A 1 Case-PR/ }*Rciofft.;Is Report

Home , Anders (crater), Cyclohexane conformation, Davydov soliton, Donner (crater), Fredholm (crater), Isotopes of gold

.A 1 case-PR/ }*rciofft.;is Report (a) This eruption site on Mauna Loa Volcano was the main source of the voluminous lavas that flowed two- thirds of the distance to the town of Hilo (20 km). In the interior of the lava fountains, the white-orange color indicates maximum temperatures of about 1120°C; deeper orange in both the fountains and flows reflects decreasing temperatures (<1100°C) at edges and the surface. (b) High winds swept the exposed ridges, and the filter cannister was changed in the shelter of a p^hoehoc (lava) ridge to protect the sample from gas contamination. (c) Because of the high temperatures and acid gases, special clothing and equipment was necessary to protect the eyes. nose, lungs, and skin. Safety features included military flight suits of nonflammable fabric, fuil-face respirators that are equipped with dual acidic gas filters (purple attachments), hard hats, heavy, thick-soled boots, and protective gloves. We used portable radios to keep in touch with the Hawaii Volcano Observatory, where the area's seismic activity was monitored continuously. (d) Spatter activity in the Pu'u O Vent during the January 1984 eruption of Kilauea Volcano. Magma visible in the circular conduit oscillated in a piston-like fashion; spatter was ejected to heights of 1 to 10 m. During this activity, we sampled gases continuously for 5 hours at the west edge.

Cover photo: This aerial view of Kilauea Volcano was taken in April 1984 during overflights to collect gas samples from the plume. The bluish portion of the gas plume contained a far higher density of fine-grained scoria (ash). At the peak of activity, lava fountained at least 100 m above the 30-m-high cone. Note the ballistically ejected scoria bombs (small red spatter) that appear to be falling like rain beneath the main lava fountain; they ranged from 0.1 to 1 m in diameter. Streaks of color at the lower right of the vent indicate the paths of bombs as they avalanched down the cone flanks. The wide red-orange ribbon is the main lava channel, which fed flows that traveled from 5 to 10 km from the vent. Isotope •msstry Division

O^ta*>orl983-Septe«)J5erl984

d LA—10366-PR DE85 016204 . Hoffman

E Heikerf , Editor

LA-10366?Pa Progress Ratwrt

"I *'' UC-4 issued: April 1935

3^1 JfiJilli 1..,., ACKNOWLEDGMENTS

Preparation of this report required the knowledge, cooperation, and skills of many people. Staff members who served as technical reviewers were James E. Sattizahn and Jere Knight (Overview). Alexander J. Gancarz (Sec. I and 2). P. Gary Eller(Sec. 3). Eiichi Fukushima(Sec. 4). Bruce M. Crowe (Sec. 5). Robert R. Ryan (Sec. 6). Basil 1. Swanson (Sec. 7). Jerry Wilhelmy and Bruce J. Dropesky (Sec. 8). Merle E. Bunker (Sec. 9). Charles M. Miller (Sec. 10). Allen S. Mason (Sec. 11). and Robert C. Reedy (Sec. 12). Word processors who prepared ihe original drafts were Jane L. Fernandez. Marielle S. Fcnstermaeher. Jean King. Cathy J. Schuch. Lia M. Mitchell. Carla E. Gallegos. Kay L. Coen. and Joann Brown; final corrections were made by Lia M. Mitchell. Jane L. Fernandez, and Carla E. Gallegos. additional assistance was provided by Michelle L. Brewer and Barbara J. Anderson. The report was designed by Gail Flower (Group IS-12). typeset by Chris West (Group IS-10) and Jane L. Fernandez, and pasted up by Janey Howard.

Photos for the cover, inside front cover, and the article by Crowe ct. al. were taken by team members Gregory K. Bayhurst. William B. Boynton (University of Arizona). Bruce M. Crowe. David B. Curtis. David L. Finnegan, Eugene ... Mroz. Diane Hermann (University of Maryland), and William H. Zoller (University of Washington). GLOSSARY

APS autocorrelator photon spectroscopy CERN European Organization for Nuclear Research CMP carbamoyl methylene phosphonate DAS data aquisition system DCX double-charge exchange DIAS double isobaric state DNC delayed neutron counting DOE Department of Energy EXAFS extended x-ray absorption fine structure FFTF Fast Flux Test Facility FOOF difiourine dioxide FWHM full width half maximum GCR galactic cosmic ray GIK glucose-insulin-potassium GSI Gesellschaft Fur Schwerionenforschung HEFT heavy-element fission tracer HESF high-energy symmetric fission HHIRF Oak Ridge Holifield Heavy Ion Research Facility HPLC high-pressure liquid chromotography IAEA International Atomic Energy Association IAS isobaric analog state ICONs program named for the Isotopes of Carbon, Oxygen, and Nitrogen ILWOG Interlaboratory Working Group INAA instrumental neutron activation analysis INEL Idaho Nuclear Engineering Laboratory IOH inside-out Helmholtz IPF Isotope Production Facility LAMPF Los Alamos Meson Facility LBL Lawrence Berkeley Laboratory LEAP Large Einsteinium Activation Program LLNL Lawrence Livermore National Laboratory MWPG multiwire proportional counters NAA neutron activation analysis NBS National Bureau of Standards NCL Nuclear chemistry Laboratory (at LAMPF) NMR Nuclear Magnetic Resonance NNWSI Nevada Nuclear Waste Storage investigations NTS Nevada Test Site MIT Massachusetts Institute of Technology ORNL Oak Ridge National Laboratory OWR Omega West Reactor PA Ps. aeruginosa PIXE proton-induced x-ray emission QCD quantum chromodynamics RBS Rutherford backscattering RNM radionuclide migration RR resonance raman SCX single-charge exchange SIR Stable Isotopes Resource SISAK short-iived isotope separated by the AKUVE technique SNC Shergottite, Nakhlite, Chassigny (meteorites) SNL Sandia National Laboratories TBAH tetrabutyl ammonium hydroxide TKE total kenetic energy TOFI time-of-flight isochronous spectrometer TRIUMF meson facility in Vancouver, BC, Canada UNILAC Universal Linear Accelerator, GSI USGS Unites States Geological Survey XRD x-ray diffraction / ' OyervieW , • v "" '. -, • - \ ' -'I , Rc3dioch©rnical Diagnostics of 1i"; Weapons Tests 17 Weapons Radiochemical Diagnostics 2r Research and Development 21 Other'Undassified Weapons Research 35 Stable and Radioactive Isotope Pro- 4• -ductioa Separation and Applications 49 "Element and Isotope iMnsport 5•; and: Fixation ^ 79 ^A0tinide and transition 6i J^etal Chemistry 105 Stmetwal Chemistry, Spectroscopy 7i andd ApplicationAliti s I^Juclear Structure anc|. Reactions

91 Advanced Analytical Techniques: Development and Applications ] 1 Ataidsphetic Chemistry and Transport

\ya o Earth and Plan«ptary Proce^es 2O7

' ;:- ' 223

DIVISIONAL OVERVIEW 3

A YEAR OF TRANSITION

Donald VV. Barr

This past year brought a transition in the leadership of INC Division. Division Leader Darleane C. Hoffman resigned her position to become Professor of Chemistry at the University of California at Berkeley, and I was appointed to succeed her as Division Leader on August 27, 1984. Darleane leaves her Los Alamos career with an im- pressive record. Beginning with her early work on the nuclear chemistry of the transuranium elements produced in nuclear explosions, she established the properties of a wide variety of new or little-known nuclides ranging from the light lanthanides to the heavy actinides. At the same time, she contributed steadily and importantly to a broad spectrum of programmatic activities, including radiochemical diagnostics of weapons tests, the nuclear rocket propulsion program, nuclear- power waste management, and the education and training of Laboratory employees. The willing application of her versatile talents has brought her a number of important international committee appointments and honors. A recent one was the 1983 American Chemical Society Award for Nuclear Chemistry. As INC Division Leader, Darleane Hoffman brought an imaginative and inspiring leadership style to the Division's programs and day-to- Darleane C. Hoffman day operations. She leaves a strong and vigorous scien- Prof. Univ. California, Berkeley tific organization. I have great confidence in the abilities of our personnel and anticipate both an expanding role for INC Division in vital Laboratory programs and continued exciting contributions to the world of science.

Donald W. Barr INC Division Leader 4 DIVISIONAL OVERVIEW

LOS ALAMOS NATIONAL LABORATORY ISOTOPE & NUCLEAR CHEMISTRY (INC) DIVISION

DIVISION LEADER 0. W. BARR DEPUTY DIVISION LEADER J. E. SATT12AHN ASSOCIATE DIVISION LEADERS RADIOCHEMICAL DIAGNOSTICS- ADVANCED RESEARCH CONCEPTS- B. R. ERDAL ASST. DIVISION LEADER FOR FINANCE H. A. LINDBERG

INC-3 IHC-4 INC-5 MEDICAL RADIOISOTOPES ISOTOPE AND RESEARCH REACTOR RESEARCH STRUCTURAL CHEMISTRY GROUP LEADER -B. I. SWANSON GROUP LEADER -H. A. O'BRIEN DEPUTY GROUP LEADER - R. R. RYAN GROUP LEADER-M. E. BUNKER ASSOCIATE GROUP LEADERS DEPUTY C-10UP LEADER" D.C. MOODY DEPUTY GROUP LEADER-M. M. MINOR FLUORINE CHEMISTRY- P. G. ELLER STABLE ISOTOPES-T.R. MILLS

INC-7 IHC-lii ISOTOPE GEOCHEMISTRY NUCLEAR AND RADIOCHEMISTRY GROUP LEADER - E. A. BRYANT GROUP LEADER - W. R. DANIELS DEPUTY GROUP LEADER - A. J. GANCARZ DEPUTY GROUP LEADER - G. F. GRISHAM ASSOCIATE GROUP LEADERS ASSOCIATE GROUP LEADERS GEOCHEMISTRY - DATA ACQUISITION - J. P. BALAGNA RADIOCHEMISTRY - K. WOLFSBERG LAMPF - B. J. DROPESKY RADIOCHEMISTRY - G. W. KNOBELOCH ASSISTANT GROUP LEADER FOR ASSISTANT GROUP LEADER FOR ATMOSPHERIC PROJECTS - P. R. GUTHALo ADMINISTRATION - C.C. LONGMIRE

In this year of transition, there have been shifts in both our Division and Group managements. This chart reflects the organization as of April 1985; the personnel changes we list here have occurred since last year's organization chart was printed. Darleane C. Hoffman left the Division in August 1984 to take a faculty position at the University of California, Berkeley. Donald W. Barr assumed the Division leadership, leaving his role as Associate Division Leader for Radiochemica! Diagnostics. In December 1984, Nicholas A. Matwiyoff resigned his half-time position as Nuclear Medicine Coordinator to become fulltime Director of the University of New Mexico/Los Alamos NMR Center for Non-Invasive Diagnosis at the UNM Medical School. James E. Sattizahn became the Deputy Division Leader in February 1984, leaving his long-time position as INC-11 Group Leader. William R. Daniels was selected to step into that group leadership; Genevieve F. Grisham succeeded him as INC-11 Deputy Group Leader. Rosemary J. Vidale, previously INC-7 Associate Group Leader for Geochemistry, left the Laboratory in December 1984. Robert A. Penneman retired in late 1983, and Basil I. Swanson succeeded him as the INC-4 Group Leader. Also in INC-4, P. Gary Eller assumed an Associate Group Leadership for Fluorine Chemistry, and Thomas R. Mills replaced B. B. IVklnteer as Associate Group Leader for Stable Isotopes when the latter became a project leader. Lamed B. Asprey vacated his position as Associate Group Leader to devote more time to research. The position of Associate Group Leader for Radiochemistry in INC-11 was filled by Gordon W. Knobeloch. David C. Moody was named Deputy Group Leader of INC-3 in September 1983. DIVISIONAL OVERVIEW 5

INC Division's mission is to develop, maintain, and supply capabilities in chemistry, nuclear chemistry, geochemistry, and stable and radioactive isotopes for solution of national security, energy, health, and environmental problems. The Division's five groups foster excellence in fundamental research.

James E. Sattizahn Deputy Division Leader

Bruce R. Erdal Associate Division Leader, Advanced Research Concepts

Helen A. Lindberg Assistant Division Leader for Finance 6 DIVISIONAL OVERVIEW

INC-3 (Medical Radioisotopes Research) Promotes nuclear medicine research through the production and use of radionuclides.

INC-4 (Isotope and Structural Chemistry) Harold A. O'Brien Performs and communicates fundamental and INC-3 Group Leader supporting research in chemistry to bring together the areas of synthesis, separation, and use of isotopic and physical methods for studies of structure and dynamics.

INC-5 (Research Reactor) Provides reactor-based facilities and services in support of Laboratory programs and conducts applied and basic research in nuclear physics and nuclear chemistry. Basil I. Swanson INC-4 Group Leader

Merle E. Bunker INC-S Group Leader DIVISIONAL OVERVIEW 7

INC-7 (Isotope Geochemistry) Addresses important national scientific problems in the fields of nuclear chemistry and geo- chemtetry by employing radiochemical and mass specjrometric. techniques. There is particular emphasis on nuclear weapons diagnostics and related nuclear research, atmospheric and geochemical processes, and development of enhanced analytical and modeling capabilities

INC-11 (Nuclear and Radiochemistry) Ernest A. Bryant Applies expertise in nuclear and ladiochemistry INC-7 Group Leader to support national needs and Laboratory programs.

William R. Daniels INC-11 Group Leader 8 DIVISIONAL OVERVIEW

Laboratory Fellows are appointed in recognition of their scientific excellence and their sustained outstanding contributions and exceptional promise for continued professional achievement in the future. They advise and consult throughout the Laboratory within their area of competence and play a key role in stimulating new research initiatives.

Llewellyn H. Jones Laboratory Fellow-

Charles J. Orth Laboratory Fellow

Jerry B. Wilhelmy Laboratory Fellow DIVISIONAL OVERVIEW 9

ABSTRACT This report describes progress in the major research and development programs carried out in FY 1984 by the Isotope and Nuclear Chemistry Division. It covers radiochemicai diagnostics of weapons tests; weapons radiochemicai diagnostics research and development; other unclassified weapons research; stable and radioactive isotope production, separation, and applications (including biomedical applications); element and isotope transport and fixation; actinide and transition metal chemistry; structural chemistry, spectroscopy, and applications; nuclear structure and reactions; irradiation facilities; advanced analytical techniques: development and applications; atmospheric chemistry and transport; and earth and planetary processes.

DIVISIONAL OVERVIEW

Three INC-Division scientists have been honored for their contributions to Laboratory programs. Genevieve Grisham of INC-11 was one of a select group chosen to receive the DOE's Weapons Complex Recognition Award, presented for outstanding contributions to the nation's weapons programs. She was cited for key calculations in the analysis of radiochemicai data from weapons tests; the citation referred to "her thorough understanding of nuclear chemistry and her imaginative and effective applications of computer methods to the analysis of resuhs." Lamed B. Asprey ana F. Gary Eller of INC-4 (with Harry J. Dewey of MST Division) shared a Los Alamos Distinguished Performance team award for their independent contributions to the development of FOOF (dioxygen difluoride), a powerful molecular fluorinating agent that shows great promise in both preparative chemistry and nuclear materials decontamination and recovery. Harold A. O'Brien of INC-3 was elected to the presidency of two national organizations in the field of nuclear medicine: the Radiopharmaceutical Science Council of the Society of Nuclear Medicine and the American Board of Science in Nuclear Medicine. (The latter is a national accrediting board for scientists in nuclear medicine.) Bruce R. Erdal of INC-DO was elected secretary of the Nuclear Chemistry and Technology Division of the American Chemical Society. Paul R. Guthals and the atmospheric studies section of INC-7 joined its counterpart under Sumner Barr in ESS-7 to host an atmospheric tracer workshop sponsored by DOE Office of Health and Environmental Research. (The proceedings have been made available in Los Alamos report LA-10301-C.) Bruce R. Erdal of INC-DO organized and conducted a workshop to examine "Fundamental Geochemistry Needs for Nuclear Waste Isolation;" this workshop, sponsored jointly by the DOE Office of Basic Energy Sciences, DOE Office nfCivilian Radioactive Waste Management, and the US Nuclear Regulatory Commission, has been recorded in DOE report CONF 84-06134. INC Division comprises 203 people. This total involves 190 full-time employees, of which 107 are staff member scientists (77 with PhD degrees) and 9 are postdoctoral appointees and long-term visiting staff members. During FY 1984, we hosted 37 postdoctorates and summer students. In addition, apart frcm our consultants, there are over 160 scientific affiliates, of which almost a third were visiting scientists from foreign countries. An important segment of these visitors consists of our visiting committees for the Nuclear and Radiochemistry, Medical Radioisotopes, and Stable Isotope Resource programs. These committees, assembled from eminent scientists in the fields of interest, serve the very important function of reviewing our plans, progress, and priorities and bringing to our scientific staff a perspective of the new and most significant developments in our areas of work. Memberships of our visiting committees during FY 1984 are listed in the Appendix of this report. Our monthly divisional and special seminars, also listed in the Appendix, serve as a valuable additional and complementary window on interesting recent progress and ideas from both within and outside the Division. 10 DIVISIONAL OVERVIEW

Construction and installation of an INC-Division Annex at TA-48 was completed during this fiscal year; we had moved in by July 1984. The building, situated near the INC-Division office and designated as RC-34, has provided quarters for the office of the Associate Division Leader for Advanced Research Concepts, the INC-3 Group office, and other division and group staff and engineering liaison. The building also serves as temporary space for consultants and uncleared staff and visitors. This report covers contributions during FY 1984 (October 1, 1983—September 30, 1984) to unclassified projects and to unclassified work related to the nuclear weanons program. The reports are grouped according to the division's strategic areas of work. Other division quarterly and annual reports are also published for certain specific programs. In the Appendix, publications and presentations for FY 1984 are given for each group. Highlights from our work in FY 1984, arranged by strategic area, are given below. The approximate funding for each strategic area is given in the Appendix.

1. RABIOCHEMICAL DIAGNOSTICS OF WEAPONS TESTS A significant fraction of INC-Division's funding and resources is devoted to the Radio- chemical Test Diagnostics Program. We must determine the yield of all Los Alamos nuclear tests at the NTS as well as provide many details of the physics and chemistry of nuclear explosives. The program is funded 76% in test diagnostics and 24% in research and development. This ensures continued progress by giving a healthy blend of direct programmatic obligations backed by appropriate research in support of the program. Results are now reported at two internal classified forums, both of which meet monthly—Experimental Review Group (ERG) and Weapons Working Group (WWG). Addi- tionally, twice a year we hold an Interlaboratory Working Group (ILWOG) meeting with Lawrence Livermore National Laboratory to review current procedures and new techniques in radiochemical test diagnostics for efficient use of our joint resources. The classified summaries of these activities can be made available to properly cleared individuals by contacting Alexander J. Gancarz of Group INC-7.

2. WEAPONS RADIOCHEMICAL DIAGNOSTICS RESEARCH AND DEVELOPMENT

• A He-jet source chamber and collection system for concentrating 235um recoil atoms from the decay of 23'Pu has been constructed. This apparatus will be used in an attempt to measure the thermal-neutron fission cross section of 235Um (26 minutes).

• Modifications being made to the two INC Division isotope separators should improve beam transmission and reduce cross contamination between Uotopes. A long-term effort is under way to implement ion-optic diagnostic techniques deve! ;ped at various accelerators over the past 20 years but not yet used by the isotope separator community.

3. OTHER UNCLASSIFIED WEAPONS RESEARCH

• Measurements of the 237Np/239Pu atom ratio in tissue samples suggests that neptunium is lost preferentially to plutonium in both liver and lung tissue.

• We have determined a set of pair potential parameters that can be used to predict the density of organic explosives within 2% for most compounds.

• Electron densities and electrostatic potentials have been determined for nitroguanidine from x-ray diffraction data; they are in qualitative agreement with theoretical calculations derived from a 321G basis set. DIVISIONAL OVERVIEW U

• The I3C NMR studies of a series of preparations of nitromethane lead to the conclusion that the aci-ion of nitromethane acts as a chemical sensitizer to detonation.

• Based on observed chemistry at high static pressure, a chemical mechanism is proposed for the detonation of nitric oxide.

STABLE AND RADIOACTIVE ISOTOPE PRODUCTION, SEPARATION, AND AP- PLICATIONS

• A 10'Cd-"wAgn generator for biomedica! applications has been developed using tin phosphate ion-exchange material and an elueit containing S2Oj, buffer, and ascorbic acid or dextrose. The llJ9Agm yield is steady at 56%, and the IMCd breakthrough is in the 1(T7 to 10"8 range.

• As a major step in our goal of preparing radiolabeled monoclonal antibodies, we have developed methods to radiolabel porphyrins with 67Cum, a potentially useful medical radioisotope. We have initiated research to conjugate porphyrins to antibodies.

• We have acquired expertise and instrumentation to give us strong capabilities for obtaining meaningful information from animal modeling systems.

• We have prepared an ultrapure source of 86Ru by using neutron activation and column chromatographic techniques. This unique source was vital for measuring the absolute cross- section for pair production in lead.

» During FY 1984, the Medical Radioisotopes Research Group irradiated, processed, and shipped 18 different kinds of radioisotopes to 5 Los Alamos groups and 39 other organizations around the world. Total shipments amounted to 49.7 Ci—an increase of 14.6 Ci from the previous year.

• Because of the nuclear medicine community's interest in high-purity 123I, a new strir.ger, target chamber, and collection station were designed and fabricated for the continuous collection, of radioxenon parents to produce 123I and 125I. Initial results from a 2-hour irradiation followed by a 2-hour growth period yielded 590 mCi of I23I with an l25I/i23I activity ratio of 0.21%. Slightly higher yield and purity are expected from a recent modification of the collection system.

' We produced record quantities of I5N and I8O to meet an increased demand from the scientific research community here at Los Alamos, across the US, and in foreign countries. o We used the nC plant to initiate a search for the X" particle postulated by the "big bang" theory.

• By using an experimental distillation column, we made new measurements on the isotope separation of sulfur and selenium. Our work confirmed earlier data for H,S, and we feel it is the preferred system for sulfur isotope separation by distillation.

• Metabolism in perfused heart models is being studied by NMR spectroscopy using l3C-enriched substrates. The effects of insults such as ischemia on substrate metabolism is observed within the intact tissue, and the protective mechanisms of therapeutic strategies are being investigated. 12 DIVISIONAL OVERVIEW

o The National Stable Isotopes Resource is sponsored by the National Institutes of Health, and its mission is to develop biomedical applications of stable isotopes. During this, 'he third, granting period, the research focused on developing stereospecific methods for the synthesis of chiral compounds labeled with the stable isotopes of carbon, oxygen, and nitrogen.

• L-carnitine serves to transport fatty acids in tissues, such as the heart, that use long-chain fatty acids as a primary energy source. We report the first direct observation of L-carnitine in perfused heart using L-[4-'3C]carnitine and in vivo nC NMR spectroscopy.

5. ELEMENT AND ISOTOPE TRANSPORT AND FIXATION

° Thermodynamic calculations based on gas, aqueous solution, and solid phase analyses indicate that the interface between vapor-dominated fluid and boiling geothermal fluid beneath Sulphur Springs will be an interesting region in which to investigate epithermal deposits through deep drilling.

• The Los Alamos Nuclear Microprobe has been used to determine the trace-element content of the different minerals found in oil shal' solids. Information about the exact mineral and/or intergrain distribution of trace elenuV: is essential for understanding the environmental behavior of products, wastes, and eiwuents from oil shale processing and the potential for contaminant mobility and transport. Our results show that trace-element content varies with the mineralogy of the shale sample and that trace-element/mineral association information is available when nuclear microprobe techniques are applied to this complex geologic matrix.

» We have developed an analytical expression for the free energy of albite below 392°C as a function of aluminum/silicon order. This expression makes it possible to calculate the effects of nonequilibrium states of order in albites or mineral equilibrium involving albite at low temperature.

• Recently acquired analytical data seem to indicate that the rhyolite of Pahute Mesa is as effective in retaining fissicn products produced resulting from underground nuclear tests as is the alluvium of Frenchman Flat.

• The geochemistry studies for the Nevada Nuclear Waste Storage Investigations project are continuing. They involve the determination of the expected retardation of waste elements in the site by sorption, precipitation, and physical processes such as matrix diffusion.

« Sorption measurements on Yucca Mountain Tuff show that zeolites are strong sorbers of many radioelements and that ground water composition can affect the sorption of radioelements on tuff.

• We have constructed a dynamic light-scattering apparatus that is capable of measuring submicron distributions at concentrations as low as IQ~°M. This technique will be used to measure the particle size distributions of natural colloids and plutonium polymer prepared under neutral conditions to determine the impact of colloids on radionuclide migration. DIVISIONAL OVERVIEW 13

6. ACTINIDE AND TRANSITION METAL CHEMISTRY

• Using high-resolution infrared specti oscopy, we have discovered a new phase of solid oxygen in thin films deposited at 10 K and have characterized auto-ionization of N,O4 in thin films at 180 K. Similar studies of SiF4 trapped in rare gas solids have led to new insight into the local site structure in such impurity-doped solids.

• The reduction of SO2 by organometallic group VI hydrides has yielded two novel complexes with unprecedented structures: a molybdenum dimer containing a bridging dithionite (SiOiH ligand and a tungsten dimer featuring strong Lewis acid bonding of SO2 to bridging sulfide ligands.

• Actinide valence and host effects are being studied in simulated nuclear waste forms by absorption spectroscopic, diffraction, and EXAFS methods.

• The use of FOOF (dioxygen difluoride) for oxidation/fluorination of uranium, neptunium, and piutonium compounds to produce hexafluorides is being studied with a view to potentially large commercial applications.

• A molybdenum-sulphur cluster was discovered that is the first example of a homonuclear butterfly cluster of a group VI-B metal.

• We have prepared an organometallic thorium complex containing terminal diphenylphosphido ligands and the first phosphido-bridged thorium/nickel complex that shows a strong thorium-nickel interaction. An unusual example of an organometallic thorium polysulfide has been characterized in which the ThS5 ring is in a twist-boat conformation.

• Studies have shown that alpha self-irradiation effects are important in long-term experiments with piutonium in solution. Equilibrium is not attained in such solutions and steady state conditions are only approached. This does, however, permit calculation of an upper limit on the solubility of piutonium in near-neutral solutions.

7. STRUCTURAL CHEMISTRY, SPECTROSCOPY, AND APPLICATIONS

• We have performed detailed studies of the temperature dependence of single-crystal polarized Raman scattering from acetanilide. These studies show that the unusual low- temperature feature at 1650 cm"1 previously assigned to a Davydov soliton arises from temperature tuning of Fermi resonance.

• Low-temperature resonance Raman studies of copper blue proteins have led to a new interpretation of the vibrational assignments for the copper blue site in these important redox metalloproleins. The results also show evidence for a temperature-induced structural change for plastocyanin and a classification of the copper blue proteins into three distinct classes.

• The structure of the extraction complex UO2('BU3PO)2(NO3)2 has been determined ai-ii establishes a bond strength/basicity scale for phosphoryl ligands. 14 DIVISIONAL OVERVIEW

8. NUCLEAR STRUCTURE AND REACTION

• The feasibility of using an on-line He-jet-couplecl isotope-separator facility at LAMPF for the study of nuclei far from stability has been established. The proposed ion-optical design of the facility incorporates a surplus isotope separator recently acquired from LBL.

• Both 243Np and 244Np have been produced by irradiation of 244Pu with l36Xe ions; the measured half-lives were 50 and 22 seconds, respectively.

• We have developed an off-shell model for pion-induced eta meson production on a nucleon and in nuclei.

« From first principles involving basic quark/quark and quark/gluon interactions within the framework of the Friedberg-Lee soliton model, we calculated the masses, charge radii, and magnetic moments of mesons and baryons.

• We measured the angular distribution ac 50 MeV for the pion double-exchange reaction l4C(7i+,7t"")14O to the double isobaric analog state in 14O for scattering angles between 20 and 130".

• Activation measurements of the cross section of four (7t,27t) reactions have been completed, and the results agree with our model calculations.

• The combined energy of the time-of-flight technique previously used to identify new neutron-rich nuclides produced at LAMPF has now been extended to give direct mass measurements of these species. The masses of 20N and 24F have been determined for the first time.

• TOFI, the time-of-flight isochronous spectrometer, is being built to make a systematic high- resolution (~ 100-keV) mass survey of the light neutron-rich mass region. Installation of the first half of the secondary beam transport line has been completed. We have tested the transport line with various alpha sources and fragmentation products to characterize the operation of the line.

• A sophisticated computer-based data acquisition system has been developed for the LAMPF nuclear chemistry laboratory.

9. IRRADIATION FACILITIES

o A total of 16 795 samples were irradiated in the OWR, and other use of the reactor amounted to 1763 experiment hours. Twenty-four Los Alamos groups and nine outside laboratories made use of the reactor.

• We used neutron activation analysis (NAA) to determine the fissile material content of 5040 samples and the trace-element content of 7514 other samples.

• A new, large (l-in.-diam) rabbit facility has been installed at the OWR for use in NAA measurements on air filters employed in atmospheric science studies.

• Stream sediment and beach sand samples collected systematically throughout the Caribbean island St. Lucia were analyzed by NAA as part of a reconnaissance-scale geochemical survey.

• A 6-year supply of OWR fuel elements was procured from Babcock & Wilcox. DIVISIONAL OVERVIEW IS

10. ADVANCED ANALYTICAL TECHNIQUES: DEVELOPMENT AND APPLICATIONS

• We used I5N to characterize acid sites in the catalyst y-zeolite.

• We designed a magnet that produces a uniform field outside its coils, allowing NMR studies of external samples.

• Several improvements to the accelerator-based mass spectrometry facility have allowed the generation of a methane beam for future use in methane-21 measurements.

11. ATMOSPHERIC CHEMISTRY AND TRANSPORT

• Three releases of deuterated methane were made to study the transport of atmospheric trace substances to Antarctica.

• We determined trace-element compositions for Hawaiian volcanic gases during an entire eruptive cycle.

• The boron content of many primitive types of chondrites differs regularly with meteorite type in a way that suggests its abundance has remained unchanged since the rocks were formed in the solar nebula. A few of these primitive chondrites and all of the more evolved ordinary types have boron contents that deviate from the expected primordial abundances. These deviations probably manifest alteration of the rocks by processes in the early solar system.

• Incorporating more realistic physiochemical processes in our geochemical model of the behavior of nitrogen oxides in the stratosphere has led to marked improvements in analysis and fitting, of nitric acid sampling data. An apparent discrepancy with models of nitrogen oxide production in a foreign atmospheric thermonuclear explosion in November 1976 has been resolved.

12. EARTH AND PLANETARY PROCESSES

• The activities expected for cosmic-ray-produced radionuclides in meteorites were calculated as a function of time in a solar cycle and for different chemistries. Cosmogenic nuclides in the Shergottite family of meteorites show that several Shergottites had different histories in space; this complicates the hypothesis that these meteorites came from Mars.

o In collaboration with Australian and Canadian geologists, we have discovered a moderate iridium anomaly at the Upper Devonian Frasnian/Famennian extinction boundary exposed in northwestern Australia; the excess iridium is apparently the result of bacterial enrichment from seawater.

• In geochemical studies of eight extinction boundaries that predate the terminal Cretaceous event, we have not found any evidence to support the popular "death star" hypothesis. Radiochemical Diagnostics of Weapons Tests 19 RADIOCHEMICAL DIAGNOSTICS OF WEAPONS TESTS 19

RADIOCHEMICAL DIAGNOSTIC OF WEAPONS TESTS

The Radiochemical Test Diagnostics Program requires a significant fraction of INC-Division funding and resource commitments. We must determine the yield of all Los Alamos Nevada tests as well as provide many details of the physics and chemistry of nuclear explosives. The program is funded 76% in test diagnostics and 24% in research and development. This ensures continued progress by giving a healthy blend of direct programmatic obligations backed by appropriate research in support of the program. Results are presently reported at two internal classified forums, both of which meet monthly—Experimental Review Group (ERG) and Weapons Working Group (WWG). Addition- ally, twice a year we hold an InterLaboratory WOrking Group (ILWOG) meeting with Lawrence Livermore National Laboratory to review current procedures and new techniques in radiochemical test diagnostics for efficient use of our joint resources. The classified summaries of these activities can be made available to properly cleared individuals by contacting Alexander J. Gancarz, INC-7. 2.

