** and J.P. Biersach**
600-keV Bi was implanted into an Al/Ti bilayer structure. There is good agreement between the Bi depth profile measured by Rutherford backscattering and corresponding theoretical prediction (Monte Carlo code TRIM). After annealing at low temperatures, the pronounced structure of Bi concentration at the Al/Ti interface vanishes, and the buildup of a surface precipitation is observed. At 500 °C annealing, strong Bi diffusion sets in, associated with the intermixing of the substrate components. A thin oxide layer present at the surface acts as a diffusion barrier for Bi, resulting in Bi segregation at the oxide/alloy interface.
«Published in J. Appl. Phys. 58 (1985) 659. •On leave from UFSCar, SP, Brazil. **Hahn-Meitner-Institut fUr Kernforschung Berlin, Glienicker Str. 100, D-1000 Berlin 39, West Germany.
RANGE PROFILES OF IMPLANTED Bi AMD Au IN AMORPHOUS SILICON*
M. Behar, P.F. Fichtner. CA. Olivieri**, J.P. de Souza, F.C. Zawislak and J.P. Biersack**
The Rutherford Backscattering technique was used to measure the depth 209 197 profiles for 10 to 390 keV Bi and 15 to 390 keV Au implanted in aaorphized silicon wafers. The obtained projected ranges and projected range -13-
stragglings arc compared with previous data and with recent universal range- energy calculations. Whereas good agreement is found between the experimental and theoretical range predictions for Bi, the measurements for Au yield, at low energies, ranges longer than predicted. The discrepancy between measured Au and Bi ranges is ascribed to the 2. - range oscillation.
«Published in Nucl. Instr. and Meth. J6 (1985) 453. **0n leave froa Universidade Federal de São Carlos, São Paulo, Brasil. ++Hahn-Meitner-Institut fur Kemforschung Berlin, Glienicker Str. 100, 0-1000 Berlin 39, West Gensany.
RANGE PROFILES OF 10 TO 380 keV 120Sn AND 133Cs IN AMORPHOUS SILICON* M. Eahar, P.F.P. Fichtner, CA. Olivierí**, J.P. de Souza, F.C. Zawislak, J.P. Biersack**, D. Fink*+ and M. StHdele** Depth profiles of Sn and Cs implanted at energies froa 10 to 4 380 keV in amorphized silicon wafers are measured by He ion Rutherford backscattering. The obtained projected ranges and projected range stragglings are compared with previous results and with recent universal range-energy calculations. The data for the Sn-Cs pair are also analysed in terms of the
Z1-range oscillation effect.
•Published in Rad. Effects 90 (1985) 103. _ **0n leave from Universidadê~Federal de São Carlos, SP, Brasil, ••Hahn-Meitner-Institut fUr Kernforschung Berlin, Glienicker Str. 100, D-1000 Berlin 39, West Grrmany.
SECONDARY ELECTRON EMISSION FROM THE ENTRANCE AND EXIT SURFACES OF THIN CARBON FOILS UNDER FAST ION BOMBARDMENT** C.R. Shi**, H.S. Toh, D. Lo, R.P. Livi**, M.H. Mendenhall, D.Z. Zhang** and T.A, Tombrello Division of Physics, Mathematics and Astronomy, California Institute of Technology, Pasadena, California 91125, USA -14-
The total secondary electron emission (SEE) yield from the entrance and exit surfaces of thin carbon foils under fast ion < 0, F, Cl) bombardment has been measured as a function of the ion energy end the ion beam current intensity. Using a retarding field, the energy distribution of secondary electrons integrated over almost all angles of emission in the backward and forward directions has also been measured. It is found that total forward •mission is larger than emission by factors of up to 2.5, 2.7 and 3.4 for O*3, F* , and Cl* , respectively. It is suggested that the enhancement of forward SEE may be partly due to effects from the instantaneous charge state of the heavy ion beam in the solid in addition to the binary collisions of the projectile with individual electrons in the target. It is also shown that the total SEE yield from the entrance and exit surfaces of the target: foils decreases with ion beam current intensity; this may bo a beam-induced temperature effect. The total SEE yield in both the forward and backward directions is less sensitive to surface conditions for high velocity ions than for low velocity ions, and the total yield from both surfaces of the foils is proportional to the ion stopping power in the target, where the constant of proportionality depends on the properties of material.
«Published in Nucl. Instr. and Meth. in Phys. Res. B £ (1985) 263. -«•Supported in part by the National Science Foundation (DMR83-18274). **Nuclear Research Institute, Lanzhou University, China. ++0n leave from IF-UFRGS, Brazil.
TWO TYPES OF MeV ION BEAM ENHANCED ADHESION FOR Au FILMS ON SiO2*+
C.R. Wie, C.R. Shi**, M.H. Mendenhall, R.P. Livi++, T. Vreeland, Jr.**| and T.A. Tombrello Division of Physics, Mathematics and Astronomy, California Institute of Technology, Pasadena, California 91125, USA
The ion beam-enhanced adhesion of thin Au films on vitreous silica substrates was studied for a wide range of Cl ion beam doses for beam energies between 6.5 MeV and 21.0 MeV. Since the residual adhesion of Au on SiO- is low, the improved adhesion can be easily seen using the Scotch Tape Test. The threshold in the enhanced adhesion corresponding to passig the tape test occurs at two different dose ranges for a given energy; one at very low dose 13 2 centered around 1 x 10 /cm , the other at higher doses with a threshold of -15-
around 1.5 x 10 /cm (depending upon the beam energy). At low doses (2 x 10 to 5 x 101 3 /cm2 ) surface cracks occur on the SiO. substrates, these cracks close up at doses higher than 5 x 101 3 /cm2 . A possible explanation of enhanced adhesion in the low dose range is associated with the surface crazing of the SiO_ substrate. To make the adhesion test store quantitative, a scratch test was also used on the samples. •Published in Nucl. Instr. and Meth. in Phys. Res. B £ (1985) 20. •••Supported in part by the National Science Foundation (DMR-8318274). **Nuclear Research Institute, Lanzhou University, China. +*0n leave from IF-UFRGS, Brazil. SDivision of Engineering and Applied Science, Caltech., Pa&adena, CA 91125, USA.
ADHESION ENHANCEMENT INDUCED BY MeV ION BEAMS** R.P. Livi** Division of Physics», Mathematics and Astronomy, California Institute of Technology, Pasadena, California 91125, USA
Enhancement in adhesion of thin Au films on vitreous SiO7 and GaAs substrates was induced by a 35Cl ion beam at energies between 6.5 and 21.0 MeV and doses from 10 1^*" ions/cm 2 to 10 15 ions/cm 2. The enhanced adhesion was studied by using the "Scotch Tape" and the "Scratch" tests. For Au on SiO, it was found that the film passes the "Scotch Tape" test in two different dose ranges; one at low dose centered around 10 13 ions/cm 2 and almost independent of ion beam energy, the other at higher dose and more strongly dependent on beam energy. In the case of Au film on GaAs, in order to study the role of the electronic properties on the enhancement in adhesion, wafers with four different dopants (Cr, Si, Te, and Zn) were used and very different adhesion modifications were found depending on the dopant. •Published in Nucl. Instr. and Meth. in Phys. Res. B 10/11 (1985) 545. •Supported in part by NSF (DMR83-18274). **0n leave from IF-UFRGS, Brazil. -16-
MEASUREMENT OF THE CARBON CONTENT OF SILICATE GLASSES BY USE
12 13 OF THE C(d,po) C REACTION*
G.J. Fine*, E.M. Stolper*, M.H. Mendenhall, R.P. Livi** and T.A. Tonbrello Division of Physics, Mathematics and Astronomy, Cattech, Pasadena, CA 91125
Carbon dioxide is a significant dissolved coaponent in a vide range of magnas and ubiquitous in gasses associated with volcanism. This fact has motivated extensive study of the influence of CO. on the petrogenesis of many types. Despite its importance, the absolute concentrations of dissolved C in silicate glasses quenched from these magmas are not well known. Standard carbon analysis techniques (e.g., gas manometry, quadruple mass spectrometry, gas chrooatography) have been applied to natural and synthetic C-bearing glasses, but a comparison of the results of these techniques shows wide discrepancies. These bulk analytic techniques are destructive and require relatively large samples; in addition, the effects of crystals, alternation phases, and C in bubbles (versus C dissolved in the glass) are often difficult to evaluate. In recent years, several meso- to microbeam techniques have been applied to measurement of the C contents of natural and synthetic silicate glasses. These beam techniques have several advantages over bulk techniques. They are nondestructive, the beam may be aimed at specific sites in the sample to avoid some of the contaminants that complicate the interpretation of bulk analytic techniques, and sample homogeneity may be checked. We have developed a microbeam infrared spectroscopic technique for the quantitative measurement of C-bearing species dissolved in silicate glasses. With the state-of-the-art Fourier transform infrared spectrometers, the diameter of the analyzed spot can be as small as 10 \m. Detection limits depend on glass composition and thickness, but. reliable analyses at the 1 pptn level are possible in some cases. Not all C-bearing species are detectable via infrared (e.g., graphite). This is often advantageous in that contaminants will not usually contribute to the infrared spectrum and, even if they do, they absorb at wavelengths different from the major dissolved species. However, infrared spectroscopy may also fail to detect forms of dissolved carbon that are of interest. Electron microprobe techniques have also been used for the qualitative analysis of low-level C in silicate -17-
glasses, but quantitative results are difficult to obtain for a variety of reasons, including the r^pici attenuation oi low-energy x rays and problems with surface contamination. More significant, sample currents required for the analysis of C result in mobility of sodium in these silicate glasses. Sodium is present in many geologically relevant glasses in relatively high concentrations. Since the mechanism of C dissolution in these glasses cay be intimately associated with Na_O, electron microprobe techniques must be usec with caution. Even if sodium mobility under the tléctron beam can be minimized, care must be taken to avoid mobilization of the carbon itself. In this paper, we describe the use of the L"C(d,p ) C nuclear reaction for the absolute measurement of dissolved C in a series of C-rich, synthetic silicate glasses. This beam technique avoids most of the problems encountered during analysis of low-level C contents by electron microprobe and by bulk analysis. It has been used previously for the analysis of C in metals, lunar samples, minerals, and meteorites. Here we doroonstrate the usefulness of the nuclear technique by the measurement of the C content of a variety of synthetic silicate glass standards.
•Published ir. the Proceedings of the Microbeam Analysis Conference, San Francisco, CA, USA, 1985. •Division of Geological and Planetary Sciences, Caltech, USA. **0n leave from IF-UFRGS, Brazil.
ELECTRICAL CONTACT AND ADHESION MODIFICATION PRODUCED BY HIGH ENERGY HEAVY ION BOMBARDMENT OF Au FILM ON GaAs*
R.P. Livi*, S. Paine**, C.R. Wite, M.H. Mendenhall++, J.Y, Tang', T. Vreeland, Jr and T.A. Tombrello Division of Physics, Mathematics and Astronomy and Engineering and Applied Science, California Institute of Technology, Pasadena, California 91125
Thin gold films over GaAs wafers with different dopants (Cr, Si, Te and Zn) were used to study the role of the sub3trate electronic properties in the electrical contact and adhesion modification induced by MeV/nucleon heavy ion bombardment. The enhanced adhesion was studied using a scratch test; the results show very different modifications of adhesion depending on the bulk -18-
electronic properties of the substrate. The sample vith a Cr compensation doped substrate shoved enhancement in adhesion for beam doses *• low as 10 ions/cm , but Si and Te doped (n-type) substrates shoved a sudden enhancement in adhesion for doses around 10 ions/cm . Samples vith Si and Te doped substrates were used to study the bombarding ion dE/dx dependence of the 19 35 induced adhesion for F and Cl ions vith electronic stopping power ranging from 161 eV/ft to 506 eV/X. In this range the dose threshold for the onset of induced adhesion has a power law dependence, D « DQ(dE/dx) , «Published in Mat. Res. Soc. Symp. 37_ (1985). •On leave from IF-UFRGS, Brazil. ««Department of Electrical Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139. «•«•Physics Department» Vanderbilt University, Mashville, Tennessee 37235. SNuclear Physics Division, Fudan University, Shanghai, People's Republic of China.
COMPARATIVE STUDY ON INTERMETALLIC PHASES FORMED BY DIRECT ION IMPLANTATION AND RADIATION ENHANCED DIFFUSION OF TIN IN TWO KINDS OF STEEL* P.M. Dionisio, B.A.S. de Barros, Jr., and I.R. Baumvol The surface layers of high-carbon and stainless steel samples, treated by both direct ion implantation of Sn+ ions and radiation enhanced diffusion of tin, are analyzed by means of Rutherford backscattering and Sn and Fe conversion electron M&ssbauer spectroscopy. The interaetallic phases formed in the treated surfaces are determined and their thermal evolution ie established. The compositions and phase transformations observed in the surfaces of the samples treated by both direct ion implantation and radiation-enhanced diffusion are very similar, and this similarity indicates that these tvo treatment processes are essentially equivalent for practical applications.
*Publihed in J. Appl. Phys. 58 (1985) 773. MASS A» EMEI6Y MPE1BBMCE OP IMfLAVTE» IOH PROFILES W THE A2111 PHOTORESIST* 1.1. Guimarães*, M. Bchsr, R.P. Livi, J.P. de Souza, F.C. Zawislak, D. Fiak** aad J.P. Biersack**
Profiles of li, Xe, Sa, Kr, Ga( Ft, K, Ar, P, Na and F implanted into the «2111 photoresist ar* compared with recent theoretical predictions. With the esceptic of the noble gaaes and F, the experimental results are well fitted by Biersack-Haggmark (Kucl. Instrua. Methods 174. 257 (1980)) Monte Carlo calculations. For the noble gases we obtain ranges up to a factor of 2 shorter than the above predictions. Floor changes the profile as function of energy, being nearly Gaussian at 30 keV and distributing according to the calculated ionisetioa at 70 fceV.
•Published in J. Appl. Phys. 60 (1986) 1322. •On leave froa the Universidade Federal Fluminense, Niterói, Rio de Janeiro, Brasil. **Hahn-K*itner-Institut fOr Kernforschung, Berlin, West Germany.
EMERCY, MASS AMD DOSE WIPEWOHCE OF IMPLAHTED ION DISTRIBUTION INTO POLYM» LAYERS* F.C. Zawislak This review covers the Porto Alegre (Institute of Physics) - Berlin (HMD collaboration work in the area of profile measurenent and calculation of iaplanted ions into organic polyaers. Using RBS and nuclear reaction techniques, 10 10, 2"? 11 10 Afl the projected ranges and range stragglings of B, 19F, Rs, P, K, uAr, ^Fe, 696«, ^Kr, l20Sn, l29U and 209Bi «planted in the AZ111 photoresist have beer Measured. The results are compared with the Biersack and Ziegler (TRIM code) theoretical predictions. The obtained distributions for Bi, Sn, Ge, Fa, K, F, Ma and F, at iaplanced energies when the nuclear stopping power (S ) is larger than the electronic stopping power (S ) follow the TRIM code calculation, being independent of dose and energy. The profiles of the noble gases (J», Kr and Ar), are not reproduced by the TRIM prediction. The profiles for • and for F, at energies when 8 i 8 , deviate strongly from -20-
th* calculated rant* distribution but follow very closed the TRIM predicted iottisation distribution. 'Published in the Proceedings of the Workshop on Solid State Reactions after Ion Implantation Detected by Nuclear Methods, p. 51, 1986. Eds. K.L. Lieb and M. Uhrmachcr - University of GBttingcn, Germany.
LARGE Zj -RANGE EFFECT FOR Eu, Yb AMD Au IONS IMPLANTED IN AMORPHIZED SILICON* P.F.P. Fichtner, M. Behar, C.A. Oiivieri**, R.P. Uvi, J.P. de Sousa, F.C. Zavislak, D. Fink** and J.P. Biersack** The Z.-range oscillation amplitude it investigated as a function of energy for Eu, Yb and Au ions implanted in amorphous Si at energies from 1C Co 390 keV. The obtained experimental results are not reproduced by the recent theoretical predictions of Burenkov and collaborators, showing large discrepancies for energies lower than 50 keV.
•Published in Rad. Effects 87 (1986) 191. **0n leave fro» Universidade Federal de São Crlos, SP, Brazil. f+Hahn-Meitner-Institut für Rernforschung, Berlin, West Germany.
IMPLANTATION AND THERMAL ANNEALING BEHAVIOUR OF Bi IMPLANTED ISTO Al/Ti AND Al/V BILAYER STRUCTURES* M. Behar**, P.F.P. Fichtner, CA. Oiivieri**, F.C. Zavislak, D. Fink* and J.P. Biersack* Two bilayer systems, (A1Ü500 8)/Ti and Al(500 8)/V systems) were implanted with Bi at energies of 600 and 150 keV, respectivel •. The implanted depth distributions are in both systems very w^ll reproduced by calculations using the Monte Carlo TRIM simulation method. Af" anneal up to 400 °C (Al/Ti) and 550 °C (Al/V) the depth profiles still resemble the as -21-
implanted one». It is concluded that the interface region acts as a trapping center the implanted ions.
•Published in Nucl. Instr. and Meth. in Phys. Res. B \^ (1986) 78. **On leave from 1F-UFRGS, Brazil. ++On leave from Universidade Federal de São Carlos, SP, Brazil. SHahn-Meitner-Institut für Kemforschung Berlin GmbH D-1000 Berlin 39, Germany
ENERGY DEPENDENCE OF THE Zx-RANGE OSCILLATION EFFECTS IN SILICON*
P.F.P. Fichtner, M. Behar, C.A. ulivieri**, R.P. Livi, J.P. àe Souza, F.e. Zawislak, D. Fink** and J.P. Biersack**
Precise measurements of projected ranges tor several ionic species implanted into amorphous silicon at energies from 10 to 380 keV ar-_- compared with the new theoretical predictions of Biersack and Ziegler. For Ga, Br, Rb, Pd, Sn and Bi ions, the experimental and calculated ranges agree within -iG~ or better. In the cases of Eu, Yb and Au however, large deviations, up to 60%, were observed at very low energies. These "Z.-oscillations" were t to diminish with increasing energies and disappeared around 100 keV.
*Published in Nucl. Instr. and Meth. in Phys. Res. B j_3 (1986) 58. **0n leave from Universidade Federal de São Carlos, SP, Brazil. ++Hahn-Meitner-Institut für Kernforschung Berlin, Germany.
RANGE PROFILES OF IOSS IN DOUBLE-LAYER STRUCTURES*
D. Pink*, J.P. Biersack*, M. StSdele**, K. Tjan**, M. Behar, P,F.P. Fichtner, CA. Olivieri, J.P. de Souza and F.C. Zawislak
By means of (n,p) or (n,a) spectrometry some concentration distributions of He, Li and B implanted into metallic and/or semiconducting double-layer structures are measured. The samples are characterised by RBS. In many cases good agreement with theory is achieved. Sometimes, the implanted ions show -22-
enhanccd mobility during the implantation into the milcilayer structure even if this is not the case for implantation into the homogeneous targets of the saae materials. This enhanced nobility is indicated by the additional occurrence of precipitations at the interface and surface, and by changes in the shape of the profiles. «Published in Nucl. Inscr. and Meth. in Phys. Res. 9 15 (1986) 71. •Hahn-Meitner-Institut für Rernforschung Berlin, GlienTcker Str. 100, D-1000 Berlin 39, Germany. **Institut filr Kernphysik der FU Berlin, Glienicker Str. 100, D-1000 Berlin 39, Germany.
RANGE DISTRIBUTIONS AND THERMAL BEHAVIOUR OF Bi IMPLANTED INTO KC1 AND A1/KC1 BILAYER STRUCTURE* M. Behar, J.P. Biersack*, P.F.P. Fichtner, D. Fink*, C.A. Olivieri** and F.C. Zawislak 300 keV Bi* was implanted into an Al(610 X)/KC1 bilayer structure, and for comparison into a pure KC1 single crystal. The Bi depth distribution, measured by RBS, agrees well with theoretical predictions (TRIM) in both cases. Thermal annealing yields two stages: first, up to 200 °C, the Bi distribution changes rapidly, probably due to diffusion enhanced by radiation damage in KC1. At higher temperatures, those defects anneal out, so that essentially regular diffusion governs the depth profiles up to 500 °C, and an Arrhenius diagram can be given. For the A1/KC1 bilayer structure, we find retarded diffusion in a rather broad interval around che interface, in agreement with previous findings for Bi in the Al/Ti bilayer structure. «Published in Nucl. Instr. and Meth. in Phys. Rei. B 14 (1986) 173. •Hahn-Meitner-Institut ftir Kernforschung GmbH, Glienicker Str. 100, D-1000 Berlin 39, Germany. **0n leave from Universidade Federal de São Carlos, SP, Brazil. -23-
COMPARISON OF SEVERAL NUCLEAR REACTIONS TECHNIQUES FOR HTDmOCEN DEPTH PROFILING IN SOLIDS* Fulin Xioftg, F. Rauch, Chengru Chi, R.P. Livi** amd T.A. Tommrello Division of Physics. Mathematics and Astronomy, California Institute of Techmology, Pasadena, CA 91125 Over the paat decade nuclear resonant reaction analysis (KRRA) techniques have baan widely employed for the study of hydrogen depth profiling in materials in a variety of scientific and technical problems. It has been found that the presence of hydrogen can have dramatic effects on the physical, chemical and electrical properties of many solids. These studies have normally used ion beams of 19F at the resonance energy of 16.44 MeV, and N at 6.385 MeV. Recently, an intensive study of hydrogen analysis and profiling with the R( F.ay) 0 reaction at the resonance energy of 6.42 MeV has been carried out in the Cal tech Tandem Laboratory and a comparison has been made with the KRRA techniques used previously. It has been found that this method has an excellent depth probe capability and resolution as well as adequate sensitivity. These characteristics guarantee its applicability for most of purposes for hydrogen study in solids. ^Published in the Proceedings of the Microbeam Analysis Conference, Albuquerque, Sew Mexico, USA, August (1986) 85. Eds. A.D.Romig Jr. and U.?.Chambers. San Francisco Press Inc., San Francisco, CA, USA. **0n leave from IF-UFRGS, Brazil.
HEASDRDBlfT OF ÊOLIAM SAND RIPPLE CROSS-SECTIONAL SHAPES* B.T. Warner, P.K. Haff, R.P. Livi* and R.S. Anderson** Division of Physics, Mathematics and Astronomy 301-38, California Institute of Technology, Pasadena, California 91125 Assuaing that the profiles of eolian sand ripples remain constant over a short distance, it is possible to measure their shapes by casting a shadow perpendicular to tha ripple crests. We describe a method whereby this can be -24-
done accurately and easily. Teats of the method demonstrate that accuracies the order of one sand-grain diameter can be achieved. «Published in Geology 14 (1986) 743. •On leave from IF-UFRGS, Brasil. ««Quaternary Research Center, University of Washington, Seattle, Washington 98195.
ELECTORAL TRANSPORT PROPERTIES 09 Bi.Ni UNDER HELIUM IRRADIATION AMD HYDROGEM IMPLANTATION* L. Amaral*, P. Nedellec, A. Traverse, H. Bernas, L. Dumoulin** and J.P. Burger** Centre de Spectrometrie Nucleaire et de Spectronetrie de Masse, BP no 1, 91406 Orsay, France We present data on the effects of a irradiation and H implantation on the electrical resistivity, pt and the superconducting T of Bi.Ni. Two regiões of flux can be distinguished. At low doses, a large resistivity increase is due to atonic disorder, irrespective of the impinging ion (ex or H); at the time, only a slight T decrease is measured, in contrast with what is observed in A1S compounds. At high doses, specific effects due to H implantation are seen, probably implying significant modification of the electronic structure. There are indications that H enters the lattice as an interstitial, but that it also foras microbubbles. •Published in J. Phys. F: Met. Phys. _16 (1986) 1239. •On leave from IF-ÜFRGS, Brazil. **Laboratoire de Physique des Solides, Bit. 510, Universitê Paris-Sud, 91405 Orsay, France. -25-
EVIOHKX FOR THE METAL-IKSULATOt TRANSITION HI A WIE 3D METAL* P. Nédellec, A. Traverse, L. Duaoulin, H. Beraas, L. Amaral* and G. Deut setter** C.S.N.S.M. - *P 1, 91406 Orsay, France The meal-insulator transition has been induced by hydrogen implantation at low Cluencc in a macroscopically inhoaogeneous percolating Al-Ce mixture near the percolation threshold. The transition is reversible by annealing, showing that hydrogen implantar ion increases the local disorder in the Al metal jrains without affecting the percolation structure. We submit that this is the first experimental evidence of an Anderson (metal-insulator) transition in a three-dimensional pure metal. «Published in Europhys. Lett., 2(6) (1986) 465. •On leave from IF-UFRGS, Brasil. **Tel Aviv University - Tel Aviv, Israel.
DIRECT ION IMPLANTATION AND RADIATION ENHANCED DIFFUSION OF TIN INTO IRON* P.H. Dionisio, C. Scherer, S.R. Teixeira and I.J.R. Baumvol The surface layers of pure iron samples treated by both direct ion implantation of Sn and radiation enhanced diffusion of tin are analyzed by means of Rutherford backscattering and Sn conversion electron Mfissbauer scattering. It is argued that both processes produce amorphous alloys of iron and tin on the treated surfaces. The presence of amorphous phases is more pronounced on the directly implanted samples, while on the radiation enhanced diffused samples there is a marked tendency for the formation of intermetallic compounds. These results are consistent with some empirical rules currently developed for predicting the formation of amorphous intermetallic phases by ion beam mixing. The thermal evolution of the phases formed on the treated surfaces is consistent with the equilibrium phase diagram for the Fe-Sn system, in spite of a certain tendency for precocious decomposition. One unifying aspect is the fact that all the samples here studied show a similar CEMS -26-
spectraa after annealing in vacuua at 550 °C, when only an unidentified singlet (6 • 1.60 sons' ) is observed; this is interpreted as being due to tin segregation at the grain boundaries of the substrate. «Published in Nucl. Instr. and Meth. in Phys. Res. B 16 (1986) 345.
ION IMPLANTATION METALLURGY* CA. dos Santos* and I.J.R. Bauovol In this work we describe some current applications of Ion Implantation in surface engineering. We discuss in detail the use of Ion Iaplantation as a coating oethod for protection of Metallic engineering components against wear, fatigue and corrosion. Other potential applications of Ion Iaplantation in Metallurgy are considered here. We discuss also m this chapter the present trends on the use on Ion Inplantation on the metallurgical industry, specially those concerning the cost of the oethod and the alternatives to lover it. «Published in Ciência Hoje, October 1986, p. 73. •Depto. Fis. Teórica e Experimental, UFRN, Natal, RN, Brazil.
INFLUENCE OF He-VACANCY COMPLEXES ON THE THERMAL BEHAVIOR OF NITROGEN PRECIPITATES IN Fe* M. Hchar, P.J. Viccaro**, M.T.X. Silva, A. Vasquez , CA. dos Santos and F.C. Zawislak The thermal evolution of Fe_N-type nitride precipitates in Fe aetal obtained for N, iaplantation is shown to be altered by post-boubardaent of oi-particles at fluences of 10 cm" . These effects as detected using Fe Conversion Electron Mttssbauer Spectroscopy are observed to depend on the type of nitride precipitate present when the a particles are implanted. In the two cases studied intermediate nitrogen rich phases (e-Fe-N) arc detected -27-
in Addition to the normal terminal phase y'-Fe N. The terminal phase is also restored in the implanted zone at temp*iatures higher than normal when Fe«N- type precipitates are present during a bombardment.
*To be published in Nucl. Instr. and Meth. in Phys. Res. ••Present address: Argonne National Laboratory, Illinois, USA. ••On leave at the Centre de Recherches Nucléaires, Strasbourg, France. {Present address: Departamento de Física Teórica e Experimental, Universidade Federal do Rio Grande do Norce, Natal, RN, Brazil.
MODIFICATIONS CF THE MECHANISMS OF HIGH TEMPERATURE OXIDATION OF STEELS BY TIN ION IMPLANTATION AND RADIATION ENHANCED DIFFUSION PART I - HIGH CARBON STEEL* P.H. Dionisio ana I.J.R. Baumvol The high temperature oxidation of the surface of a high carbon steel, modified by tin implantation or radiation enhanced diffusion, has been investigated. Significant reduction of the oxidation rate constant, *» well as pronounced enhancement of the adherence of the oxide scale to the steel substrate has been observed for the treated samples. The mechanisms for the reduction of the oxidation rate and enhancement of adhesion of the oxide are discussed on the basis of surface compositional data obtained before and after oxidation, both existent in the literature and here obtained by means of Fe and Sn conversion electron MSssbauer scattering.
*To be published in Phys. Stat. Solidi (a). -28-
PROJECTED RANGES AND RANGE STRAGGLINGS OF Au AND Bi IMPLANTED
INTO CARBON FILMS AND INTO SiO2* P.L. Grande, P.F.P. Fichtner, M. Behar, R.P. Livi, F.C. Zawislak, J.P. Biersack**, D. Fink** and P. Mertens**
Range profile* of Au and Bi implanted in C and in SiO2 at energies from 10 to 400 keV, have been determined using the Rutherford Backscattering analysis. Recent Monte Carlo TRIM code profile calculations are compared with
the experimental results: i) the Bi ranges in both C and SiO2 substrates are reprodu^od, within 102, by the calculation, ii) for Au the experimental ranges are longer than the predictions, the discrepancy reaching 70X at 15 keV in the C substrate.
*To be published in Nucl. Instr. and Meth. in Phys. Res. B. **Hahn-Meitner-Institut, D-1000 Berlin, West Germany.
HYDROGEN DEPTH PROFILING IN SOLIDS: A COMPARISON OF SEVERAL RESONANT NUCLEAR REACTION TECHNIQUES** Fulin Xiong, F. Rauch**, Chengru Shi++, Zhuying Zhou , R.P. Livi and T.A. Tombrello Division of Physics, Mathematics and Astronomy 301-38, California Institute of Technology Pasadena, California 91125 Over the past decade nuclear resonante reaction analysis (NRRA) techniques for hydrogen depth profiling in solid materials have been widely employed for the study of hydrogen in a variety of scientific and technical problems. These have typically used ion beans of 19F at the resonance energy of 16.44 MeV and N at 6.385 MeV. We report here our recent study of hydrogen analysis and profiles with the H( F.cxy) 0 reaction at the resonance energy of 6.42 MeV and investigation of the nuclear resonant reaction H( N,ay) C at the resonance energy of 13.35MeV as another new means for hydrogen depth profiling. The results show that the method of the lower energy resonance in 1H(19F,CXY)16O has an excellent depth probe capability and moderate resolution at well as adequate sensivity, and the higher energy resonance in H( N,av) C provides a new tool with higher sensitivity and good depth resolution. The comparison -29-
of these four MRRA techniques under identical laboratory conditions is shown. Their characteristics and conditions of optimum utilisation are discussed. Several examples of applications to the study of proton-implanted silicon and hydrated glasses are presented.