Development of Surface-Ionization Diffusion-Controlled Ion Sources for Actitiide Analysis 23i

Rutherford Backscattering Analysis of Heavy-Metal-Doped Light-Element Matrices 26

Particle-Induced X-Ray Emission Analysis of Metal Alloys 28

Electromagnetic Isotope Separators 30

Thermal Fission Cross-Section Measurement of 235mU 34 WEAPONS RADIOCHEMICAL DIAGNOSTICS RESEARCH AND DEVELOPMENT 23

DEVELOPMENT OF SURFACE-IONIZATION DIFFUSION-CONTROLLED ION SOURCES FOR ACTINIDE ANALYSIS

R. E. Perrin, J. H. Cappis, D. W. Efurd, and D. J. Rokop

For the past 4 years, we have conducted an extensive study of diffusion-controlled surface- ionization sources for mass spectrometry. This concept, first proposed by Rec and coworkers.' involves coating the element to be analyzed with a thin layer of high-work-function metal. The system has several advantages over loading techniques that use direct evaporation of elemental salts onto a high-work-function filament. First, because the element being analyzed is forced to diffuse through a layer of high-work-function metal, the evaporation rate is greafly reduced and higher filament temperatures are possible without sample depletion. This higher filament temperature yields significantly improved ionization efficiencies. Second, diffusion through the metal barrier causes dissociation of the salts and permits only atomic species to reach the surface. The resulting spectrum is much less complex and requires fewer corrections when isotopic ratios are calculated. Rec formed the diffusion layer by if sputtering of the desired metal. This procedure permits excellent control of film thickness but is somewhat equipment-intensive for routine work. We have investigated electroplating techniques for applying rhenium, rhodium, and platinum.2 Rhenium platings tend to crack and, thus, preclude a pure diffusion-controlled evaporation of the element to be analyzed. Rhodium forms a satisfactory plating and is valuable when filament temperatures above 1700°C are required. However, at 1700°C there is an extremely large l03Rh peak that causes a significant increase in the background because of scattered ions. This is a problem when we use a single-stage mass spectrometer. Platinum platings are relatively uniform and permit true diffusion control for elements that wiil diffuse through the platinum at temperatures below 1700T. The high work function of platinum increases ionization efficiency and its high ionization potential prevents formation of a significant number of platinum ions. We selected platinum for study as a diffusion barrier for analysis of several actinides, and the results of those studies are summarized here. When we compared the platinum diffusion barrier to previous studies that used a rhenium diffusion barrier, we observed a significant difference in the plot of ion intensity vs time, as is shown in Fig. 2.1. Although the data shown are for plutonium, similar intensity vs time rates can

200

50-

c o u 30 36 40 45 55 Time into Run (min)

Fig. 2.1. Typical ion beam intensities fora 1-ng plutonium sample. 24 WEAPONS RADIOCHEMICAL DIAGNOSTICS RESEARCH AND DEVELOPMENT

also be demonstrated for uranium, americium, and neptunium. The continuously increasing ion intensity exhibited for samples overplated with platinum is consistant with a true diffusion- controlled system.1 The behavior of the rhenium overplate is indicative of a simple evaporative mechanism. Microphotographs of the two diffusion barriers reveal numerous cracks in the rhenium that were not present in the platinum. In addition to providing much more constant fractionation control, the diffusion-controlled system allows the operator to measure minor isotopic ratios later in the analysis when the total ion beam is at a maximum. The advantages of this option are demonstrated by the excellent minor-isotope accuracy achieved for the analysis of the NBS 947 plutonium standard, as is shown in Table 2.1. Electroplating techniques provide two additional advantages over the more widely used technique of directly evaporating solutions of the element to be analyzed onto the mass spectrometer filament. First, alkalis and alkali metals are not deposited under the conditions we have selected. Second, hydrocarbons are also not deposited under these conditions. Consequently, the spectra formed from electrodeposited samples are at least (03 lower in both alkali and hydrocarbon isobaric interferences. For this investigation, we used \.5M HCI adjusted to a pH of 2.7 with gaseous NH, (Ref. 2). At a potential of 3.4 V, plating efficiencies in excess of 95% are possible for plutonium, uranium, americium, and neptunium, and the plating times are less than 30 minutes. Because many other elements will also plate efficiently under these conditions, good separation chemistry must be done before the sample is electroplated. After the sample has been electrodeposited onto the filament, a layer of platinum is plated over the sample from this same electrolyte. Platinum is added to the electrolyte in the form of a dinitrato-sulfato-platinous acid solution. This solution is prepared from a stock solution containing 5 g of platinum per 50 mS of 1M HCI. The stock solution is diluted with 1.5A/ HCI to a concentration of 5 mg/m8. Electroplating 25 ug of platinum for 30 minutes at 3.0 V will produce a 110-A platinum film. Film thickness was determined by Rutherford backscattering using 3-MeV alpha particles. The general procedure for forming a platinum diffusion barrier is described in detail in Ref. 3. Procedures have been developed for high-precision analysis of plutonium, uranium, americium, and neptunium. These procedures have been optimized to provide a complete isotopic analysis within 70 minutes after filament heating is initiated. This time scale requires some compromise between maximum precision and maximum ionization efficiency. In general, greater ionization

TABLE 2.1. Analysis of NBS Standard Sample 947a Analysis M0 239 2 239 242 239 Number 238pu/239pu Pu/ Pu -"Pu/ Pu Pu/ Pu 1 0.00368 0.24149 0.01582 0.01556 2 0.00367 0.24141 0.01576 0.01560 3 0.00369 0.24133 0.01576 0.01547 4 0.00365 0.24141 0.01582 0.01558 5 0.00367 0.24136 0.01581 0.01562 6 0.00366 0.24143 0.01585 0.01560 7 0.00366 0.24144 0.01582 0.01563 8 0.00364 0.24145 0,01577 0.01567 9 0.00367 0.24144 0.01576 0.01559 x = 0.00367 0.24142 0.01580 0.015S9 Certified 0.00363 0.24142 0.01580 0.01559 Value "AH data has been decay corrected to March 1,1981. WEAPONS RADIOCHEMICAL DIAGNOSTICS RESEARCH AND DEVELOPMENT 2S efficiency and greater beam stability can be achieved with thicker platinum coatings. However, thicker coatings increase the time required to achieve the signal intensities needed for accurate measurement of large isotopic ratios. The procedures adopted for each of the four elements are summarized in Table 2.2. For piutonium and uranium, the accuracy statements were obtained by repeated analysis of NBS isotopic standards. For americium and neptunium, precision data were obtained by repeated analysis of approximately 1:1 mixtures of 24lAm and 243Am and 236mNp and 237Np, respectively. No certified standards are available for americium and neptunium. The precision and accuracy statements for uranium and piutonium are valid for measurement of the major isotopic ratios when the ratio is no larger than 20:1. The precision statements for americium and neptunium are valid for ratios that are not greater than 20:1. The somewhat poorer precision for americium and neptunium probably reflects the fact that the purity of the material analyzed is less well known than that of the uranium and piutonium standards. Additional work remains to be done on these elements. The use of a surface-ionization diffusion-controlled ion source yields significant advantages in both sensitivity and accuracy for the analysis of uranium, piutonium, americium, and neptunium. Additional applications of the concept will be tested in future studies.

TABLE 2.2. Summary of SID Analytical Procedures Plutonium Uranium Americium Neptunium Sample size (g) 1 X 10-» 9 X 10~9 1 X 10-10 5 X 10-" Amount of platinum co-plate (g) None 1.0 X 10~5 1 X 10"5 None Plating time (minutes) 30 20 30 30 Plating voltage (V) 3.4 3.4 3.4 3.3 Amount of platinum overplate (g)' 2.5 X 10-5 1 X 10"4 5 X 10~5 2.5 X10"5 Overplating voltage (V) 3.0 3.0 3.0 3.0 Overplating time (minutes) 30 15 30 20 Drying time (minutes) 5 5 5 5 Drying current (A) 1.25 1.0 1.0 1.25 Ionizing temperature (°C) 1450 1600 1350 1580 Mean beam intensity (cps at 40 minutes) 2SO000 500000 200000 100 000 Change in fractionation/30 minutes (%) 0.075 0.25 <0.15 <0.15 lonization efficiency (%) 0.34 0.2-0.3' NDb ND" Filament to filament precision at 95% confidence (rel. %) 0.075 0.072 0.2 0.2 Filament-to-filament accuracy (rel %) 0.075 0.072 N/A N/A "Preliminary tests indicate slightly less efficiency than with plutonium. bNot determined. 26 WEAPONS RADIOCHEMJCAL DIAGNOSTICS RESEARCH AND DEVELOPMENT

RUTHERFORD BACKSCATTERING ANALYSIS OF HEAVY-METAL-DOPED LIGHT- ELEMENT MATRICES

Timothy M. Benjamin, Pamela S. Z. Rogers, Joseph R. Tesmer (P-9), and R. Neil Brown*

The weapons testing program requires that we develop many new diagnostic techniques. We reported several applications of particle probe analysis at the Los Alamos Ion Beam Facility in previous INC Division annual reports.4"7 During this fiscal year, we applied one of these techniques, Rutherford backscattering (RBS), to a light-element matrix that was loaded with compounds of the elements hafnium, tantalum, tungsten, rhenium, and osmium. The purpose of our analysis was to check for homogeneity and absolute quantity of the metals. In addition, we desired data on the residual salt anions and possible contaminants. Experimental conditions for RBS require careful optimization. Characteristics of the samples that necessitate a relatively high proton energy include: matrix, vulnerability to heat damage from beam energy loss, and elemental discrimination. The potential for undesired, radiation-producing nuclear reactions and inelastic, non-Rutherford scattering requires the lowest possible proton energy. A proton beam energy of iO MeV appears to be nearly optimum when combined with a 150° scattering angle. Under these conditions, we used a 2- by 2-mm spot to acquire the data in Fig. 2.2 and Tables 2.3 and 2.4. The samples showed some darkening as a result of beam damage, but there was no melting from the approximately 2-MeV proton energy loss. Elemental discrimination for the tantalum- loaded sample was adequate but not ideal, as is shown in Fig. 2.2. Ideally, for each element, the spectrum should show both the high-energy leading edge and the low-energy trailing edge superimposed only on background; however, only for the carbon are both edges obvious. Fortunately, the concentration data are obtained by the height of the leading edges, which are resolved. To be accurate, this analysis assumes that the matrix is homogeneous with depth. The flat tops of the tantalum peaks (channels 570 to 670) and carbon peaks (channels 460 to 500), in addition to the longitudinal homogeneity, support this assumption. The homogeneity test data are

20000 ' 1 r — 1 1 1 '

C 10000 - 3 O o / \ 0 Ta 1 400 500 600 700 800

Channel Number (10 KeV/CtO

Fig. 2.2. The 10-MeV proton RBS spectrum of a thick, tantalum-loaded matrix. The leading and trailing edges of the carbon (C) pe&k are well resolved. Only the leading edges of the tantalum, fluorine, and oxygen peaks are resolved. The essentially flat lops of the peaks are indicative of a homogeneous sample.

"United States Naval Academy WEAPONS RADIOCHEMICAL DIAGNOSTICS RESEARCH AND DEVELOPMENT 27

TABLE 2.3. Homogeneity of a Tantalum-Loaded Matrix Position Tantalum/Carbon Ratio (mm) (arbitrary units) 4 1.61 8 1.39 13 1.43 18 1.37 25 1.49 29 1.38

1.45 ±0.09

given in Table 2.3 for the tantalum-doped material. The tantalum/carbon ratio is given for the integrated counts under the flat portions of the peaks. The homogeneity values have an overall standard deviation of 6%. which is comparable to the statistical error in each measurement. Overall, the matrix appears to be homogeneous throughout its volume. Absolute quantities require that we use absolute scattering cross sections with carbon as an internal standard in the matrix. The conditions for totally elastic, Rutherford scattering were only achieved for the medium- to high-Z elements. The low-Z elements, such as carbon, required a calibration for the non-Rutherford cross sections. To use the carbon as an internal standard, we experimentally determined the total scattering cross section. We used a thin (650-ug/cnr nominal) foil with an atomic composition of W0,C, 6:. Data from ihis foil, under our experimental conditions, yielded total scattering cross sections for carbon (13.0 ± 0.6 b) and oxygen (7.4 ± 0.3 b) by ralioing to the tungsten Rutherford cross section (81.52 b). These total cross sections are nearly a factor of 15 greater than the Rutherford cross sections. This calibration is obviously of critical importance. Table 2.4 lists the absolute concentrations of the hafnium, tantalum, tungsten, rhenium, and osmium; they are based on the carbon density of 1.48 x ).0:i atoms/cm3. The loading is approximately 3 al.%, except for rhenium, which is 4 at.%. The statistical precision is 5%.

TABLE 2.4. Absolute Concentrations of Heavy Metals Loaded in Light-Element Matrices Concentration" Dopant (1019 atoms/cm3) F/Metal CI/Metal Q/Metal N/Metal Hf 4.2 ± 0.2 3.1 ± 0.2 Ta 4.3 ± 0.2 <6 0.8 ±0.2 W 4.7 ±0.3 1.2 ±0.2 Re 6.2 ± 0.4 <5 1.2 ±0.2 <25 Os 4.6 ± 0.3 <0.8 ± 0.8 1.6 ±0.2 "Calculated assuming carbon = 1.48 X 1021 atom/cm3. 28 WEAPONS RAD1OCHEMICAL DIAGNOSTICS RESEARCH AND DEVELOPMENT

We observed several low-Z elements in the spectra (Fig. 2.2). The oxygen total cross-section calibration permitted us to calculate the absolute ratio of oxygen to metal. For four of the five samples, it appears that each metal atom has an attached water of hydration. The hafnium is unique in that it is loaded as a chloride. Because chlorine is probably behaving as a Rutherford scatterer, the data show that the hafnium resides in the sample as HfCl3. The fluorine and nitrogen results are only upper limits and are actually too high by at least an order of magnitude, based on the carbon and oxygen total cross-section calibration results. The RBS technique is an accurate technique for investigating homogeneity and absolute abundances and for detecting a wide range of elements in thick samples. We will continue to study calibration and experimental optimization to enhance the technique's versatility in materials science problems.

PARTICLE-INDUCED X-RAY EMISSION ANALYSIS OF METAL ALLOYS

Timothy M. Benjamin, Clarence J. Duffy, Pamela S. Z. Rogers, Joseph R. Tesmer (P-9), and R. Neil Brown*

The National Security Program frequently calls for test components that require new alloys and metallurgical techniques. To help develop these new alloys, we have applied our particle-induced x-ray emission (PIXE) capability to the in-situ quantitative analysis of two metal alloys. Character- istic x-rays induced by proton irradiation are collected with a Si(Li) detector. By using theoretical calculations based on the fundamental parameters for proton energy loss, x-ray production, and x-ray absorption, we converted the counts in the x-ray peaks to concentrations. The results were normalized to 100% total concentration. We have published detailed discussions of our experimental configuration at the Los Alamos Ion Beam Facility, our data acquisition, and our data reduction techniques.812 The first samples analyzed were of an "alloy" formed from sintering tungsten and europium oxide powders (Table 2.5). Irradiation with 2.75-MeV protons produced characteristic x rays from the samples. Counting times were approximately 15 minutes per analysis point, which was sufficient to yield counting statistics of less than 2% for the Eu2O3 minor component in the alloy. The data was taken on orthogonal axes (X and Y) for each sample. The spot size of the proton beam was approximately 2 by 2 mm. Although micron-scale spots are attainable, the sintered, heter- ogenous nature of the samples required an averaged analysis over a large area (relative to the initial powder mesh size). The data presented in Table 2.5 show local heterogeneities on a centimeter scale. Overall, the heterogeneity of these samples is ~6%. We did not observe any significant contaminants; however, we did not optimize the experiment for trace-element investigation. The second sample was a true alloy of gold, copper, and europium metals (Table 2.6). Experimental conditions were identical to those for the first samples. This alloy appears more homogeneous than the Eu2O3-W sintered "alloy;" the variation is 3% in europium and 1% in copper. These examples illustrate the application of the PIXE technique to nondestructuve, spatially resolved, in situ quantitative analysis of macro-scale alloy pieces. Although they are far removed from the tested limits of PIXE analysis (micron-scale beam spots and 10-ppm detection limits), these results are a significant contribution to the development of new materials at Los Alamos.

"United States Naval Academy WEAPONS RADIOCHEMICAL DIAGNOSTICS RESEARCH AND DEVELOPMENT 29

TABLE 2.5. Analysis of a Tungsten and Europium Oxide Alloy

Distance Eu2Oj Sample 1 Eir,Oj Sample 2 From Center (Wt%) (Wr%) (cm) X-Axis Y-Axis X-Axis Y-Axis + 4.5 2.61 ± 0.03 2.61 ± 0.03 + 3.5 2.63 ± 0.04a 2.94 ± 0.03 + 3.0 2.32 ±0.03 2.58 ± 0.03 + 2.5 2.71 ± 0.05 2.59 ± 0.03 + 1.5 2.86 ± 0.03 2.49 + 0.04 2.44 ± 0.03 2.56 ± 0.03 0 2.69 ± 0.03 2.54 + 0.03 2.68 ±0.03 2.72 ± 0.03 -1.5 2.61 ± 0.04 2.71 ± 0.03 2.54 ±0.03 2.63 ± 0.03 -2.5 2.82 ± 0.04 2.56 ± 0.03 -3.0 2.38 ± 0.03 2.43 + 0.03 -3.5 2.39 ± 0.03 2.47 ± 0.03 -4.5 2.52 ± 0.03 2.66 ± 0.03 Averageb 2.67 ± 0.16 2.62 ±0.17 2.50 ± 0.13 2.60 ±0.09 Average 2.64 ± 0.16 2.55 ±0.12 "Errors are la, based on counting statistics. ""Errors are la of the data.

TABLE 2.6. Analysis of a Gold, Copper, and Europium Alloy Distance From Center Europium Copper (cm) (Wt%) (Wt%) + 4.5 3.06 ± 0.04° 5.15 ± 0.02 + 3.0 3.03 ± 0.04 5.22 ± 0.02 + 1.5 3.09 ± 0.04 5.12 ±0.02 0 3.20 + 0.03 5.16 ±0.02 -1.5 3.00 ± 0.04 5.22 ± 0.02 -3.0 3.22 ± 0.04 5.17 ±0.02 -4.5 3.05 ±0.04 5.17 ± 0.02 Average1" 3.09 ±0.09 5.17 ±0.04 "Errors are la, based on counting statistics. •"Errors are la of the data. 30 WEAPONS RADIOCHEMICAL DIAGNOSTICS RESEARCH AND DEVELOPMENT

ELECTROMAGNETIC ISOTOPE SEPARATORS

John P. Balagna, Edwin P. Chamberlin, David J. Vieira, Greg M. Kelley, Roland A. Bibeau, and Richard L. Stice

Because radioactive species are produced during neutron and charged-particle interactions with materials that are added to weapons test devices, we must use increasingly sophisticated weapons diagnostic techniques to measure several radioactive species of one element. For many cases, this is made possible by direct counting of the emitted radiations—usually gamma rays. When very low abundance nuclides (for example, IO5Ag, 106Ag) are produced with very high abundance species such as ' l0Ag,'" Ag, an isotope separator is used to measure all species. We have two isotope separators in operation and are building two more. The magnets for the new separators were designed by J. Camplan of the Rene Bernas Laboratory in Orsay, France. The design was optimized to provide an instrument that will maximize transmission of sample introduced to the ion source and minimize isotope cross contamination (tailing). The new ion optics code TRIO, written by H. Matsuda of Osaka University and modified by I. Chavet of the SOREQ Research Center in Isreal, was used in the magnet design. The separator will accommodate ion sources with both slit and circular apertures. Ultrahigh vacuum techniques will ensure a very low level of gas scattering in the ion beam. The magnet has a deflection angle of 126° and a field index of 0.5 to give both radial and axial focusing. The separator will have variable dispersion so that we can use reanalysing devices such as electrostatic deflectors to decrease cross contamination of masses. This requires a variable-position focal plane. To help adjust beam waist position and minimize aberrations, we will use alpha and beta coils on the magnet pole faces (Ref. 13). By this method, both the first (alpha) and second (beta) field indices can be adjusted. The collector tank is large enough to accommodate either an electrostatic deflection system for tailing reduction or for a second magnetic sector after the focal plane. The instrument can accommodate a range of masses from 30 to 275 and a collection capacity of ±10% in any one measurement. We are developing ion sources suitable for weapons diagnostic work. High-efficiency sources are required because the sample size is limited. A new plasma source will replace the Nielsen source that has been used for many years. We have also adapted a negative ion source (based on the Middleton design) to separate isotopes of gold, iridium, and platinum.

Isotope Separator 2: Upgrade There are two isotope separators presently being operated by INC-11 staff: the 55° separator (1S2) located in Building RC-8 and the 90° separator (IS1) in Building RC-1, Room 313. During the past year, we have expended nearly all our upgrade effort on IS2. The following description summarizes what we have accomplished and the planned improvements. In the past, unexpected shifts in beam dispersion have occasionally occurred on IS2. Because the entire separator system was to be relocated during FY 1984, it seemed worthwhile to determine if such shifts were caused by changes in the relative positions of separator components. Before the separator was disas- sembled for the move, we measured the effect of ion source transverse position on focal plane dispersion. The ion source was first positioned 1 mm to the left of axis and we measured the distance between l55Gd and IS8Gd peaks using the focal plane beam scanner. The ion source was then moved 2 mm to the right of axis and we rerneasured the peak spacing; it had decreased 3%. Therefore, if the full design capability (±15% spread around the central mass) of this separator is to be achieved with less than I-mm shift of the extremum masses, the ion source must always be located within 0.40 mm of the axis. The measurements also indicated what relative realignment accuracy would be required after the separator was moved to its new location in Building RC-8. We planned the move so that the separator components could initially be reassembled in their original relative positions. We then used optical alignment equipment to determine quantitatively the deviation of various elec- WEAPONS RADIOCHEMICAL DIAGNOSTICS RESEARCH AND DEVELOPMENT 31

trostatic elements from the optimum positions. The major deviation was a 1.3" offset of the 50-keV transport line at the magnet entrance. Correction of this misalignment requires new hardware because the transport line presently contains no flexible elements. Alignment apertures were made for each electrostatic element, and all elements are now coaxial. Correct relative alignment has eliminated beam steering by lenses. Vertical steering in the transport line was previously provided by the vertical elements of a quadrupole lens. The horizontal elements were grounded. Because the resulting electric field distorted the focused image, we replaced the electrodes with parallel plates. The beam spot uniformity is noticeably improved, and a greater range of vertical adjustment is available. To determine whether peak separation was dependent on focal plane position, we separated a europium sample by using the surface ionizatior. source. Foil burns of the two intense peaks (masses 15lEu and 1S3Eu) were made in the center and at each end of the foil. The l5lEu/'"Eu peak separation varied from 24.7 mm at the light-mass end of the foil to 21.5 mm at the heavy-mass end. The peak separation for the burn at the middle of the foil was consistent with a linear variation of separation with position. To eliminate this effect from sample to sample, we made all separations of each element with the same marker isotope focused to a fixed location on the collection foil.

Tailing Problems. A continuing problem with IS2 is the relatively high (and inconsistent) tailing fraction in separated samples. Tailing fraction is defined as the amount of mass M in the separated sample of mass M + N or M — N. The system should achieve (M + 1)/M ratios (assuming equivalent sample amounts) of about 10~5 under optimum conditions. A ratio of lCT4 should be attainable in day-to-day running. Ratios of about 10~3 are the rule, however, and a recent ratio of 4.25 X 1CT: has been measured.

How IS2 Should Work. The process of isotope separation using a dispersive magnet is straightforward. An ion source is used to generate a plasma containing ions of the isotopes to be separated. An electric field external to the ion source extracts ions from the plasma surface through an opening in the ion source body and focuses the ions into a beam that occupies a limited volume in six-dimensional phase space: (X, X', Y, Y', L, dp/p). This phase space description of the beam is called emittance. The coordinates X, X', Y, and Y' describe the position and angle of a.particle relative to the central axis in

What Can Go Wrong. Any phenomenon that interferes with the orderly process described above can lead to reduced beam transmission, excessive tailings, or poor focus at the focal plane. In an attempt to determine the cause of excessive tailing on IS2, we have undertaken an experimental program to determine the phase space volume occupied by the beam at various points in the separator system. Several factors contribute to tailing.

(1) The emittance of the beam exiting the extractor may be too large. The term "too large" includes micro-filaments in phase space that do not show up on a beam viewer because they are either not intense enough or do not have a projection into "normal" space. 32 WEAPONS RADIOCHEMICAL DIAGNOSTICS RESEARCH AND DEVELOPMENT

(2) The beam is not monoenergetic. This factor is actually covered in the case above (dp/p in the six-element phase space vector).

(3) Ions in the beam encounter residual gas molecules and are either scattered (X' and Y' are changed) or slowed (dp/p is changed).

(4) The beam is not collected in the focal plane of the magnet.

The poor tailing ratios measured on IS2 appear to be the result of a combination of poor beam emittance from the ion source and ion scattering from residual gas. We carefully monitored electrode voltage instabilities during tailings measurements; they are too small to cause the effects being observed. To diagnose the effects, we mounted a tailing monitor in the isotope collection plane. The monitor consists of 11 Faraday cups connected to logarithmic amplifiers. The spacing between cups is adjusted to match the dispersion of l:>'Tb and covers the range from l54Tb to 1MTb. The amplifier for the central mass cup has a gain 10"1 less than the other amplifiers. This gain difference approximates the relative intensities expected when separating a sample that has only one isotope. Each amplifier has a range of 10!.

I on-Source-InducedAberrations. The shape of the plasma surface from which ions are extracted is the primary determinant of beam phase space volume. The shape of this plasma surface is established by three parameters:

(1) the plasma density inside the source.

(2) the electric field from the extractor electrode, and

(3) the shape of the ion source surface adjacent to the plasma surface. hems (1) and (2) may be optimized by varying power supply parameters; however, item (3) was causing problems on the surface ionization source. There is a single heat shield that is used as boih an electron reflector and an outer electrode. Its electric potential is adjustable and, therefore, different from the ionizer electrode potential. Precisely aligning the two electrodes minimizes beam emittance, but the alignment cannot be maintained at elevated operating temperatures. Any relative transverse shift introduces a transverse electric field component at the points where the ions have lowest energy: the plasma surface. Present plans are to install a second (inner) shield that will be biased for electron reflection. The outer shield will then be operated at the same potential as the ionizer electrode, which will eliminate electric field distortions.

Other Planned Changes. The present collection plane is 2.6 m from the magnet exit and is oriented normal to the central mass trajectory. The magnet was designed, however, to have the focal plane center point located 2.07 m from the magnet exit and inclined only 25° from the central trajectory. In this orientation, a parallel beam entering the magnet would be focused to a minimum spot size in both the horizontal and vertical planes (Ref. 14). To compensate for our shifted collection plane, the beam envelope at the magnet entrance must be diverging rather than parallel. Whereas this divergence causes no severe problems, it does reduce the phase space acceptance of the magnet and prevents the use of certain tailing-reduction techniques. We are redesigning the collection plane apparatus to include additional diagnostic equipment and will position it at the proper location and angle. When the new collection plane hardware has been installed, we will make changes in the beam transport line between the extractor exit and magnet entrance. The beam is presently only 10 mm in diameter at the magnet entrance; it should be 40 mm high and 90 mm wide for optimum WEAPONS RADIOCHEMICAL DIAGNOSTICS RESEARCH AND DEVELOPMENT 33

resolution (Ref. 15). To allow also for variable resolving power, we will lengthen the transport line and install a quadrupole triplet (Ref. 16). We plan a double-slit emittance measuring/limiting system to allow pencil beam formation for magnet aberration measurements (Ref. 17). An additional pump will be installed in the lengthened line to further reduce gas-scattering effects.

Future Plans Obviously, the plan outlined above for IS2 will require considerable effort. Why expend such effort when two new separators are being built and made operational at the same time? There are several reasons.

(1) The new separators will not be ready to run samples for about 2 years.

(2) IS1 will be dedicated to running intense radioactive samples; it will not be available for development work.

(3) The two new separators are designed for very high resolution work; to accomplish the design goals, we sacrificed some flexibility.

(4) Only IS2 remains available for general development work. As it is reconfigured, the hardware will be designed so that the system may be moved (relatively easily) to other locations for short-term work. These locations include the Nevada Test Site, the Los Alamos Van de Graaff Facility, and a second-stage separator for diagnostic work on the new high- resolution separators.

Several new computer codes now available on the 203 VAX will help us understand various ion beam phenomena.

IS2FE: The region from the ion source to the magnet entrance on the 55° separator (extractor, Einzel lens, deflection plates) consists entirely of electrostatic elements. This region has been modeled as an array with [-ram grid spacing. Values for voltages and the extractor location are input, and Laplace's equation is solved over the array using relaxation techniques. A printer plot of the electric field distribution is generated. Particle trajectories are calculated as a function of the input beam emittance.

SNOV/: This code was written at Sandia National Laboratories and is well documented in Ref. 18. The program simulates a plasma surface, acceleration region, and drift space with space charge neutralization. Electrode potentials are simulated on a large rectangular array, and electric field distributions are solved by iterative techniques. Poisson's equation is then solved a: each point within the array by using beam space charge densities computed from ion trajectories. The interdependence between electric fields from electrodes and electric fields from the beam are recalculated until agreement at the user-specified level is achieved. Using the code can be tedious, but it has proven to be accurate and well worth the effort (and computer time) required. Approximately 2 to 3 hours of VAX CPU time are required per simulation for "rough" results. When a workable configuration has been found, 6 to 8 hours may be necessary for a well-converged solution.

1S2FP: The magnet and collector region of the 55° separator have been modeled for trajectory and focal plane investigations. Except for sharp cutoff fringe fields at the magnet edges, no approximations are used. Input energy, angle, emittance, and mass (up to 5) may be varied. Ten trajectories are calculated for each of the five masses. The program calculates focal points and separation between focii and provides a printer plot of the 50 trajectories. No further documentation of the program is planned, but inquiries are welcome. 34 WEAPONS RADIOCHEMICAL DIAGNOSTICS RESEARCH AND DEVELOPMENT

THERMAL FISSION CROSS-SECTION MEASUREMENT OF 235mU

Merle E. Bunker, Willard L. Talbert, Jr., John W. Starner, and Silvio J. Balestrini*

The properties of the isomeric first-excited state of 233U have been studied sporadically for 27 years. This isomer, which lies 73 eV above the ground state and has a half-life of 26 minutes, has a much different spin-parity (l/2+) than the ground state (7/2~) and could provide an important test of fission theories relating to the dependence of fission cross section on initial angular momentum. Because the nuclear configuration for 235mu is presumed to be similar to that of the ground state of :v'Pu, it wouid not be surprising if the :33mu fission cross section were higher than that of 215gU [oi..i,(2"EtJ) = 584 b; a, ,,,(:wPu) - 742 b]. Previous studies of the 235mU cross section were limited by sample size, typically 10s atoms/cnr collected by direct recoil from 2™Pu alpha decay. We have devised what appears to be a practical method of collecting a much larger sample of 233mU. Our initial goal is to measure the thermal-neutron fission cross section with a fission counter placed in the thermal column of the OWR. A ~^m\j sample of •—10'' nuclei should provide an adequate count rate to determine a 10% difference between the isomer and ground-state fission cross sections (the ground-state fission rate can be determined from the same sample by waiting for the isomer to decay). To obtain such a sample, we plan to use a He-jet technique. Our design makes it possible to collect :35mu recoils from a large surface of lw?u and direct these atoms to a relatively small spot on a collector, which can then be inserted into a fission chamber. The recoil energy of 90 keV allows the 2WPu layer to be as thin as 20 ug/cm:, and a surface area of about 1200 cm2 should provide the required sample size if we can achieve a 50% He-jet collection and transport efficiency. We have evaluated volatile solvents as aerosol materials because we require a sample of 2-mU that is devoid of aerosol deposit. We found that the desired density and size distribution of aerosol particles can be obtained, under simulated flow conditions, with Freon-PCA aerosol material. We made a trial collection to confirm that the (volatile) aerosol leaves no trace in the collected sample. A :33niu production chamber has been fabricated that will hold 14 disks plated with 23t)Pu and employ 13 capillaries for collecting the aerosol-loaded helium that will flow past the plates. The total active area of the plutonium-plated disks in the production chamber will be 1186 cm2. The 13 capillaries are bundled together to direct the flow onto a platinum collection disk. We built and are in the process of evaluating a prototype fission chamber of the type that will be used to detect neutron-induced fissions in the deposit on the platinum collection disk. The fission chamber will be operated as a flow-type ionization counter to allow biasing out nonfission events. Although the production chamber and fission chamber have both been constructed, neither has yet been used in a "hot" condition. The plutonium-plated disks are not yet available, and the fission chamber must be evaluated with a known amount of 235U before the experiment can proceed. Assuming that the designs of both chambers are satisfactory, we should have a preliminary result *br the fission cross section within the next year. Although the thermal-neutron fission cross section is a fundamental property of :35mU, weapon theorists are more interested in the fission cross section as a function of neutron energy up to a few million electron volts. If we are successful in the thermal fission cross-section measurement, we will be able to evaluate an extension of the technique to measurements with higher energy neutrons at, for example, the Weapons Neutron Research Facility at LAMPF.

*Los Alamos National Laboratory consultant Density Prediction of Organic Explosives 37

High-Pressure Studies of Nitric Oxide and Oxygen 37

NMR Studiesof Organic Explosives 44

Electron Density in Organic Explosives 45

Neptunium-237 in Human Autopsy Tissues 47 OTHER UNCLASSIFIED WEAPONS RESEARCH 37

DENSITY PREDICTION OF ORGANIC EXPLOSIVES

Don T. Croiner and Robert R. Ryan

The Chapman-Jouquet detonation pressure produced by an organic explosive is proportional to the square of the solid state density. Thus, if new and improved explosives are to be developed, a high density is a necessary property. It is an expensive undertaking to synthesize a new organic compound. If its density could be reliably predicted, one could make a rational decision whether to expend limited resources on the synthesis of a proposed compound. We are using the pair potential model for computing and minimizing the crystal energy of organic compounds. This model expresses the energy in the form

W = XX I-A,A)ry"+ B,B, acp[-ru(C, + C,)] + q.qyr.j ,

where the summation runs over all atom pairs in the crystal. The first term is a Van der Waals attractive term, the second term is repulsive, and the third term is a Coulomb energy that is repuisive or attractive, depending on whether the charges q have the same or different signs. Parameters A, B, and C are characteristic of the chemical species, and r,j is the distance between a pair of atoms. The computer program WMIN (Ref. 19; is being used to implement this model. Parameters A, B, and C can be determined by least squares using known structures as observations. The charges are more difficult to determine. They can be estimated by least squares fitting to known structures, by appropriate analysis of accurate x-ray diffraction data, or by theoretical molecular orbital calculations. Because the various methods of estimating charges do not give consistent results and because these different sets of charges produce variations in density that are greater than the accuracy we seek, we decided to neglect the Coulomb energy. The pair potential parameters are highly correlated, and the effect of neglecting the Coulomb term can be compensated to a considerable extent by adjusting the other parameters. We have developed a set of parameters ihat are suitable for neutral atoms. These parameters give a crystal density within 2% of the conect value for 14 of 17 test compounds, and they have been used to predict the density of several unknown compounds. These predictions are as follows: for 3-nitro-1.2.4-1riazoie-5-one, 1.94 g/cm' (a later x-ray experimental value is 1.927 g/cnv1); for dinitrofurazan. 2.01 g/cm': for l,4-diamino-2.3.5,6-tetranitrobenzene, 2.07 g/cm'; and for or- thodinitrobenzene, 1.66 g/cm1. For convenience, a planar conformation was chosen for the latter two compounds, although such a conformation is unlikely. Consequently, the density predictions for these compounds are probably too high because planar molecules pack more efficiently. In the coming year, we will attempt to predict molecular conformations using a molecular mechanics computer program.

HIGH-PRESSURE STUDIES OF NITRIC OXIDE AND OXYGEN

Basil I. Swanson, Stephen F. Agnew, and Llewellyn H. Jones

The detailed spectroscopic analysis that is possible at high static pressure in diamond-anvil cells has provided invaluable information on nitn'c oxide and its disproportion products N2O and N2O4. A definite proposal for the kinetics associated with nitric oxide detonation is appropriate now and is presented in the final section of this article. 38 OTHER UNCLASSIFIED WEAPONS RESEARCH

The a priori assumption, yet to be validated, is that the high density of the nitric oxide detonation wave induces chemical pathways that lead to initial products analogous to those observed in our static high-pressure cells. Subsequent reactions of these initial products are expected to occur in the lower density, high-temperature regime of the reaction zone. At present, we can only guess at these subsequent reactions:

N,O, ±5 2NO AH" ~ 1-2 kcal/mole NA ±? 2NO, AW ~5 kcal/mole N,O, t* NO + NO, AH0 ~ 10 kcal/mole.