*Submitted to Nuclear Instruments and Methods, 1986. •«•Supported in part by the National Science Foundation [DMR83-18274], **Institut fur Krenphysik, Johann Wolfgang Goethe UniversitMt, Frankfurt, FRG. ••Nuclear Research Institute, Lanzhou University, Lanzhou, Gansu, P.R. China. fDept. of Noel. Sci., Fudan University, Shanghai, P.R. China. SfOn leave from IF-UFRGS, Brazil.
INTERDIFFUSION AND REACTION IN THE IRON-ALUMINUM BILAYER. I - RUTHERFORD BACKSCATTERING ANALYSIS OF FURNACE ANNEALED SAMPLES*
S.R. Teixeira, P.H. Dionisio, E.F. Silveira**, F.L. Freire, Jr.** and I.J.R. Baumvol
This is the first of a series of articles concerning the experimental investigation of the interdiffution processes and solid phase reaction occurring in an iron-aluminum bilayer, submitted to furnace annealing, ion beam mixing and the simultaneous combination of these tvo kinds of metallurgical treatments. The interfiffused or reacted samples were accessed by mean* of six different analytical techniques (Rutherford Backscattering, Electron Microscopy, Sheet Resistance, Conversion Electrons MBssbauer Scattering, X-Rays Diffraction and Auger Speccroscopy). In the present paper we describe the results of the Rutherford Backscattering analyses performed on iron-aluminum bilayer samples, submitted to highvacuum annealing, at temperatures between 300 and 900 K. We demonstrate that if the iron-aluminum interface is oxide-free, then pronounced interdiffusion starts at a temperature as low as 570 K, and solid phase reactions leading to intermetallic phase formation at 600 K. The lattice and grain boundary diffusivities are extracted from the experimental data, giving 0.95 -7 UT ? -1 D. ,. - 2.8x10 ' e K1 an .6 l and -30-
. °-49 D . - 6.62xl0"2 e kT OB2.»"1 g.D. The reaction kinetics at 600 K is also determined from the experimental results. •Submitted to Thin Solid Films. **Pontif£cia Universidade Católica do Rio de Janeiro 22452 Rio de Janeiro Brazil.
CONCENTRATION-DEPTH PROFILE OF RBS SPECTRA WITH POOR MASS RESOLUTION* C. Scherer, S.R. Teixeira, I.J.R. Baumvol A numerical algorithm is presented to analyze RBS spectra for which the alpha particles scattering by two different types of atoms in different positions in the sample are counted in the same channel. The unresolved experimental spectrum is separated in two different spectra, one for each type of atom, and the corresponding depth profiles of the atomic densities are obtained. *Subtnitted to II Nuovo Cimento - D.
ION IMPLANTATION AND RADIATION ENHANCED DIFFUSION OF TIN INTO IRON AND STEELS* Paulo Henrique Dionisio We study in this work the composition, the structure and the morphology of surfaces of iron and steels treated by direct ion implantation and radiation enhanced diffusion of tin. Samples of pure iron, a tool steel and a stainless steel were treated by the two above mentioned processes and than analised by Conversion Electron KUssbauer Spectroscopy (CEMS) and Rutherford Backscattering Spectrometry (RBS). For all the samples studied we see the formation of -31-
intermetallic phases different from those usually obtained under conditions where thermodinamic equilibrium prevails. These non-equilibrium phases are interpreted as amorphous alloys or highly damaged solid solutions of tin in iron, probably with some content of C, Cr or Ni in the case of steels. The trend to form non-equilibrium phases is higher in the directly implanted samples. The study of the thermal evolution of the treated surfaces shows the transformation of these non-equilibrium phases to intermetallic phase similar to those obtained by conventional equilibrium processes. The intermetallic compounds so formed show a tendency to decompose at temperatures lower than those prescribed in the corresponding equilibrium phase diagrams. In the case of pure iron it was also suggested that tin segregates at the grain boundaries of the substrate. These results are interpreted in terms of some empirical rules currently being developed about the formation of amorphous and ict^itable intermetallic phases by ion implantation and ion beam mixing. We also show tentatively the possible relations of our results with the alterations observed on "he cribological behaviour and on the thermal oxidation properties of iron and steels treated with tin by the two above mentioned processes.
*Ph. D. Thesis, IF-UFRGS, 1986.
DOPANTS REDISTRIBUTION DURING TITANIUM-DISILICIDE FORMATION BY RAPID THERMAL PROCESSING*
A.A. Pasa, J.P. de Souza, I.J.R. Baumvol and F.L. Freire, Jr.*
Redistribution of implanted As (5 x 10 cm"2, 150 keV) and Sb (1 x 10 cm , 200 keV) due to TiSi. formation by rapid thermal processing was inves- tigated by means of backscattering spectroscopy. By choosing properly the rapid thermal processing parameters, low resistance uniform suicides layers (typically 14 u-Q cm) were obtained, and dopant loss by out-diffusion and redistribution of the dopant were made negligible. High peak concentrations of dopant within silicon substrate, beneath the suicide, were obtained for all processing times.
*To be published in J. Appl. Phye. •«•Departamento de Física, Pontifícia Universidade Católica do Rio de Janeiro, 22452, Rio de Janeiro, RJ, Brazil. l.d) MICROELECTRONICS -33-
RECOIL IMPLANTATION OF ANTIMONY INTO SILICON BY ARGON ION BOMBARDMENT*
R. Erichsen Jr., I.J.R. Baumvol and J.P. de Sousa
We report here on recoil implantation of antimony atoas fro» a 60 w thickness film deposited on a silicon substrate. The experiments were performed in order to investigate the influence of different implantation parameters on the yield and depth profile of the recoiling antimony atoas. We have used Ar energies between 40 and 800 keV, doses between 1 x 10 and 1 x 10 cm" , sample temperatures between 20 and 300 °C and dose rates between 1 and 20 uA.cm" . Another aspect considered here was the process removal of the remaining fila. We studied the influence of different conditions of film removal on the recoil yield. The results of the present work indicate that the recoil yields is a function of the energy and total dose of the bombarding ions. Furthermore, no variation with the Ar dose rate or with the sample temperature was observed. The antimony recoil depth profile depends mainly on the total dose of Ar and does not depend on its energy, dose rate or target temperature during implantations.
«Published in Mucl. Instr. and Meth. in Phys. Res. B 1J%_ (1985) 316.
THE SUPPRESSION OF RESIDUAL DEFECTS IN SILICON IMPLANTED WITH ARSENIC BY RAPID ISOTHERMAL ANNEALING*
CM. Hasenack, J.P. de Souza and I.J.R. Baumvol
We have used aligned Rutherford backscsttering to analyse the surface of 16 —2 silicon implanted with arsenic (1 to 3 x 10 cm" ) and submitted to rapid isothermal annealing. The results lead to the conclusion that an effective suppression of residual defects can only be obtained when the parameters of the anneal cycle correspond to a redistribution of the implanted profile.
«Published in Nucl. Instr. and Meth. in Phys. Res. B 9 (1985) 341. -34-
RESIDUAL DEFECTS IN IMPLANTED SILIC08 SÜ8MITED TO STA: EVIDENCE OF A CHEMICAL EFFECT* CM. Hasenack, J.P. de Sousa and I.J.R. Bauavol Silicon samples were implanted vith 100 keV, 1 x 10 cm~ As* or 74Ge ..Although the similarity in the energy deposition depth profiles for both cases would lead to similar primary defect distributions, we observed markedly different distibutions of residual defect densities after rapid thermal annealing. We invoke the different chemical nature of the implanted species to explain the observed discrepancies. «Published in Rucl.lnstr. and Meth. in Phys. Res. B 14 (1986) 290.
A CHANNELLING AND CONVERSION ELECTRON MOSSBAUER SPECTROSCOPV STUDY OF ANNEALING BEHAVIOUR OF TIN IMPLANTED SILICON E.M. Scherer, J.P. de Souza, CM. Hasenack and I.J.R. Baumvol* We investigate the solid phase epitaxial (SPE) regrowth and the substitutional solid solubility of silicon implanted with 119Sn to a dose of 1 x 101 6 cvT—2 at 250 keV, after furnace annealing, rapid thermal annealing and two-step annealing. It is shown that by means of tvo-step annealing we can reach a complete epitaxial regrowth of the amorphised layer, as well as complete substitucional 119 solid solution of the Sn impurity, to a concentration two orders of mag- nitude higher than the solid solubility limit, without any observable redis- tribution of the implanted concentration profile. •Published in Semicond. Sci. Technol. 1 (1986) 241. -35-
DOPANTS REDISTRIBUTION DURING T1TANIUM-DISILICIDE FORMATION BY RAPID THERMAL PROCESSING* A.A. Pasa, J.P. de Souza, I.J.R. Bauavol and F.L. Freire Jr.* Redistribution of implanted As (S x 101S en"2, 150 keV) and Sb 15 2 (1 x 10 cm" , 200 keV) due to TiSi2 fonaation by RTP was investigated by aeans fc backseattering spectroscopy. By choosing properly the RTP paraaecers, low resistance uniform suicides layers (typically 14 iioha.cm) were obtained, and dopant loss by out-diffusion and redistribution of the dopant were made negligible. High peak concentrations of dopant within silicon substrate, beneath the suicide, were obtained for all processing times. *J. Appl. Phys. 6l_ (1986) t228. «•Departamento de Física, Pontifícia Universidade Católica do Rio de Janeiro 22452 - Rio de Janeiro, RJ, Brazil.
THE SUPPRESSION OF RESIDUAL DEFECTS OF SILICON IMPLANTED WITH GROUP III, IV AMD V ELEMENTS* CM. Hasensck, J.P. de Souza and I.J.R. Baumwol In this work we suboitted silicon saaples implanted with group III, IV and V elements to Rapid Thermal Annealing (RTA) and we evaluated the dependence of residual defects on chemical effects as well as on the annealing parameters. We observed that in spite of the chemical nature of the implanted ions, the annealing of the residual defects is enhanced if profile redistribution by diffusion takes place. The same applies to samples that were presmorphized by means of Ge bombardment and subsequently implanted with As*.
*To be published in Semic. Sci. and Tech. RAPID THERMAL AMNEALING OF SILICON AMORPHIZEO BY IONIC IMPLANTATION* Claua Martin Hasenack lit investigated the recrystallization behaviour and the supression :haoisas of the residual defects of silicon layers aaorphized by means of ion implantation. The saaples were annealed vith the aid of a rapid thermal annealing (RTA) system at temperatures ranging iron 850 to 1200 °C and annealing tiaes up to 120 s. We used random and aligned Rutherford backscattering spectroscopy to analyse the saaples. The recrystallization behaviour displayed similarities when saaples had been isplanted with ions of a sane cheaical group such as As or Sb; Ge, Sn or Pb; In or Ga. We show that the coordination number that these elements exhibit in the amorphous silicon layer can account for this effect. Our results also show that there exist a correlation between the efficient removal of the residual defects and the diffusion of the imparities and which is not depended on the chemical nature of the implanted element. The existence of such a correlation has not been observed for those samples implanted with As and which were furnace annealed at 700 °C/1 hour prior to RTA. *Ph. D. Thesis, IF-UFRGi», 1986.
Sb RECOIL IMPLANTATION IN Si BY Ar AND Ge ION BOMBARDMENT* Rubem Erichsen Jr. We investigated the doping process of silicon with antimony by means of the recoil implantation method. In our experiments a filo of antimony deposited over <100> single cristal silicon was bombardment with Ar* or Ge* vith energies between 40 and 800 keV and doses ranging from 1,0 x 101 4 to 17 -2 1,0 x 10 cm . Single step annealing of the bombardement saaples was performed either in Rapid Thermal Ar.sealing (RTA) system or in a conventional furnace. In the former case temperatures ranged from 950 to 1150 °C and annealing times from 20 to 60 s. In the latter case saaples were annealed at 600 C for 1 hour. The samples were analyzed by means of the Rutherford -37-
Backscattering spectroscopy (RBS) technique, Auger spectrometry and eletrical measurements in Van der Pauw devices. The main results are: i) Recoil Implantation is governed by ballistic mixing process of collision cascades generated by the incident ions. ii) The maximum antimony concentration occurs at the surface «ad decays rapidly with depth. The profile extends up to a maximum depth of 0.1 um, even after annealing. iii) Antimony depth profile are independent of the bombarding particle's energy, but are dependent on the dose. iv) Ar bombardment yields imperfect recrystallization at the silicon substrate. Ge* bombardment yields perfect recrystallization and good subscitutionality of antimony atoms after annealing. *M. Sc. Dissertation, 1F-UFRGS, 1986.
FORMATION OF NÍQUEL AND TITANIUM SILICIDES BY RAPID THERMAL PROCESS* André Avelino Pasa We studied the formation of nickel and titanium suicides by rapid thermal processing (RTP), from thin films of these metals with thickness between 20 and 90 no, deposited on single crystal silicon substrates. Thermal cycles at temperatures between 500 and 1050 °C and duration between 20 and 80 s were experimented. The analytical techniques used to characterize the samples were Rutherford backscattering spectroscopy (RBS) of alpha particles and sheet resistence using the four point probe. Depending on the RTP parameters (temperature and exposure time), we observed the phase Ni-Si, NiSi and NiSi_, for the Ni-Si system, and TiSi and TiSi-, for the Ti-Si system. The seqüencial phase formation, together with the observed eletrical resistivities, are compatible with those reported in the literature for suicides prepared by conventional furnace processing. We investigated also the redistribution of implanted dopants, such as As and Sb, during the nickel and titanium suicides formation. We observed that, when the dopant* are present in that region of the substrate which is consumed -38-
by the solid phase reaction, they are incorporated in the fomed ccapound. Diffusion processes across the suicides cao lead the dopants to reach the surface and evaporate. *M. Sc. Dissertation, If-UFRGS, 1986. I.e) ELECTRONIC TRANSPORT AND MAGNETISM -40-
MAGNETIC ORDERING IN YGd ALLOYS*
P. Pureur*. A. Fert, R. Wendler** and K. Baberschke** Laboratoire de Physique des Solides» Bãtiment 510, Universitê de Paris-Sud, 91405 Orsay, France
We present magnetization and resistivity measurements on single crystal of yttrium doped with small concentrations of gadolinium (c * 1,2 and 3 at. t.). The low-field susceptibility exhibits a spin-glass-like sharp cusp for the magnetic field along the c axis. However, there is no irreversible behavior below the temperature of the cusp, which rules out the existence of a spin- glass state. Moreover, our magnetization measurements show up a spin-flop transition for H in the basal plane. The existence of a long-range ordering is confirmed by our resistivity measurements. The resistivity parallel to the c axis exhibits a maximum just below the ordering temperature, which is reminiscent of the superzone effects observed in many rare-earth metals. The antiferromagneticlike properties of the YGd alloys contrast with the spin- glass behavior observed in other Y-rare-earth alloys at similar concentrations.
•Published in J. Appl. Phys. _57 (1985) 3230. •On leave from IF-ÜFRGS, Brazil. **Institut fUr Atom-und FestkUrperphysik, Freie UniversitSt Berlin, Arnimallee 14, D-1000 Berlin, Germany.
MAGNETOSTRICTION OF SINGLE CRYSTALS OF YTTRIUM DOPED WITH RARE EARTHS IMPURITIES*
P. Pureur+, G. Creuzet and A. Fert Laboratoire de Physique des Solides, Universitê de Paris-Sud, 91405 Orsay, France
We report on magnetostriction measurements at low temperature on yttrium single crystals containing small quantities of Gd, Tb, Dy or Er. We determine Che single-ion magnetoelastic coupling coefficients and we discuss them in a point-charge model including electronics screening effects. We use our data on the magnetostriction of our dilute systems to estimate the single-ion contribution to the giant magnetostriction of the rare earth metals.
*Published in Journal of Magnetism and Magnetic Materials 53. (1985) 121. •On leave from IF-UFRGS, Brazil. -41-
HELIMAGNETIC STRUCTURE 18 DILUTED Y-Gd ALLOYS*
P.J. Brown**, R. Caudron**, A. Fcrt , D. Givord and P. Pureur
Neutron scattering studies on Y-Gd 2 and 3 at. Z single crystals show a helimagnetic ordering to occur below Neel temperatures of 7 and 12 K respectively. The same value of the propagation vector [0,0,0.28 c*] is obtained for both samples. The Gd moments lie in the basal plane of the hexagonal structure. No contribution from the conduction electrons to the magnetic amplitudes is evidenced in addition to the 4£ contribution. The Gd moment at low temperature is about 7 '• . The temperature dependence of the nsgnetic satellite intensity follows that predicted by a Brillouin function.
*Published in J. Physique Lett. 46 (1985) L-1139. **Institut Lave-Langevin, 156x, 38042 Grenoble Cedex, France. MOSTRA, BP 72, 92322 Châtillon Cedex, France. SLaboratoire de Physique des Solides, üniversité de Paris-Sud, 91405 Orsay Cedex, France. §5Laboratoire Louis Kéel, CNRS 166x, 38042 Grenoble Cedex, France. +0n leave from IF-UFRGS, Brazil.
HALL EFFECT IN Ce. Y Pd- MIXED-VALENCE ALLOYS* 1-x x 3 A. Fert, P. Pureur+, A. Hamzic and J.P. Kappler** Laboratoire de Physique des Solides, Universitê de Paris-Sud, F-911405 Orsay, France
Mixed-valence and Kondo lattice systems exhibit large anormalous Hall coefficients with a striking change of sign at low temperature in several systems (CePd~, CeCu,,....t etc.) We have studied the Hall effect of Ce, Y Pd. in which the substitution of small amounts of Y for Ce prevents the development of coherence at low temperature- We find that the Hall coefficient does not change its sign at low temperature and can be well understood in the one-impurity model of Ramakrishnan, Coleman, and Anderson. We infer that the change of sign observed in CePd_ is an effect of coherence.
*Published in Physical Review B 32(10) (1985) 7003. fOn leave from IF-UFRGS, Brazil. **Laboratoire de Magnetisrae et de Structure Flectronique dec Solides, 3 rue de 1'Université, F-67084 Strasbourg, France. -42-
SPIN-DISORDER RESISTIVITY IN NijMniSn^In^) HEUSLER ALLOYS*
G.L. Fraga, J.V. Kunxler and D.E. Brandão
Electrical resistivity measureaents have been performed on Ni.Mn(Sn^xln ) Heusler alloys, where x • 0, 0.02, 0.05, 0.10 and 0.15, in the temperature range of 4-300 K. The experimental data clearly show the existence of two distinct kinds of resistivity behaviour, both described by an aT lav, for 7£T<20 K. Between 170 and 300 K the data are well described by an AT + BT~ phenomenological fit, and the results obtained are in good agreemente with an interpretation based on electron-phonon and spin-disorder scattering.
•Published in J. Phys. Chem. Solids 46 (1985) 1071.
ANISOTROPIC THERMAL EXPANSION OF YTTRIUM METAL AND YTTRIUM-BASED RARE EARTH ALLOYS AT LOW TEMPERATURE*
P. Pureur , G. Creuzet and A. Fert Laboratoire de Physique des Solides, Bãtiment 510, üniversícé de Paris-Sud, 91405 Orsay, France
We report on thermal expansion measurements as low temperatures of pure .' and ^RE(RE: Er, Dy, Tb and Gd) single crystals. We estimate the electronic and lattice contributions for the thermal expansion of pure yttrium. For the dilute YRE alloys, the thermal expansion exhibits crystal field effects. These are explained with a free energy including crystal field, elastic, anc tnagnetoelastic terms.
*Published in J. of Mag. and Mag. Mat. 60 (1986) 161. •On leave from 1F-UFRGS, Brazil.
SPECIFIC HEAT MEASUREMENTS IN SCANDIUM - RARE EARTH ANISOTROPIC SPIN GLASSES*
P. Pureur, G.L. Fraga, D,E. Brandão, R. Caudron**, H. Safa** and G. Nieva**
We report on specific heat measurements at low temperatures of the anisotropic spin glass alloys ScDy 3 at ?, SCKT 4.25 at Z and ScEr 10 at ', -43-
We find that at the lowest temperature range the data indicate the occurrence of an anisotropy induced gap around zero frequency in the density of states of the magnetic excitations. Moreover, some of our specific heat curves present a maximum coinciding with T , raising thus the question of thermal signs for a spin-glass phase transition in anisotropic systems.
* To be published in J, of Mag. and Mag. Mat. **Direction des Matêriaux, ONERA, 92320 Chatillon, France. ++Cencro Atômico Bariloche, 8400 Bariloche, Argentina.
COMPARATIVE STUDY OF ISOTHERMAL AND ISOCHRONOUS CRYSTALLIZATION OF METALLIC GLASSES*
M.A.Z. Vasconcellos, R.P. Livi and M.N. Baibich
We have studied the isothermal and isochronous crystallization c£ v Fe • >*igQ_ B20 amorphous alloys. The experimental data were interpreted using a standard Johnson-Mehl-Avrami equa ion for the isotherms and Kissinger or rtUgis and Bennet's methods for the non-isothemal studies. The kinetic parameters thus obtained were compared through the application of the -ransferability principle of Louis and Garcia-Cordovilla for isothermal and non-isothermal transformations. We have shown that Kissinger's method is in accordance with the accepted isothermally determined values.
*Submitted to J. Phvs. F.
CRYSTALLIZATION OF FeQn Ni B_ GLASSES* 80-x x 2o M.A.Z. Vasconcellos, R.P. Livi and M.N. Baibich
Fe N K lasses We have observed the crystallization of g0_ *- 20 8 through changes in the resistivity. The activation energies for devitrification show a minimum or discontinuity at around the same composition range as the crystalline counterparts of this alloy series.Such behaviour is not seen -44-
for the crystallization temperatures, and this nay be an indication that an enhacement of the activation energy by either a temperature dependence of the configurational entropy or by a "chemical" contribution to it should be considered.
*Submitted to J. Appl. Phys.
CHEMICAL SHORT RANGE ORDER IN Fe_rtNi,nB.A AMORPHOUS ALLOYS* 20 oU 20 R.B. Guimarães, P.J. Viccaro, W.H. Schreiner, M.A.Z. Vasconcellos and M.N. Baibich We have studied through Mtíssbauèr spectr-scopy, bulk magnetization and resistivity the changes induced by thermal relaxation on the physical properties of amorphous Fe2QN*60^20' ^ne ma*n resu*ts °* tn*s stu •Submitted to J. Phvs. F. ELECTRICAL RESISTIVITY OF AMORPHOUS ¥en M-Zxn AO* P. Pureur, W.H. Schreiner, J.V. Kunzler, D.H. Ryan* and J.M.D. Coey+ We perform electrical resistivity measurements with high accuracy in a~Fe0 92^r0 08 ^etween 2.5 K and 300 K. The data several peculiarities related to the magnetic state of the sample. Amorphous FeZr alnys in the high Fe concentration range show the interesting characteristics of -45- reentrant-like syfctetns. In particular, our alloy undergoes a paramagnetic- ferroBagnetic transition at 180 K whereas below 100 K it shows the irreversible magnetic properties of a spin glass-like state. A detailed analysis of the resistivity and its derivative near T reveal a rather unusual ot-critical expoent, which goes in line with the known critical exponents for susceptibility and magnetization. Moreover, our results sugges: that magnetic fluctuations persist and dominate the resistivity in a large temperatura range well above T . These features may be indicative of some basic differences between the ferromagnetic-like phase in reentrant systems and ordinary collinear ferroraagnetism. *W'ork in progress. +-lniversity of Dublin, Trinity College. ELECTRICAL RESISTIVITY NEAR THE CRITICAL POINT IN Pd HEUSLER ALLOYS* P. Pureur, J.V. Kunrler, G.L. Fraga. W.H. Schreiner and D.E. Brandão Heusler compounds of the type Pd_MnX, where X is Sn, Sb or In, are thought to represent "ideal" localized magnetic systems. Two of the compounds are ferromagnetic (X * Sn and Sb) and one is antiferromagnetic (X » In). The oniy magnetic atoms are the Mn ones which are placed on sites of - c lattice. These Mn atoms are far apart so that the interaction betwee them is via polarization of the conduction electrons. These model systems are thus good condidates for investigating the critical behaviour of its resistivity derivative close to the magnetic transition in order to test the various theories related to such a kind of results. We perform high precision resistivity measurements using an A.C. technique above and below the critical point. The data allow us to numerically determine the temperature derivative of the resistivity. The behaviour of do/dT in our alloys looks generally quite simple in the paramagnetic range and allows the determination of the a-criticai exponents. However, in sone cases we have found complex structures in dp/dT just below T which are closely related to the atomic ordering state of the sample. In particular, the remits are shown to be sharply dependent in raepecc of Mn disordering. *Work in progress. -46- CRITICAL COEFFICIENTS FOR THE FERRO-PARAMAGNETIC PHASE TRANSITION IN METALLIC GLASSES AT HIGH TEMPERATURES* D. Mosca, W.H. Schreiner and M.N. Baibich Critical exponents for the ferro-paranagnetic transition can be determined for amorphous metallic systems using both high precision resistivity or AC susceptibility measurements. Aside from the usual information obtained from this kind of experiment, in the case of glasses, the exponent» contain information about the local order of magnetic constituents. As indicated before (Guimarães et al.; this Prog. Rep. and Baibich ct al., this Prog. Rep.) local order plays an important role in the determination of magnetic properties, therefore justifying this search for any evidence of changes induced on the nature of the magnetic interaction via chemical order. We have already made preliminary measurements that indicate that there is indeed some influence on the exponents, but better resolution is needed to really say something final about this subject. To this and we are ultimating a new resistivity measuring rig containing platinum thermometer and careful adjustement of the susceptibility equipement to otain the required precision. *Work in progress. ION BOMBARDENENT OF METALLIC GLASSES* M.X. Baibich, M.A.Z. Vasconcellos and L. Amaral The behaviour of metallic glasses under structural modification is usually studied on the direction of relaxation, which corresponds to a more stable configurational state. In order to study the reversibility of the transformation without affecting the macroscopic properties of the samples, we have performed a series of experiments of ion (protons, E * 400 keV) bombardement of the ribbons obtained previously in our laboratories. Monitoring of the experiment is done by an "in-situ" measurement of the resistance of the sample as a function of deposited dose, at different temperatures of the sample (room and liquid Nitrogen temperatures for the moment) and as a function of time after a certain dose is reached. With -47- this we can obtain information about the kinetics of creation and recombination of detects in this material, as well as study chemical disordering effects which confirms the hypotesis of a chemical short range ordering domination relaxation in the particular sample used for this work (Ni Fe)_.BOA as presented by Guimarães et ai. (see this Progress Report). As technical information about this experiment we have to point out that good control of the beam of our Ion Implanter has to be achieved in order to ensure uniform deposition at low current with high energy. Also, the resistance measurement thechnique has to withstand all the noise generated on the sample as a consequence of bombardment; this was made by using the apparatus described by Fin and Baibich (Synchronous detection this Prog. Rep.) *Work in progress. STUDY OF THE CRYSTALLIZATION AND THERMAL STABILITY OF AMORPHOUS ALLOYS TYPE (Fe ^Ni^B^* Marcos Antonio Zen Vasconcellos We have measured the electrical resistance of amorphous alloys type (Fe Nio_ )&.„ (x»40, 50, 60, 70 and 80) during isothermal crystalization. The obtained data fits a Johnson-Mehl-Avrami equation, assuming a linear ralation between the electrical resistance of the sample and the transformed material volumetric fraction (x). Assuming a crystallization mechanism similar to that or a chemical reaction, we have obtained values for the kinetic parameters for the transformation process. Temperature dependent measurements of the resistivity, at constant heating rates, allowed for the obtention of kinetic parameters and its comparison to those obtained above. Finally, we have studied the thermal stability of these alloys, analizing the electronic contribution to this stability. *M. Sc. Dissertation, IF-UFRGS, 1985. -48- SEMICLASSICAL THEORY OF THE ELECTRONIC TRANSPORT IN METALS* Jos* Antonio Cardoso Louzada This tr»at«ent of the electronic transport theory of «etals begins with the free electron theory of Drude, as it contains certain ideas still used in quantia theory. Soaserfeld's theory is treated. The difficulties with these theories are discussed. The seaiclassical theory of electronic conduction in •etals based on the Boltzaano integro-differential equation and integral equation of Chambers is discussed. The emphasis is the treatment of magnetoresistivity. Finely a brief discussion of electronic scattering processes and the respective contribution to metallic resistivity is presented. *H. Sc. Dissertation, IF-UFRGS, November, 1986. I.f) LASER -50- TUNING OF A NARROW LIHEWIDTB PULSED DYE LASER WITH A FAMY- PEROT AND DIFFRATION GRATING OVER A LARGE WAVELENGTH RANGE* M.R. Olcay, J.A. Pasqual, J.A. Lisboa and R.E. Francke It is shown that the motion of a diffraction grating and an air-spaced Fabry-Perot interferometer in a HMnsch-type dye laser can be synchronised. A nitrogen-pumped dye laser built according to this principle was capable of resolving the iodine spectra over more than 30 nm. Result and error sources are discussed in detail. «Published in Appl. Opt. 24 3146 (1985). MICROSTRUCTURE AND SOME OF ITS OPTICAL EFFECTS IN THIN FILMS* Flavio Horowitz A brief review is presented on a structural anisotropy in thin filas and its contribution to the following optical effects: i) spectral shift; ii) anisotropic scattering; iii) dichroism; and iv) birefringence. Those effects are interpreted through a columnar film-growth model «Published in Rev. Brasil. Apl. Vac., Vol. 5, N9s 1 e 2, (198S) 201. MEASUREMENT OF THE PRINCIPAL REFRACTIVE INDICES OF THIN FILMS DEPOSITED AT OBLIQUE INCIDENCE* I.J. Hodgkinson*, F. Horowitz, B,A. Macleod**, M. Sikkens** And J.J. Wharton Shadowing canses form birefringence in optical thin films that are deposited at oblioue incidence. For light incident in the plane containing the direction of deposition and the substrate normal, the TE and TM polarisations in the film are decoupled, and field transfer can be described using 2x2 matrices. The three principal indices of birefringent films are deduced from measurements made on narrow-band interference filters. In one -51- «xaaple refractive indices of 2.688, 2.429 and 2.452 were cosputed for TiO_ deposited at 27° to the substrate normal. Both TiO_ and ZrO. behave as positive biaxial nedia. «Published in J. Opt. Soc. An. A 2 (1985) 1693. •Dept. of Physics, University of Otago, Dunedin, New Zealand. **Optical Sciences Center, Univ. of Arizona, Tucson, Arizona 95721. •M-Dept. of Applied Physics, Univ. of Groningen, Ryenborgh 18, 9747 A6 Gro- ningen, The Netherlands. SAir Force Institute of Technology, AFIT-ENP Wright-Patterson Air Force Base, Ohio 45433. FECO-BASED OBSERVATIONS OF BIREFRINGENCE AT NORMAL INCIDENCE IN OPTICAL COATINGS* I.J. Hodgkinson*. F. Horowitz, H.A. Macleod**, M Sikkens"1"* and J.J. Wharton* Structural anisotropy occurs in evaporated thin films when the condensing molecules have insufficient nobility to form a tightly packed arrangement. Shadowing causes the growth of columns which are visible in electron micro- graphs of thin-film sections and, in the case of deposition at an angle 6, tend to grow toward the source at angle tan" (1/2 tana). In this Letter we discuss measurements of birefringence nade at normal incidence on a number of thin-film materials which were deposited obliquely. «Published in Appl. Opt. 24_ (1985) 1568. •Univ. of Otago, Physics Department, Dunedin, New Zealand. **Univ. of Arizona, Optical Sciences Center, Tucson, Arizona 85721. ••••Univ. of Groningen, Dept. of Applied Phys., Nyenborgh 18, 9747 A6 Groningen, The Netherlands. fU.S.Air Force Institute of Technology, AFIT/ENP, Wright Patterson Air Force Base, Ohio 45433. -52- COMPUTER SIMULATION OF THIN FILM GROWTH: APPLYING THE RESULTS TO OPTICAL COATINGS** M. Sikkens**, I.J. Hodgkinbon**, F. Horowitz, H.A. Macleod and J.J. Wharton Computer simulation of thin film growth has been used extensively to gain insight into the origin and nature of the microstructure of vapor-deposited thin films. Usually, however, no attempts are made to predict film properties other than column angle and film density from such simulations. The aim of our work is to derive quantitative data from computer simulations in order to be able to predict relevant properties of optical coatings. The deposition of 2500 to 25,000 particles has been simulated on different computers by random deposition of two-dimensional hard disks, using a simple relaxation scheme. Statistical analysis of the results yields quantitative data for the density, column «ogle, and column period. On the basis of these results, a simple model has been developed for the microstrueture of a three-dimensional film. The birefringence and the shape of water-penetration fronts in evaporated optical coatings, predicted from this model, are confirmed by experiment. *Published in Optical Engineering 25 (1986) 142. •Work performed in part in Tucson, USA, when F. Horowitz was on leave from IF-UFRGS, Brasil. **Univ. of Groningen, Dept, of Appl. Phys., Nijenborgh 18, 9747 AC Groningen, The Netherlands. ++Univ. of Otago, Department of Physics, Dunedin, New Zealand, fOptical Sciences Center, Univ. of Arizona, Tucson, Arizona 85721. SIAir Force Inst. of Technology, Wright-Patterson AFB, Ohio 45433. PIRASI PRESSURE SENSOR BUILT WITH THE FILAMENT OF INCANDESCENT LAMP* L.F. Hotter, V.M. Alves, J.S. Hickmann, T. Brahn, C.R.M. de Oli- veira, J.A. Lisboa and R.E. Francke The design and construction of a Pirani pressure sensor using the filament of incandescent lamps is described in detail. *To be published in Revista de Písica Aplicada e Instrumentação, vol. 2 (1987). -53- THE 337 ran NITROGEN LASER RESSONANCES WITH THE f 0* (3P ) - B \ g o o+u TRANSITIONS IN MOLECULAR IODINE (I2>* J.S. Hicknann, C.R.M. de Oliveira and R.E. Francke Optical double ressonance technique using a narrow linevidth tunable dye laser and a fixed frequency 337 nm molecular nitrogen laser has been used on molecular iodine (I,). Some of the accidental resonances of the nitrogen laser + with transitions between the B II (v.) - f 0 ( P )(v.) in Io have been o+u 1 g o 2 2 definitively identified. As an example the Pi (7) nitrogen laser line at -1 2) 29655.94 cm induces the transition (v2 « 2-Vj - 16) P(30) line in the B-f iodine system. The identification is based on the fact that the lower level (v. • 16, J • 30) of the B-f line is reached twice as the dye laser is scanned: first with the P(31) and then with an R(29) line of the B-X manifold. As a result each coincidence of the nitrogen laser with the B-f system appears as two close by-lines. Their separation and the identification of the well known B-X spectra positively identifies the lower level of these transitions. For the upper state there were two separate sets of spectroscopic constants differing 4) 5) basically in the value of T being '47025.917 and 47026.101 respectively. 6 4) Our assignment is in agreement with :he work of Brand et al . Resonances of fixed frequency laser with diverse molecular lines are an important spectroscopic tool in the study of highly excited states and nonlinear processes. 1. M.R.Clcay, J.A.Pasqual, J.A.Lisboa and R.E.Francke» Appl. Opt. 24(1985)3146. 2. D.Schinca, L.Scaffardi y M.Gallardo, Óptica Pura y Aplicada JM> TT983) 27. 3. S.Gerstenkorn et P. Luc, Atlas du Spectre d'Absorption de la Molecule d'lode Editions du CNRS, 75700, Paris, France. 4. J.CD.Brand and A.R.Hoy, J. Mo lee. Spectros. 9]_ 0983) 379. 5. J.P.Perrot, A.J.Bouvier, A.Bouvier, B.Femelat and J.Chevaleyre, J. Mo lee. Spectros. U± (1985) 60. *Subsitced to J. Molee. Spectroscopy. DETERMINISTIC CHAOS IN A GLOW D.C. HELIUM DISCHARGE* Thomas Braun, J.A.C. Galla», J.A. Lisboa The investigations of non-lú^ar physical systems exhibiting deterministic chaotic behavior has attracted much attention in recent year*. Among the -54- systems studied are certainly several kinds of plasmas because of its technological and fundamental interest. It has already been obtained very interesting results in a solid state plasma. In this Laboratory the first observation of chaotic behaviour occured with a perioddoubling route to chaos in a low energy gaseous helium plasma. As in any nonlinear system exhibiting deterministic chaos, there is a control parameter which in our case is the voltage applied between the discharge electrodes. The total discharge current is the dynamical variable which shows a stationary periodic and chaotic behaviour, according to the value of the control parameter. Appropriate electronic circuits were built so as to show Che oscillatory behaviour and also the phase-space diagram simultaneously in an oscilloscope screen. A spectrum analyser was also built to show how the fundamental frequency of about 190 khz would break into different stages. Up to 16 frequencies were observed before the current would break into chaos. *Work in progress. ACCIDENTAL RESONANCES OF THE 337 ran NITROGEN LASER WITH THE f-B TRANSITIONS IN MOLECULAR IODINE* J.S. Hickraann Accidental resonances of a strong, fixed-frequency laser with molecular lines are an important spectroscopic tool. As an example that laser overcomes conveniently and inexpensively a tunable laser. Furthermore, once those resonances have been identified, there is no need of a bulky wavemeter to set a line when there is a need to perform some other work on such a transition such as double resonances, tripple resonances, saturation spectroscopy and so on. A system was built to perform such a study in Iodine and other gases. It is based on a double-channel nitrogen laser in which one channel is used to pump a dye laser oscillator and the second channel pumps an amplifier cell. The linewidth of the dye laser is about 1 Ghz and it is still limited by acoustic noise. Also the shot-to-shot linewidth is Fourier-transform limited. *Work in pregress. -55- LIGKT SCATTERED BY. A MACROSCOPIC SPHERE* C.R.M. de Oliveira The light scattered by a sphere has attracted much attention because of its fundamental and applied importance. Actually, a sphere is a very common geometric body in nature. As an example, water drops in clouds, bactérias, dust and other particles. Even if they are not exactly spherical they can still be approximated by spheres. On the other hand the light scattered by a sphere from a plane wave (Mie scattering) is one of the few problems of physical-mathematics for which there is an exact solution. However, that solution is in many cases too cumbersome because it involves the addition of an unpractical number of terms. This is particularly true in the case of a macroscopic dielectric sphere. On the other hand, the complexity of such a light distribution makes Mie scattering an interesting candidate for a laser waventeter, without the complexity of those apparatus. The fringe visibility at 90 for a 12 mm diameter sphere was found to be a straightforward way to measure the linewidth of n dye laser. The backscattered light is being explored as a true wavemeter. *Work in progress. CARS STUDIES OF ENERGY-TRANSFER PROCESSES IN Na-H- SYSTEM** Silvio L. S. Cunha Coherent Anti-Stokes Raman Spectrospopy (CARS) has been applied to measure the molecular internal energy distribution produced by the quenching 2 procese of the Na (3 P) excited state by H. molecules. Population of vibra- tional levels up to v * 3 has been measured. The rotational and vibrational energy distributions found are in very good agreement with the available theoretical predictions. We determined also a value of 12 % for the integral 2 quenching cross section of Na (3 P) by H_. Relaxation times of the vibrational levels v • 1, v > 2 and v = 3 has also been measured using CARS method. The relaxation time obtained for the vibrational level V = 1 (31 us) is in good agreement with literature values. Relaxation times of vibrational levels v « 2 -56- and v » 3 has been measured for the first time and are respectively pi c 2.4 us and 3.4 us. *Ph.D. Thesis, Ludwig-Maximilians-UniversitSt ML>chen, 1986. +Laborbericht MPQ117, Max-Planck-Institut fOr Quantenoptik, 1986. **On leave from IF-UFRGS, Brazil. A VARIABLE-ANGLE ELL1PSOMETER FOR REFRACTIVE-INDEX MEASUREMENTS* R. HUbler and F. Horowitz The use of polarimetric techniques has brought relevant contributions tc the optical characterization of surfaces in the last years. For that matter and starting from a comercial Zeiss-Jena goniometer, we set up a variable-angle ellipsometer with a HeNe laser source. The polarizer and analyser are Glan- Thomson prisms with extintion coefficients of, at most, one part in 10 . Angular readings can be made with a precision better than 0.01 of arc. The holder was built to allow a horizontal scanning of the surface under test by the laser beam. Preliminary measurements in BK7 glass slides at the Brewster condition point toward indices around 1.518, in good agreement with valves reported in the litterature. Those results confirm the validity of this method, as well as indicate the potentiality of the instrument in determining the optical constants of glasses or in identifying other less-known materials. *Work in progress. Preliminary results will be presented at the 39th SBF/SBPC Annual Meeting. Posterior results will be submitted for publication elsewhere. RESEARCH IN THEORETICAL PHYSICS 11. a) CONDENSED MATTER THEORY -59- EFFECT OF THE d-f CORRELATION ON THE ELECTRONIC STRUCTURE OF INTERMEDIATE VALENCE SYSTEMS** J.R. Iglesias and P.M. Mora The electronic structure of an intermediate valence system is calculated by means of a real space renormalization technique en a Bethe lattice. The d-f Coulomb repulsion C is treated into the alloy analogy approximation. The valence and the densities of states are calculated as a function of G. We find "hat the hybridization gap decreases when G increases, and that the density of states at the Fermi level exhibits a peak as a function of G. *Published in Solid State Comm. 5_6 (1985) 557. •Work partially performed at Centre dt Recherches sur les Três Basses Temperatures, CNRS, BP 166X, 38042 Grenoble, France. REAL SPACL RENORMALIZATION OF A MIXED VALENCE HAMILTONIAN ON A BETHE LATTICE* P.M. Mors, Acirete S. Rosa Simões, J.R. Iglesias and E.V. Anda* A mixed valence system may be described by two hybridized bands: a narrow one with strong Coulomb interaction and a conduction band. We study this model by means of a decimation method originally developed for a linear chain and recently extended to a Bethe lattice. Different values of the hybridization are compared. The densities of states so obtained exhibit a more detailed structure than equivalent CPA calculations. ^Published in Solid State Comm. 5_5 (1985) 201. •Instituto de Física, Universidade Federal Fluminense, 24210 Niterói, RJ, Brasil. EFFECT OF THE d-f COULOMB CORRELATION ON THE VALENCE TRANSITION OF INTERMEDIATE VALENCE SYSTEMS* P.M. Mors and J.R, Iglesias The d-f Coulomb repulsion, G, is treated by means of a real space decimation procedure on a Bethe lattice. The valence is calculated as a -60- function of the relative position of the f-level with respect to the conduction band. No discontinuous transitions are found. •Published in Solid State Comm. 55 (1985) 205. EFFECT OF THE SPATIAL CORRELATION ON THE ALLOY ANALOGY APPROXIMATION TO THE HUBBARD HAMILTON1AN* P.M. Mors, J.R. Iglesias and E.V. Anda* The well-known alloy analogy approximation of the Hubbard Haxniltonian does not take into account the spatial correlation between site occupations. Here, an improved solution, including this effect, is obtained and numerically solved for the case of two-sites correlation. We obtain a different shape of the density-of-states and a more restrictive criterium for the metal-insulator transition. *Published in Solid State Coram. 55 (1985) 827. • Instituto de Física, Universidade Federal Flut>j.nense, 24210 Niterói, RJ, Brasil. CRITICAL EXPONENTS FOR <>3-FIELD MODELS WITH LONG-RANGE INTERACTIONS* W.K. Theumann and M.A. Gusmão 3 The critical exponents for two the Yang-Lee edge-singularity problem, and is in agreement with recent results by Chang and Sak for the Ising spin-glass problem. For the (p >2)-state Poets model there is an indication of a continuous crossover to SR behavior at a*2 -neo, with n >0. It is pointed out that a number of exact results [s = (i-eV2a)ov, i»(d-o)/(d+o), in which 5 is the Yang-Lee edge- singularity exponent, and v =(d-o)/2 for a scalar theoryj may apply within the LR expansion depending on n =2 - c (shown here to hold at least to two-loop order) being exact, to all orders. *Published in Phys. Rev. B 3j_ (1985) 379. A NEW APPROACH TO THE STUDY OF AN ANDERSON IMPURITY IN A LINEAR CHAIN* A.S. da Rosa Simões and J.R. Iglesias The local density of states and the magnetic moment of an Anderson impurity in a linear chain are studied by means of a recurrence technique, applied to the first- and second-order Green functions. This approach enables to obtain an exact solution of the "scattering correction" of the alloy analogy for the one impurity case. Both local and nearest neighbour hybridization are studied, and the results are compared with those obtained using other approximations. *Published in J. Physique 47 (1986) 967. THE SPHERICAL-MODEL LIMIT IN A RANDOM FIELD* W.K. Theumann and José F. Fontanari* The spherical-model limit n ->* of the n-vector model in a random field, with either a statistically independent distribution or with long-range correlated random fields, is studied to demonstrate the correctness of the replica method in which the n-*<» and replica limits are interchanged, ided the replica and thermodynamic limits are taken in the right order, in i>ie case of long-range correlated random fields. A scaling form for the two-point j -62- correlation function relevant to the first-order phase transition below the lover critical dimensionality of the random system is also obtained. *Published in J. Stat. Phys. jo (1986) 99. •Instituto de Física e Química de São Carlos, Universidade de São Paulo, 13560 São Carlos, SP, Brasil. EFFECTS OF TRILINEAR SYMMETRY BREAKING ON THE POTTS-MODEL TRANSITION OF UNIAXIALLY STRESSED SrTiOy- José F. Fontanari and W.K. Theumann A Landau analysis shows that a break of trilinear symmetry in the continuous three-state Potts model with linear and quadratic symmetry breaking is relevant for the trigonal-to-pseudotetragonal phase transition in uniaxially stressed SrTiO along [1 + 5#1 + 6,1 -26], and that the effects of quartic symmetry breaking are vanishingly small. The shift of the tricritical stress parameter Ó is large enough to mask fluctuation corrections to & /c in d=4-e dimensions, and a number of quantitative results for the phase diagrams are obtained. *Published in Phys. Rev. B *3 0986) 3530. •Instituto de Física e Química de Sao Carlos, Universidade de São Paulo, 13560 São Carlos, SP, Brasil. RENORMALIZATION AND PHASE TRANSITIONS IN POTTS $3-FIELD THEORY WITH QUADRATIC AND TRILINEAR SYMMETRY BREAKING* Mareia C. Barbosa, M.A. Gusm<.j and VI, Theumann Renornalized perturbation theory with generalized minimal subtraction is used as an appropriate renormaliiation-group procedure for the study of crossover behavior in the continuum version of the p-state Potts model with quadratic and trilinear symmetry breaking, within the representation of Priest and Lubensky, by means of a two-loop-order calculation in d*6-c dimensions. The boundary between first- and second-order phase transitions is studied for longitudinal and transverse ordering as a function of p. A fixed-point runaway -63- for longitudinal ordering is consistent vith a mean-field interpretation of a first-order transition for p >p*. where p* <2 but not with a second-order transition for p •Published in Phys. Rev. B j)4 (1986) 3165. CONDUCTIVITY OF A RANDOM ELECTRON CHAIN RENORMALIZATIOS GROUP APPROACH* Alba Theumann We apply a recently proposed decimation procedure together vith «normalization group techniques to the study of the conductivity of a one- dimensional random electron chain represented by Anderson's Hatailtonian. Decimation generates recursion relations for the random parameters that are converted into recursion integral equations for the probability distribution functions. For particular initial values of the random parameters the integral equations are solved exactly showing the flow of the system to a localized state. The conductivity of a tight-binding model is calculated and its average over the probability distribution functions discussed previously shows the expected exponential decrease with the system size. Published in Physica 139A (1986) 553. QUANTUM SPIN GLASS: A REPLICA-SYMMETRIC THEORY WITH POSITIVE ENTROPY* Alba Theumann In the present paper we present a detailed analysis of quantum effects in tie spin-glass transition as described by a quantum Heisenberg analogue of the Stierrington-Kirkpatrick model. The spin operators are represented in terms of two fermion fields and the problem is reduced to that of n fernion level* at -64- one site in a random time-dependent field and with an interaction delocalized in tine. It is shown that within a Rartree-Fock. approximation in a replica- syanetric theory one obtains a mean-field description of the transition with satisfactory 2ero-temperature properties. The transition is described by two order parameters: the static magnetic susceptibility and the spin-glass order parameter. The saddle-point equations obtained in this work are analogous to those of Sonaers for a theory of classical spins. *Published in Phys. Rev. B 33 (T986) 559. SUPERALGEBRA AND THE SPHERICAL MODEL OF A SPIN GLASS* Albs Theumann Supermathemati.es methods are used in the exact solution of the mean spherical model of a spin glass, first solved by Kosterlitz, Thouless and Jones. Our analysis shows that the model is pathological, in the sense that the exact solution reduces to that obtained from two decoupled repiieat». We show explicitly that even one repli:a gives the exact result, which means that the "wrong" solution of taking the :onfigurational average of the partition function is correct in this model, *To be published in J. Phys. A ^0- SIMPLE APPROXIMATION FOR THE BETHE-ANSATZ SOLUTION OF THE ONE- DIMENSIONAL FERMI GAS* M.A. Gu3tnão+ Serin Physics Laboratory, Rutgers University, Piscataway, NJ 08854 We present a simple approximation scheme for the solution of the integral equations resulting from the Bethe-Ansatz diagonalization of the one- dimensional Fermi gas with 6-function attraction. These equations arise for the Hubbard model with attractive interaction in the limit of weak coupling and low density. We obtain the ground-state energy as a function of coupling and density in very good agreement with numerical solutions, aj well as a -65- value for the paraneter determining the gap in the Magnetic excitation spectrua which strongly supports a conjecture of Larkin and Sak. *To be published in Phys. Rev. B. •On leave fro» IF-UFRGS, Brazil. NON-UNIVERSALITY OF RATIOS OF CRITICAL AND TRICRITICAL PARAMETERS IN THE THREE-STATE POTTS MODEL WITH SYMMETRY BREAKING PERTURBATIONS*' Mareia C. Barbosa and Ui.K. Theumann Fluctuation corrections to symmetry-breaking perturbations in the three- state Potts model are shown to