These equilibria have not been observed at or below ambient temperature at any significant pressure (>0.4 GPa) in diamond-anvil cells. All three reactions are facile at low pressure and therefore are deemed important reactions for any detonation mechanism for nitric oxide. The reactions

N2O — N, + O" 1/3 of AH" 2O° — O, evolve the remaining free enthalpy of the NO decomposition. However, the N2O reaction occurs only at fairly high temperatures, thereby implying a significant kinetic barrier. Because the remaining 1/3 AH° for the NO reaction is evolved in these two reactions, they must be considered important in any detonation mechanism for nitric oxide. For the N,O4 product, the subsequent endothermic regeneration of NO from NO2,

NO, — NO + O* 2O° —O2, might be important. However, because the overall reaction represents a nearly zero AH°, this reaction pair might profitably be ignored in the detonation scheme. Based upon the above analysis, a simplified detonation kinetic model is proposed. First, in terms of the overall reactions involved in energy evolution, two are considered appropriate. The first,

3N,O, — 2N2O + N,O4 2/3 of AH", is assumed to be pressure accelerated, fast, and irreversible. Second, the subsequent reaction

2N,O — 2N, + O2 1/3 of AH° would then be temperature accelerated, relatively slow, but nevertheless, irreversible. Assuming that all the nitric oxide promptly disappears as a result of the first overall reaction, only one of the three temperature- and pressure-dependent equilibria need be considered:

N2O41* 2NO2.

The product ratios that result from this scheme are 40% NO2, 409b N2, and 20% O2, assuming completion of both irreversible steps. This detonation model is the most reasonable one, judging from the experimental work thus far reported. We feel that a detailed analysis of actual detonation products for NO as well as any in situ determination of products in a detonation wave could either prove or disprove this hypothesis. OTHER UNCLASSIFIED WEAPONS RESEARCH 39

Nitric Oxide Disproportionation We have brought together eveiything we know about the nitric oxide reaction products and the paper will be published shortly.20 This article is a summary of the findings. Nitric oxide disproportionates completely at 176 K and 1.5 to 2.0 GPa to form N2O4 and N2O with the minor product N,O3. It has l.ot been determined whether the N2O3 is an integral part of the NO reaction or merely results from an incomplete reaction that allows NO to combine with NO:. Thus, the primary pathway for disproportionation at static high pressure is

3N:O2 — 2N,O + N:O4,

which evolves two-thirds of the AH° relative to N2 + O2. A minor pathway is also indicated:

2N,O, — N, + NAi,

which evolves one-half of AH° relative to N: + O2. There are several equilibria observed, including the autoionization

+ N,O4 t, NO + NOj ,

which has been reported.21 In addition, we have determined that an isomerization reaction of N,O4,

N,O4 * O-N-O-NO,,

is an important constituent in the fluid phase that contains N2O4. Figure 3.1 is a spectrum of the NO product solution and has bands at 275, 810, 830, 925, and 1225 cm"'. The 275- and 810-crrT1 features correspond to the v, (N-N stretch) and v, (NO2 in-phase scissor), respectively, for the nitro- N:O4. The remaining features, however, can be caused only by the v5 (NO2 scissor), v4 (N-O

500 1OOO CM-1

Fig. 3.1. Raman spectrum of N2O4 crystal grown frorn cell at 1.85 GPa and about 270 K, in which N2O2 has completely reacted. Crystal melted ai laser spot. 40 OTHER UNCLASSIFIED WEAPONS RESEARCH

2000

Fig. 3.2. Raman spectra of neat N2O4 at 1.1 GPa undergoing laser photolysis. The diamond first-order peak at 1332 cm"1 separates low- and high-frequency regions, making relative intensity between regions arbitrary.

stretch), and the v, (NO: symmetric stretch), respectively, for the nitrite-N:O., (ONONO:). All other reasonable possibilities have been excluded. The presence of this isomer of N2O4 is significant in that it provides a route for the formation of the ion pair NO+NO7 though breaking of the appropriate N-O bond. :i Previously reported laser-induced chemistry of neat N:O4 resulted in the formation of a new crystalline form of molecular N:O4. We have further determined that the specific overall photochemical reaction is

hv N,O, + NO! + NO, .

Previously, we knew that N2O, was being formed because a blue color appeared at the laser spot. We now have identified all the Raman features that were observed during this photolysis. The spectra are shown in Fig. 3.2, and all the features are assigned to particular species. Once again, we note the appearance of ionic species and can only conclude that they are important in the chemistry of the nitrogen oxides at high density.

A Chemical Mechanism for Nitric Oxide Detonation The chemistry that we have observed for nitric oxide at high pressure is undeniably complex. We have shown the importance of disproportionation, ionic species, photolysis, and isomeriza- tions. It is notable that these effects are largely associated with the high-density condensed-phase conditions of the experiments; that is, none of these effects could have been predicted from gas- phase kinetic information. However, we feel that a much simpler scheme could be used in a detonation simulation. The first approximation is in ignoring, for the present, the various ionic equilibria that we have observed under static conditions. We do this simply because there is no reasonable way to obtain rate constants or even equilibrium constants for these strongly pressure- dependent phenomena. Therefore, the importance of the ions in the detonation process will not be addressed. OTHER UNCLASSIFIED WEAPONS RESEARCH 41

The overall reaction schemes have been observed only at static high pressure, but until evidence to the contrary is presented, we will assume that they also obtain during certain kinetic regimes of the detonation wave where we expect high-density effects to predominate. We do believe, however, that there are also regimes in the detonation of nitric oxide where temperature may take precedence over high density in determining the ultimate kinetic pathways for NO degradation. Thus far, the only recourse for evaluating possible high-temperature pathways is by means of the very low density, high-temperature conditions of gas-phase kinetics.

Structural Determination of N2O4 The cubic structure Im3, three molecu.'os per unit cell, a = 7.85 A, has been verified upon the basis cT three independent reflections. This cell constant is consistent with r.hat extrapolated from low-temperature neutron-diffraction data. Unfortunately, we have not as yet been successful in growing the P-N,O4 crystal and therefore have not been able to determine its structure. The stability of the a-N2O4 single crystal against transformation to the salt has been determined up to 24.0 GPa. It is interesting to note that, even at these substantial pressures, this form of N ,O4 resists transformation into the ionic phase NO+NO7-

Fifimm-O-

6b :66b '-66b

(a)

Fig. 3.3. (a) Planes of oxygen molecules viewed down the molecular axes represent the model mentioned in text, (b) The Fmmm cell for 5-O; that was used at reference point for a model of e-CK 42 OTHER UNCLASSIFIED WEAPONS RESEARCH

1 oil v - '"••••If

-•1 * r' one C 2 in

;T-- "V. °H '8°8

on. 1601BD in

two in 0 t't 2 11 1 1400 1500 CM"1

O D

Fig. 3.4. Off-diagonal interaction force constants used in the model are shown in the 5-O: Fmillm ceil. Results of calculation showing calculated frequency positions as well as experimental positions (given by triangles) measured at 14.0 GPa. Off-diagonal interaction force constants used in the model and their relation lo the Fmmm S-O: unit cell are shown.

The Polymerization of Oxygen at High Pressure Further work on the infrared spectra of oxygen above 10.0 GPa provides much insight into the structure of this highly colored solid.. In a recently submitted paper, we present evidence that oxygen can be best described as a polymer chain structure above 10.0 GPa (Ref. 22). The O,-O intermolecular bond, although weak, is formed at the expense of a weakening O-O intramolecular bond by means of overlap of the pic*-O: antibonding orbilals. Ir. Fig. 3.3(a) we show how this one-dimensional "zig-zag" polymer of oxygen forms, based on the structure of a precursor phase Fmmm-O:. 1 his model explains the dramatic contraction that occurs in the a-b plane for this phase of oxygen, as reported by Olinger et air" Such a structure also leads to a force-constant calculation on the oxygen lattice shown in Fig. 3.3(b). Figure 3.4 illustrates the three interaction force constants f:, f,, and f, that are used to simulate the various spectra. These simulations are represented by solid lines in the spectra in Fig. 3.4, whereas the measured peak positions appear as arrows. Thus, the previously reported unusual isotope effects in the oxygen lattice above 10.0 GPa are due to both the extended interactions and the lowered symmetry of this phase of oxygen. OTHER UNCLASSIFIED WEAPONS RESEARCH 43

Based on the pressure dependences of these features as shown in Fig. 3.5, a straightforward assignment was made to the observed infrared and Raman features (see Table 3.1). The assignment ofthe2934-cm~' combination band to IR, + IR2 implies either that this is not a k = 0 combination or that the crystal structure is not centric. Because, to within the error of our measurements, there is mutual exclusion between infrared and Raman, we tend to support the former explanation. The model that we have proposed suggests that this high-pressure phase of oxygen e-O, is a spin- paired, diamagnetic phase of oxygen and is therefore unique among all the oxygen phases. It also supports the notion that unpaired electrons cannot survive at high density. Eventually, molecular bonds will form from unpaired electrons.

3100

3000 -

'2:2900 u 1600

1500

1400 10 15 PRESSURE (GPa)

Fig. 3.5. Pressure dependences of the Raman and infrared features for ""CK

16 TABLE 3.1. The O2 Frequency at 17.0 GPa Anharmonicity Assignment (cm1) 1460 IR, 1511 IR, 1587 R ... 2934 IR, + IR2 37 2956 (2IR2?)(IR, + R) (66) (91) 3054 IR2 + R 37 44 OTHER UNCLASSIFIED WEAPONS RESEARCH

NMR STUDIES OF ORGANIC EXPLOSIVES

William L. Ear!

This work can be conveniently divided into two sub-topics: studies of nitromethane and studies of solid high explosives.

Studies of Nitromethane This work was started in collaboration with Ray Engelke (Group M-3) in an attempt to understand the detonation sensitivity of nitromethane.-1'1 Since last year, we have definitely characterized the ad-ion of nitromethane (H:C=NO:) and have been able to identify it in several solutions of nitromclhane. These solutions, which include various inorganic and organic bases and nitromethane exposed to intense UV radiation, exhibit increased detonation sensitivity relative to pure nitromethane. We conclude that the aci-ion of nitromethane is the actual chemical sensitizer in nitromethanc. This conclusion is not a unique solution, but the evidence is very compelling. To characterize the aci-icn. we have also resorted to some rather elegant ab initio calculations of NMR chemical shifts. This work has been done in collaboration with Celeste Rohlfing (Group T-12). We have calculated chemical shifts for all of the magnetic nuclides in the various isomers of nitromethane, that is, for 'H, "C, I4N, and I7O in nitromcthane, nilromethane aci-ion, nitromethane aci-form, and methylnitrite. To date, the shifts have been me :sured for all nuclides in nilromethane and for 'H and L!C in nitrome.hane aci-ion. It appears that the calculations of chemical shifts give rather good agreement with our experiments for 'H and "C, but poor results for UN and ' O. This difference is not surprising because the bonding in nitro groups is considerably- more complicated than in simple organics and the theory does not take into account all of the complications. Finally, as reported last year, there are some rather interesting decompositions of nitromethane in basic solutions. We have found that the first step in the decomposition is the production of a species called the metha/.oiate ion:

[O-N=CH-CH=N-O] :.

This species can, presumably, react with the aci-ion to produce larger polymers. This poorly defined reaction is indicated by the NMR spectra of solutions of nitromethane in strong base because only a very few MC peaks show up even though the solutions turn a rather nasty brown.

Studies of Solid High Explosives The intent of this study is to evaluate solid state, high-resolution NMR techniques foranalysis of ••real" high explosives. We have investigated a total of five high explosives in several polymorphic forms. Unfortunately, there are severe problems that will probably prevent these techniques from ever becoming routine for analysis of high explosives. The only two nuclides that are useful for high-resolution solid state studies are L1C and I5N. The low natural abundance and inherently low sensitivity of "N NMR make it impossible to observe compounds at low concentration and even difficult to get a spectrum of a neat explosive. Most carbons in high explosives are chemically bound to nitrogen. The abundant nitrogen nuclide is NN, which has a magnetic dipole moment and an electric quadrupole moment, the combination of which yields severe broadening of the I3C resonance line. Thus, small amounts of impurities are lost in the wide lines. A final problem with the solid state NMR of high explosives is that they are pure, crystalline, hydrogen-bonded compounds—resulting in very long relaxation times T,. To an NMR spectroscopist, this means long delays in obtaining spectra and a resultant poor signal-to-noise ratio per unit time. OTHER UNCLASSIFIED WEAPONS RESEARCH 45

If NMR is to be a useful technique in studies of high explosives, it must be used to answer questions other than "How much and what kind of impurity is present?" It may be possible to obtain information about the nature of the bonding in some of these compounds. For example, preliminary interpretations of the chemical shift of triaminotrinitrobenzene indicate that the molecule in the solid state is strongly hydrogen bonded but it is probably not related to the aci-ions discussed above. It should also be possible to measure the solid state molecular mobility in some of these compounds and attempt to establish a correlation with the detonation sensitivity. Using some time-consuming but interesting spin diffusion techniques, we should be able to ascertain the intimacy of mixing in some of the mixed explosive systems.

ELECTRON DENSITY IN ORGANIC EXPLOSIVES

Don T. Cromer, Robert R. Ryan, and Harvey J. Wasserman

Shock sensitivity is an important and not well understood property of explosives, and it is of obvious practical concern. Using x-ray diffraction data, we are making detailed studies of electron density in hopes of finding clues relaiing to sensitivity. In particular, we are studying the isomorphous salts, ammonium picrate, and potassium picrate. These very similar compounds are distinguished by the fact that the potassium salt is 3 to 4 times more shock sensitive than the ammonium salt. In the analysis of the electron density around an atom, an atom-centered multipole expansion is made. The diffraction data are fit, by least squares, to population coefficients that represent the various poles. The monopole term gives the number of electrons on the atom. The dipoles, quadrapoles, and octapoles represent distortion from spherical symmetry as these electrons populate the bonding and lone-pair regions around tlie atom. Another property thai can be determined from x-ray diffraction data is the electrostatic potential throughout the unit cell. We are seeking differences in the electron density distribution or in the electrostatic potential of these two compounds that might be related to the difference in sensitivity. Figures 3.6 and 3.7 show the electrostatic potential in the unit cell in the plane of the carbon ring. The plane of the ring is tilted about !0° from the Z = 0 plane of the cell. The phenolic oxygen is at the left center of the drawings and the ammonium ion (or potassium ion) is at the upper and lower left. The other isolated peaks are neighboring oxygen atoms. For ammonium picrate the minimum value is -1.38 e/A, and for potassium picrate the minimum is —0.99 e/A (1 e/A = 332.1 kcal/mole). The potential becomes very large and positive near the nuclei, and most of the positive contours are omitted. The primary differences noted are that the potential is more negative for ammonium picrate and that there is a region of negative potential at the center of the ring in potassium picrate. We are also studying nitroguanidine, a very insensitive explosive. We are collaborating with James Ritchie, Group T-14, who is making a parallel theoretical study. The significance of these results is being investigated; we hope that a series of studies of this type, coupled with theoretical studies, will lead to an increased understanding of structure-sensitivity relationships. 46 OTHER UNCLASSIFIED WEAPONS RESEARCH

Fig. 3.6. Electrostatic potential in the plane of the ring in ammonium picrate. Contours are at 0.2 e/A. The solid contours are positive and the first dotted contour is 0.0 e/A. The horizontal axis goes from 0 to 1/2 in y. The center horizontal grid is the line at x — 1/4, z = 0.

Fig. 3.7. Electrostatic potential in the plane of the ring in potassium picrate. Other details are as in Fig. 3.6. OTHER UNCLASSIFIED WEAPONS RESEARCH 47

NEPTUNIUM-237 IN HUMAN AUTOPSY TISSUES

D. Wesley Efurd and Richard E. Perrin

Recent evaluation of the relative health hazards per unit mass of various actinides has placed :i7Np near the top of the hazards list, primarily because of its mobility.25 Neptunium-237 is present in man's environment in concentrations similar to those of 239Pu because the (n,2n)/(n,y) reaction ratio for :38U, which is the principle production mode for both species in global fallout, is 0.7 ± 0.2. Approximately 3t of 237Np was released into the biosphere by atmospheric testing. At Los Alamos, we conducted experiments on samples collected by Los Alamos and the Environmental Protection Agency to determine how much of this neptunium is still piesent in man. Liver and lung tissue samples were collected from individuals who had no known occupational exposure. Samples were dried, ashed, dissolved, and stored as acid solutions. Separate aliquots were analyzed for plutonium and neptunium. The aliquots for plutonium were spiked with 242Pu, and the concentrations were determined by the isotope dilution technique using either an alpha pulse height analyzer or a thermal ionization mass spectrometer operating in the pulse-counting mode. The aliquots used for neptunium analysis were spiked with 236Np, equilibrated, and measured by mass spectrometry. The results are summarized in Table 3.2. The average 237Np concentration measured in this study was 1.2 X 106 ± 113% atoms/g tissue, that is, 0.3 aCi/g tissue. The average 2"Np/239Pu atom ratio was 0.04. If one assumes these individuals were exposed to global fallout that had a 237Np/239Pu atom ratic of 0.7 ± 0.2, the 0.04 ratio measured in these tissues suggests that neptunium is lost preferentially. Additional studies should be conducted to determine whether neptunium is concentrated in bones.

TABLE 3.2. Neptunium and Plutonium Concentrations in Liver and Lung Tissue. Tissue i Tissue Weight M7 M9 Type (g) Np atoms/g Pu atoms/g a?Np/a»Pq Liver 803.7 1.06 X106 2.64 X107 0.04 Liver 1425.0 2.26 X I05 4.51 X 106 0.05 Liver 385.0 1.66 X 106 7.14 X 107 0.02 Liver 241.0 3.58 X 10* 7.01 X 107 0.05 Lung 736.2 1.35 X 105 1.73 X W 0.06 Lung 581.3 3.29 X 10s 3.29 X107 0.01 4

STABLE ISOTOPE PRODUCTION AND APPLICATIONS

Separation of Stable Isotopes—Production 51

Separation of Stable Isotopes—Research 53

National Stable Isotopes Resource 54

InVivoNMR Study of the Metabolism of L-Carnitine 58

Pyruvate Metabolism in Perfused Heart 63

RADIOACTIVE ISOTOPE PRODUCTION AND APPLICATION

INC-3 Isotope Production Activities in FY 1984 66

Synthesis of 67Cu jl/esoTetra (4-Carboxyphenyl) Porphine for Conjugation to

Monoclonal Antibodies 69

Improved Targeting System for' 23Xe —•] 23I Production and Recovery 71

Rubidium-86 Production 73

The 109Cd-*109mAgBiomedical Generator 73

Imaging and Biodistribution Capabilities at INC-3 76 ISOTOPE PRODUCTION, SEPARA TION, AND APPLICA TION 5/

STABLE ISOTOPE PRODUCTION AND APPLICATIONS

The ICON program, named for the stable isotopes of carbon (I2C, I3C), oxygen (16O, I70,18O), and nitrogen (MN, I5N) comprises the items listed below.

(1) Production of large quantities of the separated isotopes by low-temperature distillation of CO and NO

(2) Research into new methods of separating sulfur, selenium, and tellurium isotopes

(3) Development of efficient synthetic methods to incorporate the isotopes into complex molecules

(4) Development and applications of stable isotope labeling and NMR spectroscopy in biomedical research

(5) Participation with extramural investigators in cooperative research and development programs that are designed to develop the use of stable isotopes in the biosciences and in environmental studies

SEPARATION OF STABLE ISOTOPES—PRODUCTION

Thomas R. Mills, Raymond C. Vandervoort, Maxwell Goldblatt,* and B. B. Mclnteer

The objectives of our ICONs program are to provide separated isotopes of carbon, oxygen, and nitrogen for research purposes and to develop new or improved techniques for incorporating the separated isotopes into desired chemical forms. Isotopic materials are sold at cost to Los Alamos investigators or to the general research community through the Mound Facility. During FV 1984, the value of isctopic products produced for Mound sales was $730,805.37. We separate the isotopes by cryogenic distillation of CO for carbon isotopes and of NO for nitrogen and oxygen isotopes. (Table 4.1 shows the quantities of isotopes separated during FY 1984.) The total amounts of I5N and I8O produced are record quantities and necessitated unprecedented activity for the NO plant. We convert most of the isotopically enriched CO and NO to other labeled compounds for use by researchers. The reactions we use are summarized in an earlier report.'6 Table 4.2 lists the forms and amounts of labeled compounds prepared in FY 1984. Attention has been centered on the NO isotope-exchange feed system. (1) A totally new condenser was built to automatically drain water as well as any carryover nitric acid back into the exchange column. V2) Packing in the exchange column was replaced with larger Propak packing to lessen the likelihood of liquid flooding. (3) The present cryogenic purifier for the NO exchange loop has shown signs of physical deterioration and has limited the efficient use of the isotope feed system at high flows. The basic design of this 9-year-old purifier is still sound; two new purifiers were built incorporating a number of improvements based upon operating experience.

*Los Alamos National Laboratory consultant 52 ISOTOPE PRODUCTION, SEPARA TION, AND APPLICA TION

TABLE 4.1. Isotopic Production FY 1984 Quantity Enrichment Isotope (kg) (%) 5.4 99.95 "N 5.3 10+ 15N 0.8 60+ 15N 1.3 98+ 16Q 44.9 99.98 17O 0.2 50+ . iso 3.5 10+ 18Q 2.5 95+

TABLE 4.2. Labeled Compounds FY 1984 Quantity Quantity 100% Basis 100% Basis Product (mol) Product (nw!) 12 I5 CD4 100G NH3 246 I3 15 CD4 95 < NH4)2SO, 31 16 !5 OH2 2806 K NO3 45 17 15 OH, 14 H NO3 160 I8 15 OH2 333 N2 10

We stopped production of I3C in FY 1983 and maintained the I3C plant in a standby state in FY 1984 because of sizeable I3C inventory levels and because of the possibility that a private US company would succeed in separating the 13C product. This company has met with only limited success in their production activities, and it will be necessary to keep the Los Alamos 13C in standby- status through FY 1985. In FY 1984, we used the 13C separation plant for a special separation operation to enrich and detect the theorized X~ particle, a remnant of the "big bang." It has been suggested that an X" entering the earth's atmosphere would combine with nitrogen in the air to make an atomic nucleus that looks very much like an exceedingly heavy carbon isotope. If this "carbon" isotope were present in CO, the volatility* of the extra-heavy carbon would be approximately 10% less than thai of normal l2C'bO. Accordingly, this "isotope" would concentrate at the bottom of the CO distillation columns. The special separation operation this year has attempted to enrich the possible X~ particles by a factor of 106. Further enrichment and attempts to detect this particle will take place in FY 1985.

•"Information supplied by Jacob Bigeleisen, Stale University of New York-Stony Brook. ISOTOPE PRODUCTION, SEPARA TION, AND APPLICA TION 53

A side benefit of the isotope separation columns is our ability to withdraw extremely pure (chemically) material from intermediate points in the coiur.ms. 'We supplied especially pure NO and CO to Los Alamos personnel this year for 15 separate experiments in areas such as explosives research and laser spectroscopic work. A new large-scale methane conversion system was constructed to produce 20 kg of heavy I3 methane CD4 for atmospheric tracing experiments performed by Group INC-7. This system operated at its capacity of 1.5 kg per day (75 mol/day) this year, and we wiil use it for further conversions in FY 1985.

SEPARATION OF STABLE ISOTOPES—RESEA "«

Thomas R. Mills, B. B. Mclnteer, and Joseph G. Montoya

Selenium and Tellurium The isotopes of selenium and tellurium are used primarily as targets for the cyclotron production of specific radionuciides for a wide variety of nuclear medicine research and clinical uses (for example, thyroid scans with radio-iodine). These isotopes can presently be separated only by electromagnetic separators (calutrons) in very limited quantities at high unit costs. In 1983, we initiated a research program to investigate the use of distillation and related phase equilibrium techniques as possible means of separating sizeable amounts of these isotopes at low cost. To be considered as a possible medium for isotopic separation by distillation, a compound must be volatile and stable at appropriate temperatures, and it should have some degree of intermolecular interactions that could be affected by isotopic substitution. We identified compounds of interest, including some that boil at subambient temperatures (H2Se, H2Te, SeF6, and TeF6) and a number of compounds that boil at higher temperatures (SeF4, TeF4, and selenium oxyhalides). Because we suspected that the low-boiling-point compounds might be more promising, we designed and built a research distillation column capable of operating at temperatures over the range of-80 to O'C. The distillation column is 1 m long by 14-rnm i.d., and it is packed with stainless steel Helipak wire helices. This high-efficiency packing permits a column of these dimensions to have 100 theoretical separating plates. Heat is removed from the column by a refrigerated fluid at the condenser. We can vary the temperature of this fluid by changing the pressure over the fluid, which in turn allows us to operate the column at different temperatures. The column is enclosed in a vacuum jacket and, because of the toxicity of the compounds being used, all gas handling is done in a glove box. The only compound we have fully investigated to date is methyl selenide [(CH3)2Se]. We found that this compound has an isotopic separation with an upper limit of 1.0001 for the relative volatility of isotopes differing in mass by 1 amu. We had hoped for a sizeable isotope effect from a methyl selenide-boron trifluoride addition compound but discovered that this material is not suitable for distillation: it polymerized into nonvolatile tar that appeared even after repeated purification steps. We recently studied hydrogen selenide; it behaved well in the column, but mass spectrometer malfunctions have deferred any isotopic analyses until FY 1985. Compounds to be distilled in early FY 1985 include SeF6 and TeF6 (already on hand) and H2Te (to be synthesized). 54 ISOTOPE PRODUCTION, SEPARATION, AND APPLICATION

Sulfur We investigated a number of sulfur compounds for possible isotope separation in the selenium/tellurium experimental column to (1) gain experience with the sulfur analogues of various unavailable selenium/te'lurium compounds and (2) seek systems for actual sulfur isotope separation. We wanted to compare ihese results with those from previous work on the distillation 27 of H2S for isotope separation. Isotope separations measurements were made on four new compounds (SO2, COS, SF4, and CH3SH), and additional measurements were made on H2S. J4 32 The S/ S isotopic separation factor we observed for H2S was 1.0012 at 300 torr, which is in complete agreement with the earlier results. This agreement is quite useful in validating the accuracy of the measurements on the other sulfur compounds as well as the accuracy of the selenium isotope separation measurements. Of the new compounds investigated, the greatest observed separation factor was that for SF4: the relative volatility was 0.9992 for 34S/32S. Of particular interest is the fact that the effect is reversed from the normal—the heavier isotope is the more volatile! No explanation has yet been offered for this effect; however, boron isotopes in BF3 also exhibit the reversed effect. Observed isotope separation factors for COS, SO2, and CH3SH at roughly atmospheric pressure were less encouraging: volatilities were 1.0003, 1.0001, and 1.0001, respectively. We believe these small isotopic effects on vapor pressure are the result of the small extent of molecular association in the liquid phases of these compounds.

NATIONAL STABLE ISOTOPES RESOURCE

C. J. Unkefer, D. S. Ehler, J. L. Banners, W. E. Wageman, and T. E. Walker

The National Stable Isotopes Resource (SIR) is funded by the Division of Research Resources of the National Institutes of Health. The focus of the SIR is on developing biomedical applications of stable isotopes and includes the activities listed below.

• Development of efficient and stereose! ctive synthetic routes to isotopically labeled compounds that are of biomedical interest

• Distribution of labeled compounds to accredited external investigators when those compounds are not readily available from commercial or other sources at acceptable costs

• Development of an active program of research collaboration with investigators in the biomedical community nd provision, as necessary, of isotope-labeled compounds and analysis and data interpr tion with NMR and mass spectrometry

» A.dvice and assistance for investigators who use isotopes of carbon, oxygen, and nitrogen

• Training for visiting scientists who use stable isotopes; encouraging exchanges of presentations, short courses, and extended research opportunities

• Collaboration with other resources in synthesis and mass spectrometric and NMR analyses to speed development of isotope methodology ISOTOPE PRODUCTION, SEPARA TION, AND APPLICA TION 55

• Core research in the area of isotope applications that is designed to keep the resource at a state- of-the-art level

Threr SIR projects representing both core and collaborative research are highlighted here.

Metabolism and Kinetics of Valproic Acid in Man Valproic acid, a branched medium-chain fatty acid, is a widely used anticonvulsant drug for treating epilepsy. Recent c oncern over possible hepatotoxicity of valproic acid, especially when used concomitantly with other anticonvulsants, has led to an increased need for metabolic pharmacokinetic studies o .'this drug. One such clinical study is being conducted by Thomas Baillie of the University of Washington in collaboration with the Regional Epilepsy Center in Seattle. 3 In this study, equimolar mixtures of unlabeled and [2,3,3'-' C3] valproic acid are being given orally to volunteers; metabolites of valproic acid are then identified by GC-MS in an effort to determine pharmacokinetic parameters of both the parent drug and primary metabolites. Their recent findings indicate that (1) valproic acid does not undergo metabolism via the same (3- oxidative pathway through which fatty acids are degraded and (2) suggest that known inhibition of fatty acid metabolism induced by valproic acid is not of a simple competitive nature. The SIR supplied Baillie with [1-'3C] propyl bromide and [2-l3C] acetic acid from which he synthesized I3 [2,3,3'- C3] valproic acid via two successive alkylations of lithium enolate of acetic acid.

Mechanism of Dihydrofolate Reductase Tetrahydrofolic acid, a pterin coenzyme involved in the biological transfer of one-carbon compounds, is required for the biosynthesis of purines and thyamine. The vitamin form, folic acid, is converted to the coenzyme by a reduction scheme, the final step of which is catalyzed by the enzyme dihydrofolate reductase (DHFR). DHFR is the target of several clinically important anticancer drugs. The molecular basis for the potency of these clinically important inhibitors of DHFR has been the subject of studies by R. L. Blakley of St. Jude Children's Researc!- Hospital and R. E. London of the National Institute of Environmental Health Sciences. Using [2-'C] pterin antagonist, they have demonstrated unequivocally (and in opposition to findings cited in some of the existing literature) that the inhibitors are protonated when complexed with the enzyme and that they remain protonated to pH values above 10 (Ref. 28). Recently, Blakley and coworkers have undertaken a synthesis project designed to produce [6-'3C] pterin coenzymes and antagonists. The [6-l3C] aminopterin is being synthesized from [2-'3C] dihydroxyacetone using the general pteridine condensation procedure of Baugh and Shaw.29 (The synthetic scheme is shown in Fig. 4.1.) Subsequently, [6-'3C] aminopterin will be converted to [6-l3C] folic acid and reduced to the DHFR substrate [6-'3C] dihydrofolic acid. Blakley and cov^orkers have completed this synthesis using limiting amounts of unlabeled dihydroxyacetone as a precursor and are currently carrying out the synthesis using [2-'3C[ dihydroxyacetone. Labeling at the 6 position will allow an investigation of the carbon site of dihydrofolate, which accepts a hydride ion from NADPH as part of the reduction reaction. It is anticipated that several hypotheses regarding the nature of the enzyme-catalyzed reaction can be specifically tested using this approach. Synthesis of the labeled pteridines has been carried out collaboratively; Los Alamos is producing the required labeled precursor [2-'3C] dihydroxyacetone. The synthetic route for [2-l3C] DHA developed by the SIR (Fig. 4.2) requires D-[2-l3C] glucose as a precursor, which is prepared by epimerization of D-[l-l3C]mannose as described by Barker and coworkers.30 We isomerize the D-[2-l3C] glucose to D-[2-13C] fructose by using a commercial preparation of the enzyme glucose isomerase. The D-[2-l3C] fructose is converted to a mixture of its methyl glycosides and is treated with sodium meta-periodate. We reduce the resulting dialdol compounds with sodium borohydride and hydrolyze them to yield a mixture of [2-l3CJ DHA, glycerol, and ethylene glycol. The DHA was protected as its diethyl acetal, and the compounds were separated by chromatography on Dowex 5O-X8 in Ba++ form using water as an eluent. We provided 2.5 g of [2-l3C] DHA to Blakley as the diethyl acetal. 56 ISOTOPE PRODUCTION, SEPARATION, AND APPLICATION

HOH2C + CH2 NH, 111

HBr,

OO"

N^ H

Fig. 4.1. Scheme for the synthesis of [6-l3C] aminopterin IV from [2-'3C] dihydroxyacelone (I).

Isomerase iCH3OH( H*

HOH O^9H2OH

V—^b_,CH CH 3

"BH4

T )= CH2OH

Fig. 4.2. Chemical synthesis of [2-'3C] dihydroxyacetone. ISOTOPE PRODUCTION, SEPARATION, AND APPLICATION 57

Microbiological Production of Labeled Compounds Production of Uniformly LabeledAmino /tJds. Recent developments of multiple quantum31 and 2D NMR techniques32 that simplify complex NMR spectra have generated renewed interest in uniformly 99% I3C-enriched compounds. In addition, l3C-depleted compounds are of interest to mass spectroscopists because the isotopomer distribution in natural abundance 13C compounds complicates mass spectra. This problem becomes acute at the high masses attainable with state-of- the-art instrumentation. We have developed a novel biological method to produce uniformly labeled compounds using methylotrophs. Initial efforts have been directed toward the production of labeled amino acids. Methylotrophs are aerobic microorganisms (bacteria and yeast) capable of growth on one- carbon compounds that are more reduced ihan CO2 (Ref. 33). These organisms must condense one-carbon units to form all their macromolecular constituents. The energy and reducing power required for carbon assimilation are generated from the oxidation of reduced one-carbon compounds. Organisms that use methanol as iheir sole carbon and energy source are attractive for the synthesis of [U-13C] compounds because methanol has convenient chemical properties (for example, methanol is a water soluble liquid at 37°C), and it is synthesized from [13C] in a single step. We have selected the methanol-using organism Methylophilus methylotrophus (AS1) for this process. AS1 is a well-characterized methylotroph that is known to fix a high fraction (60%) of methanol into biomass34 and is used by ICI for production of single cell protein.35 Initial studies in a 3-8 fermentor have shown that AS1 doubles during growth on [I3C] methanol in 1.5 hours and incorporates up to 54% of the methanol carbon into biomass. We have extracted 8.9 g of a crude protein fraction from 21-g dry weight of cells. The rapid doubling time coupled with the fact that the AS1 grows in a standard fermentor make this an attractive alternative to growth of algae on I3 I3 CO; for the production of [U- C] compounds. A'vhoagh the yield of [ C] methanol into the 3 biomass of AS1 (54%) is somewhat lower than that cf r' C]CO2 into algae (~72%), the fraction of AS1 that is protein is much greater, which improves the overall yield of the isotope into amino acids (25%). We have resolved the [U-"C] amino acids on a preparative (g) scale36 and shown that there is essentially no dilution of the isotope. We have scaled this process to a 30-fi fermentor and have distributed [U-13C] amino acids to external investigators. These methods can be extended easily to produce carbon-depleted or deuterated amino acids by simply substituting the appropriate isotopomer of rnethanol (99.999% [I2C] methanol or [2H,I2C] methanol).