yield, in contrast to earlier work, non- universal ratios for t It , h /h and m /m , between the reduced temperature t, magnetic field h and magnetization m. When applied to the trigonal-to- pseudotetragonal phase transition in uniaxially stressed SrTiO, along [1 *i, 1 4-6, 1 -26], 6 << 1, we predict an experimentally accessible break to the universality of 6/5 , in distinction to previous work. ^Submitted for publication in Phys. Rev. B. THE SPHERICAL MODEL AS THE LIMITING n-VECTOR MODEL IN A RANDOM FIELD* W.K. Theumann and José F. Fontanari A proof of Kac and Thompson establishing the equivalence of the zero- field free energy for the limiting (n •+») n-vector model with that for the spherical model is extended to prove the equivalence of the free energies in a random field with Gaussian translationally invariant distributions of either statistically independent or long-range correlated random fields. ^Submitted for publication in J. Stat. Phys. •Instituto de Física e Química de São Carlos, Universidade de São Paulo, 13560 São Carlos, SP, Brazil. -66- PHASE TRANSITIONS IN ASYJMTRIC POTTS MODELS: BREAKDOWM OF THE CLASSICAL MEAH-FIELD PICTURE* M.A. Gusmão Serin Physics Laboratory, Rutgers University, Piacataway, El 08856 It is shown that mean-field theory fails to give • correct qualitative picture of the thermodynamic behavior of the q-state Potts model when the exchange interaction is anisotropic in spin-space. The correct picture is recovered either by introducing a single-particle anisotropy or by taking correlations into account via a Bethe-Peierls approximation. This analysis helps the interpretation of previous renormalization-group results for asymmetric Potts models. ^Submitted for publication in Phys. Rev. B. •On leave from IF-UFRGS, Brazil. THE STATISTICAL INFERENCE APPROACH TO GENERALIZED THERMODYNAMICS: I. STATISTICS* B.H. lavenda* and C. Scherer Limit theorems, such as the central limit theorem and the weak law of large numbers, are applicable to statistical thermodynamics for sufficiently large sample sizes of independent and identically distributed observations performed on extensive thermodynamics (chance) variables. The estimation of the intensive thermodynamics quantities is a problem in parametric statistical estimation. The normal approximation to the Gibbs distribution is justified by the analysis of large deviations. Statistical thermodynamics is generalized tc include lhe statistical estimation of variance as well as mean values. ^Submitted for publication in Annals of Physics. •Dipartimento di Scienze Chimiche, Universita di Camerino, Camerino (MC) 62032 Italy. -67- TBE STATISTICAL INFERENCE APPROACH TO GENERALIZED THSRHODTOAMICS: II. THERMODYNAMICS* B.K. Lavenda* and C. Scherer The theraodynaaic implications of dispersion in finite sanple sises or SB» 11 thcnaodyiUBiic system are investigated vithin the normal approximation to the Gibbs distribution. *Subnitted for publication in Annals of Physics. -••Dipartisento di Scienze Chimiche, Universitâ di Caaverino, Caoerino (MC) 6Z032 Italy. STATISTICAL INFERENCE IN EQUILIBRIUM AND NONEQlilLIBRIUM THERMODYNAMICS* B.H. Lavenda and C. Scherer The role of statistical inference in providing a common foundation to both equilibrium and nonequilibrium statistical thermodynamics is analyzed. •Submitted for publication in Rev. Mod. Phys. +Dipartinento di Scienze Chimiche. Universitâ di Camerino, Cauerino (MC) 62032 Italy. A DIAGRAMMATIC SOLUTION OP THE KONDO LATTICE* Acirete S. da Rosa Simões, J.R. Iglesias, A. Rojo and B.R. Alascio A Green function diagrammatic method is utilised to calculate the density of states of a Kondo lattice. The hybridization between f- and conduction electrons is included in the exact solution of the localized Green functions, and the hopping term is considered through a Dyson equation. The results at T=0 K indicates the existence of a "Kondo peak" at the Fermi level. Metallic or insulating states are obtained for different occupations of the f- and conduction states. *Submitted for publication in J. Phys. C. -••Centro Atômico Bariloche, 8400-S.C. de Bariloche, RN, Argentina. -68- LOCAUZATION PROPERTIES IN BINARY ALLOYS DESCRIBED BY A BETRE LATTICE* R. HObler, Rejane Ribeiro-Teixeira and I.H. Strauch We have been studying localization properties in binary alloys described by a Bethe lattice» which is constructed with decimated linear chains. This process renormalizes the parameters of the hamiltonian of the system . The short range order effects are taken into account by a Markovian probability distribution as a function of the atomic concentration in the alloy and of a short range order parameter o. In particular, we are interested in calculating the localization length (''• ) and the mean free path (i) for disordered or partially ordered binary alloys. With this aim, we have, at the moment, conclude the calculation of the local densities of states for ordered and disordered systems described by Bethe lattices (either diagonal and off- diagonal disorder). There is a good agreement between these results and that obtained by other approaches , which points towards the viability of the model proposed. (1) M.O.Robbins and B. Koiller, Phys. Rev. B27, 7703 (1983). (2) P.M. Mors, A.S.R. Simões, J.R. Iglesias and E. Anda, Solid State Coma. 55_, 201 (1985). (2) J. d'Albuquerque e Castro, J. Phys. C: Solid St. Phys. 17, 5945 (1984). *Work in progress. CRITICAL AND TRICRIT1CAL POINTS IN THE THREE-STATE POTTS MODEL WITH SYMMETRY-BREAKING PERTURBATIONS* Mareia C. Barbosa and W.K. Theuraann The effects of critical fluctuations are studied by means of renormalization-group (RG) calculations on the three-state Potts model with effective Landau-Ginzburg-Wilson Hamiltonian given by where $ « {*^ of this work is to determine the properties of the ordered phases, in particular the criticai and tricritical points that terminate the first-order transitions of the model in non-zero external field h , in extension of an earlier mean-field work. Tht results are' expected to be relevant for the trigonal to pseudo-tetragonal phase transition in SrTiO-> under uniaxial stress along 11*6, l-t-6, 1-25]. The off-diagoni>l stress parameter 6 is represented here by non-zero symmetry-breaking terms h and r^-r in £q. (1). .2 RG recursion relations have been generated in the course of this work , to one-loop order, in both d =6-*- dimensions (the appropriate dimensionality near the upper critical dimension) and in c = 4-E: dimensions, with weak trilinear coupling, for extrapolation to physical dimension three. Effective critical and tricritical Kamiltenians given by (2> He£f (critical) - j dx | i [tef£ '\ti *} and + )2 + G + Heff(tricricical) = j dx U it^ff ^ (^2 ] eff 4 eff 2Ísi have been constructed in terms of effective parameters t. , w , ..., ü ç, that follow from explicit solutions of the RG recursion relations. Eqs. (2) and <3) are used to locate the critical and tricritical point, respectively, and ere currently used to investigate the universality of the theory near a critical and tricritical point, in particular the scaling form of the equation of state and to discuss the role of correction-to-scaling forms which may be relevant for the phase diagram of SrTiO.. The work reported here is the first complete study of the effect of fluctuations in the ordered phases for this 3 4 model, in extension of the works by other authors and our own work . 1) José F. Fontanari and W.K. Theumann, Phys. Rev. B22> 353® (1986). 2) F.J. Wegner and A. Houghton, Phys, Rev. A£, 401 (7973). 3) D. Blankschtein and A. Aharony, J. Phys. CJL3, 4635 (1980); J. Phys. CJjt, 1919 (1981). 4) Mareia C. Barbosa, M.A. Gusmão and W.K. Theuraann, Phys. Rev. B_3j*» 3165 *Work in progress. -7 0- A STUDY OF THE HUBBARD HAMILTOiNlAN AND INTERMEDIATE VALENCE SYSTEMS ON THE BETHE LATTICE* P.M. Mors The present work is a study of intermediate valence systems using the alloy analogy to treat the Coulomb correlations. Instead of the customary approach (the coherent potential approximation, CPA), one uses for the first time a method of renoraalization in real space on a Bethe lattice, namely, by representing the system by a Bethe lattice built iteratively from decimated linear chains. The densities of state thus calculated show a more detailed structure than those obtained by other approximations. The valenct transition is discussed as a function of the Coulomb correlation between the localized electrons; the Coulomb correlation between localized and conduction electrons; and the hybridization between the localised level and the conduction band. The same technique is applied to the study of itinerant magnetism in transition metals. By performing an expansion of the one-particle Green's functions of the Hubbard Harailtonian, in projectors which depend on the occupation numbers of all the lattice sites, it is possible to take into account the spatial correlations between sites. Thus, one arrives at a metal-insulator transition as well as one from paramagnetic to ferromagnetic state, this being an entirely new result in the description of the Hubbard Hamiltonian in the alloy analogy. *Ph.D.Thesis, IF-UFRGS, June, 1935. DIAGRAMMATIC SOLUTION OF AN INTERMEDIATE VALENCE HAMILTONIAN AND OF THE KONDO LATTICE* Acirete S. da Rosa Simões We studied intermediate valence and Kondo systems using a diagrammatic technique to calculate the Green functions. The hybridization and the hopping term between localized f-electrons and conduction d-electrons are treated as perturbation terms in the intermediate valence case. The f-f Coulomb repulsion, U, and the d-f Coulomb repulsion, G, are included in an exact way. In the Kondo case, the hybridization V is included in the exact solution, with G-0 and U-*•«>. The T-0 and T^O situation were analised for the intermediate -71- valence systems for different values of the parameters of the system. We obtained discontinuous valence transitions, only at T *0, depending on the G value. Both at T»0 and T^O it is clear the existence of a peak of the density of states at the energy E +G, responsible for the stable intermediate valence state and possibly, for the peaks in the photoemission spectrum of metallic cerium. In the Kondo case, the hybridization V was included in the exactly soluble part of the Hamiltonian and we obtained a Kondo peak in the density of states. The Green functions were calculated using the spectral representation for the isolated atom, and extended for the latt:~e by means of the diagrammatic method. The solution shows, besides the Kondo peak, a similar structure to that of the Kondo lattice systems, and constitute an adequate basis f(. r the study of Heavy Fermions system. In two appendixes we discussed the one impurity case and the application of the method to the Hubbard Hast! lconian. D.Thesis, IF-UFRGS, December, 1986. Il.bj QUASTJM FIELD THEORY -73- QUANTIZATION OF QED AND QCD IN A FULLY FIXED TEMPORAL GAUGE* H.O. Girotti and K.D. Rothe* We present the quantization of QED and QCD in a fully fixed temporal gauge within the framework of the path-integral formalism. We thereby obtain an unambiguous expression for the free gauge field propagator which agrees with that proposed by Car;cciolo et ai. (5J. *Publi3hed in ?. Phys. C - P-r tides and Fields 27 (1985) 559. +Institut für Theoretische Physik, UniversitHt HêTdelberp, D-69O0 Heidelberg, Federal Republic of Germany. EXCITATION RATES OF HEAVY QUARKS* C.A. Garcia Canal , E,M, Santangelo and M.B. Gay Ducati We obtain the production rates for c, b, and t quarks in deep-inelastic neutrino- (antineutrino-) nucleon interactions, in the standard six-quark model with left-handed couplings. The results are obtained with the most recent mixing parameters and we include a comparison between quark parametrizations. The excitations are calculated separately for each flavor, allowing the understanding of the role of threshold effects when considered through different rescaling variables. «Published in Physical Review D _3_I O985) 2748. •••Laboratório de Física Teórica, Universidad Nacional de La Plata, 1900 La Plata, Republica Argentina. DYNAMICS OF GAUGE SYSTEMS AND DIRAC'S CONJECTURE* M.E.V. Costa, H.O. Girotti and T.J.M. Simões For systems possessing only first-class constraints, we rigorously prove that the secondary constraints act as independent generators of gauge transformations (Dirac's conjecture). The proof essentially consists in demonstrating that the total and the extended Hamiltonian generate the sane time evolution for the canonical realization, f(q,p), of the gauge-invariant quantities. We also discuss the alternative realization of these quantities. *Published in Physical Review D 32 (1985) 405. -74- OPERATOR QUANTIZATION OF NON-ABELIAN GAUGE THEORIES IN A COMPLETELY FIXED AXIAL GAUGE* T.J.K. S'moes and H.O.Girotti A consistent quantization of chromodynamics in a completely fixed axial gauge is carried out by using tha Dirac bracket quantization procedure. The main results are: The translation of Dirac brackets into equal-time commutators is possible. Without ambiguities, because of the absence of ordering problems. All equal-time commutators are compatible with constraints and gauge conditions holding as strong operator relations. Ail equal-time commutators are compatible with chromoelectric, chromomagnetic, and fermionic fields vanishing at spatial infinity. The colored gauge potentials A > A , and A ' are se«n to develop a physically significant, although pure gauge, behavior at a?3-*00, as required by the presence of a non-trivial topological content. Poincaré invariance is satisfied without introducing in the Kamiltonian "extra" quantum mechanical potentials. The determinant of the Faddeev-Popov matrix does not depend upon the field variables. ^Published in Annals of Physics (N.Y.), JI69 (1986) 1. CANONICAL QUANTIZATION OF A TWO-DIMENSIONAL MODEL WITH ANOMALOUS BREAKING OF GAUGE INVARIANCE H.O. Girotti*, H.J. Rothe and K.D. Rothe Institut für Theoretische Phyaik der Universitat Heidelberg, Philosophenweg 16, D-6900 Heidelberg, West Germany We investigate in detail the operator quantum dynamics of a two- dimensional model exhibiting anomalous breaking of gauge invariance. The equal-time algebra is systematically obtained by using the Dirac-bracket formalism for constrained systems. For certain values of the regularization parameter the system is shown to undergo drastic changes. For the value of the parameter corresponding to the chiral Schwinger model no operator solutions are found to exist. *Published in Physical Review D JJ3 (1986) 514. •On leave from IF-UFRGS, Brasil. -75- CAHONICAL DERIVATION OF THE GLUOB PROPAGATOR IN THE TEMPORAL GAUGE* H.O. Girotti* and H.J. Rothe Institut für Theoretische Physik der UniversitUt Heidelberg, D-6900 Heidelberg, Germany We reexamine the problem of obtaining, within the operator approach, an unambiguous expression for the longitudinal gluon propagator in the temporal gauge. A regularizar ion procedure respecting Gauss's law and the Hermiticitv of Che gauge fields is proposed. We thereby obtain a definite expression for the longitudinal propagator which agrees with that proposed by Caracciolo, Curci, and Kenotti. "Published in Physical Review D _3J O98ò) 3132. *0n laave from IF-UFRGS, Brasil. QUANTUM DYNAMICS OF CHIRAL FERMIONS IN A MODEL WITH ANOMALOUS BREAKING OF GAUGE INVARIANCE* H.O. Girotti*. H.J. Rothe, and K.D. Rothe Institut fur Theoretische Physik der UniversitMt Heidelberg, Philosophcnweg 16, D-6900 Heidelberg, West Germany We study the quantum dynamics of chiral fermion fields minimally coupled to a gauge field. The model, originally proposed by Jackiw and Rajaranan, is known to exhibit the anomalous breaking of gauge invariance, which leads to the appearance of an arbitrary parameter a. Both functional and operator techniques are used to obtain the two-point fermion Green's functions for a> 1 and d- 1. In both cases clustering holds, and the theory contains asymptotically free fermions. The quantum equation of motion for the field tensor resembles formally that of the Proca theory, but with a dynamically generated mass and a nonconserved source. It is found that for a« 1 the generating functional cannot be written in terms of a manifestly Lorentz- invariant Lagrangian. *Published in Physical Review D _34 (1986) 592. + On leave from IF-UFRGS, Brasil. -76- EXCITATION OF HEAVY QUARKS AND DILEPTONS PRODUCTION BY NEUTRINOS* Maria Beatriz de Leone Gay Ducati The production of heavy quarks is obtained for deep inelastic neutrino- nucleon interactions. The spectrum of leptons originated on heavy quark desintegration is determined by considering relevant phenomenological aspects as flavour mixing, fragmentation, threshold effects. A prediction for dileptons production from heavy quarks in neutrino-nucleon interactions is calculated and compared with available data. *Ph.D. Thesis, Universitê Louis Pasteur, Laboratoire de Physique Theorique de Hautes Energies, Strasbourg, France, June 11, 1985. OPERATOR QUANTIZATION OF KON-ABELIAN GAUGE THEORIES IN A COMPLETELY FIXED AXIAL GAUGE* Tiago Josué Martins Simões A consistent quantization of chromodynamics in a completely fixed axial gauge is carried out by using the Dirac bracket quantization procedure. The results are: The translation of Dirac brackets into equal-time commutators is possible, without ambiguities, because of the absence of ordering problems. All equal-time commutators are compatible with constraints and gauge conditions holding as strong operator relations. All equal-time commutators are compatible with chromoelectric, chromomagnetic and fermionic fields vanishing at spatial infinity. The colored gauge potentials A0>a, A1'3 and A ' are seen to develop a physically significant, although pure gauge, behavior at X3 •±°°, as required by the presence of a non-grivial topological content. Poincaré invariance is satisfied without introducing in the Hamiltonian "extra" quantum mechanical potentials. The determinant of the Faddeev-Popov matrix does not depend upon the field variables. Ph.D. Thesis, Instituto de Física- UFRGS, 1985. II.c) PLASMA PHYSICS -78- ELECTRON CYCLOTRON WAVE ABSORPTION BY THE FAST TAIL GENERATED BY THE DC ELECTRIC FIELD IN TOKAMAK PLASMAS* G. Giruzzi, V. Kriv.^ski, I. Fidone and L.F. Ziebell* Association Euratom-Cea Sur La Fusion, Départeraent de Recherches sur la Fusion Contrõlêe, Centre d'Etudes Nucléaires, 92260 Fontenay-aux- Roses, France Wave damping near the electron gyrofzequency in a Tokamak plasma with the energetic tail generated by the d.c. electric field in investigated. The electron tail is computed by a Fokker-Planck initial value coda as a function ot the relevant parameter E,,/Ec = E|tTi/(2"n e"'.\). It is shown that strong damping of the e-mode occurs for oblique propagation. The results are of. relevance for studies of ECRH in present-day Tokaiaaks and in future reactors where a nildly relativistic electron tail is naturalIy present for large Te, Special emphasis is therefore given to wave absorption for frequencies f significantly below the central electron gyrotrequency, and to the associated r.f.-driven current. •Published in Plasma Physics and Controlled Fusion, 21_ (1985) 1151. •On leave from IF-UFRGS, Brazil. D1SSIPATIVE INSTABILITIES AT IHE EDGE OF REVERSED-FIELD PINCHES DRIVEN BY A COMBINATION OF PLASMA GRADIENTS AND A PARALLEL CURRENT* J.P. Mondt and J. Goedert* Los Alamos National Laboratory, MS-F642, Los Alamos, NM 87545, USA Stability in the edge region of reversed-field pinches is analyzed within Che context of a two-fluid model. Two major sources of instability are identified: in combination with a parallel electric field, either an electron temperature gradient and/or a density gradient leads to rapid growth (of several to many Ohmic heating rates) over a region of several railimeters around the mode-rational surfaces in the edge region. The basic signature of both instabilities is electrostatic. In the case of the density gradient mode, it relies on the effects of electron compressibility, whereas the temperature gradient mode can be identified as the current-convective instability by taking the limit of zero density gradient, thermal force, and electron compressibility. The possibility of enhanced particle loss and thermal -80- obtained a single necessary and sufficient condition for a potential to admit an invariant of resonance type. These results were obtained by reformulating the problem in terms of a set of discrete moments that satisfy two separate recursion formulae. Invariants for new time-dependent potentials vere obtained and previously known invariants were recovered. *Published in Physica _N3D (1986) 213. •On leave from IF-UFRGS, Brazil. ANGULAR AND MOMENTUM DISTRIBUTION DEPENDENCE OF ELECTRON CYCLOTRON ABSORPTION AND AMPLIFICATION IN MIRROR-CONFINED PLASMAS* L.F. Ziebell and G. Granata* The absorption and amplification of fundamental electron cyclotron radiation in inhomogeneous, weakly relativistic, loss-cone and partially filled loss-cone plasmas, are studied for both perpendicular and oblique propagation, and the extraordinary mode is numerically analyzed. It is shown that there are situations where small changes in the distribution function may strongly affect the wave vector, and an explanation is given, pointing to the eventual relevance of the use of the full momentum distribution, along with relativistic effects, in the evaluation of both the real and imaginary part of the dielectric tensor. A model that could describe plasmas in actual situations like the thermal barriers in tandem mirror devices is presented and numerically investigated, and it is shown that particles scattered into the loss cone may play a relevant role. *Published in Physics of Fluids, 29 (1986) 3730. +Centre d'Etudes Nucléaires de Cadarache, 13108 Saint-Paul-lez-Durance Cedex, France. -81- ELECTRON-CYCLOTRON HEATING OF A TOKAMAK REACTOR WITH THE EXTRAORDINARY MODE* 1. Fidone, G. Giruzzi, V. Krivenski, L.F. Ziebell and E. Mazzucato** Association Euratoa-Cea Sur la Fusion, Department de Recherches sur la Fusion Contrôlée, Centre d'Etudes Nucléaices, 92260 Fontenay-aux- Roses, France Electron-cyclotron resonance absorption for oblique propagation at frequency significantly below the central electron gyrofrequency is considered. It is shown that the extraordinary mode for external launching is suited for additional heating in a tokamak reactor. The properties of wave damping at downshifted frequencies are discussed and are found to differ from those at fx f - Using the ray-tracing code, the wave damping of the e node is investigated at high densities for which strong refraction of the wave beam occurs. •Published in Physics of Fluids, 29 (1986) 803. •On leave from IF-UFRGS, Brazil. **PlasBa Physics Laboratory, Princeton University, New Jersey 08544. ELECTRON CYCLOTRON DAMPING FOR LARGE WAVE POWER IN TOKAMAK PLASMAS* V. Krivenski, I. Fidone, G. Giruzzi, R.L. Meyer* and L.F. Ziebell** Association Euratom-Cea Sur la Fusion, Département de Rechercher sur la Fusion Contrõlée, Centre d'Etudes Nucléaires, 92260 Fontenay-aux- Roses, France The power dependence of the wave damping in a tokamak plasma for arbitrary direction of propagation, mode of polarization, and wave frequency is invescitated. Using a 2-D Fokker-Planck code, it is shown that the wave damping increases or decreases with the rf power depending on the velocity range of the absorbing electrons, •Published in Europhysics Conference Abstracts, Vol. IOC, II, 235-7, April 1986. •Lab. de Physique de Milieux Ionises, Univ. de Nancy I, Nancy, France. **0n leave from IF-UFRGS, Brazil. -82- POWER DEPENDENCE OF ELECTRON CYCLOTRON WAVE DAMPING IN TOKAHAK PLASMAS* V. Krivenâki, I.Fidone, G. Giruzzi, R.L.Meyer* and L.F. Ziebell** Association Euratom-CEA sur )a Fusion, Departement de Recherches sur la Fusion Contrôlée, Centre d'Etudes Nuclêaires, 92260 Fontenay-aux- Roses, France The power dependence of the wave damping in a tokamak plasma for arbitrary direction of propagation, mode of polarization, and wave frequency is investigated. Using a 2-D Fokker-Planck code, it is shown that the wave damping increases or decreases with the rf power depending on the velocity range of the absorbing electrons. *To be published in The Physics of Fluids. +Laboratoire de Physique des Milieux Ionises, Univ. de Nancy I, Nancy, France. **0n leave from IF-UFRGS, Brazil. CROSS EFFECTS ON ELECTR0N-CYCL01S0N AND LOWER-HYBRID CURRENT DRIVE IN TOKAMAK PLASMAS* I. Fidone, G. Giruzzi, V. Krivenski, E. Mazzucato* and L.F. Ziebell** Association Euratom-CEA sur la Fusion, Département de Recherches sur la Fusion Contrôlée, Centre d'Etudes Nucléaires, 92260 Fontenay-aux- Roses, France Electron cyclotron resonance current drive in tokamak plasma in the presence of a lower-hybrid tail is investigated using a 2-D Fokker-Planck cod*. For an extraordinary mode at oblique propagation and down-shifted frequency it is shown that the efficiency of electron cyclotron current drive becomes, i) substantially greater that the corresponding efficiency of a Maxwellian plasma at the same bulk temperature, ii) equal or greater than that of the lower-hybrid waves, iii) comparable with the efficiency of a Maxwellian plasma at much higher temperature. This enhancement results iron a beneficial cross-effect of the two waves on the formation of the current carrying electron tail. The case of the ordinary modi: for outside launching in the equatorial plane is also discussed and it is shown that, i) the 0-oode is generally not suited for current drive via the lower-hybrid tail, and ii) in a hot Maxwellian plasma the efficiency at down-shifted frequencies is -83- significantly greater than that at up-shifted frequencies. *To be published in Nuclear Fusion. •Plasma Physics Laboratory, P.O. Box 451, Princeton S.J. 08544, USA. **On leave from IF-UFRGS, Brazil. ELECTRON CYCLOTRON WAVE DAMPING FOR OBLIQUE PROPAGATION IN HOT PLASMAS* I. Fidone, G. Giruzzi, V. Krivenski and L.F. Ziebell Association Euratom-CEA sur la Fusion, Dêpartement de Recherches sur la Fusion Cont.ro lee, Centre d'Etudes Nucléaires, 92260 Fontenay-aux- Roses, France Electron cyclotron wave absorption for propagation away from normal to the magnetic field in hot tokamak plasmas is considered. The relativistic dispersion relation which includes the effect of Lannor radius is presented in a relatively simple and instructive form. It is shown that for the X-mode at down-shifted frequency and T > 20 keV, the resonant frequency lies in the subharmonic range of frequency and the parallel velocity of the absorbing electrons is close to the speed of light. It is also pointed out the relevance of the parallel change of the kinetic energy and momentum induced by the ECW for relativistic resonant electrons on the quasilinear evolution of the electron distribution. *Io be published in Nuclear Fusion. +0n leave from IF-UFRGS, Brazil. TEMPERATURE EFFECTS ON ION ACOUSTIC SOLITONS IN PLASMAS WITH NEAR CRITICAL DENSITY OF NEGATIVE IONS* F.B. Rizzato, R.S. Schneider and D. Dillenburg We establish a Korteweg-de Vries type equation to describe ion acoustic solitons in a plasma made up of electrons, positive and negative ions near the critical density. It is shown that the amplitudes and widths of compressíve and rarefactive solitons are dependent on the ion temperatures, and that this -84- dependence is strongly asymmetric when Che positive «ad negative ion temperatures «re unequal. *To be published in Plasma Physics and Controlled Fusion. RATIONAL FUNCTIONS OF MOMENTUM AS INVARIANTS FOR ONE-DIMENSIONAL, TIME-DEPENDENT POTENTIALS: BASIC THEORY* João Goedert* and H. Ralph Lewis Los Alamos National Laboratory, MS-F642, Los Alamos, NM 87545, USA A framework for the momentum-resonance formulation of Lewis and Leach [Ann. Phys. (NY) 164, 47 (1985)] is presented that casts new light into th~ nature of exact, explicitly time-dependent invariants for one-dimensional, time-dependent potentials and produces additional examples of such invariants. The momentum-resonance formulation postulates that the invariant be a rational function of momentum with simple poles, which are called momentum resonances. It is shown that an invariant of resonance type can be written as a functional of the potential in terms of the solution of a system of linear algebraic equations; and a single necessary and sufficient condition for a potential to admit an invariant of resonance type is obtained. These results are obtained by reformulating the problem in terms of a set of discrete moments that satisfy two separate recursion formulas. Invariants for new time-dependent potentials can be obtained and previously known invariants are recovered. *To be published in J. Math. Phys. •On leave from IF-UFRGS, Brazil. RATIONAL FUNCTIONS OF MOMENTUM AS INVARIANTS FOR ONE-DIMENSIONAL, TIME-DEPENDENT POTENTIALS: TWO- AND THREE-RESONANCE CASES* H. Ralph Lewis and Joãc Goedert* Los Alamos National Laboratory, MS-F642, LOB Alamos, NM 87545, USA The momentum-moment formulation of Goedert and Lewis [J. Math. Phys. 2H_f 728 (1987)] and the momentum-resonance formulation of Lewis and Leach [Ann. -85- Phys. (NY) J64, 47 (1965)] are used to study one-dimensional, time-dependent potentials that admit invariants which are rational functions of momentum with two or three simple poles. New examples are presented. *To be published in J. Math. Phys. «On leave from IF-UFRGS, Brazil. QVASILIIIBAR EQUATION FOR OSCILLATIONS IN HAGNETOPLASMAS IN A WEAKLY RELATIVISTIC APPROXIMATIONS* F.B. Rizzaco The present work considers two subjects. First, some limitations to the dynamical equations of collisionless plasmas are presented. In a heuristic manner, elementary corrections are obtained to linear theory. These corrections lead directly to the so-called quasilinear theories, in non- relativistic and relativistic form. Second, using a perturbative approximation, one examines the effect of relativistic gyrofrequency on the coefficient of quasilinear diffusion. *M.Sc. Dissertation, IF-UFRGS, July 30, 1985. II.d) NUCLEAR PHYSICS -87- BACS IK TV SELL MODEL* H. ftetz, 6. Krcin «ad Th.A.J. Maris For a Fermi s«« of bag-like nucleons, qua:* statistic* laads to corrections which grow with the bag radius. The influences of this effect on rhe single-particle nature of the sea and on the nuclear structure function F2(x) are estimated. «Published in Nuclear Physics A437 (1985) 509. RECENT DEVELOPMENTS IN QUASI-FREE NUCLEOK-NUCLEOtt SCATTERING* P. Kitching*, W.J. KcDonald*, Th.A.J. Maris and C.A.Z. Vasconcellos This work is a self-contained review to discuss recent results of quasi- free scattering in a way that is understandable for a nuclear physicist without previous knowledge of the subject. The Distorted-Wave Impulse Approximation is discussed. The main results of experiments with polarized protons are reviewed. We aim nainly to significant improvements in quasi-free scatterings that refer to a number of recent developments. These are the emergence of parameter-free descriptions of nuclear elastic and inelastic scatter Ings at intermediate energies in the last year or so, the emergence of much (e,e'p) data» a symbiosis between (e,e*) and (p,pf) data and an analysis suggesting that (e,e'p) and (p,2p) reactions might develop together in a similar way. An overview of work done with different particles is also presented. In special the new (p.pir) results are compared vith the (p,2p) ones. •Published in Advances in Nuclear Physics, 15_ (1985) 43. •University of Alberta, Edmonton, Alberta, Canada T6G 2J1. -8ê- S-WAVE teSGH-lRJCLEON SCATTERING IN AN SUO) CLOUDY BAG MODEL* E.A. Veit*. B.K. Jennings, A.V. Thouas** and R.C. Barrett** TRIOKT, 4004 Wasbrook Mall, Vancouver, British Columbia, Canada V6T 2A3 The cloudy bag model (CBM) is extended to incorporate chiral SU(3) xSU(3) symmetry, in order to describe S-wave KN and KN scattering. In spite of the large mass of the kaon, the model yields reasonable results once the physical masses of the mesons are used. He use that version of the CBM in which the mesons couple to the quarks vith an axial-vector coupling throughout the bag volume. This version also has a meson-quark contact iuteraction with the same spin-flavor structure as the exchange of the octet of vector meson6. The present model strongly supports the contention that the A*(1405) is a KN bound state. «Published in Physical Review D 21 (1935) 1033. •On leave from IF-UFRGS, Brazil. **Physics Department, University of Adelaide* South Australia 5001 ++Physics Department, University of Surrey, Guildford GU2 5XH, United Kingdom KN SCATTERING IN THE CLOUDY BAG MODEL: s, p, AN;) d WAVES* E.A. Veit*. A.M. Thomas** and B.K. Jennings TRIUMF, 4004 Wesbrook Mall, Vancouver, British Columbia, Canada V6T 2A3 s-, p-, and d-wave KN phase shifts are calculated with the cloudy bag model (CBN), The results are in qualitative agreement with phase-shift analysis, except in those partial waves where exotic resonances are claimed to exist. However it seems that it is possible to get good agreement for these waves by just modifying the CBM potential, without including explicitly exotic states. "•Published in Physical Review D JJ£ (1985) 2242. •On leave from IF-UFRGS, Brazil."