Production ofDensity (U-~H,IJC,"N)-Labeled Amino Acids. Determination of turnover rates for macrornolecular and cellular components necessitates separation of newly synthesized molecules from older molecules of the same type.30-37 The use of density labeling and density gradient centrifugation is the only means by which these molecules can be separated. Density labeled algae, though commercially available, continue to be the SIR'S most often requested item because the commercial algae is unreasonably expensive. The high price does not represent the cost of the isotope itself, but rather the fact that algae are difficult to grow. We have investigated the possibility of producing density labeled amino acids by culturing 2 2 3 15 methylotrophs in 99% H2O and in the presence of [ H4,' C] methanol and [ N](NH4)2SO4. Methylotrophic bacteria have the advantage that they grow in standard commercially available fermentors or shakers. We have accomplished the difficult job of adapting Methylophilus meth- 2 2 3 ylotrophus to grow in media that contains >99% H,O, >99% [ H4,' C] methanol, and I5 [ N](NH4)2SO4. From pilot studies, we estimate that in a standard 20-C fermentor, we could produce 20 g of lyophilized cells in 3 days. This is two to three times the rate attainable with algae grown in shaker boxes.58 In addition, a higher fraction of the bacteria by weight is protein, so the overall rate of protein production is actually four or five times faster. Density labeled protein produced by using methylotrophs will be available from the SIR this year. Possible adoption of this process by the commercial sector could lower the price of density labeled amino acids. 58 ISOTOPE PRODUCTION, SEPARATION, AND APPLICATION

Methanol Synthesis. The ambitious biosynthesis program outlined above is predicated on the availability of labeled methanol. In addition to a very efficient large-scale production capability for the production of methanol, the program requires the ability to synthesize methanol as its four I3 13 2 l2 I2 2 carbon and hydrogen isotopomers [ C]CH3OH, [ C, H4] CH3OH, [ qCH3OH, and [ C, H4 CH3OH. 13 I3 In the past, [ C] methanol was produced in a high-pressure reactor in which [ C]CO2 was reduced by using a Cu-Zn-Cr catalyst to an equimolar mixture of methanoi and water.39 Although this process resulted in a high yield of isotope into methanol (>90%), it also required conversion of I3 13 [ C]CO (from the carbon distillation column) to [ C]CO: and separation of the products methanol and water. We have adopted a process by which CO is reduced directly to methanol by using a commercially available catalyst. This effectively increases the production capability of our methanol plants by 50%. In addition, none of the deuterium gas precursor is lost to deuterium oxide. We have brought a second reactor on line and now have the demonstrated capability to produce 9 moles/6 hours of methanol in any of the deuterium or carbon isotopomeric forms.

IN VIVO NMR STUDY OF THE METABOLISM OF L-CARNITINE

C. J. Unkefer, J. R. Brainard, J. Y. Hutson, D. Hoekenga, D. S. Ehler, and R. E. London

Carnitine, a quaternary ammonium compound (0-hydroxy-y-N-trimethylamino-butyric acid), is widely distributed in organisms and tissues that use long-chain fatty acids as a source of energy. The primary physiological role established for L-carnitine is in the transport of fatty acids from the cytosol across the mitocbondrial membrane via the carnitine acyltransferase and translocase systems (Fig. 4.3) (Ref. 40). Interest in the metabolism of carnitine has been stimulated by suggestions that it may be of use in the treatment of ischemic heart disease41 and by the identification of several carnitine deficiencies.42 A possible therapeutic application in the treatment of hypertriglyceridemia has also been suggested.''3 In addition to these potential chemotherapeutic applications, carnitine metabolism is of interest for evaluating an important metabolic regulatory parameter: the acetyl-CoenzymeA-to-CoenzymeA ratio. This application is based on the proposed near equilibrium of the carnitine acetyl transferase system.44"46 In this context, the substantially greater cellular concentrations of carnitine, compared with those of CoenzymeA, make carnitine an attractive target as an indirect probe of the acetyl-CoenzymeA-to- CoenzymeA ratio using in vivo NMR spectroscopy. We report the first direct determination of various aspects of carnitine metabolism in vivo. Because the principal metabolic transformations we desire to follow are the acylations and acetylations of carnitine, it was first necessary to establish the sensitivity of the I3C chemical shifts to acetylation and the relaxation behavior of carnitine and its metabolic derivatives. (Results are given in Table 4.3.) It can be seen that each of the backbone carbons has a chemical shift that is sufficiently sensitive to acetylation to permit resolution and subsequent quantification by 13C NMR spectroscopy. Unfortunately, the methyl groups that are most readily labeled show almost no shift perturbation resulting from acetylation and, hence, are unsuitable for most applications. It has been established that the biologically important form of carnitine has the L configuration;47 consequently, we synthesized L-camitine labeled at one of the backbone positions by using available 13C-labeied 3-deoxy-hexoses as precursors.48 The chirality at C2 of the sugar precursor is transferred to carnitine, and this synthesis is shown in Fig. 4.4. The 3-deoxy-D-[l-13C] ISOTOPE PRODUCTION, SEPARA TION, AND APPLICA TION 59

MITOCHONDRIA!. MITOCHONDRIA

MEMBRANE LONG CHAIN FATTY ACID!!

ACYL ACYL .JRANSFERASE TRANSFERASE _ ACYL-CoA ACYLCARNITINE . 'ACYLCARNITINE »ACYLCARNITINE » „„„.,.,.„•: CARNiriWC Co» A TRANSLOCASE t CARNITINE CoA (J OXIDATION

CoA CARNITINE \ ACETYL k i CARNITINE < > * ACETYL CoA

CITRIC ACID CYCLE

CO2 H2O. ENERGY

Fig. 4.3. Carnitine metabolism in the cell.

Table 4.3.Chemical Shift and Relaxation Data for Carnitine and Its Metabolic Derivatives0 Free Carnitine AcerylCarnitine Pa!mitoylCarnitineb Carbon S T,(s) 5 T, 5 C! 17S.0 175.0 174.3 C2 43.9 1.86 41.4 1.26 41.4 C3 65.1 2.95 67.9 2.0 68.2 C4 71.4 1.70 69.4 1.16 69.4 CS 54.9 1.31 54.9 1.12 54.9 "Chemical shift (in ppm) is from TMS using C-l of aD-glticnse at 97.0 ppmi as the internal standard. Samples are dissolved in 10% D2O 50mM phosphate (pH = 7.4). ''Palmitoyl-carnitine was sonicated and run at 47°C (above Kraft point for palmitoylcarnitine micelles). 60 ISOTOPE PRODUCTION, SEPARATION, AND APPLICATION

CH3 C <3 CHo \ / \ / N N

CH2OH C - H H - C - H H - c - OH H - C - OH (CH3)2 N NaCNBH3 H. OH H - c - H H - C - H pH 10 HO H - c - OH H - C - OH H OH H OH H - C - OH 1 3-dEOXY-D-RIBO-HEXOSE I CHgOH (3-dEOXV-D-GLUCOSE) NalO,,

O O C - H L-CARNITINE

Fig. 4.4. Stereoselective synthesis of L-carnitine.

glucose is reductively aminated with dimethylamine and sodium cyanoborohydride to the structurally related amino compound. The amino compound is oxidized in two steps to L-[4-1JC] norcarnkine, which is readily methylated, resulting in L-[4-i3C] carnitine. A problem arises from the existence of both acyl- and acetyl-L-carnitine pools, which exhibit similar chemical shifts. Acylcarnitines such as palmitoylcarnhine are relatively large, amphiphilic molecules whose properties are similar to those of fatty acids and phospholipids.'" The I3C spectra at 45°C of sonicated phospholipid vesicles containing 22 mol.% D,L palmitoylcarnitine showed barely detectable resonances for C3 and C4. We estimate that the linewidths for C3 and C4 exceed 70 Hz. The linewidth of the C2 resonance was approximately 40 Hz. The [2-13C] and [3-l3C] labeled acylcarnitines associated with intracellular phospholipids or macromolecules would be expected to have even broader resonances and consequently be undetectable in vivo. We therefore hypothesize that the observed resonances will reflect primarily the free carnitine and acetylcarnitine pools. We carried out initial studies with Saccharomyces cerevisiae cultured aerobically on glucose in medium containing 0.05mM of L-[4-"C] carnitine. Proton decoupled I3C NMR spectra of the labeled yeast cells in the presence of pyruvate (100mA/) demonstrate the ability of the cells to concentrate carnitine to intracellular levels (~- 10mA/). The absence of additional labeled resonances suggests that, other than acylation, the exogenous-supplied carnitine undergoes minimal further metabolic transformation. There is some overlap of the carniiine resonances with carbohydrate resonances, particularly those arising from a,a-trehalose. Initially, there is a low ratio of acetylcarnitine to carnitine in glucose-grown cells we observed either aerobically or anaerobically. The intensity ratio of acetylcarnitine to carnitine increases only under anaerobic conditions in cells loaded with a good acetyl CoenzymeA precursor such as pyruvate. Under these conditions, the pyruvate is metabolized primarily to ethanol and acetylcarnitine. Figure 4.5 shows a portion of I3C NMR spectra of yeast labeled v/ith L-[4-l3C]carnitine; the time course of the reaction with pyruvate is indicated for aerobic (a) or anaerobic (b) conditions. Under aerobic conditions, the ratio of acetylcarnitine to carnitins decreases as the exogenous pyruvate is metabolized. Subsequent addition of pyruvate restores this ratio to its previous value. Under aerobic conditions and in the presence of pyruvate, the ratio of acetylcarnitine to carnitine is constant (~0.2). Under anaerobic conditions and in the presence of pyruvate, the ratio increases to about 0.4. ISOTOPE PRODUCTION, SEPARATION, AND APPLICATION 61

The extrapolation of these signal intensity ratios to the estimates of intracellular concentration ratios of acetylcarnitine to free carnitine requires knowledge of the relaxation behavior of the resonances under observation. The similar molecular weights and solubilities of free and acetylcarnitine make it likely that both free and acetylcarnitine would exhibit the same or nearly identical spin-lattice relaxation times and nuclear overhauser enhancements in vitro and in vivo. Attempts to estimate the in vivo spin-lattice relaxation times for free and acetvlcarnitine in yeast were unsuccessful because of the overlapping carbohydrate resonances. At 25°C in vitro, the spin- lattice relaxation times for C4 of acetyl and free carnitine were 1.2 and 1.7 seconds, respectively. The nuclear overhauser enhancements for C4 of both free and acetylated camitine were 3.0. Using the in vitro relaxation times as estimates for the in vivo relaxation behavior, we calculate that the observed signal intensity ratio of acetyl- to free carnitine may overestimate the concentration ratio by 20%. If the in vivo relaxation times are significantly shorter, the error would be less. The acetyl-CoA-to-free-CoA ratio has been viewed as an important regulator of metabolic activity. The low intracellular concentrations of CoenzymeA (10 to 100 times lower than carnitine) make direct observation of acetyl-CoA/CoA. by NMR spectroscopy unlikely. Veech has noted that in rat liver, the mass action coefficient for the acetylcarnitine CoA transferase is approximately unity under a variety of conditions.*" Similar data have been reported for heart.46 These observations suggest that the acetylcarnitine CoA transferase is at equilibrium in vivo. If this reaction is, in fact, at equilibrium, the observation of the acetylcarnitine-to-carnitine ratio by I3C NMR allows us to estimate acetyl-CoA/CoA. In S. cerevisiae in the presence of pyruvate under aerobic conditions, we estimate acetyl-CoA/CoA is 0.15 to 0.20. As noted above, current interest in carnitine metabolism arises in connection with its possible use in the treatment of ischemic heart disease. To evaluate the feasibility of in situ studios of L- camitine metabolism in cardiac muscle, preliminary studies have been carried out using a LangendorfT perfused guinea pig heart. Carnitine pools in the heart were labeled in vitro by adding L-[4-13C]carnitine at a first-pass concentration of 7mA/. Under normoxic conditions, only a free carnitine resonance is detectable (Fig. 4.6). Adding 7mA/ pyruvate to the perfusate during 12 minutes of hypoxia or 12 minutes of total global iscr.Tnia resulted in detectable acetylcarnitine resonance intensity, which demonstrates the expected buildup of acetylcarnitine, as shown in Fig 4.6. The resonances in heart are, in fact, easier to quantify because of the lack of interfering carbohydrate resonances. Our investigations with carnitine have thus far led to several conclusions.

N2 BUBBLED

Fig. 4.5. A 13C-NMR spectra of yeast labeled with L-[4-l3C]carnitine. 62 ISOTOPE PRODUCTION, SEPARATION, AND APPLICATION

Ischemia Hypoxia (12 min.) (12 mln.) Carnitine C-4 J Acotylcarnitlna C-4 Normal Flow y Normoxia

80 so ppm 80 ppm 60

Fig. 4.6. Portion of i3C NMR spectra of perfused guinea pig heart.

(a) Carbons 2, 3, and 4 of carnitine are sufficiently sensitive to acetylation to allow observation of carnitine and acetylcarnitine in vivo.

(b) Studies of acylcarnitine in model systems suggest that in vivo the C-3 and C-4 resonances of acylcarnitines are too broad to be detected.

(d) Chemical exchange between carnitine and acetylcarriitine is sufficiently slow on the NMR time scale to permit detection of separate resonances corresponding to each metabolic state. This allows quantification of the acetylcarnitine-to-carnitine ratio using I3C NMR spectroscopy.

(e) The acetylcarnitine-to-carnitine ratio, as measured by I3C NMR spectroscopy, is dependent on substrate availability and the oxygen supply.

(f) Carnitine pools in isolated, perfused heart can be labeled in vitro.

Based on these studies, it appears that in vivo analysis of cainitine metabolism with a l3C-labeled substrate is feasible in both microorganisms and perfused heart tissue, and the data obtained can shed light on the biochemistry of this important metabolite. ISOTOPE PRODUCTION, SEPARATION, AND APPLICATION 63

PYRUVATE METABOLISM IN PERFUSED HEART

James R. Brainard, Judy Y. Hutson, and David Hoekenga*

Isotopic labeling has been used to study metabolic processes and their regulation ever since the isotopes and means for their detection became available. Recent advances in NMR instrumentation have extended the sensitivity of NMR spectroscopy to allow real-time monitoring of metabolism within living cells.50 In many applications, NMR studies can provide unique and valuable information concerning the physical state(s) of substrates, their compartmentation, and the rates of reactions in situ, which are not available by other techniques. In addition, the medical community has shown exceptional interest in the use of NMR spectroscopy as a safe and noninvasive clinical tool for human diagnosis, monitoring treatment, and assessing organ viability before and after transplant. As part of a continuing program to develop and evaluate specific 13C labeling and NMR detection as a tool for in vivo study of metabolism, we have developed a perfused guinea pig heart model to study the effects of a variety of proposed therapies on metabolism during periods of low oxygen supply. The metabolic consequences of a reduced oxygen supply are particularly severe for the heart because it depends on aerobic metabolism (primarily fatty acid oxidation) to generate more than 90% of its energy needs. Consequently, there is great clinical and research interest ir. the metabolism of cardiac muscle under conditions when the oxygen supply is limited (hypoxia). Because myocardial oxygen consumption is dependent on substrate utilization, on,; strategy for reducing the extent of myocardial damage during hypoxia has been to supply substrates that are designed to suppress fatty acid utilization by increasing anaerobic energy production. The most widely used agent for this purpose, suggested some 20 years ago, has been Glucose-Insulin- Potassium (GIK). Whether or not GIK is beneficial clinically or in experimental models, and how it exerts any beneficial effect remains unclear.51 We have used I3C labeled substrates and l3C NMR spectroscopy lo investigate the effects of this agent on metabolism in the perfused heart. Proton-decoupled 13C NMR spectra of an isolated beating perfused guinea pig heart are shown in Fig. 4.7. The lower spectrum (a) was obtained before the addition of any labeled substrate. The intense resonance at 167 ppm is from an external intensity and chemical shift standard, which is l3C-enriched formic acid doped with Gd++ in a small capillary adjacent to the heart. The broad, weak resonances at approximately 130 and 30 ppm are from naturally abundant fatty acyl olefin and methylene carbons, respectively. The resonance at approximately 55 ppm is assigned to the quaternary choline methyl carbons of phospholipids. The upper spectrum (b) was obtained 15 minutes after addition of 2.2niM [3-l3C]pyruvate to the perfusate. Resonances from labeled pyruvate, alanine, and glutamate are identified in the figure. Figure 4.8 shows the time course of label incorporation from [3-l3C]pyruvate and intermediates in the presence of GIK in a perfused heart under normoxic (a) and hypoxic (b) conditions. In these experiments, metabolism in each heart was observed under both normoxic and hypoxic conditions by first introducing the labeled precursor under normoxic conditions, then washing out labeled metabolites with fresh perfusate containing no labels, and subsequently reintroducing the labeled precursor under hypoxic conditions. Under normoxic conditions, labels are incorporated into C4, C3, and C2 of glutamate, C3 of alanine, and to a lesser extent, C2 of citrate, and C3 and C2 of aspartate. The time course of glutamate labeling in the normoxic spectra reveals the pathway by which the label from pyruvate enters the TCA cycle. The C4 of glutamate is labeled before C2 and C3 of glutamate, which indicates that the label from pyruvate is entering the TCA cycle through pyruvate dehydrogenase and citrate synthase rather than through anaplerotic pathways.

*Chief of Cardiology, V.A. Hospital, Albuquerque, New Mexico 64 ISOTOPE PRODUCTION, SEPARA TION, AND APPLICA TION

°C FORMIC ACID

15 MH AFTER ADDITION OF 2.2 n>M 3-13CPYRUVATE

BACKGROUND

h*to4^">faf^^

100

ppm

Fig. 4.7. Carbon-13 NMR spectra (proton-decoupled) of a beating perfused guinea pig heart; (b) shows the background signal from an untreated heart, and (a) shows the spectrum 15 minutes after addition of 2.2mA/ [3-'3Cl,jyruvate to the perfusate.

13 [3- c] PYRUVATE • GIK [3-i3c]pYRUVATE*GIK NORMOXIA HYPOXIA

*w,«

Fig. 4.8. Spectra showing label incorporation from [3-13C]pyruvate and intermediates in the presence of GIK in a perfused guinea pig heart under normoxic (a) and hypoxic (b) conditions. ISOTOPE PROD UCTION, SEPARA TION, AND APPLIC. TION 65

After washing out labeled metabolites with fresh perfusate, the reintroduction of labeled pyruvate and GIK under hypoxic conditions results in label incorporation into C3 of lactate and C3 of alanine (b). Visible in the first spectrum obtained under hypoxic conditions are resonances from glutamate labeled during the normoxic portion of the experiment that were not washed out by the fresh perfusate. This observation indicates that the glutamate labeled during the first part of the experiment is relatively inactive metabolically Introduction of GIK during hypoxia results in decreases in the intensity of the glutamate resonances, which shows that the pool of labeled glutamate is metabolized. Figure 4.9 compares the incorporation of label from [3-13C]pyruvate into [3-13C]lactate under a variety of conditions. This figure demonstrates that GIK markedly enhances the incorporation of label into lactate during hypoxia. Surprisingly, in the absence of GIK very little label is incorporated from pyruvate to lactate even under hypoxic or ischemic conditions. In fact, there is very little difference between the normoxic experiments and the hypoxic and ischemic experiments carried out in the absence of GIK. The observation that GIK stimulates incorporation of the label from pyruvate into lactate during hypoxia suggests that glycolysis is the primary source of reduced pyridine nucleotides in the hypoxic perfused heart. The time course of the intensities of the labeled glutamate resonances during hypoxia is shown in Fig. 4.10. The presence of GIK during hypoxia markedly stimulates metabolism of the labeled glutamate pool. Anaerobic metabolism of amino acids, primarily aspartate and glutamate, has been noted previously in skeletal muscle of diving mammals52 and in cardiac tissue during hypoxia.53 In diving mammals, the cata holism of glutamate and aspartate is an important source of high-energy phosphates by substrate-Itvel phosphorylation during prolonged dives.52 Its role in maintaining energy stores in cardiac tissue is still uncertain. Our observations suggest that in perfused heart a glycolytic substrate may be required to stimulate the metabolism of glutamate, and GIK may provide some benefit through the stimulation of amino acid catabolism.

QIK & HYPOXIA --O— HYPOXIA GIK MORMOXIA --Cr- ISCHEMIA

CO LU I-

TIME-*-

Fig. 4.9. Label incorporation into [3-"Cjlactate under a variety of conditions. 66 ISOTOPE PRODUCTION, SEPARATION, AND APPLICATION

Co G1.UTAMATE —O_ Co QLUTAMATE * WITHOUT Q!K ^^ ^ WITH QIK C GLUTAMATE —n_ C QLUTAMATE

TIME-"-

Fig. 4.10. Changes in labeled glutamate resonances during hypoxia.

RADIOACTIVE ISOTOPE PRODUCTION AND APPLICATIONS

INC-3 ISOTOPE PRODUCTION ACTIVITIES

Karen E. Peterson, Martin A. Ott, Franklin H. Seurer, Neno J. Segura, Wayne A. Taylor, John W. Barnes, Frederick J. Steinkruger, Kenneth E. Thomas, and Philip M. Wanek

A significant portion of the INC-3 effort is in producing and shipping radioisotopes for the medical research community. These radioisotopes are generally unavailable commercially, and they can only be made in high yields at Los Alamos; Group INC-3 provides these radioisotopes on a cost recovery basis to interested researchers. During FV 1984, 107 targets were irradiated at LAMPF; a summary of these targets is given in Table 4.4. A total of 49.66 Ci of 18 radioisotopes were shipped to 39 organizations from around the world and to five groups at Los Alamos, including our own Medical Radioisotopes Research Program (see Table 4.5). ISOTOPE PRODUCTION, SEPARATION, AND APPLICATION 67

TABLE 4.4. Targets Loaded at the Isotope Production Facility at LAMPF Primary Number of Target Product Loadings I23 BaCl2 I 3 CsCl 127Xe 14 CsCl ml 7 RbBr 68Ge 11 Ni «Fe 8 Mo 77Brand82Sr 21 ZnO 67Cu 21 Ai 22Na 4 In 109Cd 7 KC1 32Si 1 14S EuO2 Sm 1 Pb 195Au 3 MnCl2 «Ti 3 Radiation Damage 3

TABLE 4.5. Medical Radioisotope Shipments Number of Amount Isotope Institution Shipments (mCi) l01! Ag Los Alamos/INC-3 1 0.63 Total 1 0.63 26AI Atomic Energy of Canada, Ltd. 1 0.00002 Calif. Iwst. of Technology 1 0.00038 Fish-Oceans Freshwater Inst. 1 0.00003 Total 3 0.00043

7Be Amersham International I 20.0 Loveiace Biomedical 2 107.0 Oak Ridge ASSOL Univ. 1 0.5 Total 4 127.5

77Br Los AIamos/INC-3 12 562.0 Univ. of New Mextco 4 319.5 Washington University 7 273.75 Total 23 1155.25

77Br Univ. of California, Davis 1 1.5 Comp Total 1 1.5

82Br Los Alamos/ESS-4 3 66.42 1 0.04 Total 4 66.46 68 ISOTOPE PRODUCTION, SEPARATION, AND APPLICATION

TABLE 4.5. Medical Radioisotope Shipments Number of Amount Isotope Institution Shipments (mCi)

l09Cd Atomic Energy of Canada, Ltd. 1 1000.0 Total 1 1000.0

"Ce LosAlamos/INC-11 1 0.094 Total 1 0.094

67Cu Albert Einstein/Yeshiva Univ. 7 320.84 California State, Fullerton 8 974.4 Hospital for Sick Children 9 1396.0 IBM Research Center 2 30.2 John Hopkins Medical Inst. 1 10.0 Los Alamos/INC-3 17 722.3 Los Alamos/LS-3 4 112.7 National Institutes of Health 2 226.8 New England Nuclear Corp. 2 261.9 Univ. of California, Davis 10 1543.67 Univ. of Saskatchewan 3 124.9 USDA, Beltsville 4 40.5 USDA, Grand Forks 1 5.0 Total 71 5771.75

Univ. of Nebraska Medical Center 1 409.8 Total 1 409.8

68Ge Mem. Sloan-Kettering Cancer Center 1 5.0 MRC/Hammersmith Hospital 1 70.0 Oak Ridge Assoc. Univ. 1 5.0 OFC Des Rayonnement Ionisant, France 1 21.5 Univ. of Chicago Radiation Protection 1 2.5 Univ. of Liege, Belgium I 36.6 Univ. of Michigan 1 18.0 Washington University 1 50.0 Total 8 208.6

163Ho EP-lsolde, CERN 1 1.0 Total 1 1.0

"Na New England Nuclear Corp. 2 1240.0 Total 2 1240.0 Univ. of South Carolina/NEN 1 0.268 Total 1 0.268

E.R. Squibb & Sons 10 5101.29 MRC/Hammersmith Hospital 3 390.236 Squibb/Sloan-Kettering 1 154.1 Squibb/Sloan-Kettering/Univ. Texas 1 300.0 Univ. of California, Donner Laboratory 5 1131.88 Univ. of Liege, Belgium 1 158.4 Univ. of Wisconsin 1 146.5 Total 22 7382.406 ISOTOPE PRODUCTION, SEPARA TION, AND APPLICA TION 69

TABLE 4.5. Medical Radioisotope Shipments Number of Amount Isotope Institution Shipments (mCi)

43V California State, Northridge 2 21.7 Los Alamos/HSE-8 1 0.5 Total 3 22.2

127Xe Brookhaven National Laboratory 4 32220.0 Total • 4 32220.0

88Y Hybritech, Inc. 2 20.15 Isotope Products Labs 1 8.0 New England Nuclear Corp. 2 16.26 Univ. of Minnesota 1 8.0 Total 6 52.41

TOTAL SHIPMENTS: 156 49.66 Ci

SYNTHESIS OF 67Cu ,1/£56>-TETRA(4-CARBOXYPHENYL) PORPHINE FOR CONJUGA- TION TO MONOCLONAL ANTIBODIES

Janet A. Mercer-Smith, R. Scott Rogers,* Neno J. Segura, and Wayne A. Taylor

Monoclonal antibodies have great potential as agents to transport diagnostic and therapeutic quantities of radioisotopes to tumors with minimal deposition in other organs.54 The use of labeled monoclonal antibodies allows us to selectively target tumors and minimizes total body radiation dose and radiation damage to normal tissue. We are developing chelate conjugation as a method of radiolabeling monoclonal antibodies. At the initiation of this research, two important considerations were the selection of a suitable radionuclide and the selection of a suitable chelating agent. Copper-67 was chosen for several reasons: (1) its 62-hour half-life is in the range for biological studies; (2) its (3 decay can be used for tumor therapy; (3) its gamma emission (91, 93, and 184 keV) is in the range for conventional gamma camera imaging; and (4) it is produced at LAMPF with high specific activity. We selected porphyrins as a class of chelating agents because they coordinate Cu(II) readily,5556 form stable • omplexes with copper,57 and can be obtained with a variety of peripheral function groups for attachment to antibodits. We have investigated ;«eso-tetra(4-carboxyphenyl) porphine H2TCPP as a chelating agent for 67Cu because this porphyrin is water soluble56 and has four carboxylic acid groups for conjugation to proteins. (See Fig. 4.11 for the structure of the copper complex of the porphyrin CuTCPP.)

'University of New Mexico Medical School 70 ISOTOPE PRODUCTION, SEPARA TION, AND APPLICA TION

CO2H

COZH

C02H

Fig. 4.11. The structure of 67Cu /«e5o-tetra(4-carboxyphenyl) porphine.

The rcietalation reaction for porphyrins is shown in Fig 4.12. A study of the effect of solvent on the metalation reaction of H2TCPP indicates that dimethylformamide gives quantitative in- 67 corporation of stable CuCl2. Because Cu is usually supplied from the INC-3 hot cell production 67 facilities in 2M HC1, we studied the effect of the CuCI2 solvent on the carrier-added metalation 67 reaction where the solvent for CuCI2 represented 20% of the reaction solvent volume. We measured the results by radio high-performance liquid chromatography (radioHPLC) (see Table 4.6). A low metalation yield was found when HC1 was present. Low pH is known to retard porphyrin metalation by making the removal of the protons on the pyrrole nitrogens more difficult and by protonating the two imine-type pyrrole nitrogens. Neutralizing the HO solution increased the radiolabeling yield, but copper phosphate is only slightly soluble in dimethylformamide. We obtained a very good radiolabeling yield, 93%, when the HC1 solution was removed by evaporation

R +2HX

R R

Fig. 4.12. The porphyrin metalation reaction. ISOTOPE PRODUCTION, SEPARATION, AND APPLICA TION 71

67 TABLE 4.6. The Effect of the CuCl2 Solvent on the Radiolabeling Yield* Solvent for 67Cu;+ Yield (%) 2MHC1 61 Phosphate Buffer 76 Diinethylformamide 93 67 "The solvent for CuCI2 represents 20% of the reaction solvent volume; the remainder of the solvent was composed of dimethylformamide.

67 and CuCl2 was redissolved in dimethylformamide before initiation of the chelation reaction. In the analogous no-carrier-added reaction, we measured a radiolabeling yield of 76%. We have obtained yields as high as 90% during no-carrier-added preparative scale reactions; therefore, we 67 transfer CuCI2 to dimethylformamide for all metalation reactions. 67 + Copper-67 TCPP, H2TCPP, and Cu~ are separated by HPLC when a reversed phase C,8 column is used with a paired ion chromatography (PIC) reagent. Either heptanesulfonic acid or heptafluorobutyric acid can be used as a PIC reagent; however, heptanesulfonic acid is more difficult to remove following chromatography. It is necessary to remove the PIC reagent when the labeled porphyrin is to be used in biological studies because both of these PIC reagents can denature proteins. The PIC reagent can be removed by chromatography on an anion exchange resin. The most promising resin is QAE, a strong base cellulose resin. An 86% recovery of the 67CuTCPP from the resin can be obtained when \0~2M HC1 in ethanol is the eluent. We have begun biodistribution studies of the purified labeled porphyrin to determine the localization of this compound if it becomes detached from the antibody in vivo. We have taken two different approaches to form a covalent linkage of 67CuTCPP to proteins: (1) direct coupling of the labeled porphyrin to the protein, and (2) formation of an activated ester of 67CuTCPP before coupling to the protein. In preliminary experiments, we used l-ethyl-3-(3- dimethyiaminopropyl) carbodiimide hydrochloride salt for the direct coupling of 67CuTCPP to protein. The method does not appear to provide adequate conjugation to the protein. However, activation of 67CuTCPP via formation of the N-succinimidy! ester by using 1,3-dicyclohex- ylcarbodiimide in dimethylformamide, followed by reaction with protein, indicates that conjugation does occur. We are now studying this and other methods of coupling the labeled porphyrin to antibodies.

IMPROVED TARGETING SYSTEM FOR 123Xe — 123I PRODUCTION AND RECOVERY

Martin A. Ott, John W. Barnes, Franklin H. Seurer, Neno J. Segura, Wayne A. Taylor, Harold A. O'Brien, and David C. Moody

The radiopharmaceutical community's interest in obtaining high-purity I23I has grown considerably since the development of radio-iodinated agents that show promise for diagnosing cerebral vascular defects (stroke). In the recent past, we have reported results obtained from spallation reactions in CsCl targets operated in the batch mode. That process entails irradiating the target in a closed container, transporting the target to a vacuum line located in our hot cell complex, 72 ISOTOPE PRODUCTION, SEPARA TION, AND APPLICA TION

cryopumping the radioxenons to a growth chamber, and allowing 123Xe to decay to inl in the chamber for varying periods. Although the yield of 123I was in the range of 1 to 2 Ci at the end-of- growth period, the amount of contaminating I25I was too high for many applications. Higher I23I yields and reduced l2SI contamination are possible with a system in which, during irradiation, the radioxenons can be swept from the in-beam target continuously and can be collected in an appropriate growth chamber. At the end of irradiation, the growth chamber is detached and transported to a vacuum line in the hot cell, and the residual radioxenon is removed. During the past year, a new isotope stringer with gas-sweeping lines was installed, and a gas- coliection station was constructed and installed at the Isotope Production Facility (IPF).

• Stringer. We replaced the number 1 stringer at the LAMPF IPF with a new design to accommodate the continuous collection of spallenogenic gases—in particular, the radioxenon parents of I23I and I25I. The 25-ft-long stringer is shielded with 15 ft of magnetite concrete and is equipped with l/8-in.-i.d. (l/4-in.-o.d.) stainless tubing for gas circulation.

• Target holder. The target carrier is also a new design with all welded seals, except for the fittings that connect it to the stringer head and allow us to circulate gas over the target reservoir (2-1/4 in. by 2-1/4 in. by 0.6 in.) and circulate cooling water around the reservoir. The helium inlet of the target reservior is equipped with a gas deflector xhat was installed in an attempt to minimize BaCU transport during the gas collection.

• Collection station. The collection station is surrounded by 3-in. lead shielding and weighs 6800 lbs. The station is 46-1/2 in. long by 21-1/2 in. wide by 38 in. high; it is equipped with a door and a 14-l/4-in.-diam hole in the lid for inserting the cask. The cask houses the collector trap (or generator) and weighs 1200 lbs; it has 4-in. lead shielding of 22-3/4-in. by 13-3/4-in. o.d. The valves within the gas manifold are all operated electronically, with the exception of the physical connection of the generator to the manifold, which requires two manual ball valves that are remotely operated.

In a typical run, we pour 144 g of molten BaCU into the carrier reservoir through the gas outlet hole. The carrier is then transported to LAMPF, is connected to the stringer, and remains in place for repeated runs. We pressurize the gas circulation system to 20 psia helium, which serves as a carrier for the radioxenons, and cool the generator in liquid nitrogen to trap the xenons produced. After we initiate gas circulation, we place the carrier in beam and monitor the activity in the generator by an ionization-chamber detector. At the end of the run, we disconnect the generator from the manifold, we close the cask around the generator and remove it from the station to the hot cell facility. The generator is removed from the cask in the hot cells; after an appropriate growth period, the remaining xenons are removed by evacuation, and the iodine within the generator is extracted with hot 0.02M NaOH. The preliminary results of four runs are encouraging: a 2-hour irradiation followed by a 2-hour growth period in the generator resulted in 556 mCi I23I with a 1.2-mCi 125I contamination (0.22%). An additional 4-hour growth period for the xenons that were removed from the generator yielded another 188 mCi mI and 1.3 mCi 125I (0.7%). A 1-hour irradiation followed by a 2-hour growth period yielded 329 mCi 123I and 0.60 mCi 125I (0.18%). Both runs occurred while the beam current was approximately 570 uA. Another 2-hour irradiation at slightly higher beam current, followed by a 2-hour growth period yielded 590 mCi I23I with 1.26-mCi 125I contamination (0.21%). The second 4-hour growth period yielded an additional 163 mCi I23I and 1.1 mCi 125I (0.67%). A fourth experiment was attempted at the very end of the LAMPF run cycle using a beam current of only 470 uA. This current is approximately half of that observed during most of this cycle, and as a result, it appears as if the target only partially melted in beam. However, a 4-hour irradiation followed by a 4-hour growth period yielded 524 mCi I23I and 1.95 mCi I25I (0.37%). More studies are under way as we attempt to evaluate the effects of varying irradiation times and growth times on the quantity and purity of the 123I produced. ISOTOPE PRODUCTION, SEPAIL4 TION, AND APPLICA TION 73

RUBIDIUM-86 PRODUCTION

Philip M. Wai* * and Frederick J. Steinkruger

Experimenters at the University of South Carolina, who were interested in measuring the cross section for pair production, requested 20 to 40 uCi of 86Rb. Source specifications required that the dry salt volume not exceed 14 mm3 and that the source be free from radionuclidic impurities, the decay of which would result in 511 keV or greater than 1.022-MeV photon production. We prepared the source by irradiating Rb2CO3 salt in the thermal column at the OWR. After irradiation, the sample was dissolved in 1 mfi of water, an aliquot was removed for gamma-ray spectroscopy, and the aqueous solution was evaporated to incipient dryness. We removed the identified radionuclidic impurities 82Br, 24Na, 42K, and l34Cs by column chromatography.65 The Rb:CO3 was reaissolved in 0.01M NH4C1 and loaded onto a zirconium tungstate column, which was eluted with I.OA/ NH4C1 solution. Eluate fractions having a volume of 5 mfi each were collected. The order of elution for the radioisotopes contained in the reactor-irradiated salt was 82Br, fraction 1; 24Na, fractions 2 to 4; 42K, fractions 3 and 4: and 86Rb, fractions 4 to 8. Cesium-134 was retained on the column. S6 Eluate fractions containing Rb were evaporated to dryness, and the NH4C1 salt was removed by sublimation. We removed small amounts of the inorganic exchanger that remained in the residue by dissolving the sample in water and filtering it through a cellulose acetate filter. Our collaborators at the University of South Carolina report that the purity of the 86Rb was so high that their cross- section measurement was a complete success.

THE 109Cd — ""Agm BIOMEDICAL GENERATOR

Frederick J. Steinkruger, Philip M. Wanek, and David C. Moody

Silver-109m, with a half life of 39.6 seconds and a gamma ray at 88 keV (Ref. 59), has potential as a dynamic imaging agent and, possibly, as a pediatric imaging agent. The availability of large quantities of 1(|1)Cd suggests the feasibility of a 1OTCd — IO9Agm generator with a high l09Cd loading, perhaps in curie quantities."0 Such parent loading will overcome the low intensity (3.73%) of the 88-keV gamma by providing a substantial source of daughter l()9Agm. A biomedical generator containing curie quantities of '"°Cd, half-life 454 days, implies the use of an inorganic ion-exchange material. Such ion-exchange materials possess higher radiation resistance than do standard organic ion-exchange resins and should provide a support system that would survive over a generator lifetime of 2 or 3 years. Ogard,61 using basic AliO, as the ion- exchange material, achieved a 50% IOI)Agm yield with a "wCd breakthrough of 2.8 X 10"4. Ehrhardt et al.62 used zirconium phosphate ion-exchange material to form a generator with 40 to 60% l09Agm yield and a l09Cd breakthrough of 3 X 10"6. Yano et a!.6i used alumina to achieve a 32% l09Agra yield and a breakthrough of 2 X 10~\ In all three cases, the 20- to 40-year biological half-life of cadmium64 made the "'T'd breakthrough too high for use in human patients. Therefore, we undertook the development of a l09Cd — l09Agm generator that has a high l(WAgm yield and lower imCd breakthrough and is based on an inorganic ion exchanger. 741 ISOTOPE PRODUCTION, SEPARA TION, AND APPLICA TION

Experiments We used tin phosphate, a commercially available inorganic ion exchanger, as the column material. We ground, sieved, and retained the +80 to 115 mesh fraction of the exchanger for use in the column. This fraction was slurried in 0.! M phosphate buffer and poured into a column to form a 1.5-m8 bed. We then rinsed the ion exchanger with 0.1M phosphate buffer at pH = 7.4 until the eluate pH was 7.4. Cadmium-109 production has been described in our Ref. 60. The stock solution of 109Cd was evaporated to dryness and taken up in 200 u£ of distilled water. A 50-uC aliquot was assayed for l09Cd content. After the column was drained by gravity flow, a 50-jiC aliquot of the IO9Cd stock solution was placed on the top of the exchanger bed and was followed with 100 ufi of distilled water. The column was then capped and allowed to stand. The eluent combination was based on decreasing the reduction poiential of Ag+ (E° = 0.8 V) by complexation with SjO^", forming Ag(S2O3)'~ (E° = 0.01 V), and then reducing the complex to Ag° with a mild reducing agent. Two combinations were tested: (1) 5% ascorbic acid, 5% phosphate A buffer (pH = 7.4), and 2 X 10~ M Na2S:O3, and (2) 5% dextrose, 5% Mcllvaine's buffei {pH = 3.8), 4 and 2 X 10~ MNa2S2O3. Both eluent combinations were approximately isotonic but would require pH adjustments before they could be injected into human patients. The standard eluiion procedure was to draw a 1.5-mfi sample in approximately 7 seconds. The generator was then left static for 10 minutes to reestablish secular equilibrium before the next elution.

Results Figure 4.13 shows the results of several variations in parameters. The first eluent combination tested was the ascorbic acid combination. Initial 109Agm recovery increased to a maximum of 75% and then decreased to a steady value of 48%. Cadmium-109 breakthrough dropped rapidly into the range of 10"6 to 10~7 and remained steady. The cause of the decrease in 109Agm recovery is not known. The fluctuation of l09Cd breakthrough in samples 300 to 380 resulted from testing various reducing agents. At sample 386, a regeneration process consisting of a 200-mfi rinse with 0.05M NaOH was completed. Following this rinse, IO9Agm was eluted with the dextrose combination. The 109 7 109Agm yjgi^ gra(jUally increased to ~56%, but Cd breakthrough remained in the 10" range.

100- r 10x10-'

80- -8 o 2 gj 60- -6 as

r-4 3 K f 20- S i -2 iU.A

100 200 300 400 500 600 Sample Number

Fig. 4.J3. The 109Cd — IO9Agm elution profile. ISOTOPE PRODUCTION, SEPARA TION, AND APPLICATION 75

After sample 520, we left the generator in a static condition for 3 months under 5% Mcllvaine's buffer. After the storage period, we continued elution of 109Agm with the dextrose combination: the 109Agm yield remained steady at 54%. After an initial increase in 109Cd, its breakthrough returned to previous low levels. Long-term stability of the generator is demonstrated by consistency of yield and breakthrough over a 6-month period and 527 !.5-m£ samples.

Imaging The utility of l09Agm as an imaging agent is shown in Fig. 4.14. Silver-109m was eluted directly from the generator into the stomach of a rat through a small plastic tube inserted into the esophagus of the animal. In part A of the figure, the stomach is clearly visible, as is the tube in the esophagus. The tube is visible because we acquired the image simultaneously with elution of the 109Agm. In part B, it is possible to see the stomach dumping into the intestine and the isotope backing up in the esophagus. Both images are the result of introduction of approximately 5 mCi of l09Agm

Conclusions A 109Cd — IO9Agm generator based on tin phosphate inorganic ion-exchange material and an 4 eluent consisting of 5% dextrose, 5% Mcllvaine's buffer, and 2 X 10~ Na2S2O3 has exhibited a stable daughter yield of 56% with a l09Cd breakthrough of 10" . The breakthrough has been slowly dropping—some samples show 10"8 values. We will continue to improve the 109Agm yield and lower the parent breakthrough.

Fig. 4.14. A 109Agrn imaging of a rat stomach. STOMACH ESOPHAGUS

ES0PHAQU8 76 ISOTOPE PRODUCTION, SEPARATION, AND APPLICATION

IMAGING AND BIODISTRIBUTION CAPABILITIES AT INC-3

Philip M. Wanek, Zita V. Svitra, R. Scott Rogers*, and Wayne A. Taylor

We have developed imaging and biodistribution capabilities to estimate the potential uses of new radiopharmaceutical agents produced by our group. Although imaging and biodistribution studies are usually separate disciplines, they can be mutually supportive and are presented here as a single effort. It is possible to arbitrarily divide materials required for these types of experiments into four classifications: (1) biologically compatible radionuclides, (2) radiation detectors, (3) animal models, and (4) animal- and tissue-handling instruments. This classification is used here only for convenience and is not meant to be a rigid structure.

Biologically Compatible Radionuclides Regardless of the chemical and physical nature of the radiopharmaceutical being developed (that is, labeled organic compound, metal chelate, or inorganic salt), the radionuclide must be biologically compatible. This simply means the product must be sterile and free from toxic contaminants, including pyrogens, before it can be administered parenterally to an animal. In addition, the isotonicity and pH of the vehicle must conform to those of biological fluids. Finally, the product should be free from radionuclidic and radiochemical contamination. Several methods, including wet and dry heat, filtration, ultraviolet irradiation, and ionizing irradiation, can be used to render a product sterile.38" We commonly use filtration, especially for products with short half-lives and those used in small animals where the experiment duration is short. Sterility testing is done if the animal to be used is a primate. We rely on the radiometric test for sterility; it is based on the release and subsequent detection of 14CO, from culture media substrates by microorganism metabolism. We assume that if each ingredient used in the manufacture of the final product is sterile, pyrogen contamination does not exist, and therefore, we do not test for it. Radionuclidic and radiochemical contaminations are found by gamma-ray spectroscopy and radiochromatographic measurements. Because the quantity of the radionuclide to be administered is usually small, we can adjust isotonicity and pH in the vehicle or carrier solution. A recent paper586 lists at least 25 elements that are considered essential trace elements in human nutrition, and each element is a radiopharmaceutical candidate as a biological tracer. Isotopes of these and other elements may be bonded to an almost inexhaustable supply of organic compounds, and this variety provides an almost unending basis for experimentation. In reality, not all elements have isotopes whose decay characteristics are amenable either to gamma-ray imaging or biodistribution. Nuclides that we have studied and are studying now include 67Cu, 6

Radiation Detectors The instrumentation available at INC-3 for biological studies includes: (1) GeLi detectors, (2) an ion chamber (dose calibrator), (3) a Nal well counter, and (4) a gamma camera with collimators. Relevant information may be obtained from biological systems only if we can account for 100% of the administered radioactivity.'80 We use efficiency-calibrated GeLi detectors to assay an external standard. The ion chamber and well counter data are then cross calibrated with the results we obtain from the GeLi system. Each animal dose is treated as a unit dose; that is, a separate syringe is used for each animal. The activity in each syringe is measured before and after injection in the dose calibrator. This procedure serves as a cross check for the volume of fluid injected.

•University of New Mexico School of Medicine ISOTOPE PROD UCTION, SEPARA TION, AND APPLICA TION 77

The well of the Nal well counter accommodates the eviscerated carcass of an adult rat. The crystal measures 7-in. diameter by 10-in. depth, and the well is 2,75 in. by 8 in. Normally all biological samples are counted either in this detector or in an automated Nal well counter, depending on their size. Anatomical detail is not a criterion for a good image. The appearance and disappearance of radioactivity in a target organ as a function of time is more important. The gamma camera is used in our laboratory to qualitatively observe with time the sequestering of radioactivity by any particular organ. We can also obtain biodistribution measurements in corresponding animals at the critical time.

Animal Models The choice of an animal model is limited by availability. In our studies we are able to use standard rodents (mice including nude mice, rats, rabbits, guinea pigs), dogs (beagles), pigs (miniture swine), and primates (Rhesus monkeys). Primates are used solely for animal imaging; mice and rats are used for both biodistribution studies and imaging. Dogs and pigs have not yet been used but are available should the need arise. The choice of animal depends upon the types of experiments. For a liver study, the ratio of the weight of the liver to that of the entire animal should be kept as close as possible to that of the human. For example, a mouse liver weighs on the average 46 g/kg and the rabbit liver 27 g/kg. (The average normal human liver weighs 23 g/kg of body weight.) The proper choice for an experimental animal in this example would be a rabbit. If a disease state is being studied, the experimenter tries to find an animal whose condition mimics that state. In Menke's disease (a condition marked by abnormal copper metabolism), mottled mutant mice mimic the human symptoms and are therefore the animal model of choice. On the other hand, botulinum toxicity cannot be studied using a canine model and oral administration because the toxin is not absorbed from the alimentary canal of a dog. The route of the nuclide's administration is an important factor in animal modeling. For example, if one is interested in studying absorption for the stomach and intestines, either gavage or oral feeding would be considered. Obviously, inhalation or intravenous administration would be inappropriate. Intradermal inoculation is preferable for antigen-antibody reactions in some cases.

Animal and Tissue Handling Instruments Three factors must be considered in choosing these instruments: (1) the safety of the animal handler, (2) the animal's comfort, and (3) the prevention of contamination. When small animals are used, protection from bites, scratches, and external contamination are the primary concern. Heavy gloves offer the maximum protection against all three; unfortunately, trying to inoculate or inject a small animal using a email syringe while wearing heavy gloves can be a miserable task. Either a compromise must be made or a different approach, such as use of a restraining cage, must be taken. We commonly use restraining cages in combination with anesthesia when working with primates because an adult Rhesus monkey has a strength equivalent to three adult humans. Proper use of anesthetics is important for ensuring comfort of the animal. Proper is the key word—underdosing will not produce the desired response, and an overdose will usually cause the animal's demise. One of the animal handler's greatest assets is the quality of gentleness; treated gently, an animal can be manipulated many different ways. Gentleness seems to relax animals, and working with a relaxed beast aids immensely in ensuring its comfort. Preventing cross contamination is the most controllable feature for acquisition of useful data. Excreta must not contaminate skin or fur, individual organs must be clear of blood and serum, and all tissue samples must be free from unlike juxtapositional tissue. Choosing appropriate animals, instruments, and anesthetics, as well as cleanliness and gentle handling, will help ensure relevant and useful data from animal modeling systems. WASTE MANAGEMENT

Nevada Nuclear Waste Storage Investigations 81

Measuring Particle-Size Distributions by Autocorrelator Photon Spectroscopy 82

Thermodynamics of Albite 86

Sorption Measurements on Yucca Mountain Tuff Samples 87

Radionuclide Migration at the Nevada Test Site 88

GEOCHEMISTRY

Nuclear Microprobe Characterization of Trace Elements in Oil Shales 91

Acid Sulphate Alterations at Sulphur Springs, Valles Caldera, New Mexico 96

An Automated Calorimeter for Use at High Temperature and Pressure 98 ELEMENT AND ISOTOPE TRANSPORT AND FIXATION 81

WASTE MANAGEMENT

NEVADA NUCLEAR WASTE STORAGE INVESTIGATIONS

Allen E. Ogard

The Nevada Nuclear Waste Storage Investigations (NNWSI) program is part of the DOE effort to locate sites across the nation that are technically suitable for a high-level nuclear waste repository. Yucca Mountain, in the southwest corner of the Nevada Test Site, is the area being .investigated by the NNWSI. The mountain is composed of layers of tuff, a volcanic rock that is impermeable but quite porous. Some of the tuff layers contain large quantities of zeolites, a mineral group that is formed by alteration of tuff and is a good sorber for most radioactive waste elements. This fact, among others, makes Yucca Mountain an important site to investigate extensively for a possible repository. The following are the main topics being investigated by the Los Alamos NNWSI program. These studies are designed to further define the character of the proposed repository site.

• Water chemistry. We are determining the groundwater chemistry, including particulates, at Yucca Mountain as a function of depth and distance from the proposed repository. These studies also include modeling water composition at locations in the proposed repository site and in the accessible environment by using data collected from many drill holes in the area.

• Sorption. Because zeolitized tuff is highly sorptive, the sorption ratios for nuclear waste elements are being determined. This work also includes experiments on colloid formation of waste elements and on microbiological activities that might influence sorption.

• Solubility measurements. Lawrence Berkeley Laboratory, under contract to INC Division, is determining the solubility of plutonium, americium, and neptunium oxides in a typical groundwater found beneath Yucca Mountain. In addition, at Los Alamos we are studying the effects of alpha self-irradiation on plutonium species in solution.

• Transport experiments. Waste elements in some of the tuffs of Yucca Mountain will be transported as water flows through fractured tuff. We are measuring diffusion from this flow into the rock matrix to discover how much it might retard migration of the waste elements.

• Hydrothermal geochemistry. The temperature of the tuff around an operational repository will rise to = 130°C for a period of 800 to 1000 years. This temperature rise could change both the chemistry of the groundwater and the sorptive properties of the tuff; these effects are being examined.

• Gcochronology studies. ChIorine-36 determinations as a function of depth in the tuffs of Yucca Mountain will yield information on the recent infiltration rate of water.

• Program iiuegration. Data from the site characterization and laboratory experiments are interpreted to help design and assess the performance of the proposed repository site. All site- characterization documentation must rigorously comply with federal licensing requirements.

• Volcanism. A detailed study of past volcanism in the NTS area has been completed, and predictions have been made regarding possible future volcanism that could affect the repository. 82 ELEMENT AND ISOTOPE TRANSPORT AND FIXA TION

• Borehole/shaft sealing. Performance tests are made on the long-term seals to be used in the exploratory shaft and repository.

The following are noteworthy achievements for 1984.

(1) We issued a detailed program plan for the geochemistry portion of the NNWSI program.

(2) We completed sampling and analyzing groundwaters from available wells at Yucca Moun- tain. Results are available in a Leve' I milestone delivered to DOE Headquarters.66

(3) Long-term sorption experiments with technetium were completed, and sorption experiments on tuff were initiated with uranium, thorium, and tin.

(4) We completed solubility measurements of plutonium, neptunium, and americium oxides in water from Yucca Mountain.

(5) A thermodynamic model for albite was formulated.

(6) Fracture flow experiments were initiated to demonstrate retardation by diffusion of waste elements from water flowing in fractures.

(7) We assessed the impact of hydro volcanic activity for Yucca Mountain.

(8) We initiated a study of infiltration rates of water in Yucca Mountain by 36C1 analysis.

In addition to the above activities, in 1984 the full effect of the Nuclear Waste Policy Act of 1982 was felt on the program. Increased time and effort were required for documents such as the Siting Guidelines, the Environmental Assessment, and the Exploratory Shaft Test Plan.

MEASURING PARTICLE-SIZE DISTRIBUTIONS BY AUTOCORRELATOR PHOTON SPECTROSCOPY

Robert S. Rundberg, Alfred Zeltmann*, and Alan J. Mitchell

The safe disposal of nuclear waste relies, to some extent, on the barrier posed by the chemical interaction of radionuclides with the minerals present in the rock surrounding a nuclear waste repository. One of the concerns raised in radionuclide migration research is "Will radiocolloids or pseudocolloids circumvent the geochemical barrier?" To address this concern, the NNWSI project will examine the groundwater in the area of Yucca Mountain to determine the size and number of particles present in the natural system. The size distribution of actinide colloids and the stability of these colloids will be studied. We will also measure the filtration of colloids by Yucca Mountain tuff.

'University of North Carolina ELEMENT AND ISOTOPE TRANSPORT AND FIXA TION 83

Autocorrelator Photon Spectroscopy (APS) or dynamic light scattering is a modern instrumental technique of sizing particles in colloidal suspension. The INC APS system consists of (1) a 15-M W He(Ne) laser (or alternatively, a Spectra Physics 2-W argon ion laser can be selected by inserting a mirror), (2) a Brookhaven Instruments Corp. BI-200 automatic goniometer, which has a temperature-controlled sample cell holder, and (3) a Brookhaven Instruments Corp. B1-2030 autocorrelator. The photomultiplier detector can be replaced by a fiber-optically coupled, peltier junction cooled photon counter (PAR-1191-1) for very dilute suspensions. The apparatus is a simple light- scattering system. Laser light is impinged on the sample vial, and scattered light is detected by a photomultiplier through a telescope mounted on the goniometer arm. The light pulses are then correlated in the autocorrelator circuit and accumulated. The autocorrelation function of Rayleigh scattered light is measured directly with photon autocorrelation. The autocorrelation function C(At) is defined as the intensity at some time, t, multiplied by the intensity at some later time (t + At). For a monodisperse suspension, the autocorrelation function can be expressed as

C(At)=B(l+e-2r4tX

where the time constant T can be related to the brownian diffusivity.67 The particle diameter can then be determined from the diffusivity by using the Stokes Einstein equation.68 For convenience, it is often simpler to use the following form of the correlation function:

For a monodisperse suspension,

g(At) = e'rAl.

However, for a polydisperse system, the correlation is integrated over many time constants resulting from the particle-size distribution. In this case, g(At) = J

where f[T) is the distribution of partial widths or time constants. This integral is of the form of the Fredholm Integal of the First Kind. One would like to determine the function f(F) by fitting the correlation function g. This is a classic problem of inverting first-kind integrals, which is often termed an "ill-posed problem." It is "ill-posed" because the integral is not very sensitive to rather large fluctuations in the distribution function. This means that, for instance, simple matrix inversion will generally be unstable. Several methods6970 have been.applied to the prob'em of inverting this integral, particularly for APS. The approach we have chosen to achieve stable solution is one developed by Tikhonov71 and called "regularization." This method achieves stability by minimizing the expression

[g(At) - fe^'flX)]2 + a/f2(r)dr, where a is a smoothing factor rather than simply the square of difference. The minimization of the second term damps out any large fluctuation in f. The smoothing factor must be chosen large enough to prevent the fitting of noise in the data. This can be accomplished by using the method of optima! smoothing developed by Bulter et al.n The Bulter method employs an auxiliary function H(a), which minimizes when the error in the fit is equal to the error in the data. 84 ELEMENT AND ISOTOPE TRANSPORT AND FIXA TION

To illustrate the application of this technique, a typical autocorrelation spectrum is shown in Fig. 5.1. In the autocorrelation spectrum, the random background is substracted. A reasonably short time is required to achieve a spectrum such as this; for concentrations of about 10~47l/, that is typically 1 hour. For lower concentrations (<10~6 M), the INC dynamic light-scattering system has an argon ion laser (1.5 W at 514.5 nm) to provide higher intensity and a pettier junction cooled photomultiplier to limit the dark current that becomta significant in extremely dilute suspensions. The next step in the technique is to download the data to a mainframe computer, such as one of the Los Alamos CRAYs, to be inverted.

l.O-i

0.8-

06-

04-

0.2-

00 00 1.0 20 3.0 40 50 6.0 7.0 8.0 TIME (sec) *10"'

Fig. S.I. Autocorrelation function 0.06 urn polystyrene.

The optimization of the smoothing factor is shown in Fig. 5.2. At large values of a, H(a) is decreasing with decreasing a. Below a certain point, H(,n) will abruptly increase; this minimum is the optimal value of a. This criterion rus a certain conservatism built into it because cancellation of errors is not allowed in the definition of H(a). A smaller a may, in fact, give a better fit. But there is no rigorous way of determining that a. The end result is shown in Fig. 5.3, which shows the fit to the particle-size distribution. In conclusion, dynamic light scattering is a useful tool for studying colloids and can yield more information about submicron particles than more conventional techniques such as filtration or certrifugation can. The INC system provides enough sensitivity to make the study of natural systems feasible. The method of Butler et al. for inverting the Fredholm integral equation is extremely stable and can be applied to many other measurements as well as APS; for example, adsorption isotherms can be inverted to yield the number of sites as a function of the free energy of adsorption. The only drawback of the Butler method is that it must invert a rather large matrix each time it iterates towards a solution for a given a (this is again iterated in a to find an optimum). It is CPU-intensive and requires up to 20 minutes CPU (on the CRAY) for a single sample. ELEMENT AND ISOTOPE TRANSPORT AND FIXATION 85

-ao-

-4.0-

-6.0-

-8.0-

H(a) -10.0-

-12.0-

-14.0 •

-16.0 -

-18.0 -

-20.0 —I ' 1 • 1 • 1 ' 1 '—i ' 1 ' 1— 0.1 0.2 0.3 0.4 0.5 06 07 0.8 ALPHA

Fig. 5.2. Optimal smoothing function.

l.O-i

70 80 90 100 110 12C DIAMETER (nm)

Fip. 5.3. Size distribution for 0.06 jim polystyrene. 86 ELEMENT AND ISOTOPE TRANSPORT AND FIXATION

THERMODYNAMICS OF ALBITE

Clarence J. Duffy

The formula of albite is NaAlSi3O8. The aluminum and silicon are distributed over four tetrahedral sites, and at low temperatures the aluminum is concentrated in one particular site (the Ti site). With increasing temperature, the aluminum is more evenly distributed over the four sites, and the crystal structure changes from triclinic to monoclinic symmetry; the t. ^nsition is at about 1050°C. These changes affect the thermodynamic properties of albite, but the effects of the aluminum/silicon disordering are not measured by calorimetry because changes in the state of order do not occur on the time scale of the calorimetric measurements. Mazo73 has proposed a statistical mechanical model for albite that describes the aluminum/silicon ordering as a function of temperature and the effects of this disordering upon the thermodynamic properties. This model assumes that the tetrahedral sites (other than the Tl site) arc energetically equivalent. This assumption is based on the fact that these sites have approximately equal aluminum occupancies at all temperatures.74 Maso's model also includes a site- preference energy, which is the energy difference between (1) having an aluminum atom on 3 Tl site and a silicon atom on one of the other sites, and (2) the energy that would exist if the silicon and aluminum were reversed. Mazo indicated a model could be made that more closely describes the temperature dependence of ordering in albite if the site-preference energy (U) were made a function of temperature, but he did not investigate the matter further. That U should decrease with increasing temperature seems probable, because as albite approaches monoclinic symmetry, the Tl tetrahedra will approach the others in similarity. As noted above, albite approaches monoclinic symmetry with increasing temperature. The data given in Thompson et al.1* for the state of order vs temperature could fit with Mazo's model if U were a linear function of temperature. A least squares fit to that data gives

U = -6.35X 10-20 + 5.12Xl(r23T, where T is the temperature in K and U is in J/atom. If the order parameter p is now defined as the fraction of the T1 sites that are occupied by aluminum, the difference in enthalpy AH between two albites with order parameters pi and p2 is defined by

AH = NC/(pl-p2), where AH is in J/mol and N is Avagadro's number. Hemingway et al.n give the enthalpy difference between high and low albite as 10 880 J/mol. This number was based on measurements of Amelia albite at about 50°C. Using the cell dimension data of Opersliaw et al.16 for Amelia albite, the equations for the Y- and Z-order parameters given in Thompson et a/.74 the corrections by Helgeson et ai.,11 and noting that

(Z + 2Y+ 1) p= , we found that p = 0.894 for the low albite used in the measurements and p = 0.282 for the high albite. The value of U calculated from this data corresponds to 392°C, but the measurements were made at about 50°C. A probable explanation for this discrepancy is that t/can be expected to vary only over the temperature interval of the tricJinic-to-monoclinic conversion. The data for the state of order vs temperature in Thompson ?t al.14 does not extend below 420°C, so it does contradict the assumption that {.'remains constant below 392°C. The data of Winter et al.n on the unit cell angles of albite vs temperature show relatively little change between 25 and 392°C compared with that above 392°C. Therefore, we can assume that below 392°C, U assumes a constant value of—17 778 J/niol. ELEMENT AND ISOTOPE TRANSPORT AND FIXATION 87

Mazo's model71 also provides the configurational entropy of aluminum/silicon order as a function of the order parameter p. Thus,

S, = R + 3(2 + p)in(2 + p) - (4/3)(l + 2p)ln(l + 2p)],

where Sc is the configurational entropy and R is the gas constant. The Gibbs energy of an albite within an arbitrary state of order p can then be expressed by

Gf=Gr-(l-p)tf-TSc,

where for T < 392°C, V is —17 778 J/mol, and Gf is the Gibbs energy of perfectly ordered albite.

SORPTION MEASUREMENTS ON YUCCA MOUNTAIN TUFF SAMPLES Kimberly W. Thomas, Sylvia D. Knight, Francine O. Lawrence, Barbara P. Bayhurst, and Michael R. Cisneros

As part of the NNWSI, we have been investigating the sorption behaviour of nuclear waste elements on Yucca Mountain tuff. Some of the tuff layers found at Yucca Mountain contain large quantities of zeolites, which are good sorbers for most radioactive waste elements; this fact makes Yucca Mountain an attractive candidate for further investigation as a possible nuclear waste repository silt. Among the isotopes we studied by batch sorption techniques are strontium, cesium, barium, radium, europium, technetium, uranium, neptunium, plutonium, americium, tin, and selenium. Limited studies have also included sodium, manganese, cerium, molybdenum, ruthenium, antimony, iodine, and protactinium. Some of our most recent work has focused on thorium. Thoriurn-230 is the long-lived parent of :26Ra, a nuclear waste element of concern. Because of this longevity, "''Ra may be transported in the form of its thorium parent. We have measured batch sorption coefficients for thorium on 10 different tuff samples under both ambient and controlled- CO; atmospheric conditions. Special care was taken to ensure that the measurements were made in the pH range of greatest thorium solubility. The sorption coefficients range from a low of —143 mC/g (measured under ambient conditions for a partially welded, devitrified tuff from the Bullfrog Member of Yucca Mountain) to a high of ~23 800 mB/g (measured under a CO,-controlled atmosphere for a zeolitized tuff from the Tram Member. In spite of the fact that the highest sorption coefficient corresponds to a high zeolite content, thorium sorption does not appear to correlate with tuff mineralogy. The use of a CO,-controlled atmosphere was initiated after we observed that over the course of an experiment, the pH of solutions rose to around 8 to 8.5, whereas the pH of Yucca Mountain groundwater, represented by water from Well J-l 3, is arcund 7. This rise in pH results from the loss of CO: from the solution because of low atmospheric pressure at 7000-ft elevation. We designed a chamber to maintain the pH of Well J-l 3 groundwater at 7 by regulating the CO2 content of the atmosphere. When we compare measurements made under these conditions with those performed in the laboratory, we see that for most elements there are few, if any, effects resulting from the two different atmospheres and that the laboratory results are conservative. 88 ELEMENT AND ISOTOPE TRANSPORT AND FIXATION

Because groundwater composition may vary between the repository and the accessible environment, we have been investigating the effects of groundwater compositions on the measured sorption ratios. We are examining deionized water and water from Wells J-13, UE-25p# 1, and H-3. Well J-13 water has been used as the reference groijndwater for our laboratory experiments and generally yields sorption coefficients that are similar to those of deionized water. Water from Well UE-25p#l, which comes from the paleozoic rocks below the tuff layers at Yucca Mountain, has a much higher concentration of calcium, magnesium, strontium, barium, sodium, bicarbonate, and sulfate than does Well J-13 water. Sorption coefficients from this water for elements that sorb by ion exchange (such as strontium, cesium, or barium) are still quite large but are lower than in Well J-13 water with its lower ionic strength. There is much greater competition for exchange sites in this case. For elements that have insoluble complexes such as europium or tin, however, the sorption coefficients in the higher ionic strength UE-25p#l water are much higher. Presumably, these elements are precipitating out of solution. Water from Well H-3 is intermediate in ionic strength, but it exhibits the highest pH measured thus far at Yucca Mountain: ~9. Studies with this particular water are just beginning. Our results indicate that groundwater composition does indeed influence the sorption of elements on Yucca Mountain tuff, but just what the effects will be depends upon the individual element's chemistry.

RADIONUCLIDE MIGRATION AT THE NEVADA TEST SITE

Joseph L. Thompson

In 1973, the Radionuclide Migration (RNM) project was started at the Nevada Test Site (NTS) to determine the potential for movement, both on and off the NTS, of radioactivity from underground nuclear explosions. Particular emphasis has been placed on measuring the extent of migration of radionuclides from explosion-modified zones in various types of geologic media. Contributions of INC Division personnel to the RNM program are detailed in a number of publications.79'84 In the INC Division FY 1984 Annual Report,85 we reviewed our continuing monitoring of the Cambric site, which is in tuffaceous alluvium, and described a new study begun at the site of the Cheshire test, where the detonation occurred in rhyolite. We now have sufficient data from the Cheshire study to begin comparisons between radionuclide behavior in rhyolite and alluvium under field conditions. This is important because a significant fraction of the weapons testing at the NTS has taken place in these two media. Table 5.1 shows the radionuclide concentration in water pumped from the re-entry hole at Cheshire in September 1983 and August 1984. The analytical procedures employed to obtain these data include evaporation of 55-gal. samples to dryness and counting the "boildown" residues in a gamma-ray spectrometer, radiochemical separation and purification of specific elements from solution, analysis of gaseous material using vacuum line techniques, and evaluation of the tritium content by liquid scintillation counting. Agreement between the 1983 and 1984 analyses is generally within the estimated 54 precision of the data. The relatively short-lived Mn (tl/2 = 312 days) was no longer detectable by the time of the 1984 sampling. Although the relative amounts of fission product and tritium in water from the Cheshire site appear to be reasonable, the absolute concentration of tritium is almost a factor of 30 lower than the source-term calculations indicate it should be. We suspect that water may be moving under a natural hydraulic gradient away from the cavity region. We would like to determine if this is the case and to what extent fission products and plutonium have moved with the water. Future experimental work at the Cheshire site includes sampling from the transmissive zones in the rhyolite that may serve as conduits for water moving away from the cavity. ELEMENT AND ISOTOPE TRANSPORT AND FIXATION 89

TABLE 5.1. Radionuclides in Water at Cheshire Concentration" (atoms/mfi) Radionuclide (9/83) (8/84) Method of Analysis 3H 1.23 X1013 1.12 X1013 liquid scintillation counting "Na 2 X 1013 2X104 boildown, gamma spectroscopy 54Mn 2X104 not detected boildown, gamma spectroscopy 60Co 2X103 2 X 103 boildown, gamma spectroscopy 85Kr 5.7 X 109 5.1 X 109 vac line separation, beta counting 9»Sr 4X106 6X106 radiochemical purification, 90Y gamma count 106Ru 4X106 4X106 boildown, gamma spectroscopy 125Sb 2X107 1 X 107 boildown, gamma spectroscopy l34Cs 3X104 4X104 boildown, gamma spectroscopy 137Cs 5X107 IX 10" radiochemical purification, gamma count J37Cs 5X107 1X107 boildown, gamma spectroscopy 152Eu 1X104 1X104 boildown, gamma spectroscopy 154Eu 1X104 2X10" boildown, gamma spectroscopy 15SEu 6X103 1X104 boildown, gamma spectroscopy '39Pu 1X107 4X106 radiochemical purification, alpha count

"Corrected to to values as of February 14,1976.