*" ••Department of Physics, University of Adelaide, South Australia 5001, Australia -8»- PION-KUCLEON SCAXTEftlNG Iü THE CLOUDY BAG HOWL* E.A. Veit, B.K. Jennings* «od A.V. Thorns** We investigate s- and p-vave pion-nuclecn scattering in the coupling version of th« cloudy bag model. The earlier conclusions «bout the nature of the A(1232), based on surface coupling, are cot altered. This nodel also provides a good description of the "small" p~wave phase shifts, and the s-wave scattering lengths. However, there are indications fro» the s waves at energies above 100 MeV, and fro» the P . channel, that soa* physics if still missing. 'Published in Physical Review D 33 (1986) 1859. +TRIUHF, 4004 Wesbrook Hall, Vancouver, British Columbia, Canada V6T 2A3. ««Department of Physics, The University of Adelaide, C.P.O. Box 498, Adelaide, South Australia 5001, Australia. HYBRID QUARK HOWLS AND UNITARY THEORY OF PION-SUCLEOK SCATTERING* M. Bfttz The development of hybrid quark aodels (HQM) which include a pion cloud by coupling the quarks to the pion field has aroused renewed interest in theoretical studies of pion- «cleon (ITN) scattering. Host works published so far have dealt with the low-energy region in which inelastic (pion production) channels can be ignored. In order to extend these studies to higher eaergies, an approximation schene which maintains three-body unitarity and therefore correctly includes the influence of the pion-production channel on elastic scattering has been developed. The derivation relies on the classification of time-ordered diagrams in terms of the number of pions present in intermediate states. Considering the full pion-baryon amplitude T, we first isolate the sum T of all graphs containing at least one pion in every intermediate state, obtaining where V is the dressed one-line irreducible pion-baryon vertex and C is the full baryon propagator. Pions and bare baryons are represented by dashed and -90- continuous '. '.nes, respectively. The equations giving V and G are where g is the baryon propagator in the presence of a spectator pion. A three- body unitary approximation can be obtained by dropping all graphs with intermediate states containing more than two pions. This results in the following equations for g and T : k X. In these graphical equations, a solid line represents any one of the three-quark bare baryor.ic states included in the calculation. In order to obtain the physical irN amplitude, it is necessary to form a linear combination of the ab^ve amplitudes T for the various bare-baryon initial and final states, with weights given by the amplitudes for finding these bare baryons in the physical nucleon. For consistency, these amplitudes should be calculated in the one-pion approximation; they can be easily extracted from the propagator g. A KQM hamiltonian usually contains a bare coupling constant and a set of bare baryon masses which must be choosen such as to yield the correct physical masses and coupling constants. A renormalization procedure which garantees that the physical masses and coupling constants are correctly reproduced, both at the one- and two-pion approximation levels, has been worked out. The three- body unitarity of the resulting theory has been checked. It has also been shown that scattering equations identical to the above can be derived exactly from a few-body model defined on a space (B) 9 (Bw) © (Bun), where B indicate» anyone of the baryon types, and characterized by a hamiltonian containing a set of vertices that couple the various slices of the space. The -9t- The equivalence between «n approximation to the field theory and the exact solution of a few-body model permits an easy appraisal of which further simplifications or improvements can be nade without endangering unitarity: they are those that maintain the hemiticity of the few-body model haoiltonien. Work is in progress to apply the above formalism to a study of the Roper resonance N (1470) in the PB wN scattering channel and to an investigation of the admixture of that state in the physical nucleon. An extension of the formalism to include the four-leg vertices which appear in some versions of the HQM is also being pursued. (1) A.W. Thomas, Adv.Nucl.Phys. J_3« 1 0984). *Work in Progress. LIFETIME OF A NUCLEAR HOLE STATE IN A RELATIVISTIC MODEL* M. Betz, Th.A.J. Maris and M.H. Steffani The aim of this work is to calculate the lifetime of a nuclear hole state, employing the field theoretical model of Walecka , where the nucleus is considered as consisting of elementary nucleons coupled to meson fields. The Walecka model ha» given considerable insight into important nuclear structure properties, as the real and spin-orbit potentials for bound nucleons and the complex optical potentials. In the case of the central potentials cancellations of large terms of opposite sign take place, whereas in the spin- orbit potential the sum of such terms occur. We thought it therefore to be interesting to see whether this model is able to give a reasonable picture of the hole state widths and their dependence on the separation energy as measured in quasi-free scattering experiments. The relativistic quantum field theory proposed by Walecka includes explicitly the mesonic degrees of freedom and contains a baryon field where M, u and m are the masses of the nucleon, scalar meson and vector mason, respectively. Fro» nuclear matter densities upwards the quantum, theory may be approximated by replacing the meson field operators with their expectation values: $-••<$> = $a and V -* 1 i up v The total width of a nuclear hole state in nuclear matter due to direct and exchange diagrams showed in figure 1 is given by (2) r(k) (k) rE (k) where (k) • -2 .»[» 00 + (k) • «?(»] _v F (k) - -2 Imf (k) (k) * E + •'] If one take» the non-relativistic limit of the nucleon propagator and neglects the squares of the energy differences in the meson propagators, which are at most equal to the square of the Fermi energy, one obtains the curves showed in figura 2. In this figure a comparison is made between the «elected experimental results (crosses) and our calculated widths for nuclear matter -93- with different values of the nucleon effective aass M • M-g • . s o 30 20 Figure 2. 20 40 «0 * Mp. 938.3 MeV * 0.5 Mp « 0.73 Mp Work is now in progress to calculate (2) using the full relativistic nucleon propagator in the mean field. 1. J.D. Walecka, Ann. of Phys. J83 (1974) 491. *Work in progress. III. ASTRONOMY AND ASTROPHYSICS -95- THE CANCELLATION OF MAGNETIC FLUX. I ON THE QUIET SUK** S.H.B. Livi**, J. Wang** and S.F. Martin Solar Astronomy 264-33, California Institute of Technology, Pasadena, CA 91125, U.S.A. We studied the disappearance of magnetic flux in an area of the quiet Sun from digital and photographic aagnetograms recorded at 2.5 min intervals for many hours on 9 July 1984 at the Big Bear Solar Observatory. We limited the quantitative part of the analyses to features which had a total of 10 Mx (1 Hx : 10~ Wb) or greater and at least a 20 G (1 G = 10 T) contour, and which changed by more than 10Z of the maximum measured flux during the 5-5 hours of most consistent image quality during the observing day. Sixteen examples of flux disappearance and chree ephemeral regions met these criteria. The disappearance of flux in these examples occurred only in closely spaced features of opposite polarity. The mutual disappearance of magnetic flux in closely spacedfeatures of opposite polarity is herein defined as 'cancellations' The 16 examples of cancellation were observed in combinations of network features, intranetwork features, and ephemeral regions. In two of the three ephemeral regions, an imbalance of magnetic flux between the two poles within each of the ephemeral regions was created, at least in part, by the cancellation of one pole with an adjacent feature of opposite polarity. Many smaller cancellations are clearly recognized below the threshold that we established for our initial measurements. We conclude that cancellation is the dominant ' ay in which magnetic flux is observed to disappear on the quiet Sun. *Published in Aust. J. Phys. 38 (1985) 855. -••Paper presented at the R.G.Glõvanelli Commemorative Colloquium, Part II, Tucson, Arizona, January 17-18, 1985. **0n leave from IF-UPRGS, Brazil. ••Beijing Observatory, Beijing, China. -96- THE CANCELLATION OF MAGNETIC FLUX. II IN A DECAYWG ACTIVE REGION** S.F. Martin, S.H.B. Livi** and J. Wang** Solar Astronomy 264-33, California Institute of Technology, Pasadena, CA 91125, USA An active region was studied in detail during its period of decay froa 3 to 8 August 1984 using Ha filtergrams and videoaagnetograms acquired at the Big Bear Solar Observatory. The decay was initiated by a process of fragmen- taticn in which very small knots of magnetic flux separated from larger i ncentrations of flux. The fragmentation was observed at discrete locations around the periphery of both the dominant areas of negative and positive field, but p^riMv occurred more frequently in the sain polarity inversion zone. The fragmentation and migration of knots of magnetic flux were common predecessors to the disappearance of flux. The disappearance of magnetic flux was always observed when the small fragments of flux encountered other small fragments or concentrations of flux of opposite polarity. This type of disappearance of magnetic flux, called 'cancellation', is shared by both polarities of magnetic field. It was deduced that the disappearance of flux occurred either at or within 5 arcsec of the apparent dividing line between the opposite polarities. Cancellation was the only observed means of major loss of flux in the photospheric magnetic fields of the active region. Approaching fragments of opposite polarity flux always collided and, after apparent collision, permanent loss of magnetic flux was subsequently and invariably observed. Thus, cancellation is a highly predictable phenomenon. All of the 22 flares observed during the decay of this region were initiated around the sites where magnetic flux was cancelling OT was deduced to be cancelling during the flares. The intervals of time during which mag- netic flux was decreasing at the flare sites was very much longer than the duration of the flares. Abrupt changes in magnetic flux on the time scales of the Ha flares were not observed. Several flares started at a site of disappearing flux but spread to other locations of plage where no loss of flux was observed during the flares. We hypothesize that cancellation was a necessary condition, but not the only necessary condition, for flares to occur in this active region. •Published in Aust. J. Phys. 38 (1985) 929. •«'Paper presented at the R.G.Clõvanelli Commemorative Colloquium, Part II, Tucson, Arizona, January 17-18, 1985. **0n leave from IF-UFRGS, Brazil. ••Beijing University, Beijing, China. -97- G BAND AND He PHOTOMETRY OF LMC AND SMC RED CLUSTERS*'*' Eduardo Bica**, Horacio Dottori and Hiriani Pastoriza We present an age-metalIfcity calibration for the color-color diagram obtained by means of G band and H« narrow band photometry of 41 LMC and 10 SMC clusters. The chemical evolution of the Clouds are compared: th« LMC presents a steeper chemical enrichment slope. An intrinsic metallicity dispersion is detected for the LMC, ^Published in the Proceedings of the ESO Workshop on "Production and Distribution of C,N,0 Elements", Garching, 13-15 May 1985. +Based on observations made at ESO, La Silla. **Observatoire de Meudon 92195 Meudon - Principal Cedex, France. THE PRIMEVAL HADRON AND THE REGGE LAW* C.A.Z. Vasconcellos, H.A. Dottori and A.A. Schmidt The property of potential homogeneity conduces in the hadron semi- classical model proposeJ to scalings of angular momentum-mass compatible with the behaviour expected by the Regge law. The scaling of the fundamental quantities (length and time) leads in the gravitational case through the same property (potential homogeneity) to scalings of some observable physical quantities (mass, density, intrinsic angular mementum) which in turn together with the imposition of covariance of the Lagrangian give a Regge-like condition. "Published in Astrophysics and Space Science 113 (1985) 383-390. THE AVERAGE DENSITY OF THE UNIVERSE AND THE REGGE LAW* A.A.Schmidt, H.A. Dottori ami C.A.Z. Vasconcellos We calculate the principal inertia moments of a three-dimensional mass distribution rotating with angular velocity w in a self-gravitational homogeneous field with axial symmetry. We show that the angular momentum J may, under certain conditions, be of the Regge-like type. These result* -98- are used to evaluate the aass and average density of the Universe. «Published in Astrophysics and Space Science, 127(1) 15 (1986). HII REGION AGE INDICATORS* M.V.F. Copetti, M.G. Pastoriza and H.A. Dottori The evolution of aome properties of HII regions such as the relative volume R of the He and H zones, the equivalent width V „ oi the Hg emission line and the ratio [0 IIIJ/H. of the lines [0 II] ÀÀ4959, 5007 to Ho, was studied through models which cake into account: a single burse for the formation of the ionizing association with different initial mass function IMF (1 < x S 3) and upper stellar mass limits (30 S Mj% * 120); different chemical composition models of stellar evolution with and with-out mass loss. It was found that W^g, R and (0 III]/Hg decrease monotonically as a function of time and consequently they are good H II region age indicators. «Published in Astron. Astrophys. 156, 111-120 (1986). PHOTOMETRIC MEASUREMENTS OF WHQ AND [0III]/Hc OF HII REGIONS p p IN M83* M.V.F. Copetti, H.A. Dottori, M.G. Pastoriza WH~ and (0III]/H& were measured photoelectrically in 12 HII regions of M83. It was not found any systematic variation of WH or [0IIl]/Ho across M83. The very low excitation of the emission nebulae in M83 nay be a consequence of the evolution of the HII regions. «Published in Rev. Mexicana Astron. Astrof. 12, 137-138 (1986). -99- A COMPARATIVE STUDY OF THE STELLAR CONTENT IN NORMAL AND ACTIVE NUCLEI OF SPIRAL GALAXIES* Horacio A. Dottori and Miriani G. Pastoriza We present spectrophotometry and ÜBV photometry of the central region of spiral galaxies. The sample consists of the Seyfert galaxies NGC 1566, 3783 and IC 4329A; NGC 1097, 2997, and 5236 containing peculiar nucleus and NGC 5530, 5643, and 6699 with normal nucleus. The stellar composition of the nuclei was derived by treating the equivalent widths of a sample of absorption lines with the method of constrained nonlinear optimization. The observed continua and the UBV colours were compared with the theoretical results in order to obtain the internal reddening and the contribution of the hot gas or non-thermal radiation. The age of the last cycle of star formation, the internal absorption and the theoretical relations M/L and H/K Call present differences among the three types of nuclei. *Published in Astrophysics and Space Science 121 (1986) 147. SPECTROPHOTOMETRY OF THE NUCLEUS OF NGC 7552* Horacio Dottori, Miriani Pastoriza, S.J. Codina Landaberry and J.A. de Freitas Pacheco In this paper we present new spectrophototnetric measurement of the Sersic-Pastoriza nucleus of NGC 7552, giving absolute fluxes of the continuum between 3650 A and 6900 A and intensities of the lines H_, HQ, [0 III] í p 4959+5007 A and HCH-N II. The synthesis of the absorption spectrum indicates 3 or 4 bursts of star formation. *Published in Rev. Mexicana Astron. Astrof. V2, 119-123 (1986). •Observatório Nacional, CNPq,Brasil. -100- BV SURFACE PHOTOMETRY OF SOUTHERN GALAXIES. I. NGC 4507* I. Storchi Bergmann and M.G. Pastoriza From B and V photographic surface photometry we have obtained photometric parameters, mean-luminosity profiles, and B-V color indices for the barred spiral galaxy NGC 4507. The decomposition of the mean-luminosity B profile 1/4 shows the existence of an r bulge» an exponential disk, a bar, and possibly a lens. The dimensions and colors of these structures are derived. The mean B-v distribution shows a color gradient of 0.4 mag between the nucleus and arms region. A reddening of E(B-V) = 0.2-0.3 of the southern region can be detected when we compare its B-V values with those of the northern region. Subject headings: galaxies: individual - galaxies: photometry - galaxies: structure. *Published in The Astrophysical Journal 304:3Q5-3T1, 1986 May 1. BV SURFACE PHOT0METY OF THE SOUTHERN GALAXIES NGC 6769, 6770 AND 6771* T. Storchi Bergmann, M.F. Saraiva Schroder and M.G. Pastoriza From B and V photographic surface photometry we have obtained isophote maps, photometric parameters, luminosity profiles and B-V color indices for the group of the spiral galaxies NGC 6769, 6770 and 6771. The observations were made with the 1.6 m telescope of Observatório Astrofísico Brasileiro using Che combination of )03a-O or IIa-0 plate plus GG385 filter for the B system and Ila-D plate plus GG495 for the V system. The reductions were made using the Zeiss-Jena microdensitometer of Instituto de Física - ÜFRGS, Porto Alegre and the nethod of Sérsic (1968) or the PDS microdensitometer of Observatório Nacional, Rio de Janeiro, and the software developed in that observatory by da Costa et al. (1982). The values obtained for the total apparent magnitudes (nig), total color indices (tUg-iUy), absolute .nagnitudes (lO, major (D) and minor (d) diameters are listed in the table below, together with the isophotal level uã where these values were obtained. -101- TABLE t. Photometric Parameters NGC B y^ g kpc kpc 6769 12.70 0.65 -21.27 130.0 93.0 24.86 28.1 20.1 6770 12.91 0.71 -20.97 174.0 128.0 24.86 36.7 27.0 6771 13.76 0.90 -20.25 143.0 34.5 25.17 In general, Che color indices vary from about 1.1 nag in the nuclear regions to about 0.3 mag in the blue regions. Exponential and r ' laws have been adjusted to the luminosity profiles. da Costa, L.A.K., Carvalho, R.R., Rite, C.P., and Pellegrini, P.S.S. 1982, "Image Processing at the O.K.I. Surface Photometry", Publicações do Observa- tório Nacional, n9 2. Sérsic, J.L. 1968, Atlas de Galáxias Australes (Universidade de Córdoba: Brasil). *Published in Rev. Mexicana Astron. Astrof. 12, 133 (1986). COLOUR GRADIENTS IN GLOBULAR CLUSTERS* M.C. Pastoris.», E.L.D. Bica, H.V.F. Copetti* and H.Â. Dottori Radial colour gradients in the globular clusters NGC 2808, NGC 1851, NGC 5139, NGC 5139, NGC 6388, NGC 6441, NGC 6541, NGC 6723, and NGC 7099 were searched by B - V and DDO photoelectric photometry, using a set of circular diaphragms. Two of the observed globular clusters, NGC 5139 ú Cen) and NGC 7099 (M30), showed B - V and C(45-48) colour gradients; the colour C(42-45) is essentially constant in these clusters, which means that the physical reason for those gradients cannot be attributed to chemical composition variations, since C(42-45) is a good metal abundance indicator. B - V colours in the external regions of NGC 5139 and NGC 7099 were obtained by synthesizing the observed HR diagrams of these clusters. The ages and the relaxation tines for NGC 5139 and NGC 7099 indicate that mass segregation must have taken place in both clusters, which is probably related to the observed colour gradients. •Published in Astrophysics and Space Science J[»9 (1986) 279-285. +Departamento de Matemática, Universidade Federal de Santa Maria, Santa Maria RS, Brasil. -102- AGES AND METALLICITIES OF LMC AND SMC RED CLUSTERS THROUGH HB AND G BAND PHGTO!ETRY*+ E. aica**, H. Dottori** and M. Pastoriza We present narrow band integrated photometry of the HB ami G band absorption features for 41 LMC and 10 SMC red star clusters. An ags-aetallicity calibration is provided for the color-color diagram. We derive SUB types betweer IV and VII tor 23 unclassified clusters and discuss their distribution in the a&e vs raetallicity plane. We study the chemical evolution of the Magellanic Clouds (MC): the LMC presents a steeper chemical enrichaent slope. An intrinsic setallicity dispersion is found in the LHC chemical evolution, indicating that the gas has been inhomogeneous at any time, prevailing a local enrichment over a global one. One zone models describe the evolution of both Clouds, being the efficiency of star cluster formation larger in the LKC. The LMC presents a burst of star cluster formation at t = A.5 10 vr. We also present new B - V data for fainter SMC clusters, providing an essentially complete color histogram for clusters with globular cluster appearance. «Published in Astron. Astrophys. j^ 0966) 261. •Work performed in part in Meudon, France; Bochum, West Germany and La Si 11a, Chile. **On leave from IF-LTRGS, Brazil. THE DISTRIBUTION OF ISTERSTELLAR EXTINCTION NEAR THE SUN* J.R. Ducati Centre de Données Stellaires, Observatoire de Strasbourg, Prance Photometric data in uvbyfi system from 3713 stars is used to map the distribution of colour excesses up to 500 parsec from the Sun, producing diagrams fot a series aligned with the galactic plane. Individual clouds are detected, with a mean diameter of 6 parsecs, while a cloud complexes have a mean diameter of 100 pc. From the maps it seeots that the interstellar aadium near the Sun presents regions of non-negligible extinction, while the Sun itself is embedded in a diffuse cloud, or slightly off its border. The large scatter in the distribution of E(b-y) is confirmed, with a mean excitactic: of A c 0?38 up to 500 pc, *Publi*h*d in Astrophysical and Space Science j_26» 2f>9 (1986) •On Uave from IF-UFRGS, Bil -103- STRIP PHOTOMETRY OF COMET HALLEV* Ducat i, J.R., F. Storchi Bergmânn, Bevilacqua, CM., Bout to, C, Cavalcanti, ft.l., Costa, R.D.D., Dottori, H.A., Girardi. L-, Hadjimichef, D., Kepler, S.O., Livi, S.H.B., Pastorita, H.G., Santos, J.F., Schmidt, A., Schroder, H.F.S. Post-perihelical observations of Comet Halley were perforate o* 23 tights at the 50-cm reflector of UFRGS by the technique of stria photometry. A «lit of dimensions 8' x 8" scanned the cotaet image at a sp**** of I.MS** x cos (declination)/sec, in east-west direction or inversely. For photocstry we used NASA interference filters C2, C3, CO*, H20+, Á 4É65 and A 6140. Calibration used IHV standard stars and scans of field. Significant signals are detected for H20+, C2 and C3. Time evolution of COB* is seen fro» profiles. No color effect was observed from the continuum filters. *To be published in Rev. Mexicana Astron. Astrof., Proceedings of the IA0 V Latinamerican Regional Meeting. GALAXIES WITH STRONG NITROGEN LINES* T.S. Bergmann and H.G. Pastoriza From a qualitative spectroscopic survey of southern galaxies made by Pastoriza, a group vith different morfological types whose nuclear region snowed particular strong emission (Nil}X6548-6584 lines when compared to Ha, was selected in order to investigate why (Nil} is so strong. This work presents the results of a first analysis of ;he spectra of some of the galaxies above obtained with the 1m telescope plus 2DFRUTTI detector of the Cerro Tololo Inter- As?» ri can Observatory. The spectra are all very similar showing strong scellar continuum and absorption lines, and all the emission spectra show [0IIIJ>{0IIj, [NII]>Ha. None of the spectra show HB in emission. Using the relative intensities of the H and K Call lines (Talent, 1902), the obtained integrated spectrum for all the observed galaxies is latet than GO, what means that the H3 absorption lines should not be strong. From the relative intensities of the emission lines, we conclude that these galaxies can not be classified as Starburst or LIBfJtS. They are similar to Seyfert 2 (Osterbrock, 1986), but the PWHH of the lines is less than 300 ka/s. Also 01 A63O0 is not clearly seen, and the absorption -104- spectrwn is strong -j;. alive to Che aviation spectrum. Tha «reliannery conclosion ia an activity siailar but milder than that present in Seyfert 2 galaxies, as suggested by ftoee and Saarla (19S2) and loa* and Cacil (19*3) for the nucleus of M51, **ybe affected by an anômalo** nitrogen 1. Osterbrock, D.E. 19*6. Active Galaxies and QSOs, preprint. 2. Roa«, J.A., Cecil, C. t9»3. Ap. J. 2t», 53t. 3. Rose, J.A., Searle, L. I9S2. Ap. J. 253, 554. 4. Talent, D.L. t982. Pub. A.S.P. 94,36. *Subsictad to Kev. K-'xicaoa Astron. Astrof. '987. SUCLEAR STELLAR POPULATION OP MGC772 (ARP 7»)* Alex A. Schsidt and Horacio A. Dottori The nuclear spectrum (5" x U") of the Sb I Arp'« galaxy KC772. obtained with che IDS spectrograph at the 1.5 nts ESO talaacopa. «as uaad to synthetize the stellar population through the analysis of the absorption features and the continuum. The results show that the flux around 5340 A is dominated by C and K stars. The last and weak star fo mat ion cycle was found with turn-off-point (TOT) at AOV. The possible association between two nearby high redshift objects and nuclear phenomena is discussed. *To be published ia Rev. Mexicana Aatron. Astrof., Proceedings cf the IAV V Latinanerican Regional Meeting. ÍV SURFACE PHOTOMETRY OF THE SOUTHER* GALAXIES KGC 2855 AMD KGC 4507* T. Storchi Bergmann, K.G. Pa»torisa and H.F.S. SchrBder Surface B «od V photoottry was obtained for the southern galaxies RCC 2855 and HCC 4507. Total «agnitudes, distances, absolute Magnitudes, as well as lenghts of major and ainor axes ars detemined. Isophote B and V asps, t and V luminosity profiles along aajor and -105- minor axes as veil average profiles are shown Tb* average B profile is decomposed and the different components identified. The behaviour of the R-V profiles is discussed. «Published in Rev. Mexicana Ascron. Astrof. 