Although the Cheshire site provides important information concerning the behavior of radionuclides in a particular geologic environment, the site is not a hazard from the point of view of he?lth physics. Only tritium and s"Kr concentrations exceed the US Department of Energy concentration guide limits'*'' for water in an uncontrolled area. Our task is to better understand the processes that have maintained these concentrations at their relatively low values. The water samples pumped from the Cheshire site contain a small amount of paniculate material, which can be separated by filtration or cenlrifugation. We examined samples of such paniculate material qualitatively to determine if they contained any radionuclides not detectable as dissolved species. All the gamma-emitting radionuclides present in solution were also present in the paniculate material, and we also detected very small amounts of '•"Ce. In addition, the 54Mn was still detectable in particulates from the 1984 samples. Because the absolute concentration of these radionuclides is affected by water movement in and out of the cavity icgion, we focused on the concentration of the nuclide relative to tritium (which is essentially only in the form of tritiatcd water). Such relative concentrations are shown in the first column of Table 5.2. The observed relative concentrations may be compared with the radio- nuclidcs actually produced by the nuclear event, that is, the source-term ratios, which are given in the second column. A radionuclide that is incorporated in the fused debris or sorbed by the rock will have a much smaller observed atom ratio than the source-term atom ratio. Thus, the number in the third column of Table 5.2 indicates the amount of that particular radionuclide retained by the rock. The retention at Cheshiie may be compared with the retention at Cambric (data given in tne fourth column). Because the Cambric samples were pumped from specific zones from the bottom of the cavity to a region adjacent to the chimney, there is a corresponding range of retention values. We do not know from exactly which region the water samples at Cheshire are drawn, but 90 ELEMENT AND ISOTOPE TRANSPORT AND FIXA TJON

most of the Cheshire retention values are comparable to or slightly higher than those from Cambric. This suggests that the rhyolite at Pahute Mesa is at least as effective as the alluvium at Frenchman Flat for retaining fission products. The retention of :39Pu appears to be higher in alluvium; however, the retention at Cambric may be in error because the source term for Plutonium was rather small, and the sample concentrations were quite close to the limit of detection.

TABLE 5.2. Observed and Source-Term Concentrations: Cheshire and Cambric CHESHIRE CAMBRIC b c (N^NJobs" (Nx/Nf)st (Nx/N,)st/(NX/N,)obs (Nx/Nt)st/(N,/N,)obs' 85Kr 4.6 X 10 ~* 5.9XJ0~4 1.3 1.1-1.5 MSr 3 X 10 7 1.1 X 10"" 3X102 4X10'-2X103 106Ru 3 X 10"7 6.3 X 10"3 2X104 1 X 102 - 2 X 102 I25Sb 1 X 10"6 1.0 X 10~3 1X103 3 X 102 - 4 X 102 137Cs 4X10~* 1.6 X 10~2 4XI03 7 X 102 - 2 X 104 IX 10-* 1.2 X 10"' IX 10s 2 X 107 - 3 X 107 ' "atio of atoms of element X to atoms of tritium. bAtom r: tie is calculated for the source term by using fission yield data. This ratio is a measure of the radionuclide retention in or on solids in the cavity region (sec "retention factor Ed" in Ref. 82.) "Data from Ref. 82; d?*H ranges over all regions pumped.

Although the relative amounts of fission product and tritium in water from the Cheshire site appear to be reasonable, the absolute concentration of tritium is almost a factor of 30 lower than the source-term calculations indicate it should be. We suspect that water may be moving under a natural hydraulic gradient away Sra the cavity region. We would like to determine if this is the case and to what extent fission products and plutonium have moved with the water. Future experimental work at the Cheshire site includes sampling from the transmissive zones in the rhyolite that may serve as conduits for water moving away from the cavity. Although the Cheshire site provides important information concerning the behavior of radionuclides in a particular geologic environment, the site is not a hazard from the point of view of health physics. Only tritium and 85Kr concentrations exceed the US Department of Energy concentration guide limits86 for water in an uncontrolled area. Our task is to better understand the processes that have maintained these concentrations at the' - relatively low values. ELEMENT AND ISOTOPE TRANSPOR T AND FIXA TION 91

GEOCHEMISTRY

NUCLEAR MICROPROBE CHARACTERIZATION OF TRACE ELEMENTS IN OIL SHALES

P. S. Z. Rogers, T. M. Benjamin, C. J. Duffy, E. J. Peterson, and C. J Maggiore

Introduction Health, safety, and environmental issues may affect both how extensively and how rapidly the US oil shale resource is developed. Among the most pressing environmental issues are concerns about land disruption, air and water contamination, and waste disposal. Characterization of solids is essential for understanding solid-waste behavior and water quality impacts from energy development, because the processes that control the mobility and transport of contaminants in the environment occur at the molecular level. Aided by solids characterization information, we can explain various issues:

(1) the role of process parameters in the formation of wastes and effluents;

(2) the degree of mineral/water interaction during leaching and weathering;

(3) the influence of the microstructure of the lolids en the leaching process;

(4) the availability of major ions for solubility control; and

(5) trace-element residences and their role in contaminant mobility.

Information about the exact mineral and/or intergrain distribution of trace elements is essential for understanding the environmental behavior of products, wastes, and effluents from oil shale processing and the potential for contaminant mobility and transport. Because in situ trace-element analysis with spatial resolution of a few microns is required, use of a nuclear microprobe is fundamental to these studies. We have conducted a series of experiments using the Los Alamos nuclear microprobe87 to see how particle-induced x-ray emission (PIXE) could be used to characterize rrace-element residences in oil shale mineral assemblages. Our primary interest in this study was to obtain information about detection limits for the many elements that occur in the shale samples. To our knowledge, only one other study has addressed the question of PIXE detection limits for a broad range of elements in thick, geologic samples.88 The coal samples examined in that study have a matrix with fewer mineral phases; these phases also have lower atomic numbers (and hence, they provide less x-ray adsorption) than the oil shale samples of our study. For these reasons, we expected the PIXE detection limits for oil shale samples to be higher than those for coal, and this was found to be the case. However, detection limits for most elements were low enough to determine that the PIXE technique is a feasible method for in situ study of trace elements in oil shales.

Experimental Techniques The samples examined in this study were a raw (nonretorted) shale and a spent shale from the Occidental Oil Shale, Inc., Logan Wasn site. Previous work with samples from this development site has been documented.89'92 Tables 5.3 and 5.4 list the elemental compositions as determined by instrumental neutron activation analysis (INAA) and the mineralogy by x-ray diffraction (XRD). 92 ELEMENT AND ISOTOPE TRANSPORT AND FIXATION

TABLE 5.3. ELEMENTAL CONCENTRATIONS IN THE!SOLID SHALES BY INAA" Element Raw Spent Na (%) 0,85 1.3 AI (%) 3.8 4.3 K(%) 3.2 2.3 Ca (%) 11.5 18.0 Sc 7.0 6.6 Ti 1778.0 1705.0 V 83.0 79.0 Cr 37.0 52.0 Mn 287.0 405.0 Fe (%) 2.5 2.1 Co 11.0 7.0 Cu

The mineral assemblage of the spent «hale sample suggests that the material experienced relatively high temperatures (1100 K) and oxidizing conditions during the in situ retort. The leaching behavior of this material also indicates that several environmentally sensitive trace elements are mobilized from tiis material.91 Experiments to determine in situ trace-element concentrations ana detection limits in oil shale samples were conducted at the Ion Beam Facility of Los Alamos National Laboratory.879' The Los Alamos nuclear microprobe is unique in that it provides a highly focused particle beam while maintaining high beam current.87 This is accomplished by using a superconducting solenoid magnet to provide final focusing of the particle beam into spot sizes as small as 5 um without severely sacrificing beam intensity (and thus, trace-element sensitivity). These features are an important requirement in the analysis of geologic samples, where both precise beam location and trace-element sensitivity are necessary. In the present experiments, we obtained spot sizes of approximately 20 um with a 2-MeV proton beam and 20-uC integrated beam current on sample. The total charge deposited on each sample was monitored to within 10% to provide relative calibration between the oil shale samples and a standard of known composition. PIXE spectra of the raw and spent oil shales were obtained using a lithium-drifted silicon detector. ELEMENT AND ISOTOPE TRANSPORT AND FIXATION 93

Quantitative analysis of PIXE spectra from geologic samples obtained with the Si(Li) detector is difficult because the large number of detected elements results in a spectrum with severe peak overlap. To overcome this problem, we have developed an accurate spectrum-fitting procedure that uses theoretical information on ionization cross sections, fluorescence yields, transition probabilities, elemental stopping powers, and x-ray adsorption94 to calculate the relative intensities of the multiple peaks detected from each element, 1 .cause we know peak widths and positions, we can reduce spectrum-fitting variables by this procedure to only one variable (concentration) per clement and thus provide an unambiguous linear regression. An example of part of the PIXE spectrum from a spent oil shale sample is shown in Fig. 5.4. Here the experimental counts per channel are given by lines with a height corresponding to the ±lo counting statistics uncertainty. The highest solid line represents the overall fit to the experimental data, whereas the element peaks are shown by the individual Gaussian curves. Note the importance of including the sum peaks (which in this case arise from the combination of calcium and iron K lines) in the spectrum fit. We obtained conversion of peak areas to quantiiative concentrations by comparing the calculated peak intensities per integrated charge to that of a major peak in a well-known standard. This method of calibration relies heavily on theoretical calculations, but that cannot be avoided because standards of similar matrix composition are not available for many of the trace elements. We estimate that systematic errors in converting spectrum peak areas to element concentrations produce an uncertainty of ±15% in the absolute concentrations. Separate errors result from the counting statistics and the peak-fitting procedure, and 'hese errors only (at the la level) are listed in the accompanying tables.

TABLE 5.4. Mineral Components of Raw and Spent Shak from X-Ray Diffraction" Mineral Raw Spent Calcite W-M Dolomite M-S w0 Quartz M 0 Analcime W 0 Plagioclase W 0 Orthoclase W T Pyrite T 0 Illite W-M 0 Argonite 0 M Akermanite 0 M-S Diopside 0 M Monticellite 0 W-M Kalsilite 0 M •S = Strong; M = Moderate; W = Weak; VVV =- Very Weak; T = Trace; 0 = None Detected. 94 ELEMENT AND ISOTOPE TRANSPORT AND FIXATION

Oil Shale R3E2-6T Dark 13.5 'ZnKa

Ctannel Number UO *r/Cb)

Fig. 5.4. Segment of the PIXE spectrum of the retorted oil shale sample. The hi«.hcst solid line is the overall fit to the experimental data. The zinc peaks correspond to a cone, "tration oT 40 ng/g.

Results and Discussion Elemental concentrations and detection limits for 36 elements were analyzed for two areas of the raw and spent shale samples. On each shale sample, we analyzed a dark carbonaceous area and a light-colored clay area. Data are listed in Table 5.5. Values are in ug/g unless otherwise indicated, and the ±\a is also tabulated. The < sign in the tables indicates the fitting procedure gave a positive result for the element but that the uncertainty was larger than the calculated result. The assigned magnitude is the fitted value plus 2<7 and is intended for use as an upper limit. This suggests that the element is probably present but the counting time was not sufficient to give reasonable statistics. The values in parentheses indicate detection limits for elements that were represented by negative values in initial fits and were not considered in the final calculations. The detection limits are defined as two times the uncertainty from the least squares fitting calculations. Detection limits for the majority of the elements range from 2 to 30 ppm, which shows that the PIXE technique is a suitable method for broad-spectrum, trace-element analysis in geologic samples. These limits should be compared with detection limits of about 1 to 2 ppm, which were obtained by Minkin et al. in coal samples.88 Because spectrum deconvolution must be used to determine the concentrations of many elements, the more complex matrix encountered in the oil shale samples increases the uncertainty in spectrum fiting and thus raises the detection limits. ELEMENT AND ISOTOPE TRANSPORT AND FIXA TION 95

Comparison of the analyzed areas on the raw and spent shale in Table 5.5 indicates that the light and dark areas on the spent shale are quite similar in both major- and trace-element composition, whereas the two areas on the raw shale are noticeably different. This difference in the two raw shale areas suggests that trace-element partitioning depends on the mineral content of the areas and indicates that trace element/mineral association information is available when the PIXE technique is applied to this complex geologic matrix.

TABLE 5.5. Elemental Concentrations of Major, Minor, and Trace Elements From P.3 <10 <9.6 Th 13.3 ± 5.6 26.2 ± 7.3 20.1 ± 7.6 22.7 ± 8.3 U 13.4 ± 6.4 18.6 ± 7.0 <30 28.2 ± 9.5 "All values in (ig/g unless otherwise indicated. 96 ELEMENT AND ISOTOPE TRANSPORT AND FIXATION

ACID SULPHATE ALTERATIONS AT SULPHUR SPRINGS, VALLES CALDERA, NEW MEXICO

Robert W. Charles, Rosemary J. Vidale, Gregory K. Bayhurst, and Fraser E. Goff (ESS-1)

Sulphur Springs, an acid sulfate springs and possibly a vapor-dominated surface expression of the Jemez volcanic field, is located on the west side of the Valles Caldera, New Mexico. The springs occur at the intersection of Sulfur Creek Fault and Bathhouse Fault, which offset caldera fill and intracaldera rhyolites. Geothermal wells in the area have temperatures of 200°C at depths of 600 to 1000 m. Hot springs and fumaroles discharge at boiling temperatures with 0.6 to 2.5 pH and SO4 > 8000 mg/8. (See Goff el al?i for a detailed discussion of the fluid geochemistry.) The percolation of the fluids through country rock has created a series of alterations of progressive intensity as one approaches the springs; these alterations lead to an advanced argillic assemblage characterized by various aluminum sulfate hydrates. The principal alterations are adularia, alunite, alunogen, anatase, gypsum, halotrichitc, kaolinite, montmorillonite, pyrite. and szymolnokite; quartz and sulfur are almost ubiquitous. Gypsum and anatase are diagnostically less important. Gypsum appears as the result of digestion of limestone by acid sulfate waters, and anatase is the sole remnant of ferromagnesian minerals digested by the low pH waters. Approaching the Sulphur Springs area, the first alteration product encountered is adularia, which is recrystallized from the original potassium feldspar-rich rhyolite. As the original rhyolite and caldera fill are progressively leached, the alteration sequence is (1) adularia —«• (2) montmorillonite — (3) kaolinite + alunite —• (4) kaolinite, alunogen, halotrichite, alunogen + halotrichite, szymolnokite + pyrite, and szymolnokite + alunogen. The alteration assemblages represent changes in chemical potential with distance and possibly time. The last assemolages are crystallising contemporaneously. Kaolinite is precipitating from the springs. Pyrite-bearing rocks are recrystallizing to syzymolnokite. Samples from vents in the main fumarole area show halotrichite and alunogen crystals growing from the vapor. Figure 5.5 depicts these assemblages in chemical potential space. The figure graphically presents the increasing argillization with decreasing distance to the main pools.

Fig. S.5. Iron-free chemical potential net for the Sulphur Springs system (f = —4); note the progressive argilhzation with distance and time. Assemblage 4 is the most recent. ELEMENT AND ISO fOPE TRANSPOR T AND FIXA T1ON 97

Solution analyses indicate that the main pools (iron's bathhouse mudpot, women's bathhouse, lemonade spring, and footbath spiing) hive Sfte'ij = 0.05 M with an ionic strength of about 0.01: well within the range of the Debye-Huckel approximation for yr Maximum temperature is about 90°C—roughly boiling at this altitude. Figures 5.6 and 5.7 present some of the phase relations consequent to these observations. Thermodynamic data were taken from Henley el al.% and an updated EQ3/6 database." The appearance of szymolnok'.e + pyrite is clearly compatible with the pH of 0 to 2 for a log (f02) at a relatively high (at this temperature) —47. For the activities of silica observed in solution (about 220 ppm), kaolinite is the stable clay mineral. Gas analyses contain N, that is, although possibly representing contamination with air, compatible with a szymolnokite- bearing assemblage. Figure 5.7 shows plots for the solution analyses of spring fluids (see also Table 5.6). These analyses indicate compatibility with kaolinite and are near amorphous silica saturation at 90°C. However, the silica content probably reflects deep-reservoir temperature (TQuaru ~ 190°C), which compares well with the observed deep-well temperatures of nearby geothermal wells. The solid phases, solutions, and gases yield an interpretable picture of the Sulphur Springs hydrothermal system when they arc analyzed with the appropriate thermodynamic calculations.

MAGNETITE

Fig. 5.6. Log (foj - pH net for the iron-bearing surface system. T = 90T, S(tol) = 0.05M. and I = 0.01.

"Information received from J. Kerrisk, Group WX-4 (after Helgeson97). 98 ELEMENT AND ISOTOPE TRANSPORT AND FIXA T1ON

KSPAR 2 Fig. 5.7. Log (aK+/aH+) '"' log as,o: for the surtkce system, at 90°C. Dashed curves are log as,t>i =—3.1 (quartz saturation/ and log as,o: =—2.2(amorphous silica saturation). The four circles are solution analyses from the four springs.

K-MONTMORILLONITE

TABLE 5.6. Solution Analyses of Spring Fluids

SiO2 Potassium Content Content Temperature Pool (ppm) (ppm) pH (°C) Footbath 216 94 1.1 33 Women's 168 72 1.4 90 Lemonade 229 7.6 2.0 57 Men's Footbath 221 8.2 1.5 78

AN AUTOMATED CALORIMETER FOR USE AT HIGH TEMPERATURE AND PRESSURE

Pamela Z. Rogers and Clarence J. Duffy

Introduction Knowledge of the thermodynamic properties of electrolyte solutions at high temperaLures is important in studies of geothermal systems, hydrothermal alteration processes, and elemental transport. The purpose of this investigation is to determine the activity coefficients of the major ionic species in aqueous solutions over a wide range of composition and temperature (25 to 350°C). The number of different electrolyte solutions of interest at high temperatures is large, so a method of obtaining thermodynamic properties from a minimum amount of experimental data is desirable. Heat-capacity measurements are ideal for this purpose because the data can be integrated to yield enthalpy and activity coefficient information by using literature data for room temperature to evaluate the integration constants. An automated flow calorimeter has been constructed to measure the heat capacities of single- and mixed-electrolyte solutions and, in this manner, determine high-temperature activity coefficients. ELEMENT AND ISOTOPE TRANSPORT AND FIXATION 99

Calorimeter Design Two previous flow calorimeters, designed for use at high temperatures, have encountered problems related to temperature control and stability. A calorimeter built by Rogers98 maintained excellent short-term temperature stability at the expense of an overall slow response time for the calorimeter. Smith-Magowan and Wood" obtained a fast response time by directly heating their calorimeter block and using a separately heated adiabatic shield to control power loss. Un- fortunately, many of their published measurements had to be revised when they discovered changing power losses as a result of a temperature drift in the adiabatic shield.100 The present calorimeter, shown in Fig. 5.8, has been designed to avoid these problems by using a large, directly heated thermal mass for the calorimeter support C and by including two adiabatic shields A and B. Both shields and the support are evenly heated to ±0.02°C. The corrosion-resistant platinum tubing that contains the experimental fluid samples is wound for 2 m around a preheater D that is used to protect the temperature stability of the calorimeter by heating the experimental solution from room temperature to nearly the calorimeter temperature before it reaches the calorimeter support. Within the inner adiabatic shield, a 6-cm-long section ot the tubing is wrapped with insulated, nichrome resistance wire, forming a solution heater. The platinum tubing then is wound into a tight spiral to provide a well for the fast-iesponse platinum resistance thermometer used to detect the temperature rise in the solution that is caused by the solution heater. To obtain a heat capacity measurement, water is pumped (through the tubing) past one heater/thermometer assembly then into a solution-exchange loop where it displaces an equal volume of the experimental sample. The sample solution is pushed through a second heater/thermometer assembly, and the power to the second heater (Ps) is adjusted to match the temperature rise of the sample and that of the pure water. The ratio of the heat capacity of the sample solution (cps) to that of pure water (cpw) at the experimental temperature is then given by the ratio of the powers in the heater multiplied by the ratio of the mass flow rates of the solution and water (f, and fj:

(!) P -L

The heater power is also corrected for unequal heat losses Lw and Ls that occur when pure water and a salt solution are heated by a few degrees celcius in the calorimeter. Comparing temperature changes between the two thermometers helps cancel out the effects of small pump pulses and drifts in calorimeter-case temperature; this provides a more sensitive measurement. The present calorimeter is unique because it has been completely automated. A Hewlett- Packard minicomputer and 80-channel multiplexer allow constant monitoring of the calorimeter as well as control of the extensive peripheral equipment (shown in Fig. 5.9) that is needed to operate the calorimeter. Through the use of the multiplexer and the 6'/2-place digital voltmeter the following data can be constantly recorded: the temperature of five thermometers in the calorimeter and three thermometers in outside baths, the temperature difference between the two solution thermometers, the voltages across the solution heaters and across standard resistors in series with the heaters, and the pressure of the fluids in the calorimeter and in the sample loop. The power in one heater can be changed by ±80% by using an appropriate computer program and the multiplexer to select the combination of parallel resistors to be added in series with the heater. High-current relays in the multiplexer allow computer control of the 6-port valve used to switch the sample loop in and out of the calorimeter circuit, the sample-loop loading pump, the pressure intensifies and additional solenoid activated valves. Separate interfaces are used to computer- control the 20-port sample-selection valve and to read the clock and balance needed to determine the solution flow rate. 100 ELEMENT AND ISOTOPE TRANSPORT AND FIX4TION

1 — -*_.M iM—

Fig. 5.8. Cross-section diagram of the calorimeter shows one of the heater/detector assemblies surrounded by the two adiabatic shields. A and B. The cases Tl, T2, T3, and T4 contain platinum resistance thermometers used for control and readout of the shield temperature. The thermometer cases are separale pieces that can be removed from the shield sides, allowing the shield to be lowered for access to the inner calorimeter support. In this manner, the thermometer leads (which exit through the top of the vacuum chamber) do not have to be cut every time the calorimeter is opened, and the fragile wire junctions at the top of the miniature thermometers are protected by the case. Cartridge heater E and platinum resistance thermometers C and D provide readout and control of the support temperature; thermometer F is an NBS Certified Secondary Standard used to provide a check on the calibration of thermometer C. The entire assembly fits inside a steel vacuum chamber 20 cm in diameter and 60 cm tall. Dimensions on the figure are in inches. ELEMENT AND ISOTOPE TRANSPORT AND FIXATION 101

Pnroure Trsmducer

Back Pmtsura Regulatoi

Syphon

Sample Cooling Bvth Loop Bath !25° C|

Balance Warn

Fig. 5.9. The extensive peripheral equipment needed to operate the calorimeter is shown here in schematic form. For automation, the multiplexer acts as the main switching station: on command from the computer, it is able tc control equipment or connect circuits for reading by the digital voltmeter.

Calibration Accurate calibration of the calorimeter is the most difficult step in obtaining heat capacity data. Extreme differences both in the power loss characteristics of the two previous calorimeters: and in the methods used to calibrate those losses have lead to some confusion over the appiopriate method of calibration. The importance of accurate calibration can be seen by examining the basic Eq. (I) for the heat-capacity ratio. Under typical conditions, a 2% error in the value of the power losses Ls and Lu will result in a 0.02% error in the heat-capacity ratio, although, as the heat-capacity ratio decreases from unity, the percentage error will increase. Thus the power loss, which in the present calorimeter is roughly 15 to 25% of the total power P. must be determined to within 1 to 2%. White and Wood!l!0 postulated that the power loss from a flow calorimeter consisted of three main effects, which are represented by 102 ELEMENT AND ISOTOPE TRANSPORT AND FIXATION

The first term accounts for loss by conduction down the various leads and is proportional to the temperature rise AT. The additional power lost because of a temperature gradient between the heater and thermometer is proportional to the temperature rise divided by the heat-capacity flux AT/tfcp—the second term of Eq. (2). Finally, thermal resistance between the heater and calorimeter tubing will result in an additional temperature rise in the heater, and the extra power lost from the heater will be proportional to the actual power applied P. In experiments extending to 200°C, Rogers and Pitzer10' calibrated their calorimeter simply by measuring the actual temperature rise obtained in pure water with a known power input. This yielded a calibration factor that is a combination of the three power loss terms. The suitability of this approach was shown by measuring the heat capacity of a standard NaCl solution over a suitable range of flow rates; they found no dependence on flow rate. On Ihe other hand, While and Wood100 measured the power loss in their calorimeter by using a second pump to change the flow rate. They found that the results differed by 30 to 40% from measurements of the temperature rise in pure water. They did not measure the terms in K.,, K:, or K., directly. The reasons for the discrepancy in calibration results are not clear on the basis cf design differences between the two calorimeters. To characterize the calibration behavior of the present calorimeter, we have determined the individual constants Kh K.:, and K, by measuring the temperature rise AT obtained in pure water at a series of different flow rates f and powers P. By approximating the total power as

P = (AT)(fcp). (3)

we can plot the results of calibration experiments on a single graph as

P : ^ =K: + K, (fcp) + K,(fcP) . (4)

The results of calibration at 96°C and 1-atm pressure are shown in Fig. 5. SO, where the obvious parabolic shape of the curve indicates that Eq. (4) may be a suitable model for the heat loss. Results of fitting the calibration data to Eq. (4) indicated that the magnitude of the first term was not statistically different from zero. For this reason, the fit was redone to include only the parameters K: and K3. and the results are given in Table 5.7. The redundancy of the terms K, in AT and K, in P probably indicates that conductive heat loss from the thermometer is simply proportional to that in the heater.

The relative magnitudes of the terms in K: and K3 for a "typical" experiment run at a flow rate of ~ 2 me/minute are shown on line 2 of the table. The term in K3 is an order of magnitude larger than that in K2, and it is the large magnitude of this term that leads to different results when two different methods of calibration are used. This situation is illustrated on line 3, where the magnitude of the correction terms is calibrated assuming use of a solution with heat-capacity flux fcp 30% less that that of pure water. Equivalently, the flow rate of pure water in one side of the calorimeter could be decreased by 30%, which is the calibration method used by White and Wood.100 Tr- resulting calibration term (L/AT) would be 0.0205, rather than 0.0259, which was obtained simply by measuring the total temperature rise of pure water flowing at 2 me/minute. The difference in ihe two calibrations is 20%—similar in magnitude to the difference noted by Wood when he performed the same experiment using his calorimeter. The observations of Rogers98 are st apparent odds with these results; she found no dependence on heat-capacuy flux in the calibration of her calorimeter. The calibrat on terms for the present calorimeter, operated at 0.8 mfi/minute, are given on line 4 of Table 5.7. Because the flow rate has been decreased by 60%, the magnitudes of the two terms have become comparable. At this low flow rate, a decrease of 30% in the heat-capacity flux causes oniy a 4% change in the overall calibration ELEMENT AND ISOTOPE TRANSPORT AND FIXATION 103

EJ. BJ 1 1 1 1——i r

7.0 1(13)-

8. 0

5.0 yf(17)

4.0 - X jr

5 3. 0 • -

2.0 - - O X%(41) P IT 1.0 -"•(12) - =•- T(8) O n a _i_ . • i i i i • • ' i i i—i—i—i—, 'XI CD B 10 CD ea B (S 8 s d d d d d d d d d d

HEAT CAPACSTY FLUX, fcp (JK 1 s ~1)

Fig. 5.10. Plot of the calorimeter calibration factor vs the heat-capacity (lux shows that the calibration factor is a smooth, parabolic curve. The values in parentheses indicate the number of repetitive measurements plotted at each flow rate.

TABLE 5.7. Dependence of Power Loss on Heat-Capacity Flux Heat-Capacity Flux

(fcP) Power Loss Terms Comments L _ 0.00042 1. Variable Eq.(4) AT~~(fcT + 0. 2. 0.140 (~2 mC/minute) ^j, = 0.0030 + 0.0229 = 0.0259

3. 0.100 20% change (30% decrease) ^j, = 0.0042 + 0.0163 = 0.0205

4. 0.0556 (~0.8 me/minute) ^j, = 0.0075 + 0.0091 = 0.0166

5. «.O389 3.5% change (30% decrease) rx, = 0.0108 + 0.0064 = 0.0172 104 ELEMENT AND ISOTOPE TRANSPORT AND FIXATION factor because increases in the second term offset decreases in the third term. The solutions studied by Rogers differed by 4% (at most) in heat-capacity flux, so that the resulting change in the calibration factor would have been negligible, as was observed. Thus, the apparent difference in calibration behavior simply resulted from the different flow rates used.

Conclusions Flow calorimetry has many features that are ideal for use at high temperature. Because the experimental fluid flows through the calorimeter, it is possible to keep the calorimetric temperature constant while changing samples. The fast response and the high sensitivity that make flow calorimetry powerful at room temperature are also advantageous at high temperatures, and several design features of the present calorimeter have been used to maintain these characteristics at elevated temperatures. Complete automation of the calorimeter has enormously improved its ease of operation. Automation also has enabled repetitive calibration of the calorimeter. Knowledge of the factors influencing the calibration, the reproducibility of the calibration, and the change in the calibration over a given time span are critical to obtaining accurate measurements. Finally, the ability to calibrate the calorimeter over a wide range of flow rates and applied powei has been used to determine the main contributions to ^.ower loss and to explain conflicting results in the calibration of the two previous flow calorimeters. ofMattu-Isolated Molecule* and Neat

Elftus in NucV«r Waste 1 orrns

* .1 . Aciimdc Transition > 'stalChi-mistry

> The Fir,i Molybdi nuni Butterfly Clus cr ACTINIDE AND TRANSITION METAL CHEMISTR Y 167

APPLYING HIGH-ENERGY OXIDIZERS TO STRATEGIC NUCLEAR MATERIALS

Lamed B. Asprey, P. Gary Eller, Scott A. Kinkead, and Richard J. Kissane

In last year's annual, we described our discovery that dioxygen difluoride (FOOF) is capable of forming volatile PuF6 at temperatures as low as —78°C under a variety of conditions on a range of substrates. During the past year, this work has been e?;panded; it has led to a large collaborative program with Group MST-12 ($1.7M funding for FY 1985) to evaluate the potential use of FOOF in recovering plutonium from a wide range of waste and scrap forms. Scoping studies (with potential additional funding) are also under way for several other applications that arc of interest to the Hanford Engineering Development Laboratory (plutonium rec very from fast flux test facility, or FFTF, fuels), Oak Ridge National Laboratory (cladding huil plutonium and fission product decontamination), and Westinghouse Corporation (uranium decontamination and recovery). These FOOF applications are viewed as relatively high risk, but the potential payoff's are so high that intense interest has been generated. Table 6.! summarizes our results from experiments directed towards plutonium recovery from various scrap forms. Table 6.2 illustrates results of decontamination studies. Obviously, both sets of experiments show promising results. Figure 6.1 gives a conceptual flow diagram for reprocessing F+TF fuel.

Table 6.1. Preliminary Los Alamos Scrap Recovery Results

MF6 Contact Temperature Volatilized Substrate Conditions Time (<-) (%)

Phe&olytic PuF4 gaseous FOOF minutes ambient 90 Kydrolyzed PuF6 gaseous FOOF minutes ambient 29 PuF4(300°C firing) gaseous FOOF minutes ambient 15 PaO2(500°C firing) gaseous FOOF 30 minutes ambient 85 lanford incinerator ash (Pu) gaseous FOOF 30 minutes ambient 5-10 Hanford incinerator ash (Pu) C1F3 pretreatment 30 minutes -78 69 then HF/FOOF (residual readily soluble) Contaminated metal fittings (Pu) gaseous FOOF 30 minutes -78 10-100 NpF4 HF/FOOF 2-4 hours -78 100 NpO2 gaseous FOOF 1 hour ambient 98 UO2 (high fired) (Westinghouse) HF/FOOF 2-4 hours -78 35 UO2 (high tired) (Westinghouse) gaseous FOOF 1-2 hours ambient >10 U3Og (high fired) (Westinghouse) gaseous FOOF 1-2 hours ambient 75 U3Og (high fired) (Westinghouse) HF/FOOF 2-4 hours -78 86 108 ACTINIDE AND TRANSITION METAL CHEMISTR Y

Table 6.2. Plutonium Oecontaminaton Results Using FOOF* Drying Plutonium Removal Substrate Temperature HF FOOF/HF (C) (%) (%) Copper 100 99 Nickel 100 99 Stainless steel 100 99 Stainless steel 900 <5 >9S *The plutonium was deposited by drying aqueous HC1 solution at 100°C (heal lamp) and 900°C (red heat using a flame). The plutonium was removed at —7S°C with anhydrous HF and a 2:5 solution by volume of FOOF in HF.

~~We are preparing a number of FOOF-related manuscripts for publication, and some other highlights of the last year are summarized here.~~

~~• We have developed a photolytic synthesis of FOOF from fluorine and oxygen that yields several grams of FOOF per hour.~~

• A very interesting result of our experiments with FOOF and the neptunium compounds NpO, and NpF4 was that FOOF in AHF did not produce NpF6 when NpO2 was the starting material. In contrast, NpF4 gave 100% yields of NpF6 under the same conditions. Further study showed that the product obtained from FOOF on NpO, was water soluble—it certainly was not NpO2. The absorption spectrum showed clearly that neptunium in the hexavalent state was obtained and that no other oxidation state was present. This suggests that oxidation/fluorination with FOOF formed an oxy-fluoride—either NpOF., or NpO,F2. The same reactions may occur with plutonium.

~~SUBSEQUENT CLADDING PROCESSING las HULLS per oxide fraction) H», BF,, -TB'C~~

~~VOLATILES SIF,,PFS, SFg, Krl?) SPENT FUEL MIXED RODS MECH*NIC*l. OXIDE DISENGAScUENT -78'C NonVOLATILES~~

NonVOLATILES 20* C VACUUM 20* C STRIPPING VOLATILES a*sEOus REDUCT.1MT 20' C \COUPi_EXANT VOLATILES Uo,W,Tc,Xj, I LATILES L , Trani Pul, ~I.S»t% INITIALLY/ Rt'.; Ci, MFg(U,Np,Pu,Uo,W,Tc, NonVOLATILES Rb:Ci. «-, Rh, X«) Zr.Bo.Ag, Pd.Rul?). U,ua,w,Ts,xi,i NonVOLATILES UO.F, [Cr( P+(?) Pu +Hh,Cr(?), Ru(?)

~~-1.0 «»% INITIALLY~~

~~ft Dam from J. MeOuln, HEDL, !o> BRET lull oltir 6110* MWD Bu'nup and 1 yiat iloraga. Eliminit Hind Ofil) If prmnt £001*1% Nominal umpoaltloo 25% PuOj/75% UO;.~~

~~Fig. 6.1. Conceptual flow diagram for a FOOF/mixed oxide fuel process. ACTINIDE AND TRANSITION METAL CHEMISTR Y 109~~

The use of FOOF with neptunium ietrafluoride in the absence of a moderating solvent such as AHF usually resulted in a run-away thermal decomposition of the FOOF with little or no formation of NpF6, which suggests that a practical use of liquid FOOF will require the use of a solvent. We have prepared about 3 g of NpFb during these studies. We found that C1F3 reacts cleanly am! completely with FOOF to give C1F5 gas in a 100% yield; FOOF dissolved in AHF reacts with Pr6On or PrF3 at -78°C to give solid PrF4. We are examining other nonactinide systems. We are studying the use of gaseous FOOF at various temperatures to optimize its use. The effect of variables such as temperature and pressure are being examined by using UO2 and UF4 initially; we then plan to extend the experiment to the use of neptunium and plutonium.

~~REDUCTION OF SO2 AND COORDINATION OF MOLECULAR HYDROGEN BY GROUP VI-B METAL COMPLEXES~~

~~Gregory J. Kubas, Robert R. Ryan, and Harvery J. Wasserman~~

Our continuing research on the basic chemistry of SO2 reduction by metal hydrides and hydrogen has resulted in significant advances in both stoichiometric and catalytic conversion. The 102 previously reported study of SO2 insertion into the metal-hydride bond in CpM(CO},H to give CpM(CO}3(SO2H) was expanded to include the pentamethylcyclopentadienyl (Cp*) analogues. Re- examinacion of the crystal structure of CoMo(CO):(SO2H) revealed that the proton in the unprecedented —SO2H group is bound to oxygen, which is in line with the inequivalent S-O distances (1.51 and 1.64 A). This contrasts with .usertion of SO2 into CpMo(CO)3R (R = alkyl or ary! organo group), which gives O I M—S—R

~~(Ref. 103), as well as CO2 insertion into M—H bonds, which gives O O II /^ M—OC—H or M CH~~

(Ref. 104). The Cp*M(CO)3(SO2H) derivatives were much more thermally stable than the Cp complexes, although decomposition occurred at 75°C and gave H2O, CO, [Cp*Mo(CO)3]2, [Cp*MoO(u-S)]2, and another oxo species. Solution reduction of SO2 by Cp*(CO)jH yielded similar products—evidence that the insertion complexes represent the first step in SO2 reduction. The M-SO2H complexes are difficult to characterize in solution because of dissociation to M-H and SO,. Our 'H NMR experiments did reveal that dissociation is suppressed at low temperature by the presence of excess SO2, and the —SO2H resonances were located. A second type of product, a dithionite-bridged complex [Cp*Mo(CO)3]2(u-S-O4) (Fig. 6.2), was isolated from reaction of Cp*(CO)3H and SO2 under conditions similar to those that produced Cp*Mo(CO)3(SO2H). This complex is the first example of a sulfur-coordinated dithionite and contains an S-S bond length of 2.26 A, which is 0.13 A shorter than that in Na2S2O4. Both the Mo and W dithionites are unstable in solution, giving sulfido/oxo complexes that are similar to those 110 ACTINIDE AND TRANSITION META L CHEMISTR Y

~~Fig. 6.?.. Ivlolecuiar structure o:"[Cp*Mo(CO)3]2(S304).~~

from protonged Cp*Mo(CO)3K-SO2 reaction. This indicates that ihe dithionites may be further intermediates in SO2 reduction; perhaps they are generated by deprotonation of Cp*Mo(CO)3(S02H) and coupling. Yet another interesting complex [Cp*W(CO)2(u—S • SO2)j2 resulted from piolonged reaction of Cp*W^CO)3H and SO2. Our x-ray crystallography revealed relatively strong Lewis acid bonding of SO2 to bridging sulfides (Fig. 6.3)—the first example of this type of interaction involving sulfide. After being heated to 150°C, the complex evolves SO, and CO, along with CO2 and CCS, which is possibly indicative of reduction of SO: by the coordinated CO ligands. This fact is of interest because there are few examples of SO2 reduction at a metal complex center.

~~C12'~~

~~€10'~~

~~Fig. 6.3. Molecular structure of [Cp*W(CO)2(S • SO2)i2. ACTINIDEAND TRANSITION METAL CHEMISTRY 111~~

105 The previously reported homogeneously catalyzed reduction of SO2 by hydrogen has been markedly improved in terms of rate, completeness of reaction, and catalyst solubility and stability. This is the first example of catalysis of SO2 reduction to sulfur and waier that uses a soluble transit.'on metal catalyst, in this case [(C5R5)MoS(SH)]2. The rate of conversion has now been enhanced several hundredfold by using a Bronsted-base co-catalyst such as benzyl alcohol or trietbylamine for one of the reaction steps: 2H2S + SO2 -» 3S + 2H2O. Without this modification, the conversion had been slow and incomplete, but now 51 catalyst turnovers/hour resulted for a system containing SO2, H2, and [(CsMe5)MoS(SH)]2 in 4:1 chlorobenzene-benzyl alcohol at 100°C and atmospheric pressure. When the reaction was allowed to continue in the presence of excess H2, H2S rather than sulfur was the final product. Further increases in rate can be expected when other experimental conditions such as hydrogen pressure are optimized. We have carried out further research on the unique molecular hydrogen complexes.l06'107 Solid 1 state deuterium NMR studies of W(CO)3(PPr 3)2(D2) provided information on the molecular motion of the side-bonded D2, which showed nearly free rotation at a rate >130 kHz at 20°C. 108 Theoretical calculations of H2 binding indicated only a 0.3 koal/mole difference in energy between conformations in which the H2 is either parallel or perpendicular to the P-W-P axis; these calculations agree with NMR results that show little barrier to rotation. We found that isotopic exchange occurs betv/een W(CO)3(PR3)2(H2) and D2 in both solution and solid states and gives a statistical mixture of H2, HD, and D2. The mechanism for this H-H bond cleavage process is unknown and is quite puzzling because the complex is very crowded sterically, which discourages coordination of a second H2 (or D2). The H2 does not readily split photochemically to give two hydride ligands and, except for displacement from the metal, is generally nonreactive. We hope that future investigations will clarify the exchange mechanism.

~~HIGH-RESOLUTION INFRARED STUDIES OF MATRIX-ISOLATED MOLECULES AND NEAT THIN FILMS AT CRYOGENIC TEMPERATURES~~

~~Llewellyn H. Jones, Basil I. Swanson, Steven F. Agnew, and Scott A. Ekberg~~

Orientationai Ordering and Site Structure of SiF4 Trapped in Rare Gas Solids When octahedral and tetrahedral molecules are trapped in dilute low-temperature matrices, the perturbations by the matrix cage often lead to lowering of the molecular symmetry from Oh or Td to C3v or lower. This, in turn, causes the triply degenerate infrared-active stretching mode to split into a doubly degenerate and a singly degenerate mode. For several cases we have studied,109""3 the polarized infrared absorption studies show a high degree of orientationai ordering; the singly degenerate mode is perpendicular to the substrate plane and the doubly degenerate mode is parallel to this plane. We have recently made similar studies of the v3 mode of SiF4 trapped in argon, krypton, and xenon matrices. Polarization studies of SiF4 in an argon matrix prepared from large pulse deposits (about 1.3 torr-C per pulse) show strong site symmetry splitting and a high degree of orientationai ordering, as is indicated in Fig. 6.4. A quantitative treatment1'' of these data indicates close to 100% orientationai ordering of the SiF4 molecules on sites of C3v symmetry, and the C3 axir. is perpendicular to the substrate plane. Krypton and xenon matrices of SiF4 show no site symmetry splitting, and the v3 peaks are at 1026 and 1023 cm"1, respectively, compared with 1023 cm"1 for an argon matrix. Normally, for similar sites the frequencies decrease in the order argon > krypton > xenon; we conclude that in argon the SiF4 molecule occupies a 4-atom substitutional site and in krypton and xenon it occupies a 3-atom substitutional site, which leads to greater repulsive forces and higher frequency. Spectra 112 ACTIN1DE AND TRANSITION METAL CHEMISTR Y

~~tn CM~~

~~1022.00^ 1029.00 I/CM~~

Fig. 6.4. Absorption by V3 mode of S1F4 in an argon matrix; Ar/SiF4 = 20 000. Deposited at 18 K; coated with krypton at 30 K; annealed at 38 K; spectrum recorded at 11 K. Substrate is a Csl window rotated about vertical axis 45° to incident beam; solid line shows polarization at 45° to matrix plane; dashed line shows polarization parallel to matrix plane.

3 of SiF4 impurity in argon-UF6 matrix studies" show only on: SiF4 site, the same as that when UF6 is not present. From this we conclude that the two sites for UF6, assigned to HCP and CCP environments,"3 do not arise from a mixture of HCP and CCP crystallites but rather from local stacking faults induced by UF6 molecules to give local HCP symmetry.

Pulse Expansion Deposits and Orientational Ordering for Low-Temperature Matrices Matrices of SF6 in xenon were prepared by pulsed expansion of premixed gas through a 0.5-mm orifice onto a cold cesium-bromide window at temperatures ranging from 10 to 50 K. We expected that the rotational cooling of the gas that was induced by pulsed expansion would lead to less scrambling and, thus, to greater orientational ordering than we had previously found for large pulse deposits."' To the contrary, we found that for temperatures from 10 to 40 K the orientational ordering was the same as found for large pulse deposits and for 50 K deposits it was substantially less for pulse expansion. Furthermore, the matrices were found to be more imperfect, which led to an anomalously low refractive index. However, there are some advantages to the pulse expansion technique: the matrices showed greater clarity, less aggregation of solute, and more pronounced polarization effects because of the anomalously low refractive index.

Spectroscopic Studies of Thin Films of Small Molecules at Low Temperature It was previously shown"4 that under certain conditions, high pressure converted molecular + m N2O4 to NO NOJ. Bolduan et al. showed from Raman studies of thin films of soiid N2O4 that at + temperatures of ~ 180 K, N2O4 is converted to NO NOJ. They concluded that all the N2O4, + predominately the symmetric form O2N-NO2, was converted to NO NOJ. They saw no evidence ACTIMDEAND TRANSITION'METAL CHEMISTRY 113

of the nitrite form of N2O4:0-N-0 NO2 and concluded that the ionizalion must take place through an intermolecular process. We have investigated thin films of N2O4 by using infrared spectroscopy. When N2O4 is deposited at SO K, the dominant form is the symmetric O2N-NO2 molecule. However, there are relatively weak peaks at 1841 and 1622 cm"', which were previously assigned"6 1 to the nitrite form O-N-O-NO2, and there is another set of weak peaks at 1961 and 1580 cm" , which we believe arise from a distorted nitrite form with considerable ionic character: O—N- O—NO2. When heated to 150 K, the 1961,1580 pair disappears, and peaks characteristic of the ionic form NO+NOjat 2230 and 1400 cm"1 grow in. The 1841,1622 pair remains, as do the very + intense O:N-NO2 peaks. Heating to 170 K drives oft" the N2O4 and leaves only NO NOJ in an amount similar to that formed at 150 K.. We conclude that the auto-ionization iakes place through an unstable nitrite form and that the bulk of the material, including the most stable nitrite form, is not ionized but evaporates at 170 K. The infrared spectra at various stages of these experiments are quite complex, and we are presently attempting to glean from them the structures of the many species appearing in the N2O4 system.

Infrared Spectra of Solid Oxygen Solid oxygen below 14 K. exhibits an infrared absorption peak"7 at 1549 cm"', which is the value of the fundamental vibrational mode of oxygen. Because oxygen is a homonuclear diatomic molecule, its fundamental mode should be Raman active but not infrared inactive. Its activity 7 8 indicate^ interaction among O2 molecules and suggests a dimer." Cairns and Pimentel" investigated this absorption further and showed by isotopic substitution that it was not caused by a dimer. Because the bulk phase of oxygen has only one molecule per unit cell, such a vibrational mode should not be active even if there were interaction among O2 molecules; Cairns and Pimentel concluded that it occurred because of lattice imperfections."8 We decided to investigate this absorption further because it may help us to understand the infrared absorption of the high- pressure phase of oxygen.'" We find that this absorption consists of three, and possibly four, rather 18 lu sharp peaks (0.2 to 0.1 cm"', FWHM). Mixtures of O2 and O2 at 10 K show the presence of eight 16 I8 difference peaks in both the O2 region and in the O2 region. This suggests a crystal structure containing at least eight molecules per unit cell. Adding small amounts of CO to an oxygen matrix at 10 K yields four infrared CO stretching peaks. When it is heated to 14 K, the oxygen fundamental peaks disappear, three of the CO peaks disappear, and the fourth becomes more intens?. We conclude that low-temperature deposits of oxygen (below 14 K) contain a mixture of two phases: the normal a-phase, which persists up to 24 K, and an unspecified phase of low symmetry and large unit cell, which is transformed to the normal a-phase at 13 to 14 K. Further studies of this system are in progress.

~~THE EFFECTS OF ALPHA SELF-IRRADIATION ON MIXTURES OF Pu(IV)-COLLOID, Pa(V), AND Pu(VI)~~

~~Thomas W. Newton, David E. Hobart, and Phillip D. Palmer~~

Introduction This report describes investigations oi plutonium chemistry in near-neutral solutions that are designed to help predict the behavior of plutonium in the environment. We study the effects of alpha-irradiation on mixtures of Pu(lV)-colloid, Pu(V), and Pu(VI) to judge the feasibility of determining equilibria in this system. If the equilibi im attainment rate is rapid compared with the rates of alpha-particle-induced reactions, we can correct for or ignore the latter. For slower approaches to equilibrium, a knowledge of the alpha-induced rates may make it possible to set upper and lower limits on the equilibrium concentrations. 114 ACTINIDEAND TRANSITION METAL CHEMISTRY

The Pu(IV)-colloid is an important species in near-neutral solutions and could easily play an important role in transporting plutonium in groundwatev. Plutonium(IV) forms very stable colloidal sols that exhibit characteristic absorption spectra.120 The exact nature of these sols is 121 unknown, but Lloyd and Haire have precipitated PuO2 from alkaline solutions and prepared sols by peptization in dilute HNO3 at temperatures up to 80°C. Electron diffraction measurements on dried sols showed either amorphous or crystalline primary particles with a cubic fluorite structure. We have found that alkaline conditions are not necessary for the formation of crystallite- containing sols. Sols that were prepared at pH values <3 and were subsequently concentrated or precipitated by centrifugation showed lines corresponding to crystalline PuO2 when they were analyzed by x-ray diffraction.* The most common isotope of plutonium 239Pu emits alpha particles with an average energy of 5. i 5 MeV and has a half-life of 24 110 years.122 If the plutonium is in solution, this self-irradiation has important effects in any long-term experiment. Some of these effects for acid solutions are discussed in Refs. 123 and 124. In a 1M HC1O4 solution, both Pu(IV) and Pu( VI) disappear at rates such that the mean oxidation number (ox) decreases by 0.013 to 0.015 per day. The effects of alpha irradiation on colloidal sols have not been described previously. The equilibrium in the reaction

~~PuOf + PuO2(coln = 2PuOt (1)~~

~~is of particular importance because a determination of its equilibrium quotient Q, = 2+ (PuO2)V(PuO ) would allow the calculation of the equilibrium quotient for the reaction~~

~~4+ PuO2(coi,)+2H2O = Pu + 4OH-. (2)~~

This equilibrium quotient is the solubility product for the Pu(I V)-colloid. We have used data from the literature120125'7 to calculate values for the concentration quotient for mixtures of various ages. Values for -log Q' ranged from about 2.4 to 4, where Q' corresponds to measured concentrations. The measured concentrations do not necessarily correspond to equilibrium values, and correction for possible alpha-irradiation effects could not be estimated. We have surveyed a wide range of mixtures of Pu(VI), Pu(V), and colloidal Pu(IV) to study some of the alpha-radiation effects that occur in this system and their effects on the dissohuion of colloidal Pu(IV). In addition, we have sought evidence for the net occurrence of the reverse of reaction (1). Such evidence would allow us to place limits on the equilibrium quotient and thereby extend the work of Rai127 to colloidal Pu(IV).

Experiments Samples of electrorefined 239Pu metal** were dissolved in 6M HC1 to give Pu(III). High-fired y2 Pu02 was dissolved in fuming HC1O4 containing a trace of HF to give Pu(VI). Plutonium(V) and plutonium(IH) were prepared by electrolytic reduction. Colloidal sols of Pu(IV) were prepared by diluting solutions of Pu(IV) in 3M HC1 to <0.01M HC1 and then purifying them by (1) passing them through a cation exchange column (Dowex 50, X-8) to remove ionic impurities or (2) centrifuging them at about 16 000 G with repeated washing with O.OlMHCi. The various oxidation states of plutonium were determined by spectrophotometry. Solutions in HC1O4, which were assayed spectropnotometrically, were aliquoted and taken to dryness at about 200°C and then alpha-counted. Appropriate mixtures were made volumetrically and stored at room temperature (23 ± l°C) in stoppered Pyrex flasks or small glass vials. Periodically, samples were removed for analysis as described above.

~~•Information provided by Alfred H. Zeltmann, University of North Carolina. "This sample was provided by Larry J. Mullins, Los Alamos National Laboratory. ACTINIDEAND TRANSITION METAL CHEMISTRY 115~~

Results Only three components, Pu(V), Pu(VI), and the colloid, are important for the range of the experimental conditions used. Although Pu(III) might be expected at high Pu(V) and low Pu(VI) concentrations, careful examination of the spectra of such solutions showed no evidence for Pu(III). Therefore, ternary diagrams are used to indicate the observed changes in composition. With Pu(V) at the apex, a vertical line on these diagrams corresponds to the stoichiometry of reaction (1), which occurs without a change in ox. Composition changes with vectors to the right of venijal indicate net reduction, and vectors to the left indicate net oxidation. Figures 6.5 through 6.8 illustrate the results of runs with various initial compositions; more complete data are summarized in Tables 6.3 and 6.4. Figure 6.5 shows the results of runs starting with either 239Pu(VI) or 239Pu-colloid. The runs starting with pure Pu(VI) show decreases in ox. The average values for the three runs range from -13.4 X 10~3 to -16.1 X 1 (T3 per day with a mean of -15.2 X 10~3 per day; these values are in good agreement with the results at higher acidities.124 The two runs with higher concentrations (9.7 X 10~3 and 3.02 X 10"2 M) show significant formation of colloid after an initial period, and the run at low concentration shows primarily the formation of Pu(V). For pure colloid, ox increases as the colloid dissolves to give Pu(V) and/or Pu(VI). At concentrations less than about 10""A/, the product is primarily Pu(V). The average increase in Sx in the individual runs ranged from 0.5 X 10~3 to 2.1 X 1 (T3 per day; the average value was 1.3X10~3. The concentrations of Pu(V) and Pu(VI) continued to change for as long as 260 days; thus there is no evidence for approach to equilibrium or steady state. Figure 6.6 shows the results of Typical runs starting with 2j9Pu(V). These runs show disproportionation according to the reverse of reaction (1), but they also show the formation of relatively large amounts of colloidal Pu(IV). The initial changes in ox (determined for the first 41 to 46 days) ranged from—4 X 10~3to — 12.2X 10~3; the mean waf>—9.1 X 10~3 per day. There is no evidence for approach to equilibrium, but a steady state consisting primarily of colloidal Pu(IV) is apparently being approached.

~~,Pu(¥)~~

~~Fig. 6.5. Ternary composition diagram (right) fcr reactions ot"239Pu(Vi) and collodial i39Pu(IV).~~

~~Pu(V)~~

~~Pu(IV)- Pu(VI) Colloid~~

~~Fig. 6.6. Ternary composition diagram (left) for reac- \ tions of 239Pu(V).~~

~~Pu(VI)/ Colloid H6 ACTINIDEAND TRANSITION METAL CHEMISTRY~~

Figure 6.7 summarizes runs started with mixtures of Pu(VI) and colloid. These mixtures were prepared in an attempt to observe reaction (1) in the forward direction. The results for the run labeled "q" are c^uite anomalous. The run with the least colloid ("o") shows a decrease in ox close to the values observed for pure Pu(VI). For the remaining runs, decreases in ox range from 6.3 X KT3 to 7.6 X 1CT3 per day. At total concentrations of less than about 1.5 X 10~4M the observed changes correspond primarily to reduction of Pu(VI) to Pu(V). At higher concentrations, (1.1 to 1.5) X \QTZM, additional colloid is formed as well. Figure 6.8 summarizes the runs made using the less radioactive 242Pu. The results starting with Pu(V) are similar to those with 23'Pu, except that the tendency to form colloid without forming Pu(Vl) as weil is less pronounced. At the higher pH values (3.8 and 4.3), much larger —log Q' values were observed. As expected: the changes in ox are considerably smaller than those observed in the ::wPu mixtures: the values ranged from -0.16 X 1(T3 to —1.8 X 10"3 per day.

~~Pu{V) A Fig. 6.7. Ternary composition diagram for reactions of mixtures of / \ :3"Pu(Vl) and colloid.~~

~~Pu(IV)- Pu(VI) icoSiold~~

~~PU(V)~~

~~\ Fig. 6.8. Ternary composition diagram for reactions of 242Pu(V).~~

~~\ \~~

~~/ \ Pu(iV)- .•».c\.Colloii d ACTINIDE AND TRANSITION METAL CHEMISTR Y 117~~

~~TABLE 6.3. Data for IMPu~~

Total ox Aox/At/10-3/day Change I Total Pu Time Final With Run pH M /MX MT4 (day) Initial Final Initial Final -Log Q' Time a 2.2 0.02 0.44 111 6.00 5.05 -15 -0.5 2.62 — b 1.5 0.75 97 113 6.00 4.77 -18 -6.2 2.5S + c 1.8 0.1 302 61 5.97 4.97 -17 -17 2.87 +

~~d 2.9 0.02 0.64 112 4.00 4.07 +0.9 0 e 3.7 0.01 0.64 56 4.00 4.10 +1.3 +1.3 — f 1.1 0.01 59 291 4.00 4.41 +2 +0.8 4.76 + 8 1.5 1.0 137 213 4.00 4.15 +1.1 +0.5 5.18 0~~

~~h 2.0-1.1 1.0 100 285 5.00 4.13 -15 0 351 + i 5.2-1.3 1.0 100 285 5.00 4.18 -11 0 3.64 + j 1.3 0.1 282 57 5.01 4,66 -7 -4 3.03 +~~

k 1.9-1.4 1.0 304 242 5.00 4.14 -7 -2 4.54 + 1 1.9-1.1 1.0 340 113 5.00 4.27 -12.5 J 2.97 0 m 2.2 0.01 0.74 112 5.22 4.67 -8 -0.7 3.30 - n 3.0 0.01 1.5 30 4.65 4.45 -7 3.96 0 1.5 0.75 107 113 5.81 4.73 -17 -0.6 2.60 0 P 1.5 0.75 147 113 5.32 4.66 -10 -0.4 3.16 q 1.7 0.01 180 133 4.96 5.17 +2.1 +1.7 5.32 0

~~Table 6.4. Data for M2Pni~~

Total Change I Total Pu Time ox A ox/At Final With Run pH M /M X 10-" (day) Initial Final /10~3/day -LogQ' Time a 2.8 0.01 0.95 213 4.00 4.07 +0.3 b 1.5 1.0 99.5 57 4.00 4.01 +0.4 ... c 2.0 0.01 99.5 56 4.00 4.01 +0.24 d 1.9 1.0 10 215 5.07 4.52 -2.46 1.64 _ e 1.8 1.0 50 215 5.10 4.83 -0.13 2.83 + f 1.6 1.0 100 215 5.15 4.93 -0.14 3.21 + g 2.1-1.5 1.0 380 254 4.92 4.60 -0.12 2.45 -

h 3.8-1.9 1.0 380 254 5.04 4.80 -0.94 3.18 _ i 2.8 e.oi 1.45 213 4.69 4.57 -0.5 4.43 j 2.0 1.0 200 57 5.02 5.00 -0.3 4.54 _ k 2.0 0.01 200 56 5.00 5.01 +0.2 3.74 — 1 2.0 1.0 10G 57 6.00 5.94 -1.0 4.41 _ m 3J-2.6 0.01 101 56 5.99 5.93 -1.2 4.28 - 118 ACTINIDEAND TRANSITION METAL CHEMISTR Y

~~(1) Equilibrium in reaction (1) is not attained using either 239Pu or 242Pu because of the effects of alpha self-irradiation.~~

~~(2) The rate law for the disproportionate of Pu(V) developed128 for 0.2 < [H+] < 1.0M appears to be satisfactory at acid concentrations at least 10 times lower.~~

~~(3) Steady states are approached that depend on the total concentration of plutonium in the system.~~

~~(4) The most important reactions involved are the alpha-reduction of Pu(Vl):~~

~~+ PuOf+ 1/2 H2O = PuOl + H +1/4 0,, (3)~~

~~and reaction (1).~~

(5) Conventional long-term solubility experiments on PuO2 probably will not reach equilibrium because of the effects of alpha self-irradiation. We must either understand and correct for them or compensate for these effects by using an Eh moderator capable of rapid reaction with the plutonium species present. Discussion Values for the cccentration quotients Q' were calculated from the analytical dala. These change with time and the firal values are included in the Tables 6.3 and 6.4. The symbols in the last column indicate the sign of the change in -log Q' with time. The wide range of values and their changes with time indicate that equilibrium in reaction (1) is not being approached in these experiments. Rate constants for the disproportionation of Pu(V) have been reported by Rabideau128 for solutions 0.2 to l.OAf in HC1O4 at 25°C. Approximate values calculated from our data for pH values from 1.5 to 2.0, at 23°C, and at unit ionic strength are only about 10% smaller than those from the more acidic solutions (240M~2 day^'w 264AT2 day"'). This is satisfactory agreement if we consider the experimental difficulties. The data for the various experiments show that the observed changes in the concentrations of the three components depend on both the composition and the total concentration of plutonium in the solution. The largest decreases in ox occur in solutions that are principally Pu(VI). Solutions containing principally Pu(V) show changes about 70% as large; these decrease with time as colloid forms. Mixtures containing principally colloidal Pu(IV) show oxidation. Some mixtures of all three components show no changes in <5x within the experimental error; these results indicate approaches to steady states where the individual rates of oxidation equal those of reduction. The runs using 239Pu with relatively high initial concentrations of Pu(VI) and Pu(V) show significant formation of colloidal Pu(IV), whereas runs starting with low concentrations show the formation of Pu(V) and very little colloid. This can be explained, at least qualitatively, on the basis of two reactions: the disproportionation of Pu(V), which is second order in its concentration, and the alpha-induced reduction of Pu(VT), which is approximately first order in total plutonium. These different reaction orders make disproportionation relatively unimportant at low concentrations of Pu(V). The alpha reduction of Pu(VI) in the presence of Pu(V) depends primarily on the total plutonium concentration (total irradiation flux), and the presence of colloid appears to decrease the rate. Some of this effect might be due to (1) absorption of the alpha particles by the colloidal material and (2) concommitant oxidation of the colloid. However, these effects are not sufficient to explain the observed rates of change for ox. An additional possibility is thai the colloid inhibits reduction by removing the radicals that would otherwise reduce Pu(VI). We have tested this assumption and found that it partially explains the results, but we have not as yet devised a completely satisfactory model. Our work on this problem is still in progress. ACTINIDE AND TRANSITION METAL CHEM1STR Y 119

~~ACTINIDE VALENCE AND HOST EFFECTS IN NUCLEAR WASTE FORMS~~

~~P. Gary EUer, Gordon D. Jarvinen, John D. Purson, Robert R. Ryan, and R. A. Penneman~~

Our program studies the valences and lattice sites selected by actinides when they enter ceramic and vitreous nuclear waste forms. In this report, we will descr ibe three sets of experiments that illustrate our approach during the past year.

(a) A borosilicate glass frit typical of those used in nuclear waste immobilization studies was fired in air with dioxides of uranium, neptun; >m, plutonium, and americium. We then examined the resulting glasses directly by absorption spectroscopy to ascertain the actinide valence states as a function of time. A typical result is shown in Fig. 6.9. Only a single predominant valence was observed for each element [specifically U(VI), Np(IV), Pu(IV), and Am(III)]. For the americium and plutonium samples, aging produced more intense broad absorption in the ultraviolet and near-visible regions as a result of self-irradiation, but we found no noticeable change in the actinide valence state.

~~NANOMETERS 400 500 600 700 800 1. a -9 z~~

~~O 5 .3~~

~~Fig. 6.9. An electronic absorption spectrum of plutonium in air-fired borosilicate glass (nominally 4 wt% PuO2).~~

(b) It has been reported that barium plutonate (BaPuO3) has a distorted perovskite structure, but the nature of the distortion is unknown. Because structures of this type will probably be generated to some degree during fabrication of ceramic nuclear waste forms, because the nature of the structural distortion in BaPuO3 will provide a good test of our bond length/bond strength arguments for actinide ion "fit" in such matrices, and because such compounds have widespread materials-science significance, we are conducting a neutron diffraction study on BaPuO3. We have made ~35 g of BaPuO3 that is enriched ~95% in isotope 242Pu (to minimize neutron absorption), and our synthesis appears to be the first reported production of a highly phase-pure product. Excellent neutron-diffraction datasets on this material and its thorium analogue have been obtained at the Weapons Neutron Research Facility at LAMPF in studies done with Gary Christoph of Group P-8. In Fig. 6.10, the outstanding quality of this data is illustrated for only 1 of the 16 banks of data collected! 120 ACTINIDE AND TRANSITION METAL CHEMISTR Y

~~Fig. 6.10. Neuti on powder diffraction data for BaPuCh.~~

(c) In a new initiative, we have established a collaboration with the EXAFS expert Farrel Lytle of Boeing Corporation. The EXAFS (extended x-ray absorption fine structure) technique measures and analyzes oscillations of the x-ray absorption coefficient of a particular element near the x-ray absorption edge. The effect is caused by backscattering of the x-ray photoelec- tron from neighboring atomic shells. The technique is extremely element specific, can yield detailed information on bond distances and coordination number, and has extremely good sensitivity. At this point in our study, we are evaluating the potential of the technique for actinide problems. With the assistance of Lytle, we collected a number of data sets at the Stanford Synchrotron Radiation Source, and we have adapted Lytle's data analysis software to the INC Division VAX computer. Figure 6.11 shows a typical EXAFS spectrum (15 minutes of data collection on 100 mg of sample). Note the very high signal/noise ratio and the characteristic "fingerprint" pattern in the vicinity of the absorption edge. Figure 6.12 shows a radial distribution function derived from this spectrum. Note that several discrete distances resulted; they correspond to several resolvable coordination shells, as expected for UOf. Our preliminary results show that EXAFS spectra are easily obtained on very small quantities of actinide-containing samples that pose little difficulty with radioactive containment. We should be able to collect data on samples containing 10 to 100 ppm of the element of interest. Our near-term efforts will now be devoted to evaluating how well the data can be analyzed to yield precise near- neighbor environment siructural information. In the corning year, we will increase our emphasis on studies of ceramics doped with transuranics. ACTINIDE AND TRANSITION METAL CHEMISTR Y 121

~~ANGSTROMS~~

~~Fig. 6.11. An x-ray absorption spectrum for UOi(NO3)i • 6H2O.~~

~~ENERGY(KEV x 10"2)~~

~~Fig. 6.12. A radial distribution function for UO2(NO3)2 • 6H-O. 122 ACTINIDE AND TRANSITION METAL CHEMISTRY~~

~~ACTINIDE-TRANSITION METAL CHEMISTRY~~

~~Debra A. VVrobleski, Robert R. Ryan, Harvey J. Wasserman, Kenneth V. Salazar, Robert T. Paine,* David C, Moody, John M. Ritchey,** and Alexander J. Zozulinf~~

The preparation of heterobimetallic transition metal complexes is currently of interest in inorganic chemistry because heterometallic compounds are widely perceived to be of practical value; they possess novel physical and spectroscopic properties and interesting chemical reactivity, including the activation of smali molecules such as CO. Also, because there are no molecules with an actinide-transition metal bond, there is considerable effort to prepare actinide-transition metal complexes. We have chosen to explore the chemistry of flexible bridging ligands, such as diphenylphosphide, that are able to accommodate a short M-M' distance in actinide-transition metal complexes. The tact that molecules containing actinide-actinide bonds are highly sought after has led us to investigate organometallic actinide sulfur chemistry in the hope of preparing actinide sulfide cluster compounds. In our effort to prepare heterobimetallic complexes containing an actinide and a transition metal, we have prepared and characterized the first organometallic thorium complex that contains terminal diphenylphosphido ligands and the first phosphido-bridged thorium nickel complex that shows a strong thorium-nickel interaction. The purple, diamagnetic Cp5Th(PPh2)2,1, [where Cp*= C5(CH3)5] (Ref. 129) was synthesized by the reaction of CpjThC!;, with LiPPh2 in toluene. We characterized it by combustion analysis, 31P and 'H NMR spectroscopy, uv-vis spectroscopy, and a single-crystal x-ray crystallographic structural determination. The molecular structure of 1 (Fig. 6.13) reveals a pseudo-tetrahcdral thorium center coordinated to two pentamethylcyclopentadienyl ligands and two diphenylphosphido ligands. The pyramidal nature of the phosphorus atoms indicates no multiple bonding between thorium and phosphorus; this differs from the multiple bonding observed by Baker et a/."° in Cp2Hfl(PEt2)2. The phosphorus atoms of 1 are ideally set up tc coordinate to a transition metal to form our target molecule.

~~Fig. 6.13. Geometry of the~~

~~"University of New Mexico, Albuquerque, New Mexico **Fort Lewis College, Durango, Colorado fGeorgia Southern College, Statesboro, Georgia ACTINIDE AND TRANSITION METAL CHEMISTR Y 123~~

Treatment of Cp*2Th(PPh2)2 with Ni(COD)-, (where COD = 1,5-cyclooctadiene) in the presence 131 of CO gave the orange microcrystalline Cpjfhfu-PPhj), Ni(CO)2, 2, in good yield. It was also characterized by combustion analysis, uv vis, infrared, llP and 'H NMR spectroscopy, and x-ray crystallography. Figures 6.14 and 6.15 show the structural features of molecule 2. The most striking feature of this molecule is the thorium-nickel distance, which is approximately 0.5 A shorter than that expected in the absence of a metal-metal bond. Molecule 2 represents the first example of a strong interaction between an actinide and a transition metal.