10 (1965) 81. MORPHOLOGY OF LMC CLUSTERS* Alexandra Fonseca Zepka and Boracío Alberto Dottori it has been observed that the LMC globular ci1 stars are, is average, acre elliptical than the galactic ones and their ellipticity is not necessarily constant th-oughout the cluster, tesides, an internal distribution of position angles has beet» inve&cigated, although not yet confined. If »ot thest clusters artí not flat due to rotation, but they are actually triaxlai structures in equilibrium. In order to carry out a systematic study of the morphology of these clusters, we obtained isophotal contours tbrough PDS scanning of the original ESO's B Survey plates in Munich. The image process system at Carching allows the smoothing of the cluster iaage asd renoves bright stars fro» the isophotal contour. The analysis of an initial sample of 17 clusters has shown variation of ellipticity in 301 and position angle in 60% of then. Ho systematic pattern in the internal distribution of both parameters was observed. Besides the error introduced by imposing ellipses to the isopbotes, the fittings are affected mainly by background brightness, cluster richness and the presence of bright stars. Errors in the position angles increase for steal I ellipticities. *To be published in Rev. Mexicana Astron. Astrof., Proceedings of the IAÜ V Latinamerican Regional Meeting. -106- KGC 2209: THE KATUEfc OF THE DARK PATCH* Horacio A. Dottori, Jorge Helnick «ad Eduardo lie« The LMC globular cluster 3IGC 2209 present a coospicuos dark patch about 15 arc sac in diaaeter located at about 10 arc sec from the center of the cluster. Hodge argued that the feature could be an absorption globule either internal to the cluster of galactic, or else belonging less probably to the LMC itself, cving to the large distance froa the aaie body. The air of this contribution is to present a study of the nature of the dark patch on cbe basis of a deep Ht diagram of the cluster aad the analysis of the photoactric properties of the ft» stars that appear projected on top of the patch. The photometric observations in the 3V systeai were carried out wich a OCD camera at the CT10 4 at telescope, with exposure of tS «in in photometric nights of «acelent seeing. Our conclusion is that the patch is an internal structure of the cluster. Ve also discuss the controversial problem of the aetallicity and age of the cluster. *To be published in Rav. Mexicana Aetna. Astrof., Proceedings of the IAU V Latinearrican Regional Meeting. CQSmOGIOU. XASS DENSITY ASD THE BE«Z LAW* A.A. Schmidt, C.A.Z. Vasconcellos aad H.A. Oottori Tha property of potential homogeneity nay conduce in hadron physics to 5 a lings for aptn-aass vich are coapatible with the behaviour predicted by the R«gge law. Scaling of the fundanental quantities (length «nd tiae) oay lead, in the gravitational case, through potential hoaogeneity, to seal ings of some relevant observable physical quantities (mass, density, angular tsoaentua) which, together with the imposition of covariance of the Lagragian, gives a Regge-lifce condition. We calculate the principal inertia moments of a three-dimensional mass distribution rotating in a self-gravitational homogeneous field with axial «ytmetry. We show that the angular momentum may, imder certain conditions» be of the Regge-like type. These results are used to evaluate the mass and density of the universe, *Tcr be published in Rev. Mexicana Astron. Astrof., Proceedings of the IAU V Latinaaerican Regional Meeting. -10?- EVOLUTIOH OF HI I REGIOKS* Horacio A. Dottori In this p*p*r the influence of the evolution (ageing) on general properties of Che HII regions is analreed. The problem of the paraaetricity, the line ratios generally calibrators are particularly discussed. Existing determination of age in the LMG, Jit, and ICG axe reviewed, tot analysis of radio data on VH* and VHe* to determine ages for HII regions of the Kilky Way is presented. Finitely» it is alto discussed the nav idea an the Irak between HII region evolution and nuclear activity in galaxies. *To be published in lev. Mexicana Aatron. Astrof., Proceedings »f th* 1AU V Latinamerican Region*! Masting. AGE DCTUMIBATIÚH OF THE MMZLUMC CLOUDS AVD ISOLATED EXTRAGALACTIC HII KEGIOftS* H.V. Copetti*, R. Dottori and if. Pasterisa The age of extr*galactic Mil regions belonging to LMC, SNC and isolated «xtragalactic Mil regions is obtained through the parameters V^-- and OIII/H. , recently calibrated by us as age indicators. The results show a younger burst of star .'oraation ia the SMC than in the LMC. Initial Mass Function with x-2.0 must be disregarded, which have a profound meaning from the point of view of star generation. It is not necessary to supposse H. larger than 60 H to explain all the observations. *To be published in th* Proceedings of the first IAP meeting on ftar Forming Dwarf Galaxies and Related Objects Ld: D. Kunth, T.X. Thuan and T.T. Van, Editions Frontiers, 19W. ^Universidade Federal de S. Maria. -108- A SEARCH FOR PERIODICITIES IK WE LIGHT VARIATION Of SOS SETFEKT GALAXIES* S.M. Bitch» M.C. Pastorixa, B. De-ttori, I. •«•*&** Fenfola's UBV observations ©f the Sfuclei of Che Seyfert galaxies MGC SGC 3227, ICC 3783, KGC Wt4, HOC 7469, Mi 50 aod IC 432*4 are examined to look for a possible periodicity in the variation of the msgaitud»* and colors. A atechod ba»«d OR Che fitting of »iftu«ei4al» aa4 tWm csiculatioc of tin aultiplc correlation coetticicac atàv^facc* to ch* analytis ef obscrvacioos unequally spaced in lima is us*4 to analyse th* éata. Pour of the S«V*B galaxies «tuàícd show a high probability of having perieéic rusmit in the variation. Recest Uiv observations were used to test the coapoaents in two of thea. *To S>« ptiblistwâ ÍB the froceedisgs of tbe IAU Siasp. S? !2I "Observational Evidence of Activity in Vuclei of Calaxies", fircvaa, Arawkia, URSS, Juae fe-í STRIP PflOTOKETlY Of COMT IftLLEY* Ducati.J.X., Bergvaan.T.S., loaatte^C, Cavalca«tivR.L.t Costa,R.D.D., Dot tori,I.*., Cirardi(L.v RMjiaicbef rD.f Kepler, S.D., Livi.5.J.t., PastorisavK.C, S«atos,J.F., Sctwidt,A., Schroder,M.F.S. Post-perih«lical observatioas of Coa*t lalley «ere pcrfonwõ on 25 nights at the SO-c» reflector of VFtCS by the technique of strip photometry. A slit of diaensions 8' x 8" scanned the coaet iaags at m speed of 1.345" x cos (de- clination) /sec, in cast-west direction or inversely. For photosetry we used RASA interference filters C2, C3, CO*, 820*, A4B65 Mid XW40. Calibration used IRK standard stars and scans ef field stars. Significant signals are detected for H20*, C2 and C3. Tin» evolution of con» is seen froa profiles. Ho color effect was observed frost the continwu» filters. *fresented at the XX ESLAB Symposium on the Exploration of Bailey's Comet, Heidelberg, October 19êt; published in the Proceedings of the meeting. -109- STUDIES OF SOCTBEKt OPEN CLUSTERS, II: NGC 3766 AKD SCC 5460* Roberto D.O. Costa, Jorge R. aucati and Hiriani G. Pastorita DDO, USV, Ka and Kfi photometry of the open clusters MGC 3766 end NGC 5460 were performed, to derive mean color excesses E(B-V), distance modulus aad mean metal abundant*; tuis last parameter is analysed in terms of the galactic abundance gradient. The astrophysical parameters surface gravity, effective temperature and spectral type were also obtained for the red stars, leading to the star»* aasses. Using Salpeter's law, minimum tetai masses of each clusters were eutiaatee. Measurement» in Bet and Hi lead to iãentificatioe of possible 5e stars in both clusters. Membership of the observed star* i* aiso discussed. tc Tht Aitrozumiczi Jcuraal. JtXTlCOLOR PHOTOKETtY OF TWEE SOUTHERN OPEK CLUSTERS* Roberto D. D. Costa Usina; DDO photometric photometry, reddening and physical properties of red giants and supergiant» is the southern open clwscer» NGC 25)6, NCC 3766 and XC 5460 ««era calculated. 7h* aassav of these stars were deteraincd with the results and their na«s lo*« in the giant branch investigated. Metalic abondaaces of these clusters were also determined to investigate their relation to the abundance gradient of the Galactic disk. Osing UBV photoelectric photone try obtained in this work or taken fro» literature, reddening, distance nodulos and spectral classifications of che cluster stars were calculated. With these classifications, the «asses of these clusters were estimated using Salpeter's law. In the clusters NGC 3766 and NCC 5460 possible Be stars ware foend, using Feinstein's criterion» with to - H6 photoelectric photometry. Membership of the stars and their proper motions, when available, were also investigated. *M.Se. Dissertation, IF-OFRCS, January 20, 1986. SPECTROPHOTOMETRY OF THE KUCLEI OF SGC 772 AMD KGC 5325* Alex Andre Schmidt Nuclear spectrophotosetric (5"xt3") ami BV photographic observations are shows for zhe spiral galáxias KCC772 (Sb 1 - peculiar) and IC5325 (Sc(r) II). Several absorptions lines were identified and cheir respective equivalent vidths were useJ to synthecise the nuclear stellar population. The synthesis was csrriftw out by Che Sooke-Jeeves penalty function Method, based upon a constrained mm-iirtear programing. Appropriate data for the synthesis were obtained from the Cunn * Stryker stellar spectrophotoaetrie atl&s ia oráet te build up a self-ccssistsftt sqaivaleat width base from 22 representative stellar types: 13 for the sain sequency (05Y - StBK) and 9 for the giant branch. So restriction to nsre than one stellar formation cicles seeas to be essential to detect several «tarbursts in the nuclei of the studied galaxies. The internal absorption and ché K/L *mi SCail/KCail relations are also obtained. t The analysis of IC5325 eeission Lines Ha, TMl\ and ISIIJ iodicates that thtty can be consequence of a Liner ouclaus of low excitation. The energy flax at 3360 % in KGC?72 is doainated by C and K stars (702) and in IC5325 by B ãoú A stars (42%). The analysis of the stellar types proportions shows 2 star íomatíoo cicles in IfCC/72 (TOP at K3 and AO) and 2 in IC5325 (TOP at C5 and Bo). The first starburst in both galaxies is the aost strength, followed by anether discreet burst. The ionixia§ population BOV given by the synthesis explains the emission spectrum of IC5325. *H.Sc. Dissertation, IF-UFRCS, August 22, 1986. GALAXIES WITH STRONG NITROGKK LINKS* Tltaisa Storchi Bergaann and Mir tan i C. Pastoriza From a spectroscopic survey of abowt 200 galáxias a group that showed {IIIIJX6584 stronger than Ha was selected in order to investigate why IMIJ is so strong. Fart of the observations vas concluded in the Cerro Tololo Inter-Anerictn Observatory fro» Aug. 3! to Sept. 6» 1986. Pro* a list of 13 galaxies that w» observe*., only KGC 6300, 7743, 1358, 1368 showed Che [MIIJA6584 line stronger Ha, [0II1J / [011} >1 «ad «bience of HE. The spectrum of NGC 6690 is also -111- simiinr but presents [NIIjMta. The 01 6300 is not clearly present and the stellar absorption spectrum is strong: H and K Ca lines, 6 band, Mg bands are seen. This fact suggests that the non-thermal contribution for the continuum, if exists, is low. A representative spectrum of this type of object is the one we obtained for NGC 1386, showed in the figure below. Even though the reddening correction has not been applied, the intensity ratios of [Nil]/Ha and [01II]/H8 will not be reversed. From the characteristics described above we conclude that this type of spectrum cannot be easily identified with a defined class of object (Liner, Seyfert, normal galaxies). We already made most of the reductions at La Serena and now we are analyzing in detail the line profiles and studying the physical conditions of the gas component from 1 2 the relative intensities of the emission lines ' . The spectra seem to be similar to the nuclear spectrum of M51 ' . For M51 the conclusion was a nuclear activity similar, but milder than that observed in Seyfert galaxies. Another possibility to be investigated is an overabundance of Nitrogen. Once the abundance of N, 0 and other heavy elements is obtained ' , 7 8 9 we will verify any correlations between N/D and 0/H abundance ratios ' ' . Special attention will be payed to the metal enrichment mechanisms, without 0BJ843 WWCLCHCTM Spectrum of NGC 1386 without reddening correction -112- neglecting the possibility of the presence of supernova remnants. From the distribution of the continuum and equivalent widths of absorption lines we will investigate the nature of the stellar population using a computing program of constrained non-linear stellar population synthesis * Having obtained initial estimates for the physical parameters of the ionizing source, density distribution, and the relative abundance of the elements, we will calculate a model for the emitting region using ionization 12 equilibrium, thermal equilibrium and radiative transfer equations 1. Osterbrock, D.E., 1974, "Astrophysics of Gaseous Nebulae", W.H. Freeman and Co. San Francisco. 2. Edmunds, M.G., Pagel, B.E.J. 1984, M.N.R.A.S. 211, 507. 3. Rose, J.A., Searle, L. 1982, Ap. J. 253, 556. 4. Rose, J.A., Cecil, G., 1983, Ap. J. 266, 531- 5. Peimbert, M. Costero, R. 1969, Boi. Obs. Tonantzintla Y Tacubaya 3, 3. 6. Rayo, J.F., Peimbert, M. Torres-Peimbert, S. 1982, Ap. J. 255, 1. 7. Kunth, D. Sargent, W.L.W. 1983, Ap. J. 273, 81. 8. Edmunds, M.G., Pagel, B.E.L. 1978, M.N.R.A.S. 185, 77. 9. Dufor, R.J. et al. 1980, Ap. J. 236, 119. 10. Dottori, H.A., 1986, Ap. Sp. Sc, in press. 11. Faber, S.M. 1972, Astron. Astrophys. 20, 361. 12. Gruenwald, R.B., Aldrovandi, S.M.V. 1985, Astron. Astrophys., 145, 324. *Work in progress. HALLEY'S COMET* J. R. Ducati Observations of Halley's Comet were performed, mainly by photoelectrical photometry (photographs were also taken in many nights), in the period from March to June 1986, at UFRGS Observatory, which is located at Morro Santana, near Porto Alegre. Data were collected from approximately 25 nights. Measure- ments were made in molecular bands C_, C_, H_0 and CO*, and at continuum around 4860 A and 6810 A. The C_ and H_0 bands revealed to be very intense, if compared with the neighbouring continuum measurements; this indicates that these molecules are present at the comet's coma. The C, molecule can possibly be present also. For CO , emission seems to be faint, suggesting underabundancy, Furthermore, data from continuum do not evidence any color effect as measure- ments are made from nucleus to tail. This suggests a flat distribution in grains' sizes over these regions. *Work in progress. -113- A MEASUREMENT OF SECULAR EVOLUTION IN THE PRE-UHITE DWARF STAR PG 1159-035* D.E. Wingel, S.O. Kepler*, E.L. Robinson, R.E. Nattier and Darragh O'Donoghue** Department of Astronomy and McDonald Observatory» University of Texas, Austin We have analyzed 96 hours of high-speed photometry of the pulsating variable star PC 1159-035, obtained from 1979 through 1984. We find that the pulsation period with the largest amplitude, at 516 s, is changing at a rate dP/dt • (-1.2+0.1)X10~ s s~ , corresponding tc at> evolutionary tin» scale of T - (1.4±0.1)X10 yr. This period change is consistent with theoretical descriptions of a gravitationally contracting pre-white dwarf object undergoing nonradial g-mode pulsations. The analysis of the light curve is materially complicated by the presence of at least seven additional periodicities, ranging from 350 to 842 s, and by the inevitable presence of 24 hours aliases for all of them. We describe in detail the methods used to measure dP/dt and to eliminate all possible al- ternative values for it. •Published in The Astrophysical Journal 292 (1985) 606. +0n leave from 1F-UFRGS, Brazil. **Department of Astronomy, University of Cape Town. THE MOST RECENT VALUE FOR THE RATE OF PERIOD CHANGE IN THE ZZ CETI STAR G117-B15A* S.O. Kepler , D.E. Winget, E.L, Robinson and R.E. Nather McDonald Observatory and Department of Astronomy, The University of Texas at Austin, USA The rate of change of period with time for the g-mode pulsations in ZZ Ceti stars is a direct measurement of the cooling timescale for a DA white dwarf, and therefore a measurement of an evolutionary timescale. We have obtained an upper limit for the rate of change of the period of the dominant pulsation in the light curve of the ZZ Ceti star G117-B15A of |dP/dt|s9.9xlO~i5s/s -114- at the 68Z confidence level, equivalent to a tiaescale for period change of |p/PJ26.9xtO8 yr. ^Published in Proceedings of the IAU Symposium 123, Helio- and Astrosisaology, ed. J.C.Daalsgaard, and S. Frandsen (D. Re ide1, Holland), 1986. -«On leave from 1F-UFRGS, Brazil. A COMPARISON BETWEEN OPTICAL AND X-RAY SIMULTANEOUS OBSERVATIONS OF THE VARIABLE PRE-WHITE DWARF STAR PCI 159-035* S.O. Kepler*. D.E.Winget**, M. Barstow++, J.B. Hollberg**, A.D. Crauer , D.O'Donoghue and M. Cropper We present 48.7 hr of high-speed optical photometry and 16.8 hr of con- tinuous X-ray observations of the pulsating pre-white dwarf star PG1159-035. A part of the optical observations is simultaneous with the X-ray data. We have detected variations in the X-ray light curve which have exactly the same periods as the optical variations, but the amplitude of the X-ray variations are about 18 tines larger. The X-ray and optical light curves are out of phase by $174 pm 38$ degrees. Supposing that the light variations are doainated by temperature variations, as is the case in the ZZ Ceti stars, we have calculated the amount of temperature variation from the observed amplitudes to be xxxx. «Submitted to Astrophysical Journal, 1986, +Work performed in part at Instituto de Pesquisas Espaciais and at IF-UFRGS. **Dept. of Astronomy and McDonald Observatory, Vriversity of Texas, Austin. •M-Earth & Space Science Institute, Tucson. IDpt. of Physics and Astronomy, University of Arkansas, Little Rock. SfDpt. of Astronomy, University of Cape Town, South Africa. IV. PHYSICS EDUCATION -116- TWESES OK PHYSICS TEACHING IN BRAZIL* M.C. Diber de Ure** and «.A Moreira Following a brief introduction on graduate program» on physics education in Brazil, a complete list of the master's dissertations presented at the Institute of Phyãic» of the Federal University of Rio Grande do Sul (UFRCS) in this area is given and the abstracts of several of them are provided. At the time this paper vas written there were only two graduate programs in physics education in Brazil, one at UFKGS and the other at the University of São Paulo (ÜSP), both at the M.Sc. level. The UFRGS program started in 1968 and is a master's program in physics with emphasis on physics education whereas the USP program is in science education with emphasis on physics. Both programs have so far produced more than twenty graduates in physics education. •Published in Ensenanza de Ia? Ciências, Barcelona, 3(1): 63-66 (1985) [in Spanish]. ^Universidade Federal Fluminense. TEACHING AT THE UNIVERSITY: SUGGESTIONS TO THE TEACHER* M.À. Moreira Instructional strategies such as concept mapping, task analysis, programmed individual tasks, questionnaires, and modules are described and suggested for college teachers in a language appropriate for those not familiar with the educational jargon. Some basic concepts on teachins and learning are discussed at the beginning of the book to serve as an advance organizer for the proposed strategies. •Published in Porto Alegre, Editora da Universidade, 1985. 130 p. [in Portuguese]. -117- COLLEGE TEACHING: INSTRUCTIONAL ALTEMATIVES* M.A. Moreira First, instructional alternatives, such as Che Keller Plan» «re des- cribed and discussed. Then, an alternative approach to the traditional lecture foraat is proposed. Finally, nore recent instructional strategics such as concept mapping. Govin's five questions and Gowin's epistcaological Vee are introduced. The book is designed for college teachers not faailiar with the educational jargon. ^Published in Porto Alegre, D.C. Luzzatto Editores Ltda.; Rio Grande, Editora da FURG, 1985. 135 p. [in Portuguese]. TEACHING AND LEARNING: THEORETICAL APPROACHES* M.A. Moreira This book includes a set of six monographs and theoretical approaches to learning and instruction. Each one deals with a specific author (B.F. Skinner, R. Cagné, J. Bruner, J. Piaget, D. Ausubel and C. Rogers) and is written with the purpose of beeing accessible to college teachers who are not familiar with the educational jargon. *Fublished in São Paulo, Editora Moraes, 1985. 94 p. [in Portuguese]. STÜDENX EVALUATION OF TEACHER'S PERFORMANCE: NEW EVIDENCES OF VALIDITY OF AN INSTRUMENT* Fernando Lang da Silveira , Marco Antonio Moreira and Antonio Dias Nunes +* From Che answers of 1982 students to a questionnaire designed to evaluate teacher performance of 36 teachers of the Institute of Physics of PUCRS, additional evidences are presented for the validity of such instrument. •Published in Ciência e Cultura 17 (8):1237-1240, 1985. [in Portuguese]. -••Instituto de Física e Faculdade de Educação da PUCRS. +•Instituto de Física da PUCRS. -1 t8- COBCETT MAPTIXG: AN ALTERNATIVE STRATEGY FOR EVALUATION* M.A. Moreira Concept maps «re proposed as aa alternative tool for evaluation in higher education and examples of concept maps, dram by college students performing evaluation teaks, are presented in the areas of physics and literature. «Published in Assessment and Evaluation in Higher Education 10(2):159-168, 1985. CTSKA1CH METHODOLOGY AMD TEACHING METHODOLOGY: A PRACTICAL APPLICATION* M.A. Moreira An experiment carried out in an introductory college course is analysed with the purpose of illustrating an approach for critical analysis of research papers. This approach can also be used to extract knowledge from documented clains in order to render this knowledge into a fora appropriate for instruction. «Published in Ciência e Cultura 37(10): 1588-1594, 1985. [in Portuguese]. BETA COEFFICIENT: ESTIMATE OF THE RELIABILITY COEFFICIENT OF A COMPOSITE VARIABLE* Fernando Lang da Silveira It is proved that the square of the correlation between a component and a composite variable is an estimate of the reliability coefficient of the couponed.. From this result, the beta coefficient (reliability coefficient of a composite variable) is deduced. The Cronbach's alpha coefficient and the beta coefficient are then calculated in twelve psychometric tests. The results suggest that the beta coefficient is a more acurate estimate of the reliability coefficient than the alpha one. «Published in Educação e Seleção, H^Jan/Jun): 105-108, 1985 [in Portuguese]. -119- SOME CHARACTERISTICS OF POftTO ALBCU HIGH SOWS. FaTSKS TEACHERS* A..C.R". doa Santos» M.A. Moreira «ai CE. Levaodowaki Ais work reporta the results of a survey coaceraiag the conditions of school physics teaching, particularly the teaching of laboratory, ia Forte Alegre, which waa coaducted through interviewing teachers aad visiting schools. «Published ia Caderno Catarinense de Ensino de Física, Florianópolis,-2(2): 51-56, 1985. [in Portuguese]. COGNITIVE MAPPINC IK THERMODYNAMICS THROUGH MULTIDIMENSIONAL SCALING* C.A. Santos and M.A. Moreira The content of Themodynaaics at introductory college level vas taught to engineering students under two different approaches. One was based on the learning theory of David Ausubel stressing progressive differentiation and integrative reconciliation while the other one was the traditional approach found on aost textbooks on the subject. Word association tests were applied to the experimental and control groups before and after instruction. Data gathered with these tests originated a similarity matrix whose structure waa investigated through multidimensional scaling (MDS). The MDS configurations thus obtained were supposed to provide a cognitive mapping which, in turn, was used to investigate the effect of the Ausubelian approach as compared to the traditional one. «Published in Physica Didactic*, Bad Salzdetfurth/Hildesheim, 1_2(4): 3-10, 1985 [translated from Spanish into German and «published]. INTUITIVE CONCEPTS IN OBJECTIVE ITEMS APPLIED IN ENTRANCE EXAMINATIONS AT THE UNIVERSIDADE FEDERAL DO RIO GRANDE DO SUL* Rolando Axt Data from objective itass about Newton's laws of motion, applied in a sequence of entrance examinations at the Universidade federal do Rio Grande -120- do Sul, suggest the existence of a spontaneous conceptual structure» a kind of alternative notion "lam", which conflict with formal law and frequently prevail «hen conceptual understanding of tkese fomal lavs is expected. Some reasons for the persistance of this intuitive conceptual structure, exhibited even by students that pretend to enter at the university, are discussed in function of local teaching practice and of a teaching model which establishes conditions for replacement of one conceptual structure by another. •Published in Ciência e Cultura 38(3): 444-452, 1986. [in Portuguese]. CONCEPT MAPS* M.A. Moreira and P. Rosa Concept maps are proposed to high school physics teachers as a useful tool for physics instruction. After a brief description of the concept map- ping technique examples of concept maps drawn for teaching purposes are given. In addition, examples of concept maps drawn by high school students in the area of kinematics are also provided suggesting that they can be used as a nontraditional instrument for cognitive learning evaluation. "Published in Caderno Catarinense de Ensino de Física, Florianópolis, ^ 17-25, 1986 [in Portuguese]. ~" CONCEPT MAPS IN PHYSICS TEACHING* S.T. Gobara* an< M.A. Moreira Aiming at the investigation of the potentialities of concept naps as instructional aid in physics teaching, an experiment was carried out in an introductory college course on electricity and magnecistn. Tor the experimental group, the treatment encompassed four steps characterized by individual interviews (not clinical) with the students. In two of these steps, the students were instructed with concept maps and stimulated to draw their own maps and to use them as a learning aid. In the other two, they were requested to draw, and explain, a concept map for a given list of key concepts. With -121- Che students fro» the control group the concept sapping technique was never used, however, at the end of the course, corresponding to the fourth-step of the experimental group, they were also requested to draw a concept sap receiving juat brief instructions on now to do it. All these maps, together with data collected in the interviews, vere analysed both qualitative and quantitatively, This paper is concerned only with the qualitative analysis, whose results sees to indicate that: 1. in the experimental group, end-of- -course concept Mips drawn by the students were qualitatively different frost those they drew at the saddle of the course, suggesting that learning Has take» place; 2. the great Majority of the students of the experisentai group was highly favorable to the use of concept naps ms instructional aid, judging them very helpful in learning physical concepts; 3. the saps drawn by students of the experimental gioup, in the fourth step, were qualitatively superior than those drawn by the students of the control group. *Published in Ciência e Cultura 38(6): 973-982, 1986.[in Portuguese]. +Departaneoto de Ciências Exatas e Naturais, PIDENE/IKIJUI. CURRICULUM EMPHASES AMD SCIENCE TEACHER PREPARATION* H.A. Moreira and R. Axt It is argued that some of the existing problems in the preparation of science teachers result from a lack of frameworks in terms of curriculum. Therefore, alternative frames of reference for designing and analysing the curriculum of science teacher preparation courses are offered through the presentation of different curriculum emphases. In addition, some comments on the present preparation of science teachers are made in the light of these curriculum emphases. By science teacher is understood not only the one who teaches science at primary school but also the one who teaches physics, chemistry or biology at high school. ^Published in Caderno Catarinense de Ensino de Física, 3(2): 65-78, 1986. [in Portuguese]. ~~ -122- THE ÁKTRAMCE EXJKIKATlOtt OF THE FEDEIUU, UMIYEftSlTY OF 110 CBATOE DO SUL (UFRGS)* Bernardo Buchveits A general description and analysis of the entrance examination of the UFRGS since 1972 is presented. The data show that various changes in th« testing system and selection criterion happened throughout these years, mostly because of aspects such as increasing number of students, content emphasis, accuracy of grading system, achievement level, administration requirements, and previous results. «Published in Educação e Seleção, J_3 (Jan/Jun): 59-65, 1986 [in Portuguese]. AN EPISTEMOLOGICAL ANALYSIS OF CURRICULUM* Bernardo Buchweitz This curriculum study presents a method of curriculum analysis and the results of an analysis of six physics laboratory experiments. The analysis shows that experiments provided procedures for making knowledge, considering that in each experiment students were expected to answer questions after they had caused events to happen, gone through records and data, and used the conceptual structures. The structures of knowledge of the experiments differed from each other in terms of the number of key concepts per experiment, the number of results and conclusions per experiment, and the kinds of conclusions. The epistemological method of curriculum analysis proved to be very useful for showing and improving the structures of knowledge of physics laboratory experiments. Concept mapping was shown to be a helpful technique for analyzing the conceptual structures of the experiments in detail. •Published in Educação e Seleção, 1£ (Jul/Dec), 1986 [in Portuguese!. -121- VALIDATIOK OF A TEST TO DETECT UHETJB& TBX STUDUT POSSESSES TBE KEVTOHIAN CONCEPTlOti ON FORCE A» MOTION* P.L. da Silveira, M.A. Moreira ead It. Axe A pencil and paper test is proposed to detect whether or set an individual possesses the Kevtoai** conception oft fere* amd motion, lesults of the application of this test to different group* of students are presented and evidences of validity of such an instrument are provided. «Published in Ciência e Cultura 36(12): 2047-2055, 19S6. [in Portuguese}. CONCEPT MAPPING IN THE INVESTIGATION OP STUDENT'S CONCEPTUAL KNOWLEDGE STRUCTURES IN PHYSICS* M.A. Moreira and W.A. Guerra* A szudy in which concept napping was used as a technique to gather information about changes in the learner's conceptual knowledge structures in physics is described. Research findings suggest that this technique is useful for such a purpose and enabled the researchers to distinguish between two broad classes of students according to their abilities to build their own conceptual organizations. Sample concept maps from each of these classes are presented. Research findings also suggest that concept napping *night be a useful tool to gather evidence of meaningful learning. «Published in Revista Ensenanza de Ia Física, Argentina, 1986. [in Spanish]. +Universidad del Norte, Chile. PHYSICS LABORATORY: LEARNING MEASURING INSTRUMENTS* Bernardo Buchweitz and Hernán Janete In order to gather evidence about some possible learnings that can occur vhen students perform physics laboratory activities, various measuring instruments were designed to get information about the different categories of learning (concept, method, inquiry structure, attitude, and ability). The use of such instruments is proposed and discussed after they had been tried out with the students. FRTSICS LABORATORY: AH AHALYSIS OF CUttlOILUK* Hernia Jasett*, Bernardo Buchveitz and Marco Amtooio Moreira A method of curriculum analysis of laboratory experiments io physics, with emphasis on the knowledge structure of th« esperimeat», is presented- This method was used co aaalyze the currioiliai of the Experimental Physics IV course of UFUGS» which envolves experiments in optics. la general, the analysis carried out shows the Methodological and conceptual structure of each experiment and, as such, the knowledge that can be learned by doing these experiments. «Published in Ciência e Cultura 38(12): 1995-2003. [in Portuguese]. +Universidad de Oriente (Venezuela) CONCEPT MAPS* Karco Antonio Moreira and Bernardo Buchweitz This book presents a general description of the concept sapping technique. It also shows how concept saps can be used *9 instructional tools in teaching, as learning evaluation instruments, and in the analysis of curriculum. *São Paulo, Editora Moraes, in press [in Portuguese}. AN EMPIRICAL STUDY ABOUT THE RELATION EE'tMfN THE PERIOD AND THE AMPLITUDE OF A SIMPLE PEHDUUttl* Fernando Lang da Silveira The relation between the period and the amplitude of a simple pendulum is studied through an appropiate statistical treatment and by using simple equipment. *To be published in Caderno Catarinens-? de Ensino de Física, 3(3) C*n Portuguese]. *~ -125- DETECTION OF INTUITIVE CONCEPTS IN ELECTRICITY USING CLINICAL INTERVIEWS* M. Eugenia Domínguez* and Marco Antonio Moreira The results of a pilot study in which clinical interviews were used to look for college students' misconceptions in the area of electricity are reported. The use of clinical interviews as an instrument to detect student's misconceptions is discussed with some detail and several excerpts of interviews are presented in order to give to prospective users of such technique an idea of the kind of work that is Lehind it as well as of the kind of data it provides to the researcher. *To be published in Revirta Ensenanza de Ia Física» Argentina, [in Spanish]. +Universidad de Oriente. (Venezuela) THE INFLUENCE OF THE INSTRUMENT OF EVALUATION ON THE KIND OF EVIDENCE GATHERED ABOUT LEARNING FROM LABORATORY PHYSICS* + A.C.K. dos Santos f M.A. Moreira and C.E. Levandowski Two studies in the area of physics laboratory teaching at high school level in schools of Porto Alegre are described. The teaching which included laboratory was compared with the exclusively theoretical teaching in terms of knowledge acquired by the student, and the influence of the instrument of evaluation on the kind of evidence gathered about learning from laboratory was shown. *To be published in Caderno Catarinense de Ensino de Física, HD-l™ Portuguese] ^-Departamento de Física da FURG. THE ATTITUDE TOWARD PHYSICS: DOES LABORATORY PHYSICS MATTER? A.C.K. dos Sartos*, M.A. Moreira and C.E. Levandowski Three studies are described in which an attempt was made to detect the influence of laboratory classes on changing the attitude of high school students toward physics. ^Submitted to Reviste da FURG. •Departamento de Física da FURG, -126- EVIDENCE OF LEARNING PRODUCED BY LABORATORY PHYSICS TEACHING: INFLUENCE OF THE EVALUATION INSTRUMENT* M.A. Moreira, A.C.K. dos Santos* and C.E. Levandowski An experiment in the area of laboratory physics teaching at high school level is described. Research findings suggest a strong influence of the evaluation instrument on the nature of the evidence gathered about learning from such kind of teaching. «Submitted to Revista de Ensino de Física. -••Departamento de Física da FURG TEXTBOOKS AS VEHICLES OF CURRICULUM EMPHASES IN PHYSICS TEACHING* M.A. Moreira and R. Axt Assuming that textbooks are vehicles of curriculum emphases in science education, a series of different curriculum emphases are introduced and some texts ^.n the area of physics teaching are examined in the light of these emphases. *To be published in Revista de Ensino de Física 8(1). [in Portuguese]. FRAMEWORKS FOR CURRICULUM ANALYSIS AND DESIGN IN SCIENCE TEACHING* M.A. Moreira and R. Axt Different curriculum conceptions and emphases are briefly described as frameworks for curriculum analysis and planning. In addition, some comments are made on the teaching of science in the light of these emphases and conceptions. -'To be published in Ciência e Cultura 39(3). [in Portuguese]. - I 2 7 - LABORATORY TEACHING MATERIALS FOR SECONDARY SCHOOLS* R. Axt, V.H. Guimarães and B. Buchweitz The problem Even if many school teachers recognize that experimental work at secondary level is fundamental for increasing the quality of Physics teaching, in fact most schools offer very little laboratory activity. Conventional laboratory materials are generally demonstrative, tirae consuming for preparation and little effective in engaging the student actively. Acquisition and maintenance of such materials use to be expensive and sometimes very difficult to accomplish. In many schools, as a result of discontinuous laboratory activity, components are spoiled or lost. Perhaps as a consequence, school administra- tors generally show little interest in acquiring new laboratory materials. Bes.-les this, the educational system makes the teacher to run from class to class, so that his laboratory teaching plans are left behind from one day to another. In addition, one also has to take into account a shortage of qualified teachers. Laboratory materials: a new version Assuming that laboratory work is an important part of Physics teaching at secondary level and that a variety of materials avalilable in the schools' laboratories are inadequate for practical activity and dissociated from reality, we decided to develop laboratory materials, in the form of kits, for experimental teaching of Mechanics, Electricity & Magnetism and Optics. Our purpose was to produce simple materials, which could be easily handled, without unnecessary sophistications, aiming at a student-centered teaching and at an enrichment of the learning environment. The apparatus should encourage teachers to use it: they shouldn't have reasons to fear laboratory work. The apparatus should be of good quality and nevertheless not too expensive. It should be possible to collect it safely and rapidly. The conciliation of all these characteristics involved some definite options: a) in order to involve students actively we preferred to multiply the apparatus instead of offering a great number of different experiments; b) in order to reduce costs, the measuring instruments were simplified and many components were used in more tnan one apparatus arrangement; c) in order to supply the lack of a good (and safe) laboratory room and to facilitate the displacement of the material, it was paaked in wooden boxen, each one of them containing enough apparatus for five times Welve different experimenl&; -128- d) in order to help teachers to overcome possible defficiences in laboratory work experience, a teacher's gvids was written for each unit. The three kits (Mechanics, Electricity & Magnetism and Optics) contain experiments about motion, forces, energy, fluids, simple circuit elements, magnetic and electromagnetic phenomena and optical phenomena. Most experiments are quantitative and, since there are five sets of apparatus available in each kit, enquiry methods are suggested as a common teaching practice. A more detailed and theoretically based description of this project is found elsewhere . Results The apparatus kits were multiplied and lent to physics teachers. In four years of existence, this project has introduced laboratory classes in more than forty secondary schools, many of which don't have any equipment al all. Reports account for greater involvement of students in learning activity, students feeling physics closer to real life, less rote learning from textbooks and teachers feeling stimulated by well succeeded laboratory classes. The simplicity of the apparatus is pointed out by students and teachers as an important aspect, because it reduces the chance of losing sight of physical phenomena and facilitates concept comprehension. As a matter of fact, the results of this project are so encouraging that we are planning to extend it to the elementary school: a kit for physics teaching at eight grade has been already designed and a prototype is being built. In this case, the activities are even more directed to concept comprehension, particularly those concepts about which the students usually acquire misconceptions. Thus, a closer theory-experiment interaction is tried to be assured through the corresponding written units. 1. Axt, R. and Guimarães, V.H. Experimental physics teaching in secondary schools: an attempt to make it feasible. Ciência e Cultura, }]_(.\), 1985 [in Portuguese], It is discussed the role of laboratory teaching in schools, examining contributions from learning theories and the nature of scientific knowledge itself. In addition, it is described a specific project aimed to give support to experimental teaching of physics in secondary schools of Rio Grande do Sul. *Work in progress. -129- STÜDIES CONCERNED WITH PHYSICS LABORATORY IK PORTO ALEGRE HIGH SCl«X)LS* Arion de C.K. dos Santos Initially, this work is concerned with a review of the literature on the conditions of high school physics teaching before and after the teaching reform (Law 5692/71). Afterwards, it reports the results of a survey concerning the conditions of high school physics teaching, particularly the teaching of laboratory, in Porto Alegre, which was conducted through interviewing teachers and visiting schools. Following this second part, the focus is on three studies in the area of physics laboratory teaching which were carried out in order to compare the results of physics teaching including laboratory classes and physics teaching without laboratory classes. Data collected with nontraditional achievement tests showed statistically- significant differences favoring the teaching accompanied by laboratory classes, in terms of content acquisition. No significant differences were found concerning changes on students attitude towards physics. *M.Sc. dissertation. Porto Alegre, Instituto de FÍsica-UFRGS, 1984. 336 p. [in Portuguese]. PHYSICS LABORATORY: CURRICULUM AND ACTUAL LEARNING OUTCOMES ANALYSIS* Hernãn D.J. Carrasco In this study the curriculum of a General Physics laboratory course and the learning outcomes resulting from performing the activities of this course were analyzed. The curriculum analysis consisted basically of an epistemological analysis of the methodological and conceptual structures of ten laboratory experiments of the course "Experimental Physics IV" at UFRGS, trying to ascertain the learning outcomes that could result from its development. The findings of this analysis have shown that the possible learning outcomes may be classified according to the following types: of content, of the method, of the structure of scientific research, of abilities (practical ând intelectual), and of attitudes (scientific and towards laboratory work). The analysis of the actual learning outcomes, on the other hand, was designed to investigate at what levels the possible learning outcomes were attained by students taking this course in the two semesters of -1 30- 1934. Several instruments of neasureoent were designed and developed for such analysis, and evidences of validity were gathered for these instruments. By and large, data collected in this part of the study have shown that the learning levels reached by the students in bath semesters were good in terms of content, sethod» structure o£ scientific research, practical ability, and attitude towards laboratory work, but were unsatisfactory concerning intellectual ability and scientific: attitude. *M.Sc. dissertation. Porto Alegre, Instituto de FÍsica-UFRGS, 1985. 208 p. [in Portuguese]. INTUITIVE CONCEPTS ON ELECTRICITY DETECTED THROUGH CLINICAL INTERVIEWS* Maria E. Dominguez Clinical interviews were used to detect intuitive concepts held by students concerning electric field and potential and current intensity and potential difference in simple electric circuits, as well as to study the permanence of these intuitive concepts after instruction. The subjects of the study were engineering students enrolled in an introductory electromagnetism course at the Federal university of Rio Grande do Sul, in 1984. Research findings showed that the clinical interviews which had been conducted allowed the identification of certain intuitive concepts and that, in general, they remained almost unaltered after instruction. *M.Sc. dissertation. Porto Alegre, Instituto de FÍsica-UFRGS, 1985. 247 p. [in Portuguese]. SPONTANEOUS CONCEPTIONS ON TERMODYNAMICS: A STUDY AT COLLEGE LEVEL USING CLINICAL INTERVIEW* Laércio E.F. da Silva This study used clinicai interview in order to investigate spontaneous conception." on temperature, heat and internal energy held by college students before and after the instructional process had been carried out. Physics and Chemistry students enrolled in an introductory phygics course at the Federal V. INSTRUMENTATION -133- SCKIISOLATED LIQUID HELIUM DEUARS AND VALVES FOR RIGID TRAKSFEJt Tl'BES* V.I. Schreiner and J. Schaf Be describe MR very simple cryogenic solutions in the construction of svperisolated Dewars for liquid He «ad of valves for transfer tubes which operate at • K. «Published in Revista de Física Aplicada e Instrumentação, U.b) 413 (1986). A PRACTICAL GOXDUCTAJKZ METER FOR LOW TEMPERATURE RESISTANCE TtfRMOMETRY AND CONTROL* M. Fin and M.R. Baibich He htve built • »rst«m that allow* masuracnt of electrical conductances raatiag frost 10 «icho to 2 •ho.This is achieved by using synchronous detection technology to analyse the signal costing fro» the resistance being owasured vhich is excited by a square wave current. All that is needed for the aeasureaent, including a calibration resistance, i* contained in one snail box and the reading of the conductance is nade on any cosswrcial voltmeter. «Submitted to J. Phys. E. SYHCHUMOUS DETECTIOK OF SMALL CBANGES III THE RESISTANCE OF AMORPHOUS METALS* M. Fin and M.H. B»ibich We have built a complete system for resistance measurements using synchronous detection technology. The overall resolution is better Chan 50 pnm for changes on samples around 1 to 100 ft, with total svitchable gain of 10 . «Submitted to J. Phys. E. APPENDIX -135- LtST OF PUBLICATIONS - 1985/1986 W.K.Theusonn and K.A.Gusmão: Critical Exponents for • -Field Models with Long-Range Interactions, Physical Review B ^1 ("85) 379. K.Betz, G.Krein and Th.A.J.Meris: Bags in the Shell Model, Nuclear Physics A437 (1985) 509. R.Axt and V.H.Guimarães: O Ensino Experimental de Física em Escolas de Nível Médio; Una Tentativa de Viabiliza-Io, Ciência e Cultura 21 (1985) 39. S.Zimmerman and W.Graves: A Fastbus Master Controlled by a Multibus SBC and by a Personal Microcomputer, IEEE Transactions on Nuclear Science NS-32 (1985) 298. M.Behar, A.M.J.Perrero, A.Filevich and A.O.Macchiavelli: High Spin States in 97Rh, Zeitschrifc fur Physik A 320 (1985) 467. J.A.H.da Jornada, S.Block, F.A.Mauer and G.Piemarini: J.Phase Transition and Compression of LiNbO, under Static High Pressure, Journal of Applied Physics 57 (1985) 842. URE, M.C.D., M.A.Moreira: Tesis de didactics de Ia Física en Brasil, Ensenanza de las Ciências, 3 (1) 63 (1985). M.A.Moreira et ai.: Aprendizagem: perspectivas teóricas, Porto Alegre, Editora da Universidade, 1985, 167 p. M.A.Moreira (Org) Ensino na Universidade: sugestões para o professor. Porto Alegre, Editora da Universidade, 1985, 130 p. M.Behar, P.F.P.Fichtner, C.A.Oiivieri, J.P.de Souza, F.C.Zawislak aod J.P.Biersack: Range Profiles of Implanted Bi and Au in Aaorphous Silicon, Nuclear Instruments and Methods in Physics Research B6 (3) 453 (1985). R.Erichsen Jr., I.J.R.Baumvol and J.P.dc Souse: Recoil Implantation of Antimony into Silicon by Argon Ion Bombardment, Unclear Instrument* and Method* in Physics Research, B7/8, 316 (1985). -136- M.Deicher, G.Grübel, E.Recknsgel, Th.Wichert and M.Behar: f11In-Pd Interactions in Defect Cascades in AgPd and CuPd, Kueleer Instruments and Methods in Physics Research, B7/8, 119, Part.I (1985). C.R.Wie, C.R.Shi, M.H.Mendenhall, R.P.Livi, T.Vreeland Jr., and T.A. Trombello: Two Types of MeV Iou Bean Enhanced Adhesion for Au Pila» on SiO2, Nuclear Instruments and Methods in Physics Research B9, 20, 1985. E.A.Veit, A.W.Thonas and B.K.Jennings: KN Scattering in the Cloudy lag Model: s,p and d-vaves, Physical Review L>3_[, 2242, 1985. E.A.Veit, B.K.Jennings, A.U.Thomas and R.C.Barret: S-Have Heson-Nucleon Scattering in an Extended SU(3) Cloudy Bag Model, Physical Review D31, 1033, 1985. R.P.Livi: Adhesion Enhancement Induced by MeV Ion Beams» Nuclear Instruments and Methods in Physics Research, BIO/It, 545, rart.I (1985). C.R.Shi, H.S.Toh, D.Lo, R.P.Livi, M.H.Mendenhall, D.Z.Zhang and T.A. Tronbeilo, Secondary Electron Emission from the Entrance and Exit Surfaces of thim Carbon Foils under Fast Ion Bombardment, Nuclear Instruments and Methods in Physics Research, B9(3), 263 (1985). C.M.Hasenack, J.P.de Souza and I.J.R.Baumvol, The Suppression of Residual Defects in Silicon Implanted with Arsenic by Rapid Isothermal Annealing, Nuclear Instruments and Methods in Physics Research B9(3), 341, 1985. M.H.P.Corrêa, W.H.Schreiner, J.E.Schmidt, P.J.Viccaro and A.Vasques, Magnetic Properties of the Hydride Pd.FeH- _, Journal of Physics F, 15(8) 1779 (1985). M.E.V.Costa, R.O.Cirotti e T.J.M.Simões, Dynamics of Caugc Systems and Dirac's Conjecture, Physical Review D3Z (2), MS (1985). P.X.Kors, A.S.R.Simões and J.R.Iglesies, Real Space Renormslisation of a Miwd Valence Ramiltoniaa on a Betbe lattice. Solid State Communication*, 55 (3) 201, 1985. F.M.Mors aad J,R.Iglesiasr Effect of the d-f Coulomb Correlation on the Valence Transition of Intanvtfiat* Valence Systems, Solid State Commnication» 55 (3), 203, f985. -137- T.S.Bergmann, M.G.Pastoriía and M.F.S.SchrBder, BV Surface Photometry of the Southern Galaxies NGC 2855 and NGC 4507, Revista Hexicana de Astronomia j Astrofísica, ^0, 81, 1985. J.P.Mondt and J.Goedert, Dissipative Instabilities in the Edge of Reversed- Field Pinches Driven by a Combination of Plasaa Gradients and a Parallel Curent, The Physics of Fluids, _28(6), 1816 (1985). C.A.Z.Vasconcellos, H.A.Oottori and A.A.Schmidt» The Primeval Hadron and the Regge Law, Astrophysics and Space Science, JH3Í2) 383, 1*85. W.H.Schreiner, W.Stamp, and E.F.Wassernann, Re-Entrant Spin-Glass Behaviour in Ordered and Disordered Pt_(Mn Fe ) Alloys, Journal of Physics F, 15(9) 2008, 1985. A.Vasquez, J.M.Friedt, J.P.Sanchez, Ph. l'Heritier and R.Fruchart, Spin Reorientation Phenomena in RE^Fe-.B (RE =Ce,Dy,Er) alloys from Fe and Dy MBssbauer Spectroscopis , Solid State Communications, 5M9) 783, 1985. P.M.Mors, J.R.Iglesias and E.V.Anda, Effect of the Spatial Correlation on the alloy Analogy Approximation to the Kubbard Hamiltonian, Solid State Communications, _55(9) 827, 1985. C.A.Olivieri, H.Behar, P.F.P.Fichtner, F.C.Z?.wislak, D.Fink, J.P.Biersack, Depth Profile and Thermal Annealing Behaviour of Bi Implanted into an Al/Ti Bilayer Structure, Journal of Applied Physics, ^8(2) 659, 1985. P.H.Dionisio, B.A.S.Barros Jr, l.J.R.Baumvol, Comparative Study of Internetallic Phases Formed by Direct Ion Implantation and Radiation Enhanced Diffusion of Tin in Two Kinds of Steels, Journal of Applied Physics, 58(2) 773, »98>. D.Fink, J.P.Biersack, J.T.Chen, K.StSdele, K.Tjan, M.Behar, C.A.Olivieri and F.CZawislak, Distributions of Light Ions and Foil Destruction After Irradiation of Organic Polymers, Journal of Applied Physics, 58(2) 668, 1985. K.A.Moreira, Atividade Docente na Universidade: Alternativas Instrucionais, Porto Alagre D.C. Luzzatto Ed. Rio Grande Ed. da FURG, 133 p., 1985. M.A.Mora ira, Concept Happing: an Alternative Strategy of Evaluation Assessment and Evaluation in Higher Education, _tO(2) 159, 1985. -138- J.B.M. da Cunha» P.J.Viccaro and A.Vasques, Spin ftaorientatioa in (tr,Cd)Pe_ Compounds, J.Phys.F: Ket.Phys. 15 O985) 709. P.L.Silveira et ai.: Avaliação do Desempenho do Professor p«lo Aluno: Movas Evidências de Validade de un Instrumento. Ciência e Cultura, 37(8) 1237, 1985. M.A.Moreira: Ensino e Aprendizagem: Enfoques Teóricos, Editora Moraes, São Paulo, 94 p., 1985. F.L.Silveira: Coeficiente Beta: Estimativa do Coeficiente de Pidedignidade de uma Variável Compõsita, Educação e Seleção, _U.» 105 O985). M.Behar, P.P.P-Fichtner, C.A.Olivieri, J.P. de Sousa, F.C.Zawislak, J.P. Biersack, D.Fink and M.Stgdele: Range Profiles of 10 to 380 keV i20Sn and "Cs in Amorphous Silicon, Radiation Effects, 90, (1/2), 103 (1985) M.A.Moreira: Metodologia da Pesquisa e Metodologia de Ensino: Una Aplicação Prática, Ciência e Cultura, 37(10), 1588 (1985). S.Jha, H.M.Seyoum, G.M.Julian, R.A.Dunlap, A.Vasquez, J.B.M. da Cunha and S.M.K.Raaoa: Byperfine Fields at sp Sites in the Heusler Alloys RtuMnZ (Z «Ge,Sn,Pb), Physical Review B 32(b) 3279, 1985. S.Block, J.A.H. da Jornada and G.J.Piermarinz: Pressure-Teaq>erature Phase Diagram of Zirconia, Journal of the Anerican Ceramic Society, £8(9) 497, 1985. M.Behar, E.R.Fraga, A.Maciel, W.H.Schreiner and H.Saitovitch: Temperature Behaviour of the Electric Field Gradients in the Switching inSe Conpound, Journal of Physics C J_8( 31) 5863 (1985). G.L.Fraga, J.V.Kunzler and D.E.Brandão: Spin-Disorder Resistivity in Ni2Mn(SnJj(Inx) Heusler Alloys, J.Phys. Chen. Sol ids, 46(9) 1071 (1985). W.C.L.Pttppel and E.R.Vieira: A Southern Atlas of Galactic Hydrogen (The Region 24Ou < 1 < 359°, • 3° E.H. da Jornada, J.D.Gaffey Jr., D.Wineke: Instabilities Excited by an Energetic Ion Baas and Electron Temperature Anisotropy in Tandem Mirrors, Fnys. Fluids 28(2) 611 (1985). -139- M.R.Olcay, J.A.Pasqual, J.A.Lisboa and R.E.Fraifke: Tuning of a Narrow Linewidth Pulsed Dye Laser vith a Fabry-peroC and Diffraction Grating Over a Large Wavelength Range, Appl.Opt. 24, 3146 (1985). M.B.Gay Ducati, C.A.Garcia Canal and E.M.Santangelo: Excitation Rates of Heavy Quarks, Phys.Rev. D JJU 2748 (1985). P.Pureur Kato, A.Fert, K.Baberschke and R.Wendler: Magnetic Ordering in YGd Alloys, J. of Appl. Physics, 57(1) 3230 (1985). H.O.Girotti, K.D.Rothe; Quantization of QED and QCD in a Fully Fixed Temporal Gauge, Zeitzchrift fur Physik C, 27(4) 559, 1985. S.P. da Cruz and F.P.Livi: Inductive Observation of Transitions from [100] Domains to [010] and [001] in Silicon-Iron, J. Applied Physics 57(1) 4220, 1985. I.J.Hodgkinson, F.Horowitz, H.A.Macleod, M.Sikkens and J.J.Wharton: FECO- Based Observations of Birefringence at Normal Incidence in Optical Coatings, Appl. Opt. 2J4(11) 1566 (1985). R.Wendler, P.Pureur, A.Fert and K.Baberschke: Magnetic Properties of Gd Doped Y and Sc Single Crystals, Journal of Magnetism and Magnetic Materials, 4Jp_ (2/3), 185, 1985. P.Pureur, G.Creuzet and A.Fert: Magnetostriction of Single Crystals of Yttrim Doped with Rare Earths Impurities, Journal of Magnetism and Magnetic Materials, _53 (1/2), 121, 1985. I.J.Hodgkinson, F.Horowitz, H.A.Macleod and J.J.Wharton: Measurement of the Principal Refractive Indices of Thin Films Deposited at Oblique Incidence, J.Opt.Soc.Am. A 2(10) 1693 (1985). P.Kitching, W.J.McDonald, Th.A,J,Maris and C.A.Z.Vasconcellos: Recent Developments in Quasi-Free Nucleon-Nucleon Scattering, Advances in Nuclear Physics, Vol. 15, 43, 1985. R.P.Livi, S.Paine, C.R.Wie, M.H.Mendenhall, J.Y.Tang, T.Vreeland Jr. and T.A.Tombrello: Electrical Contact and Adhesion Modification Produced by High Energy Ion Bombardment of Au Films on GaAs, Materials Research Society Symposium V_f 467 (1985). -140- G.Giruzzi, V.Krivenski, I.Fidone and L.F.Ziebell: Electron Cyclotron Wave Absorption by the Fast Tail Generated by the DC Electric Field in Tokamak Plasmas, Plasma Phys. and Contr. Fusion, £7(10) 1151 (1985). J.R.Iglesias and P.M.Mors: Effect of the d-f Correlation on the Electronic Structure of Intermediate Valence Systems, Solid State Coins. 56(7) 557 (1985). P.J.Brown, R.Caudron, A.Fert, D.Givord and P.Pureur Neto: Helimagnetic Structure in Diluted Y-Gd Alloys, Journal de Physique Letters, 46_(23) 1139 (1985). S.Zincnermann: Development of a Fastbus Diagnostic System, Interfaces in Computing, _3_i 295 (1985). A.Theumann: Quantum Spin Glass: a Replica-Symmetric Theory with Positive Entropy, Physical Review B, **(1) 559 (1986). M.Behar, J.P.Biersack, P.F.P.Fichtner, D.Fink, C.A.Olivieri and F.C.Zawislak: Range Distributions and Thermal Behaviour of Bi Implanted into KC1 and A1/KC1 Biiayer Structures, Nuclear Instr. and Methods in Phys. Research, B14(2) 173 (1 *•/•). H.R.Lewis and J.Goedert: Exact Invariants in Resonance form for Time- r>ependent Potentials, Physica D, J8D (1/3), 213 U986). J'.F.P.Fichtner, M.Behar, C.A.Olivieri, R.P.Livi, J.P. de Souza, F.C.Zawislak, D.Fink and J.P.Biersack: Energy Dependence of the Z.-Range Oscillation Effect in Silicon, Nucl.Instr. and Meth. in Phys.Res. B15, 58 (1986). I.Fidone, G.Giruzzi, V.Krivenski, L.F.Ziebell and E.Mazzucato: Electron- cyclotron Heating of a Tokamak Reactos with the Extraordinary Mode, Physics of Fluids, 2jK3) 863 (1986). C.M.Hasenack, J.P. de Souza and I.J.R.Baurovol: Residual Defects in Implanted Silicon Submitted to RTA: Evidence of a Chemical Effect, Nucl.Instr. and Meth. Phys. Research, JJH, 290 (1986). R.Axt: Conceitos Intuitivos eic Questões Objetivas Aplicadas no Concurso Vestibular Unificado da Universidade Federal do Rio Granae do Sul, Ciência e Cultura, 38(3) 444 (1986). -141- J.F.Fontanari and U.K.Theumann: Effects of Trilinear Symmetry Breaking on the Potts-Model Transition of Uniaxially Stressed SrTiOj, Physical Review B, ^3(5) 3530 (1986). P.F.Fichtner, M.Behar, C.A.Olivieri, R.P.Livi, J.P. de Souza, F.C.Zawislak, D.Fink and J.P.Biersack: Large Z -Range Effect for Eu, Yb and Au Ions Implanted in Amorphized Silicon, Rad. Eff. Letters 87 (1986) 191. P.H.Dionisio, C.Scherer, S.R.Teixeira and I.J.R.Baumvol: Direct Ion Implantation and Radiation Enhanced Diffusion of Tin into Iron, Nucl.Instr. Metr. Phys. Research JM6(4/5) 345 (1986). D.Fink, J.P.Biersack, M.StSdele, K.Tjan, M.Behar, P.F.P.Fichtner, C.A. Olivieri, J.P. de Souza and F.C.Zawislak: Range Profiles of Ions in Double- Layer Structures, Nucl. Instr.Meth.Phys. Research B15, 71 (1986). M.Behar, P.F.P.Fichtner, C.A.Olivieri, F.C.Zawislak, D.Fink and J.P.Biersack: Implantation and Thermal Annealing Behaviour of Bi Implanted into Al/Ti and Al/V Bilayer Structures, Nucl. Instr. Meti. ?hys. Research BJJ5, 78 (1986). B.T.Werner, P.K.Haff and R.P.Livi: Measurement of Eolian Sand Ripple Cross- Sectional Shapes, Geology _U. 743 (1986). J.M.Friedt, A.Vasquez, J.P.Sanchez, P.L'Heritier and R.Fruchart Magnetism and Crystal Field Properties of the RE.Fe ,BH (RE -Y,Ce,Dy,Er) from MBssbauer Spectroscopy, J.Phys. F: Metal Phys., _1j6, 6u1 (1986). H.Northfleet Neto, A.Bristoti and A.Vasquez: A Simple Method for Pyritic Sulphur Determination in Coal, Using MBssbauer Spectroscopy, J. of Mineral Processing J£, 147 (1986). J.M.Friedt, A.Vasquez, J.P.Sanchez, Ph.L'Heritier and R.Fruchart: MBssbauer Spectroscopy on RE_Fe ,BH (RE «Y,Ce,Dy,Er) Alloys, Hyperfine Interactions, 28(1/4) 611 (1986). S.Jha, H.M.Seyoum, S.Yehia, C.Mitros, G.M.Julian, R.A.Dunlap, A.Vasquez, J.B.M. da Cunha and S.M.M.Ramos: MBssbauer Measurement of the Hyperfine Magnetic Field at sp Site in Heusler Alloys Rh?MnZ (Z>In and Sb), Hyperfine Interactions, 28(1/4) 491 (1986). A.S. da R.Simões and J.R.Iglesias: A New Approach Co the Study of on Anderson Impurity in a Linear Chain, Journal de Physique, 47^(6) 967 (1986). -142- R.B.Guimarães» M.Behar, R.P.Livi, J.P. de Souza, F.C.Zawislak, D.Fiak and J.P.Biersack: Mass and Energy Dependence of Implanted Ion Profiles in the AZ111 Photoresist, Journal of Applied Physics 60(4) 1322 (1986). H.O.Girotti, H.J.Rothe and K.D.Rothe: Quantum Dynamics of Chiral Pensions in a Model with Anomalous Breaking of Gauge Inv&riance, Physical Review D, 34(2) 592 (1986). H.O.Girotti, H.J.Rothe and K.D.Rothe: Canonical Quantization of a Two Dimensional Model with Anomalous Breaking of Gauge Invariance, Physical Reviaw D 33t 514 (1986). H.O.Girotti and H.J.Rothe: Canonical Derivation of the Gluon Propagator in the Temporal Gauge, Physical Review D 3JJ, 3132 (1986). T.J.M.Simões and H.O.Girotti: Operator Quantization of Non-Abelian Gauge Theories in a Completely Fixed Axial Gauge, Annals of Physics (NY) 169, 128 (1986). T.S.Bergmann and M.G.Pastoríza: BV Surface Photometry of Southern Galaxies I NGC 4507, The Astrophysical Journal, 304(1) 305 (1986). M.G.Pastoriza, E.L.D.Bica, M.V.F.Copetti and H.A.Dottori: Colour Gradients in Globular Clusters, Astrophysics and Space Science, 119(2) 279 (1986). H.A.Dottori and M.G.Pastoriza: A Comparative Study of the Stellar Content in Normal and Active Nuclei of Spiral Galaxies, Astrophysics and Space Science, 121(1) 147 (1986). E.M.Scherer, J.P. de Souza, C.M.Hasenack and I.J.R.Baumvol: A Channelling and Conversion Electron Mftssbauer Spectroscopy Study of Annealing Behaviour of Tin Implanted Silicon, Semiconductor Science and Technology, ViU) 241 (1986). M.C.Barbosa, M.A.Gusmão and W.K.Theumann: Renormalization and Phase Transitions in Potts C.A.Olivieri, M.Behar, P.F.P.Fichtner, F.C.Zawislak, D.Pink and J.P.Biersack: Implantation and Thermal Annealing Behaviour of Bi Implanted into the Al/KCT Bilayer Compound, Radiation Effects, £8(1/4) 27 (1986). -143- V.K.Theumann and J.F.Fontanari: The Spherical-Model Limit in a 1—irm Field, J. Scat. Phys. 45, 99 (1986). P.Pureur Meto: Anisotropic Thermal Expansion of Yttriuat Metal and Tttrium- Based Base Earth Alloys at Low Teaperatures, J. of Mag. and Mag. Mat. 60 (1986) 161. P.Nedellec, A.Traverse, L.Dumolin, B.Bernas and L.Amaral: Evidence for the Metal-Insulator Transition in a Pure 3D-Metal, Europhysics Letters 2_ n9 6 (1986) 465. L.Amaral, P.Hedellec, A.Traverse, H.Bemas, L.Dumolin and J.P.Berger: Electrical Transport of Bi-Ni under Helium Irradiation and Hidrogen Implantation, J. Phys. Ft Metal Phys. J£ (1986) 1239. M.Sikkens, I.J.Hodgninson, F.Horowitz, H.A.Maclead and J.T.Vharton: Computer Simulation of Thin Film Growth: Applying the Results to Optical Coatings, Opt. Eng. 25 (1986) 142. E.A.Veit, B.K.Jennings and A.V.Thomas: Pion-Nucleoo Scattering in the Cloudy Bag Modal, Phys. Rev. D 33 (1986) 1859. L.F.Ziebell and G.Granata: Angular and Momentum Distribution Dependence of Electron Cyclotron Absorption and Amplification in Mirror-Confined Plasmas. The Physics of Fluids, £9(1t) 3730 (1986). A.Vasquez, S.M.Friedt, J.P.Sanchez, Ph.L'Heritier and R.Pruchart: 166 Er MSssbauer Spectroscopy in the Zt-a ,BH Alloys, Solid State Comm. 5J (1986) 309. J.R.Ducati: The Distribution of Interstellar Extinction Near the Sun, Astrophysics and Space Science, 126(2) 269 (1986). I.Fidcne, G.Giruzzi, V.Krivenski and L.F.Ziebell: Electron Cyclotron Wave Damping for Oblique Propagation in Hot Plasmas, Nuclear Fusion, 26(11) 1537 (1986). A.A.Schmidt, H.A.Dottori and C.A.Z.Vasconcellos: The Average Density of the Universe and the Regge Lav, Astrophysics and Space Science, .127(1) 15 (1986), CA. dos Santos and I.J.R.Baumvol: 0 Aço Tratado, Ciência Hoje, ^(26) 72 (1986). K.H.Schreiner and J.Schaf: Recipientes Superisolados e Válvulas para Tubos de Transparência Rígidos para Hélio Líquido» Revista de Física Aplicada e Instrumentação, t(4) 413 (1986). A. de C.K.Santos, M.A.Moreira, C.E.Levandowski: Influência do Instrumento na Avaliação da Aprendizagem Decorrente do Ensino de Laboratório em Física, Caderno Catarinense de Ensino de Física, M3) 122 (1986). F.L. da Silveira: Estudo Empírico da Relação entre o Período e a Aaplitude de um Pêndulo Simples. Caderno Catarinense de Ensino de Física, 2(3) 134 (1986). J.Goedert and R.R.Lewis: Exact Invariants in the Form of Momentum Resonances for Particle Motion in One-Dimensional, Time-Dependent Potentials. In: Local and Global Methods of Nonlinear Dynamics, p. 254-63 (Lecture Botes in Physics, 252, Eds. A.W.Saenz, W.W.Zachary and R.Cavley, Springer Verlag, 1986). A.Theumann: Conductivity of a Random Electron Chain, Renormalization-Group Approach, Physica 139A, 553 (1986). -145- Papers accepted for publication S.D. de Souza, R.N.Saxena, W.Schreiner and F.C.Zawislak: Magnetic Hyperfine Fields in Heusler Alloys Cc.YZ (Y - Ti.Zr; Z * A2,Ca,Sn). Hyperfine Interac- tions. A.Vasquez and J.P.Sanchez: Spin Reorientat ion Phenomena in (Er. Gd )-Fe.,B Alloys. Journal of Less Common Metals. S.Jha, Mohaaed Elfazani, Sherif Yehia, C.Mitros, Sanjeev Kumar, Glenn M.Julian, R.A.Dunlap. A.Vasquez, J.B.l*. da Cunha and S.M.M.Ramos: TDPAC and MBssbauer Measurements of Hyperfine Fields in Chromium-Based Chalcogenide Spinels. Kyperfine Interactions. M.Behar, P.J.Viccaro, M.T.X.Silva, A.Vasquez. C.A.dos Santos and F.C.Zawislak: Influence of He-Vacancy Complexes on the Thermal Behavior of Nitrogen Preci- pitates in Fe. Nuclear Instruments and Methods in Physics Research. ?.B.Dionisio and I.J.R.Baumvol: Modifications of the Mechanisms of High Teapera- ture Oxidation of Steels by Tin Ion Implantation and Radiation Enhanced Dif- fusion Part I - High Carbon Steel. Physica Status Solidi (a). P.L.Grande, P.F.P.Fichtner, M.Behar, R.P.Livi, F.C.Zawislak, J.P.Biersack, D.Fink and P.Mertens: Projected Ranges and Range Stragglings of Au and Bi Implanted into Carbon Films and into SiO_. Nuclear Instruments and Methods in Physics Research B. A.A.Pasa, J.P.de Souza, I.J.R.Baumvol and F.L.Freire Jr.: Dopants Redistribution During Titaniun-Disilicide Formation by Rapid Thermal Processing. Journal ->f Applied Physics. C.M.Hasenack, J.P.de Souza and I.J.R.Baumvol: The Suppression of Residual Defects of Silicon Implanted with Group III, IV and V Eleaents. Semiconductor Science and Technology. P.Pureur, G.L.Fraga, D.E.Brandão, R.Caudron, H.Safa and G.Rieva: Specific Heat Measurements in Scandium-Rare Earth Anisotropic Spin Glasses. Journal of Mag- netism and Magnetic Materials. Alba Theumann: Superalgebra and the Spherical Model of a Spin Glass. Journal of Physics A. -146- M.A.Gusmão: Simple Approximation for the Bethe-Ansatz Solution of the One- Dinensional Fermi Gas. Physical Review B. V.Krivenski, I.Fidone, G.Giruzzi, R.L.Meyer and L.F.Ziebell: Power Dependence of Electron Cyclotron Wave Damping in Tokamak Plasmas. The Physics of Fluids. I.Fidone, G.Ciruzzi, V.Krivenski, E.Mazzucato and L.F.Ziebell: Cross Effects on Electron-Cyclotron and Lower-Hybrid Current Drive in Tokamak Plasmas. Nuclear Fusion. I.Fidone, G.Giruzzi, V.Krivenski and L.F.Ziebell: Electron Cyclotron Wave Damping for Oblique Propagation in Hot Plasmas. Nuclear Fusion. F.B.Rizzato, R.S.Schneider and D.Dillenburg: Temperature Effects on Ion Acoustic Solutions in Plasmas with near Critical Density of Negative Ions. Plasma Physics and Controlled Fusion. João Goedert and H.Ralph Lewis: Rational Functions of Momentum as Invariants for One-Dimensional, Time-Dependent Potentials: Basic Theory. Journal of Mathematical Physics. H.Ralph Lewis and João Goedert: Rational Functions of Momentum as Invariants for One-Dimensional, Time-Dependent Potentials: Two- and Three-Resonance Cases. Journal of Mathematical Physics. M.A.Moreira and R.Axt: Frameworks for Curriculum Analysis and Design in Science Teaching. Ciência e Cultura. Ducati,J.R., T.Storchi Bergmann, Bevílacqua.C.M., Bonatto,C, Cavalcanti,R.L., Costa,R.D.D., Dottori.H.A., Girardi.L., Hadjimichef,D., Kepler,S.O., Livi.S.H.B., Pastoriza,M.G., Santos,J.F., Schmidt,A., Schroder,M.F.S.: Strip Photometry of Comet Halley. Revista Mexicana de Astronomia y Astrofísica. Alex A.Schmidt and Horacio A.Dottori: Nuclear Stellar Population of NGC772 (ARP 78). Revista Mexicana de Astronomia y Astrofisica. Alexandre Fonseca Zepka and Horacio Alberto Dot tori: Morphology of LMC Clusters. Revista Mexicana de Astronomia y Astrofisica. Horacio A.Dottori, Jorge Melníck and Eduardo Bica: NGC 2209: The Nature of the Dark Patch, Revista Mexicana de Astronomia y Astrofisica. -147- A.A.Schmidt, C.A.Z.Vcsconcellos and H. A.Dot tori: Cosmological Mass Density and the Begge Lav. Revista Mexicana de Astronomia y Astrofísica. Boracio A.Dottori: Evolution of HII Regions. Revista Mexicana de Astronomia y Astrofísica. H.V.Copetti, B-Dottori and M.Pastoriza: Age Determination of the Magellanic Clouds and Isolated Extragalactic HII Regions.. Proceedings of the First IAF Meeting oe Star Foming Dwarf Galaxies and Related Objects. S.H.Bisch, M.G.Pastorixa, H.Dottori, X.Busko: A Search for Periodicities in the Light Variation of Some Seyfert Galaxies. Proceedings of the IAU Symposium «9 121. Bernardo Suchveitz and Hernin Jaeett: Physics Laboratory: Learning Measuring Instruments. Educação e Seleção. Marco Antonio Moreira and Bernardo Buchweitz: Concept Maps. São Paulo, Editora Moraes. Fernando Lang da Silveira: An Empirical Study about the Relation Between the Period and the Amplitude of a Simple Pendulum. Caderno Catarinense de Ensino de Física. M.Eugenia Doaínguez and Marco Antonio Moreira: Detection of Intuitive Concepts in Electricity using Clinical Interviews. Revista Ensenanza de Ia Física. A.C.K. des Santos, M.A.Moreira and C.E.Levandovcki: The Influence of the Instrument of Evaluation on the Kind of Evidence Gathered about Learning from Laboratory Physics. Caderno Catarinense de Ensino de Física. M.A.Moreira and R.Axt: Textbooks as Vehicles of Curriculum Emphases in Physics Teaching. Revista de Fnsino de Física, -148- PAPERS PRESENTED AT MEETINGS AND CONFERENCES International Meetings and Conference Second European Conference on Atopic and Molecular Physics, £ SCAMP. Holland. April, 1983 S.L.S.Cunha, L.Ulivi, P.Hsring, K.L.Konpa CARS Studies of NaH2 Collision Complexes ESO Workshop on Production and Distribution of_ £, N, £ Elepent», Garchtng. FRGr May 13-15, 1985 E.Bica, K.Dottori, rt.Pastoriza G Band and Hg Photometry of LMC and SMC Red Clusters 7th International Conference on Laser Spectroscopy, Wauit Hawai, June, 1983 S.L.S.Cunha» P.Hering, K.L.Kompa CARS Studies of NaH,, Collision Pairs First IAP Meeting on Star Forming Dwarf Galaxies and Ralatgd Objects, Institute d'Astrophysique d^e Paris, Paris, France, July 1-3, 1985 M.V.Cop«tti, H.Dottori, M.Pastoriza -Age of Extragalactic HII Regions -Age Indicators in Emission Regions J[X Latin American Symposium on Solid State Physics, Mar del Plata, Argentina, August 19-2A, 1985 I.S.Aveline e M.N.Baibich Transporte Eletrônico em Metais Amorfos Irene Strauch Aveline e Mario Baibich Resistividade Elétrica para Ligas Amorfas da Cu. Zr : üm Modelo Teórico -14*- t2th European Conference on Co*crolle4 Fusion ami Haa— Ifcyie», 2-*. »» C.GiruBti, V.Rrivenski and L.F.iiebell Electron Cyclotron Heating of * Tokawk Plasa* AC Dow-Shifted Pirat Itttern«cio«f 1 Congress on tesearch about Didactics is Sci—ce» —á j* lUthe—tic», l»rc»loaet Spain, Septeaber, 1985 H.A.Moreir», S.T.Gotwra CoacepCualcs coin Recursos lastruccionales •« la EaMAaasa 4* la Física IAU SypO5ÍUB HÇ H5 on Star Forming Regions, Tokyo, iapa», jfavedber II-T3» H.Dottori, M.V.Cop-tti Age De:*rninacioc of Hli Reçionâ in the Milky Kay Frit» Haber Internacionai Syaposiu» on Mesbo^s o£ Laser Syctreac^py, Dead Sea, Israel, December,, j985 S.L.S.Cunha, P.Hiring, K.L.Kompa CARS Studies of ftonadiabacic Collision Processes Annual Meeting o£ cfta carman mysicat Society, Heiuelberg, RFA, March, T9>» S.L.S.Ctmha, T.Wo«chnih, P.Kering, K.L.Koapa CARS Studies on Sa-He 13th European Conference on Control led Fusion and Plaiaa Phygics, Schliersee, April U-18, 1986 V.Krivenski, l.Fidona, C.Ciruzzi, R.L.Meyer and L.F.Ziebell Electron Cyclocron Daoping for Large Wave Power in Tokastsfc Plasms Annual Meating, Preach Croup of MBaabauer Spectroacopy, Aussoig, Franca, P.Ronville, J.A.Rodges, P.Hulliger, P.Inhere, J.B.K.da Cunha, K.R.Ctt Evidence H^ssbauar pour le Ordre Magnetique dans It YbP et YbAs IAU Syapoaiw oe "Observational Eviceoce stf activity i* •icial ot galaxies"» , Araema. US»» Jww »-TT. ». S-M.Bisch, K.C.Fascoriz«, H.Dettari, l. A Search for Periodicities in the Light variation of Saaw 3*yfert Galaxies li. Ljt^n «—eric»»» Heetiag on L«a*r P'.tV>íc» xsã its Aypticatioaa, Niterói, £J, -hn» 3g-J«Iy 55, , C.R.M.dc Oliveira. J.S.HícRfiSon, Y.A.Feisr i.H.Rickaftm. C.Scfc3aev«t Francke Espalhaaccto de Luz por Esfsr** J.S.Hickaan, T.Braun. H.Li&ardi» L.te>cter e R.E.Frtocke Resssnlacias aciãsatsis és Las«r 4* iiicrogânis ;33?noi} cos Transições de Sanaa B-t da Hoiácuia d* ledo J.A.Lisbca, L.C.P.ÍfoCta e T.Braun Evolução Tesçoral de KÍveis do Estado BK. ds I_ Populacos por Colisão R.E.Franrka üticxs •« us L»bcracsr£o se Espectroscopxa Laser International Conference oft Aaoaalotis Rara Earths an Aceiaides. Grenoble, Franca. July /-It. T$$6 P.Bonville, J.A.Hodges, F.HulIiger, P.ltãstrt, J.B.M.da Cunha and K.K.Ott HSssbauer Evidence for Magnetic Ordering in the "Heavy-Electron" Compounds YbP and YbAs STATPHYS-16 Conference, Boston University, USA, August It-tS, 1986 Mareia C.Barbosa, José F.Fontanari, M.A.Cueaão and W.K.Theuaenn Physical Relevance and Renormalization-Croup Calculations of Symaetry-Breaking Effects in the Continuum-Field Potts Model V Local Latinaaerican Meeting o£ the International Aatronogical Union, Herida, Mexico, October 6-10, 1986 J.R.Ducati, T.S.Bergmann, CM.Bevilacqua, C.Bonacto, R.L.Cavalcanti, R.D.D.Cos- ta, H.A.Dottori, L.Girard., D.RadjÍBÍchef, S.O.Kepler, S.H.B.Livi, H.C.Psstori- za, J.F.Santos, A.Schmidt, H.F.S.Schroder Storehí iertaesm e Kiri««i C. rastorisa Calaxias vitfc Scroag litrogen Lift** Hi! tcgiooc tvoiutioa, Invite* Talk i, X.V.F.Copetti Spiral Structure and Age Distribution of CHe «II Kagúns of clw Milky U«y AUx A.Scteitft. i.O»ttori Stuáy of Che Ifecletr SttlUr Pe^vlatioa tar ch* Spiral Cataxics NCC 772 «tut i, H.Dottori VB- y fOXil]/H4 de Betiooes HII y la Bittorie d* Ia Foraacióp Estelar R«cienes «a la faqaana ttubc de Mega Ilanes A.Fonseca 2epka, H.&ettori Horphclogy of LMC Cluster* p.poccori, J.Meinick, C.Biea NCC 2209: Ike K*tur« of the Dark Patch J.R.Ducati, T.S.Bergsttmt, C.Bonacto, R.L.Cavalcanti, R.D.D.Costa, H.A.Dottori, L.Girardi, D.Radjiaichsi, S.D.Kepler, S.H.B.Livi, M.C.Pastoriza, J.F.Santos, A.SctttidT. K.F.S.Schroder Strip Photometry of Coaet Halley A.A.Schaidt, C.A.Z.Vatconcalloa, H.Dottori Cosaological tiama Density end the Rftgg* Lav 20ch ESLAB Syposiwa on Halley'» Cowat, Heidelberg, FRC, October 1986 J.R.Ducati, T.S.Bergaann, C.Bonatto, R.L.Cavalcanti, R.O.D.Costa, H.A.Dutton, L.Girardi, D.Radji»ichef, S.D.Kepltr, S.H.l.Livi, M.G.Pastorisa, J.F.Santos, A.Schmidt, a.P.S.Schroder Strip PttotoMtry of Coaet Bailey -152- National Muting* and Conf*r*ne*8 VI national Symposium on Physics Teaching (SWEF), Niterói, RJ, January, 1983 B.Buchweitz, H.Jamatt Análise do Currículo de Experimentos de Laboratório de Física B.Buchveitz. M.J.Bellé Um Método Fotográfico para Produzir Dispositivos de Difraçâo da Luz E.Dominguez, M.A.Moreira Detecção da Alguns Conceitos Errôneos es Eletricidade Através de Entrevistas Clínicas S.T.Cobara, N.A.Moraita Mapeamento Conceituai como Recurso Didático no Ensino da Física V.H.Guimarães, R.Axt, B.Buchweitz Equipamento para Escolas de Nível Médio H.Jamett, B.Buchweitz Instrumentos de Avaliação da Aprendizagem no Laboratório de Física A.C.K.Santos, M.A.Moreira Alguns Aspectos do Ensino de Laboratório de Física e das Instalações para Labo ratório em Escolas de 29 Grau de Porto Alegre L.E.F.Silva Conceitos Espontâneos em Termodinâmica; um Estudo Utilizando Entrevistas Clí- nicas B.M.M.Zawislak A Análise do Conteúdo como Instrumento de Medida da Aprendizagem na Área de Física M.A.Moreira Pós-Graduação es Ensino de Física: o Modelo da UPRCS I Meeting on Elipsomotry, IFCW-ÜKICAMP, Campinas, SP, Juna, 1985 F.Horowitz Aplicações da Elipsooatria em Filmes Finos -153- VIII National Meeting on Condensed Matter Physic», São Loureaço, MG, May 30-June 1, t985 José F.Fontanari e W.K.Theumann Efeitos de Quebra de Simetria Trilinear na Transição de Fase et Titanato de Estroneio sob Pressão Alba Theumann Impurezas cora Correlações de Longo Alcance em Sistemas Magnéticos F.Horowitz Trabalhos sobre Ótica de Filmes Finos em Andamento no IF-UFRGS. XXXVII Annual Meeting of the Brazilian Society for the Advancement of Science, Belo Horizonte, MG, July, 1985 M.A.Z.Vasconcellos e M.N.Baibich 0 Papel do Ni na Cristalização de Ligas Amorfas Tipo (Fe Ni, )OQ820 I.S.Aveline e M.N.Baibich Transporte Eletrônico em Metais Amorfos M.Fin e M.N.Baibich Ponte de Corrente Alternada a Baixa Frequincia para Detecção de Resistência M.Fin e M.N.Baibich Resistõmetro Diferencial em Corrente Contínua para Experiências de Longa Dura- ção L.C.P.Motta, C .'C.honeweg, F.Horowitz e R.E.Francke Astigmati—. i- •..adt» úc Difração e seus Efeitos na Cavidade do Laser de Co- rante V.M.Alves, J.A.Lisboa e R.E.Francke Sensor de Pressão Tipo Pirani Construído com Materiais Nacionais J.M.Hickmann, Y.A.Folz e R.E.Francke Desenho e Construção de Transladadores de Precisão T.Braun, J.A.Lisboa, C.R,M,de Oliveira e L.F.Motter Calibração do Comprimento de Onda de Laser de Corante por Sinulação do Espectro do I, -154- T.Braun, J.S.Hictanann, J.A.Lisboa e R.E.Francke + d Atlas da Transição B it. - x'E g » Molécula de Iodo (I2> XII Annual Meeting o_f_ the Brazilian Astronomical Society, Belo Horizonte, MG, July, 1985 R.D.D.Costa, J.R.Ducati, M.G.Pastoriza Fotometria BV-DDO de Estrelas Vermelhas nos Aglomerados Abertos NGC2516, NGC 3766 e NGC5460 v* Brazilian Congress on Vacuum Application j^n Industry and Science, IME, Rio d_e Janeiro, July, 1985 F.Horowitz Microestrutura e Alguns de seus Efeitos óticos em Filmes Finos VIII Workshop o£ Nuclear Physics in Brasil, São Lourenço, MG, September, 1985 M.H.Steffani, M.Betz e Th.A.J.Maris Estados de Buraco Nucleares E.A.Veit, B.K.Iennings e A.W.Thomas Modelo de Sacola no Espalhamento Káon-Núcleon VI National Meeting on Particles and Fields Physics, São Lourenço, MG, September 18-22, 1985 M.B.Gay Ducati, C.A.Garcia Canal e E.M.Santangelo Taxas de Excitação de Charm Bottom e Top Seminar Education for Science - Fundão Project, UFRJ, October, 1985 M.A.Moreira A Ênfase em Conceitos, numa Perspectiva Ausubei.iana, como Estratégia Viabiliza dora de uma Abordagem Interdisciplinar ao Ensino de Ciências III Workshop on Statistical Mechanics and Theory o_f Fields, USP, São Carlos, December 11-13, 1985 Mareia C. Barbosa, M.A.Gusmão e W.K.Theumann Renormalizaçao do Modelo de Potts em $3 com Quebra de Simetria Quadrática e Trilinear -155- W.K.Thevmann e José F. Fontanari Replicas no Modelo Esférico num Campo Aleatório Alba Theumann Superalgebra na Teoria de Vidros de Spin Seminar on Admission Examination Today, MEC-SESU/SEPS, Brasilia, December, 1985 B.Buchweitz Admission Examination to UFRGS DC National Meeting on Condensed Matter Physics, Poços M.A.Z.Vasconcellos, R.P.Livi e M.N.Baibich Estabilidade Térmica de Ligas Amorfas do Tipo (Fe. Ni )anB,ft i™X X OU Á\J M.A.Z.Vasconcellos, W.H.Schreiner e M.N.Baibich Coeficientes Críticos para a Transição Magnética de Ferromagnetos Amorfos M.A.Z.Vasconcellos, L.Amaral e M.N.Baibich Defeitos Induzidos por Bombardeamento de FeNiB Amorfo M.Fin e M.N.Baibich Medida de Pequenos Sinais Alba Theumann Condutividade de uma Cadeia de Elétrons Desordenada. Grupo de Renormalizacão R.B.Guimarães, L.Amaral, M.Behar, J.P.de Souza e F.Zawislak Alcance e Difusão de íons de Bi Implantados em Polímeros R.Erichsen Jr., C.M.Hasenack, J.P.de Souza e I.J.R.Baumvol Implantação de Sb por Recuo em Silicio por Bombardeamento com tons de Germã- nio C.M.Hasenack, J.P.de Souza e I.J.R.Baumvol Defeitos Residuais em Silício Implantado com lona de Ga, In, As, Sb, Ge e Pb e Submetido a Recozimento Térmico Rápido -156- A.Avelino Pasa, J.P.de Souza e I.J.R.Baumvol Formação de Silicetos de Ni e Ti Induzida por Processo Térmico Rápido Elza M. Scherer, C.M.Hasenack, J.P.de Souza e I.J.R.&aumvol Análise de Silício Implantado com Sn por CEMS e Channeling F.Horowitz e R.F.Sandoval Anisotropias em Filmes Finos Exposition a£ the Federal University of_ Rio Grande do Sul, Porto Alegre, Bra- sil, Jan. 22 - May U, 1986 Silvia H.B.Livi e R.P.Livi 0 Cometa e o Cosmos 1 Vl_ National Meeting on Intermediate Energy Physics, Poços M.H.Steffani, M.Betz e Th.A.J.Maris Widths of Nuclear Hole States in a Relativistic Many Body Theory E.A.Veit, B.K.Jennings e A.W.Thomas The Cloudy Bag Model and Meson-Nucleon Scattering M.Betz Nucleon Excited States and Unitary Description of Pion-Nucleon Scattering XXXVIII Annual Meeting of_ the Brazilian Society for the Advancement o£ Science, Curitiba, PR, July 198b S.H.B.Livi, R.P.Livi, Roberto D.Dias da Costa, Marcos Vasconcellos A exposição "O Cometa e o Cosmos" uma ótima oportunidade de divulgar ciência. Miriani G. Pastoriza, Maria de Fátima S.Schrtíder a Thaiea Storchi Bergmann Fotometria Superficial de Galáxias Austrais Silvia H.Becker Livi, Sara Martin e Jingxiu Wang Análise dos Fenômenos Característicos de Campos Magnéticos Solares de Pequena Escala e sua Contribuição em uma Região Ativa -157- M.A.Z.Vasconcellos, R.P.Livi « N.N.Baibich Estudo da Transformação de Fase Amorfo-Cristal ea Ligas Metálicas R.B.Guimarães» P.J.Viccaro, U.H.Schreiner, M. A.Z.Vasconcellos e M.N.Baibich Evidência de Ordenação Química nas Ligas Aaorfas (F'B*V«QB2Q P°r K^laxação Estrutural C.R.M.de Oliveira, J.S.Hickmann, Y.A.Folz, J.M.Hickaann, C.Schftaeweg e R.E. Francke Espalhaaento de Luz por Esferas Macroscópicas J.A.Lisboa, T.Braun e D.C.da Silva Mesa Digitalizadora de Baixo Custo J.S.Hickmann, T.Braun, H.Libardi, L.Motter e R.E.Francke Ressonâncias Acidentais do Laser de Nitrogênio (337 na) com Transições da Ban- da B-f da Molécula de lodo J.A.Lisboa, L.C.P.Motta e T.Braun Evolução Temporal de Níveis do Estado BIT do 1. Populados por Colisão R.E.Francke Montagens óticas ea um Laboratório de Espectroscopia Laser M.A.Moreira e M.E.Dominguez Concepções Intuitivas em Eletricidade L.E.F.Silva, M.A.Moreira Concepções Espontâneas sobre o Conceito de Temperatura: Detecção Antes da Ins- trução e Evidências de sua Permanência após a Instrução F.L.Silveira Um Experimento sobre a Relação entre o Período e a Amplitude de um Pêndulo Sim pies XIII Annual Meeting of the Bragilian Astronomical Society, Curitiba, PR, July, 1986 R.D.D.Costa, M.G.Pastoriza e J.R.Ducati Metalicidade de Aglomerados Abertos e o Gradiente de Abundância da Galáxia -158- J.R.Ducati Resultados Preliminares de Observações do Cometa dc Halley na UFRGS R.O.D.Costa, M.C.Pastoriza « J.R.Ducati Massas de Estrelas Venaelhas •• Aglonerados Abertos J.R.Ducati e L.Girardi Matéria Circuaestelar em Estrelas Quentes Symposium "Research ija Sciences Teaching" which Took Place Daring the 9th Annual Meeting o£ the Brazilian Chemical Society, Curitiba, July, 1966 M.A.Moreira Ensino de Ciências: Implicações de uma Perspectiva Ausubeliana para a Prática Docente e para a Pesquisa First Congress o£ the Microelectronics Brazilian Society, CPqD, Telebrás, Campinas, July, 19S6 A.A.Pasa, J.P.de Souza e I.J.R.Baunrvol Formação de Silicetos de Níquel por Processo Térmico Rápido A.A.Pasa, J.P.de Souza e I.J.R.Baunvol Formação de Dissilicetos de Ticânio por Rscozinento Térmico Rápido C.M.Hasenack, J.P.de Souza e I.J.R.Bauovol Recozisento Isotérmico Rápido de Silício Implantado com Arsênio R.B.Guimarães» M.Behar, R.P.Livi, J.P.de Souza, L.Amaral, F.C.Zavislak, D. Fink e J.P.Bicrsack Alcance de Ions Implantados em Fotoresina AZ 1f t C.M.Hasenack, J.P. de Souza e I.J.R.Baumvol Efeitos Residuais em Junções Rasas em Silício Implantado; Efeitos Químicos R.Erichsen Jr., J.P.de Souza e I.J.R.Baumvol Dopagen de Silício com Antimônio por Recuo Induzido por Bombardeamento coa tons de Gsrmânio -159- South-Bra*i I ian Svaposiua on Physics Teaching» £, Santa Cru» do Sul, RS, Brazil. July 29-August 1, 1986 R.P.Livi e Silvia H.B. Livi Hallay's Coast. Audio-Visual VII national Heating on Particles and Fields Physics. Caxaabu, MS, Septeaber 17-21. 1986 Mareia C. Barbosa e W.K.Theuaann Ruões Universais de Parâmetros Críticos e Tricríticos na Teoria de Caapos do Modelo de Potts Meeting on Gagas i£ Metals and Alloys, São Carlos, SP, Septeaber 24-27, 1986 Rogério P. Livi, Juan C. Acquadro e Fernando C. Zawislak Medida de Perfil de Concentração de Hidrogênio ea Materiais por Reação Nuclear Ressonante IV Meeting of^ Northeastern Physicists, Natal, RN, November 3-7, 1986 Sérgio R. Teixeira, Carlos A. dos Santos, Paulo H. Dionisio, Ênio Silveira e Israel J.R. Baunvol Estabilização da Fase Metaestável FeAl. eo Filmes Finos de Fe e Al -160- M.Sc. THESES - 1985 and 1986 Arion de Castro Kurtz dos Santos - Jan. 16, 1935 Um Estudo sobre o Ensino de Laboratório de Física em Escola* de 29 Grau de Porto Alegre Bernardo Augusto St am» de Barros Junior - Jan. 29, 1985 Oxidação em Alta Temperatura de Aços: Influência da Iaplantação lônica e Di- fusão Auxiliada por Radiação Stella Maris Moura Ramos - April 3, 1985 Estudo Sistemático dos Campos Hiperfinos em Ligas de Heusler do Tipo Rh- YZ 119 com Impurezas Sr. por Espectroscopia MBssbauer Mariana Eugenia Dominguez Dellepiane - July 4, 1985 Detecção de Alguns Conceitos Intuitivos em Eletricidade Através de Entrevis- tas Clinicas Hernan Jamett Carrasco - July 11, 1985 Laboratório de Física: Uma Análise do Currículo e da Aprendizagem Pelipe Barbedo Rizzato - July 30, 1985 Equação Quase-Linear para Oscilações era Magnetoplasmas na Aproximação Fraca- mente Relativística Marcos Antonio Zen Vasconcellos - Nov. 13, 1985 Estudo da Cristalização de Ligas Amorfas do Tipo (Fe Ni )on*20 Roberto Dell'Aglio Dias da Costa - Jan. 13, 1986 Potometria Multicor de Três Aglomerados Abertos Austrais Laercio Evandro Ferracioli da Silva - March 14, 1986 Concepções Espontâneas en Termodinâmica: Um Estudo Utilizando Entrevistas Clínicas em um Curso Universitário Básico Alex Andre Schmidt - Aug. 21, 1986 Estudo Espectrofotooitrico dos Núcleos das Galáxias Espirais NGC 772 c IC5325 Ruben Luis Sommer - Aug. 28, 1986 0 Efeito Barkhausen en Ferromagnetos -161- tube» Ericbsen Junior - Sept. 19, 1986 Implantação por Recuo de Antiaônio e» Silício por Boabardeaaeato cosi Ions de Argonio e ruaJiiiíii André Avelino Pasa - Oct. 23, 1986 Formação de Silicetos de Níquel e de Titânio por Processo TÍrsúco Rápido José Antonio Cardoso Louzada - Nov. 14, 1986 Teoria Sesn.-Clássica do Transporte Eletrônico e» Metais Ph. D. THESES - 1985 and 1986 Tiago Josué Martins Simões - May 24, 1985 Quantizaçio Operatorial de Teorias de Gauge não-Abelianae es ua Gauge Axial Completamente Fixado Suzana Gostes Pries - May 27, 1985 Efeito de Alta Pressão e de Tenperatura no Gradiente de Caapo Elétrico am Compostos Interaetãlicos sp Paulo Machado Mors - June 25, 1985 Estudo do Hasriltoniano de Hubbard e de Sistemas de Valencia Intermediária na Rede de Bethe Paulo Henrique Dionísio - Aug. 1, 1986 Implantação lõnica e Difusão Auxiliada por Radiação da E&canbo es Ferro e Aços Claus Martin Hasenack - Aug. 22, 1986 Recoziaento Térmico Rápido de Canadas de Silício Anorficados por laplantação Tônica Acirete Souza da Rosa Simões - Dec. 4, 1986 Solução Didgramãtíca de um Haaíltoníano da Valencia Intermediária e da Rede Konde -162- STAFF MEMBERS OF THE DEPARTMENT OF nttSICS Almeida, R.M.C. Amaral, L. (Ph.D.) On leave at OrsayT Franca, from 08/30/83 to 08/29/85 Ave line, A. (M.Sc) Axt, R. (M.Sc.) Baibich, M.N. (Ph.D.) Baumvol, I.J.R. (Ph.D.) Behar, M. (Ph.D.) On leave at Mex-Planck-Inatitut, Heidelberg, West Germany, since 04/01/86 Betz, M.E.M- (Ph.D.) Bonilla, I.R. (Ph.D.) Brandão, D.E. (Ph.D.) Bruschi, E. (M.Sc.) Buchweitz, B. (Ph.D.) Carvalho, R.M.V. (M.Sc.) Corrêa, H.H.P.F.V. (M.Sc.) Costa, M.E.V. (M.Sc.) On leave at Institut fur Theoretische Physik der Uni/ersitSt Heidelberg, West Germany, from 11/01/85 to 10/31/86 Costa Jr., M.I. (Ph.D.) Cunha, J.B.M. (Ph.D.) On leave at Centre d'Etudes Nucléaires de Saclay, France, since 02/01/86 Cunha, S.L.S. (Ph.D.) On leave at Max-Planck Institut fur Quantenoptik, Mttnich, West Germany, from 03/16/81 to 03/11/86 Dillenburg, D. (Ph.D.) Dionisio, P.H. (Ph.D.) Epstein, M. (Ph.D.) Francke, R.E. (Ph.D.) Fries, S.G. (Ph.D.) Girotti, H.O. (Ph.D.) On leave at Institut ftlr Theoretische Physik der Universityt Heidelberg» West Germany, from 07/01/85 to 06/30/86 Goedert, J. (Ph.D.) On leavf at Los Alamos National Laboratory, Los Alamos, NM, USA, from 03/02/83 to 02/01/85 Guimarães, L.B. Guimarães, V.B. Gusmão, M.L.V. (M.Sc.) Contract interrupted since 10/16/85 Gusmão, M.A.C. (Ph.D.) On leave at Rutgers University, Mew Jersey, USA, from 09/01/85 to 08/31/87 Herscovitz, V.E. (Ph.D.) Horovicx, F. (Ph.D.) Iglesias, J.R. (Ph.D.) Jacob» G. (Ph.D.) Jornada, E.H. (Ph.D.) Jornada» J.A.H. (Ph.D.) Kunrath, J.I. (Ph.D.) Kunzler, J.V. (Ph.D.) Laier, W. Levandowski, C.E. (Ph.D.) Liberman, 8. (Ph.D.) Livi, F.P. (Ph.D.) Livi, R.P, (Ph.D.) On laavc at U.K. Keilcg Radiation Laboratory, California, USA, iron 03/21/83 to 02/28/85 Maciel, A. (Ph.D.) Maris, Th.A.J. (Ph.D.) Medeiros, J.T.N. (Ph.D.) Medero, I.M, (M.Sc.) Medero, J.L. (M.Sc.) Moreira, H.A. (Ph.D.) Or. leave at Cornell University, Ithaca, USA, since 09/01/86 Mors, P.M. (Ph.D.) On leave at Laboratoire de Physique des Solides, Universiti Paris-Sud, Orsay, France, since 09/01/86 Mílller, C.S. (Ph.D.) Mundt, W.A. (M.Sc.) Petr«, P.P. (Ph.D.) Pureur Neto, P. (Ph.D.) On leave at Laboratoire dc Physique des Solides, Universíté Paris-Sud, Orsay, France, iron 01/01/80 to 08/01/85 Riccí, T.S.P. (M.Sc.) Schaf, J. (Ph.D.) Scherer, C. (Ph.D.) Schmidt, J.E. (Ph.D.) Schneider, C (Ph.D.) Schneider, R.S. (Ph.D.) Schrciner, R.L. Schreiner, W.H. (Ph.D.) Ulva, M.T.X. (M.Sc.) Silveira, F.L. (M.Sc.) Simões, T.J.M. (Ph.D.) On leave at Laboratoire de Physique Theorique et Hautes Energies, Paris, France, since 09/11/86 Souza, J.P. (Ph.D.) Steffani. M.H. (M.Sc.) Strauch, I.M.F. (Ph.D.) Teixeira, R.M.R. (Ph.D.) Teixeira, S.R. (M.Sc.) Teodoro, M.R. (Ph.D.) Theumann, A.G.R. (Ph.D.) Theunann, U.K. (Ph.D.) Thomas, C.L. (M.Sc.) Vasconcellos, C.A.Z. (M.Sc.) Vasquez, A. (Ph.D.) On leave at Centre d*s Rechcrches RuclSaircs, , France, fro» 01/01/85 to 12/31/85 Veie, E.A. (Ph.D.) Viccaro, M.H.A. (Ph.D.) Contract interrupted since 07/01/85 Viccaro, P.J. (Ph.D.) Contract interrupted since 08/01/85 Wackerritt, H.H.K.E. ZawisUk, B.M.M. (M.Sc.) Zawislak, F.C. (Ph.D.) Zawislak, L.I. (M.Sc.) Ziebell, L.F. (Ph.D.) On leave at Centre d'Etudes Nucleaires, Fonte- nay-aux-Roaes, France, froai 08/01/84 to 06/30/ 86 STAFF MEMBERS OF THE DEPARTMENT OF ASTRONOMY Bergnann, T.S. (M.Sc.) Dottori, H.A. (Ph.D.) Ducati, J.R. (Ph.D.) Livi, S.H.B. (M.Sc.) On leave at Department of Astronomy, Pasadena, California, from 03/21/83 to 02/28/85 Oliveira F9, K.S. (Ph.D.) Pastoriza, M.G. (Ph.D.) Schrtíeder, M.F.S. (M.Sc.) Vieira, E.R. (Ph.D.) -165- EHGIKEERING STAFF OF THE INSTITUTE Ot PRSXCS Bocs Jr., A. BulU, A. A. Fachin Jr., N. Fin, M. Michelin. K.J. Kochs» AiL> wyrzykowski, M.P. Ziaaiera«Qa, S. On leave at Fermi National Accelerator Lab.» Illinois, USA, from 12/01/83 to 01/31/86 -166- CRADUATE STUDENTS OF THE INSTITUTE OF PHYSICS Ph.D. students Almeida, R.M.C. Barbosa, M.C.B. Barros Jr., B.A.S. Bergmann, T.S. Brunnet, L.C. Caldela F9, R.A. Copetti, M.V.F. Costa, R.D.D. Corrêa» M.H.P.F.V. Costa, M.E.V. Cubillos, S.P.Z. Cruz F9, S.P. D'Ajello, P.C.T. Dionisio, P.H. Erichsen Jr., R. Fichtner, P.F.P. Fraga, G.L. Fries, S.G. Gallas, M.R. Guimarães, R.B. Gusmão, M.L.V. Hasenack, CM. Krein, G.I. Lisboa, J.A. Medero, I.M. Moraes, O.L.L. More, P.M. Mundt, W.A. Ogiba, F. Oliveira, J.C.P. Oliveira, L.S. Olivieri, C#A. Paea, A.A. K&moe, S.M.M. Rícei, T.S.F. -167- Rizzati, M.R. Rircato, F.B. r-^-'-dt, A.A. .: rl-- , -..F.S. c i ^ », C. * . M. Silva, M.T.X. Simões., A. S.R. Simões, T.J.K. Sonmer, R.L. Steffani, H.H. Teixeira, S.R. Thomas, G.L. Varriale, M.C. Vasconcellos, C.A.Z. Vasconcellos, M.A.Z. Zawislak, L.I. f r M.Sc. students Balzaretti, N.M. Barros Jr., B.A.S. Belle, M.J. Bernardes F9, R. Bernhard, B.H. Bonatto, C.J. Borge», V. Braum, T. Brusch, L.R.F. Carrasco, H.J.D. Consiglio, R. Correia, R.R.B, Costa, R.D.D. Dagnino, R.P. Dellepiane, M.E.D. Domingues, D.R.C. Erich»en Jr., R. Escobar, W.A. Ferlin, BtL. Grande, P.L. -168- Gravina, M.H. Hickmann, J.M. Hickmann, J.S. Hübler, R. Idiart, M.A.P. Krebs, P.R. Leitão, R.S. Louzada, J.A.C. Magalhães, S.G. Monteiro, P.R. Mot ter, L.F. Mosca Jr., D.H. Oliveira, C.R.M. Pasa, A.A. Pereira, A.S. Pereira, L.G. Ramos, S.M.M. Rizzato, F.B. Rosa, P.R.S. Ruas, C.A.A. Santos, A.C.K. Santos Jr., J.F.C. Scherer, E.M. Schmidt, A.A. Silva, L.E.F. Silva, L.A.L. Scrmer, R.L. Szwtc J. Vasconcelos, M.A.Z. Zepka, A.F.