~~1 Fig. 6.14. Overall geometry of the Cp2Th(PPh2)2Ni(CO)2 molecu ? (ORTEP II diagram; 30% thermal ellipsoids).~~

~~Fig. 6.15. Geometry of the Th((i-P)2Ni core with distances shown in angstroms and angles in degrees. 124 ACTINIDE AND TRANSITION METAL CHEMISTR Y~~

Our continuing efforts in the preparation of actinide-transition metal complexes will include (1) exploring the chemistry of other transition metal fragments with molecule 1 and the uranium analogue by using electron-rich, low-valent transition metals (such as the platinum metals) to enhance metal-metal bonding and (2) the preparation of Cp2M(SR)2M'Ln (where M'Ln = a transition metal fragment). We also intend to investigate the activation of small molecules such as CO by these complexes?. Our efforts to investigate organometallic actinide sulfur chemistry have led to preparation of the yeilow Cp2ThS5, 3, from Cp2ThCl2 and Li2S5. The molecular structure of 3, shown in Fig. 6.16, consists of pseudotetrahedrally coordinated thorium in which the six-membered ThS5 ring is in a twist-boat cyclohexane conformation that contrasts with the chair conformation observed for Cp2MS5 where M = Ti and V. We plan to extend this work to uranium and to investigate the desulfurization chemistry with phosphines to form multimetaliic actinide sulfur complexes that may exhibit metal-metal bonding.

~~Fig. 6.16. ORTEPII drawing oftheCp2ThS5 molecule.~~

~~THE FIRST MOLYBDENUM BUTTERFLY CLUSTER~~

~~Gordon D. Jarvinen, Roben R. Ryan, and Harvey J. Wassennan~~

Our investigations of the metal-mediated reactivity of SO2 continue to reveal a fascinating and complex coordination chemistry. While examining a variety of transition metal complexes and searching for those with the ability to catalyze the reduction of SO2 with H2, we found that the 5 dimeric complex [MoCp(CO)3]2 (Cp = T| -C5H5) would indeed catalyze this reaction to give primarily sulfur and water under H2 pressures of 10 to 100 atm. at 100 to 125°C in toluene. Under 1 atm. of Hj/SO^ where more detailed monitoring of the chemistry was possible, we did not observe the reduction of SO2 with H2, and the same molybdenum-containing products resulted with or ACTINIDE AND TRANSITION METAL CHEMISTR Y 125 without H, present. Analysis of the gaseous and solid products of the reaction of SO, and [MoCp(CO)3j2 indicated that CO from the complex was involved in reducing SO, to give CO,, and sulfur-containing metal complexes. One product that formed early in the reaction mixture (but gradually disappeared at longer reaction times) was distinguished by its CO-stretching frequencies in the infrared. These v(CO) bands suggested bridging CO ligands that are relatively rare in CO complexes of the VI-B metals. This species appeared iikely to be an intermediate in the reduction of SO, by [MoCp(CO)3]2, and we sought to characterize it in more detail. A single-crystal x-ray diffraction study was necessary to reveal the nature of this compound. The molecular structure of I, Mo4Cp.,(CO),(ui-S),(u-O),, is shown in Fig. 6.17 and indeed contains the elements of reduced SO, molecules. An overall reaction to give I can be formulated as follows:

2[MoCp(CO)3], + 2SO, — I + 8CO + 2CO2; the average molybdenum oxidation state changes from -r 1 to +3 and sulfur changes from +4 to —2 (assigning charges in I as Cp~, S:~, and O2"). Examining the coordination environment of each molybdenum individually, however, leads us to assign oxidation states of+3 for Mo I and Mo I', +2 for Mo2, and 4 4 for Mo3. The presence of three different oxidation states for the metal is a feature of I that is not commonly observed in homonuclear clusters. The structure provides a model for some of the intermediates that have been proposed for metal- catalyzed .eduction of SO, with CO. One can envision SO, coordinating to a metal surface or unsaturated cluster and dissociating into sulfido and oxo ligands (terminal or bridging). The oxo species could then react with nearby CO ligands to give CO,. In I, for example, each oxo ligand is 2.58( 1) A from the carbon atom of a semibridging CO. This distance is less than the sum of the van der Waals radii (~3.0 A) and suggests a weak interaction between the oxo and CO ligands. In further studies of I, it will be our goal to determine if CO, elimination can be induced by thermal or photochemical means. The complex I is the first example of a homonuclear butterfly cluster of a group VI-B metal. The term butterfly is commonly used to describe the geometry of tetranuclear clusters containing five M-M bonds, where two triangular arrangements of metal atoms share a common side with a dihedral angle between the triangles (wings) of 90 to 170°. The dihedral angle between the wings of I is 123°. Butterfly clusters of the group VIII meta!s are the focus of considerable current work because of the novel struciu—s and reactivity exhibited by these complexes, especially relating to the reduction of coordinated CO. The synthesis and characterization of I suggest that chromium, molybdenum, and tungsten can provide a new class of butterfly clusters with their own rich chemistry.

Fig. 6.17. Molecular structure of Mo4Cp4(COh(urS)2(u-O),. Cyclopentadienyl rings bonded to Mo I and Mol' and hydrogens bonded to carbon atoms in cyclopentadieny! rings attached to Mo2 and Mo3 have been omitted for clarity. •"f-rf>-f-» ^••*V^$$sftwT"

~~Vibrational Speclfoscopic Studies of Acctanilide '\' 130~~

' " LowrTemperatuwX-RayBiiraactionStF^tureoflJranyl ,, .''JVw * "Bis(Tri-Iso-Butytph6sphate)Nitrate,; - ~ 132 •- ' r v , - • ^ ' > -1" "- "-- /4 Resonance Rarnaa Studies of Blue Copper Proteins: Effects cf Isotopic - -> ' Substitutions and Temperature 134

~~iiST ~* t*e r -Sis. >r-i~~

~~•#. STRUCTURAL CHEMISTRY, SPECTROSCOPY, AND APPLICATIONS 129~~

~~STRUCTURE OF ACETANILIDE AT 113 K~~

~~Harvey J. Wasserman, Robert R. Ryan, and Scott P. Layne (CNLS)~~

The room-temperature x-ray structure determination of acetanilide was reported in 1954 (Ref. 132), and further refinement on these same data was described several years later.'" Recently, acetanilide has become the center of some interest because of certain anomalous properties that may become evident as a consequence of soliton behavior. An absorption at 1650 cm"' in the vibrational spectrum has been assigned to a soliton that results from coupling the amide-I vibration to an out-of-plane displacement of the hydrogen-bonded proton.'34 The peak at 1650 cirT1 appears only as the molecule is cooled and is well formed at 140 K. (The room-temperature amide-I absorption occurs at ~ 1665 cm"'). We have therefore undertaken a single-crystal x-ray diffraction analysis of acetanilide below this temperature to explore the possibility that the new absorption results from a structural change upon cooling. Our results are described below. Figure 7.1 depicts a view of the molecule in which important interatomic distances from the room-temperature study'11 and the present (T = 113 K.) study are compared. We have observed only one significant structural change in acetanilide after it cools. At low temperature there is a 0.015-A lengthening of the carbonyl C(7)-O distance; the discrepancy here is significant at the 4o level. As a result, the hydrogen-bonded N-H O' distance is shortened by 0.029 to 2.914(3) A. All other distances differ by less than 3a. Differences in interatomic angles are even smaller: the largest discrepancy occurring in the amide side-chain of the molecule is only 0.2°. Our low-temperature structural analysis of the acetanilide molecule has allowed a more precise determination of hydrogen atom parameters, and in particular, those of the amide proton H( 1). We note the following important features:

Fig. 7.1. A view of the molecule thai compares selected bondlengths. Values with asterisks (*) are from the room-temperature study1" and are subject to a mean estimated standard deviation of 0.0034 A; values without asterisks are derived from the present analysis and are subject to a mean estimated standard deviation of 0.002 A. 130 STRUCTURAL CHEMISTR Y, SPECTROSCOPY, AND APPLICA TIONS

~~(1) The observed N-H(l) bondlength of 0.90(2) A is reasonable for an x-ray determined distance.135~~

(2) The sleric interaction betw n the phenyl and acetyl groups is reflected in the angles subtended at the nitrogen atom, with C( 1 )-N-H( 1) = 115( 1)° and C(7)-N-H( 1) = 117( 1)°. The C( 1 )-N-C(7) angle is 127.6(1)°.

~~(3) The hydrogen bond is, as expected, nearly linear, with N-H(l)-O' = 171(1)". The intermolecular H( 1) O' distance is 2.02 A.~~

In conclusion, we have shown that the temperature dependency of the vibrational spectrum of acetanilide results from factors unrelated to gross structural changes in packing of the molecules, for example, phase changes, it is interesting to note that the largest difference [0.015(4) A] between room- and low-temperature studies occurs in the carbonyl bond and that an increar-e in the C-0 distance is not inconsistent with the amide-I shift to lower frequency at low temperature.114 We plan to carry out further studies, especially single-crystal neutron analyses, on isotopically substituted species to determine if there is a structural basis for additional spectral anomalies136 that occur in these molecules.

~~VIBRATION AL SPECTROSCOPIC STUDIES OF ACETANILIDE~~

~~Clifford T. Johnston and Basil I. Swanson~~

A peculiar feature in the amide-1 region of the low-temperature ir spectrum of crystalline acetanilide, a hydrogen-bonded organic solid, at 1650 cm"1 has recently been assigned as a vibrational state corresponding to a self-trapped Davydov-like soliton.137"8 In Fig. 7.2, the crystal structure of acetanilide illustrates the linear network of hydrogen bonds. The proposed self- trapping mechanism Invokes a nonlinear, intermolecular, energetic interaction between amide-I quanta and low-frequency phonons. Self-trapped, Davydov-like solitons have been proposed as energy storage mechanisms in many different complex biological molecules, including structures containing the alpha-helix.139 However, there is no unambiguous spectroscopic evidence to support the existence of such self-trapped states in biological molecules. Consequently, considerable attention is currently being focused on acetanilide as a potential candidate for the obseivation of biological solitons.137"8140 In view of the potential importance of self-trapped solitons in biology, and because similar splittings of the v(C-O) bands have been observed in other carbonyl- containing compounds,U1 we have initiated a study of the temperature dependence of both internal and external modes of acetanilide and its isotopic derivatives. Isotopically substituted derivatives of acetanilide were synthesized by acetylation with acetic- pi valic anhydride.M2 The organic solids (mp 113°C) were then purified using a multiple-pass zone refiner. Single crystals of the labeled compounds were grown from the melt using a modified Bridgeman furnace; crystals were cut in a dry atmosphere, and crystal orientations were confirmed using an x-ray precession camera. Single- rystal, low-temperature Raman spectra were obtained in a specially designed cold cell, which incorporated a positive pressure of helium to facilitate cooling of the single crystal. STRUCTURAL CHEMISTR Y, SPECTROSCOPY, AND APPL1CA TIONS 131

The z(xx)z component of the Raman spectra for the normal isotopic species of acetanilide in the amide-I [v(C-O)] region is shown in Fig. 7.3 as a function of temperature. These data are in qualitative agreement with the low-temperature, polycrystalline ir data of Careri et al.ni Upon cooiing, a distinct band at 1650 cm"' increases in intensity at the expense of the room-temperature amide-v band at 1665 cm"'. Single-crystal polarization measurements have shown that the 1665- 1 aiid 1650-cnT bands are of Ag symmetry. Observation of two prominent amide-I components, both of A6 symmetry, cannot be explained in terms of factor group spatting because only one AB component is allowed according to the selection rules for the D2h factor group. Because the observed spectral changes are continuous and reversible over a broad temperature range, a first- order phase transition can be ruled out as an explanation for the appearance of the low- temperature 1650-cm"' band. In view of the absence of a soft mode in the low-energy region of the Raman spectra, or indeed, any splittings that signal a change in the space group, a continuous phase change is also unlikely. One possible explanation for the appearance of the 1650-cm"' band that has not been explored previously is that the 1665- and 1650-cm ' bands arise from a Ferrni resonance interaction involving the Ag, amide-I fundamental and a combination band of A6 symmetry. To assign the origin of the 1665- and 1650-cm"' bands, we obtained low-temperature, single-crystal Raman spectra for isotopically substituted derivatives of acetanilide. Low-temperature, single-crystal Raman spectra of L1C and N-D labeled acetanilide in the z(xx)z polarization are shown in Fig. 7.3b and c. As the isotopic spectra indicate, the temperature-dependent behavior of the amide-I region is perturbed strongly by isotopic substitution. Analysis of the temperature and isotopic dependence of the Raman and ir spectra of acetanilide in the 10- to 4000-CITT1 range provides conclusive evidence that the 1650-cm"1 band is a result of Fermi coupling between a combination band in resonance with the amide-I fundamental. The surprisingly strong temperature tuning of the Fermi resonance results from the strong frequency and lineshape changes of one component in the combination mode of the Fermi diad, a low-frequency torsional mode at 104 cm"'. Accordingly, we believe that the ir feature at 1650-cm"1, which Careri et a/.'371'10 originally attributed to a Davydov-like soliton, is a result of Fermi coupling. Additional experiments, including matrix isolation, and measurements of the Raman and ir spectra at high pressures and low temperatures are currently being studied.

~~Fig. 7.2. Crystal structure of acetanilide; note the linear network of hydrogen bonds extending along the y-axis. 132 STRUCTURAL CHEMISTR Y, SPECTROSCOPY, AND APPLICA TIONS~~

~~13 C6H.NHC0CH3 C6H9NH C0CH3 C6HsNDC0CH3~~

~~1610 1650 1690 1610 \6J0 1690 16 !0 1650 1690 cm"1 cm'1 cm"1 a b c~~

Fig. 7.3. Temperature dependence of the Raman spectra of normal acetanilide and Ihe I3C and N-D substituted analogues in the amide-I [v(C'-O)] region. The z(xx)z single-crystal polarized scans are shown.

~~LOW-TEMPERATURE X-RAY DIFFRACTION STRUCTURE OF URANYL BIS(TR3-ISO- BUTYLPHOSPHATE)NITRATE~~

Robert R. Ryan, Robert A. Penneman, John H. Burns,* and George M. Brown*

We have initiated a new program to explore the structural characteristics of extractant complexes. The primary goals of the project are to gain an understanding of the coordination requirements of the actinide elements for various commoniy used extractants and to extrapolate this information to the design of new complexants with superior extraction capabilities, especially to improve analytical methods. Toward this end, the structure of the title complex UO2(NO3):[OP(O'Bu),]; has been determined at low temperature (-134°C). At Oak Ridge National Laboratory, ihe structure of this complex was examined at. room temperature using x-ray and neutron methods. Although the basic configuration of the complex was established in those studies, large mean amplitudes of vibration precluded an accurate assessment of the structural details. The present study at Los Alamos resulted in an approximately 10% reduction of the unit cell volume and strong diffraction to large 26 angles, which allowed an accurate determination of the struciure (Fig. 7.4), including hydrogen atom positions. The molecular conformation we found is ubiquitous among complexes having the formula

*Oak Ridge National Laboratory STRUCTURAL CHEMISTRY, SPECTROSCOPY, AND APPLICATIONS 133

UO:(NO3):L2, in which L represents a variety of neutral organophosphorus ligands. Two bidentate nitrate ions plus two phosphoryl oxygen atoms occupy six coordination sites around the equator of r the linear UOt ion. The conformation differs from that found in the omplex UO2(NO3)2L, where L is the bidentate CMP (carbamoyl methylene phosphonate) ligand, only in that for the latter complex the bidentate ligand occupies adjacent equatorial positions. We can conveniently compare the U-O bond distances using Zachariasen's bond length/bond strength relationships,143 which are listed for the ligands L in Table 7.1. It is expected, because of inductive effects, that triaryl phosphine oxides should be more basic than tri-butyl phosphate and should form a stronger bond to the acidic actinide center. These characteristics would be in agreement with the larger bond strength for complexes 2 and 3 compared to complex 1 (see Table 7.1). The binding of the CMP ligand appears to be weaker than that of the phosphoryl ligands mentioned above, and both the carbamoyl and phosphoryl groups bind with approximately the same strength. The bond strengths should sum to 6 for the metal atoms in these complexes and indeed they do in all cases; the decrease in bond strength in complex 1 is balanced by increased bonding to the nitrato ligands. The similarity of the bond strengths for the triaryl and trialkyl phosphine oxides is interesting in that the Russian literature refers to an anomalous aryl strengthening effect,147 which gives the phenyl ligand a higher extraction capability than alkyl diphosphine oxides have. The present comparisons indicate thai ary! phosphine oxides bind as tightly as the alkyl phosphine oxides (within experimental error), in spite of the widely held notion that aryl groups are stronger electron-withdrawing substituents.

~~Fig. 7.4. ORTEP projection of the structure of UOi 134 STRUCTURAL CHEMISTRY, SPECTROSCOPY, AND APPLICATIONS~~

TABLE 7.1. Bond Strengths for Known MO;(NOj)2L2 Compounds Complex U-O(P) Distance Bond Strength (A) j UO2(NQ3)2( Bu3P)2 2.371(3) 0.439 UO2(NO3)2(TBPO)2" 2.347(8) 0.470 h UO2(NO3)2(4>,PO)2 2.359(7) 0.457 b NpO2(NO3)2(«>3PO)2 2.363(8) 0.433 C UO,(NO3)2(CMP) 2.420(4) 0.382 2.406(5)" 0.397

~~•Reference 144. •"Reference 145. 'Reference 146. 'Distance to C=O oxygen.~~

~~RESONANCE RAMAN STUDIES OF BLUE COPPER PROTEINS: EFFECTS OF ISOTOP1C SUBSTITUTIONS AND TEMPERATURE~~

~~William H. Woodruff, Basil I. Swanson, Herbert A. Fry, David F. Blair,* Sunney I. Chan,* Harry B. Gray,* Bo G. Malmstrom,** and Israel Pecht+~~

The blue copper proteins include the simple one-copper blue proteins and the multicopper oxidases that contain a blue (type I) copper site. The function of these proteins is generally electron transport (for example, plastocyanin in photosynthesis and azurin in bacterial metabolism) or activation of O2 in its reactions with organic substrates (for example, oxidases). It is now widely recognized that blue copper proteins have a number of remarkable spectroscopic and chemical properties. These include:

~~• intense low-energy electronic absorption features in the visible spectrum (which are the source of the intense blue color, see Fig. 7.5),~~

~~• very low energy Cu:+ ligand field transitions,~~

~~• small copper hyperfine coupling constants in the Cu2+ electron spin resonance spectra,~~

~~• unusually strong (and variable) oxidizing power for the Cu:+ oxidation state, and~~

~~• facile electron transfer dynamics.~~

~~"California Institute of Technology ••University of Goteborg, Sweden tWeizmann Institute of Science, Israel STRUCTURAL CHEMIS/RY, SPECTROSCOPY, AND APPLICATIONS 135~~

The x-ray crystal structures of three blue copper proteins have recently been determined. The structure of the copper site of poplar plastocyanin is typical and is shown in Fig. 7.5. Some of the spectroscopic and chemical observations can be interpreted on the basis of the more obvious features of these now-known structures. On the other hand, many important observations remain

~~4 500 -~~

~~e 30001—~~

~~1500 -~~

~~30,000 24,000 18,000 12,000 6000 Wavenumbers~~

Fig. 7.5. (Top) Structure of the copper site of popla- plastocyanin, including the copper-ligand bond distances. The atoms marked ® are the alpha-carbon atoms of the polypeptide backbone. (Bottom) Electronic absorption spectrum of trench bean plastocyanin at J5 K. The dashed lines represent the Gaussian resolution of the spectrum. 136 STRUCTURAL CHEM1STR Y, SPECTROSCOPY, AND APPLICATIONS incompletely understood despite intense and continuing investigation. These properties must be •;ifiuenced by structural parameters that are beyond the present resolution of x-ray methods or by dynamical effects to which determinations of average structure are insensitive. It is evident irom recent resonance Raman (RR) studies of blue copper proteins under cryogenic conditions that the RR spectra are more sensitive to differences among the structures and the quantum dynamics of the proteins than are spectra derived from more commonly applied spectroscopies. For example, plastocyanin and azurin are quite similar by most spectroscopic criteria and also by existing x-ray crystallographic observations. However, the RR spectra of azurin and plastocyanin are considerably dissimilar in the number of RR modes observed, their frequencies, their relative intensities, and their temperature dependences. Satisfactory structural interpretation of blu £ copper RR spectra is not yet available. Consider- able progress can be made toward understanding their structural significance by carefully examining a wide variety of protein systems, their isotopically substituted derivatives, and the effects of temperature. We have performed such studies for a number of blue copper proteins: the single- copper blue proteins azurin, plastocyanin, and stellacyanin and the multicopper oxidases laccase, ascorbate oxidase, and ceruloplasmin. Isotope studies (HCu/6:)Cu and H/D) of azurins allows us to refine the vibration.-;! assignments in this protein. As a group, the blue copper proteins exhibit a number of notable similarities in their RR spectra. A typical spectrum is that of Ps. aeruginosa (PA) azurin, shown in Fig. 7.6 at 300 and 12 K. The most conspicuous features are the intense peaks near 400 cm"1. All the proteins have one or two medium-intensity peaks in the 250- to 280-cirT1 region. In all cases, the RR features below 500 cm"1 are caused by vibrational fundamentals. By contrast, above 500 cm"' the spectra are dominated by overtones and combinations. This is particularly evident at low temperature (Fig. 7.6), where both the relative intensities and the resolution of the overtones and combinations are enhanced. The three sets of peaks observed at about 800, 1200, and 1600 cm"' represent the overtone/combination progressions of the fundamentals near 400 cm"'. A few fundamentals do appear above 500 cm"', the most evident being the sharp peaks at 569, 657, and 1407 cm"' and the broad, incompletely resolved feature : ?ar 1050 cm"' (Fig. 7.6). For each system examined, all the peaks exhibit polarized Raman scattering with a depolarization ratio of approximately 0.3, as is expected of symmetric vibrations in low-symmetry environments. Notwithstanding the generic similarities among the RR spectra, substantial differences are observed among the different proteins and even among preparations of the same protein from different organisms. The differences include the number of vibrational modes observed and their frequencies, relative intensities, peakwidths (that is, resolution) and lineshape (degree of Gaussian or Lorentzian character), overtones and combinations, isotope shifts, and the temperature dependences of all these characteristics. Two types of isotopic substitution can be performed in the single-copper proteins without resorting to microbiological techniques: all the labile protons can be replaced by deuterium, or natural-abundance copper (70% 61Cu) can be removed and replaced by either pure 63Cu or 65Cu. We have performed these substitutions on three azurins. The data for PA azurin are given in Table 7.2. These results are analyzed in detail in a recent publication.148 The inferences drawn from these data are summarized below. The principal conclusions from RR data, the isotope shifts, and the temperature dependences include the following. The only Cu-L stretching mode near 400 crrr' is the Cu-S(cys) stretch, and the remainder of the elementary motions near this frequency are internal ligand deformations. All the observed modes near 400 cm"' are highly mixed, and most derive their intensity from their fractional Cu-S(cys) stretching character. The Cu-N(his) stretching motions are best identified with the ubiquitous peak(s) near 270 cm"1, although in azurin these modes have contributions from other coordinates. Internal histidine and cysteine motions contribute to the features near 400 cm"1. STRUCTURAL CHEMISTR Y, SPECTROSCOPY, AND APPLICA TIONS 13

~~PS. AER. AZURIN~~

~~300 K~~

~~12 K <~~

~~100 300 500 700 900 1100 1300 1500 1700~~

~~"V. CM'~~

~~Fig. 7.6. The RR spectra of PA azurin, a typical blue copper protein. Top traces at 300 K; bottom traces at 12 K. 138 STRUCTURAL CHEMISTR Y, SPECTROSCOPY, AND APPLICA TIONS~~

TABLE 7.2. PA Azurin Isotope Shifts at 25 K and (300 K) Peak, v Deuterium Shift Copper Shift (cm "') (2H-'H) (65Cu-"Cu) 266.1 0 ~+l 286.7 -5 ~0 348.2 2 ~0 372.6 -0.9 (-0.3) -0.6 (-0.7) 400.5 — -0.6 (-1) 408.6 -1.0 (-0.3) -0.6 (-0.8) 427.9 -1.2 (-1.4) -0.2 (0.0) 441 -1.S 4S4.6 0.0 (-0.6) -0(0) 474 -1.0 -0(0) 492 +1.3 -0(0) 569 2 657.1 +0.3 753.2 0.0 780.3 -2.4 814 -2.1 836.2 -1.7

Even with improved resolution and signal-to-noise at 10 K, the RR excitation profiles show negligible variation of relative intensities among the resonance-enhanced modes of a given protein. This is consistent with a single resonant electronic chroniophore [namely RS~(cys) —- Cu:+(LMCT)] and extremely facile vibrational dephasing or other damping processes in the electronically excited state. Temperature effects upon the spectra suggest a significant temperature- dependent structure change at the plastocyanin active site and a more subtle change in azurin. The Cu-S(cys) stretching frequency is closely correlated to the electron transfer exothermicity for several protein*, thereby indicating that the reduction potential can be fine-tuned by the effects of polypeptide backbone structure on the copper ligand field. The RR data suggest that the blue copper centers of the proteins examined are typified by pi? s*"cyanin, azurin, and stellacyanin. The key structural features of plastocyanin appear to be the availabiiity of a maximum of four donors to coordinate to copper, the effective coordination of only three of these donors under at least some conditions, and large excited-state structural changes resulting in strong Duschinsky mixing, as evidenced by the RR overtones and combinations. Azurin may have four or possibly five donors in the vicinity of copper. The RR data suggest that certain motions of the copper atom are constrained because the copper atom under all conditions is coordinated to at least four of these donors. Of all the blue copper systems, azurin shows the weakest Duschinsky effect, as evidenced Lvy the intensity of the overtones and combinations. This suggests that the excited-state structure is not grossly different from the ground state in azurin, which reinforces the idea of a somewhat constrained copper site. Steilacyanin alone lacks STRUCTURAL CHEMISTR Y, SPECTROSCOPY, AND APPLICA TIONS 139 methionire. Some form of interaction of a protonated peptide group with the blue copper chromophore is indicated. The presence of another potential donor, for example, disulfide, cannot he excluded. The Duschinsky effect in stellacyanin is somewhat stronger than it is in azurin. Within a given structural group, a number of more subtle structural parameters may vary with readily observable effects on the frequencies und intensities of correlated RR modes. These parameters, which include the Cu-S(cys) distances and apical bonding interactions, are subject to control by the overall protein structure. Any of the parameters may modulate the biological function of the protein by affecting the thermochemistry or quantum dynamics of the electron transfer function of the blue copper site. 8,

~~NEW EXPERIMENTAL FACILITIES~~

~~Time-of-Flight Isochronous (TOFI) Spectrometer 143~~

~~LEAP at Los Alamos 147~~

~~Development of Fast Neptunium Chemistry and the Search for~~

~~New Isotopes of Neptunium 151~~

~~LAMF He-Jet Coupled Mass Separator Project 154~~

~~LOS ALAMOS MESON PHYSICS FACILITIES~~

~~Direct Mass Measurements ir the Lighi Neutron-Rich Region by Using a~~

~~Combined Energy and Time-of-Flight Technique 158~~

~~Pion N ucleus Double-Charge Exchange at Low Energies 162~~

~~A Unitary Off-Shell Model for Threshold Piomc £ca Production and ti Production by Fast Pions 164 Eta-Nucleon Scattering 167~~

~~Nucleons, Deltas, anc1 On •" 2a' yons as NontopologiGal Solitons 170~~

~~LAMPF Nuclear Chemislry Data Acquisition System 172~~

~~NUCLEAR FISSION~~

~~Fission of:55:56Es, 255257Fm, and :58Md at Moderate Excitation Energies 173~~

~~Measurement of Neutrons Emitted in Fission of 158Er 177 NUCLEAR STRUCTURE AND REACTIONS 143~~

~~NEW EXPERIMENTAL FACILITIES~~

~~TIME-OF-FLIGHT ISOCHRONOUS (TOFI) SPECTROMETER~~

Jan M. Wouters, David J. Vieira, Hermann Wollnik,* Gilbert W. Butler, Kamran Vaziri,** James R. Sims (MP-8), Joseph W. Van Dyke (MP-8), Donald C. Clark (MP-8), John R. Zerwekh (MP-8), John H. Gill (MP-8), Delbert D. Kercher (MP-1), James D. Little (MP-1), and the TOFI Collaboration!

This report is the third in a series of progiess reports describing the design and construction of the TOFI spectrometer and its associated secondary beam line. TOFI, which is being constructed jointly by INC and MP Divisions, is designed to measure in a systematic fashion the ground-state masses of the light neutron-rich nuclei with A<70 that lie far from the valley of beta-stability. In the past year, we ordered all the long-lead items necessary for construction of the spectrometer and installed the first naif of the secondary beam line. Furthermore, a major portion of the control system for both the spectrometer and beam line was designed and installed. This annual report will briefly summarize the current status of the spectrometer and describe in some detail the design and installation of the first half of the transport line. For a summary of the scientific goals and overall design of the TOFI spectrometer, see the 1982 INC Division annual report.149

Secondary Beam Transport Line Beginning in February, we began installing the secondary beam transport line by unstacking the shield wall between the LAMPF switchyard and the TOFI room. Since then, all the optical and vacuum elements have been installed up to the first beam box in the TOFI room, and the wall has been restacked. The optical and vacuum elements include a quadrupole triplet that captures a portion of the recoils from the target, a mass filter that filters out the light, high-intensity reaction products (protons, deuterons, and alphas) that are produced in a variety of proton-induced reactions, and a final triplet that focuses the filtered beam down to a magnified image of the source. To characterize its operation, this first section of line has been tuned with various alpha sources and reaction products from 800-MeV protons on thorium. The tuning process is divided into three steps:

(1) focusing the beam to obtain an image of the source, (2) determining the transport line's energy transmission window, and (3) characterizing the electrostatic deflector/dipole magnet combination to determine its mass filtering ability.

~~To focus the beam, a new multiwire proportional counter has been built that is position sensitive (0.05 cm FWHM for alpha particles) in both the x and y directions. A good image (1.0 x 1.4 cm2~~

•University of Giessen, Geissen, West Germany **Utah State University fA collaboration between scientists from Los Alamos, Clark University, Iowa State University, and the University of Giessen 144 NUCLEAR STRUCTURE AND REACTIONS

~~JU.ViJ~~

~~• 4 -~~

~~ENERGY~~

I'm. HJ. Fncrg\ spctira u!'ii i-< kt plus 'Tk alpha source thai illustrates the energy !ransmission of the first l:al! ••>';in transport line, (a) is the H-U'rena- spfctrum when a source is located dire^'v ,.i front of the Jete'.-inr and (b) uv and (d) aiv spec'i-.i irom a source located at the ta.rget.position when the line is iii.'ieii ;.:.• • 2 --• -t. .!•?-.! S.-! \U'\ . .'..••.: • • '

source when ihe iranspiir; line is set lor an encrg\ ot 3.2, x4. and 8.4 MeV. respectively. Through a comparison ot the line intensiiies measured at ditVerent nerg\ or momentum settings of the transporl line, ihe relaii' e iransnnssion is momentum deviation Sp/p has been deduced for the first half of the transport hue (sec hig. S.2) I hese data show that the momentum transmission of the transport line is5p/p= 23% (FWHM). which is much larger than required for the spectrometer (5p/p = NUCLEAR STRUCTURE ANE> REACTIONS 145

~~i 1 1 i i~~

~~-60~~

~~Fig. 8.2. Momentum transmission of the first half of the transport line, as determined from the alpha-source line intensities shown in Fig. 8.1.~~

To determine the filtering properties of the mass filter, a AE—E solid-state telescope was used to identify protons, deuterons, tritons, JHe, and alphas, which are produced in 800-MeV proton- induced reactions on a thorium target. For this test, the transport line was set for a particular momentum-to-charge value, and then the mass filter was tuned for various rnass-to-charge ratios. Comparing the intensity of the alphas and tritons at various mass-to-charge settings, we obtained the mass-to-charge transmission for the first half of the transport line (see Fig. 8.3). A clear filtering of the neighboring mass-to-charge species is observed. More specifically, at a setting optimized for tritons (that is, A/Q = 3), those species with mass-to-charge ratios of 2 or less are reduced by more than 2 orders of magnitude. (Background events resulting from single- and multiple-wall scattering limited the measurement of this reduction factor). This mass-to-charge filtering is particularly important in our future experiments because the protons, deuterons, and alpha particles are produced with yields that are, respectively, 10s, 104, and 103 times larger than those of the ions for which measurements are planned. These tests pointed out several improvements that must be made before the line will achieve optimum performance. The first is the addition of antiscattering collimators in the shape of springs that will line the inside of the beam lines. Secondly, an additional x-y steering magnet is needed after the first quadrupole triplet to correct for any misalignment of the beam axis produced by the target/collimator/first triplet combination. Finally, we will use an additional detector box, located in front of the electrostatic deflector, to tune the first quadrupole triplet more precisely and steer the beam to the midplanes of both the electrostatic deflector and the dipole bending magnet of the mass filter. We have also made progress on the control system for both the secondary beam Sine and the spectrometer. This control system is different from previous control systems used at LAMPF in that a microprocessor controls all the interlock logic needed to safeguard the system. Such a system is i..ore flexible as the spectrometer develops; in addition, installation of the control system is greatly simplified because only a single cuaxial cable is needed to connect the central processing unit to the remote I/O chassis from which the various devices are driven. All the controls needed to run the magnets, electrostatic deflector, and vacuum system have been installed; only the devices that they control remain to be installed. This work has been completed for the first half of the transport line, and it is now fully operational. 146 NUCLE4R STRUCTURE AND REACTIONS

~~wo ^ a*8~~

~~§76~~

~~/ \~~

~~• L V" A/0 V 25~~

~~0 1 1 2.0 2.5 3.0 3.6 4.0 Mass-to-Charge Ratio Setting (amu/Q)~~

Fig. 8.3. The ruass-to-charge transmission of the first half of the transport line for alphas (dashed line) =>nd tritons (solid line), as emitted from a thorium larger The transport line is set for a central momentum-to-charge value of 190 MeV/c/Q.

Spectrometer All long-lead items for the construction of the spectrometer have been received or are on order. Specifically, the four dipcles that constitute the spectrometer have been designed, and the appropriate coils und stands have been received. The iron cores for the magnets are being manufactured and assembled; they should arrive during the early part of FY 1985. The first magnet will then be set up for mapping and optimizing of the magnetic field. During the same period, we plan to fabricate on site the vacuum tanks for the four dipoies. An order has already been placed for the special nonmagnetic stainless steel that is needed for this fabrication.

~~In the Future During the coming year, our effort will be directed towards four tasks, which we will try to accomplish in parallel.~~

• Installation of the second half of the transport line and incorporation of improvements to the first half, as outlined above. Once completed, the entire transport line will be tested to first characterize and then optimize its performance.

• Assembly, testing, and mapping of the first dipole magnet, which will be trimmed by various adjustment features built into the design of the magnet (see the FY 1983 INC Division Annual Report for details).150

~~• After this first, magnet is fully understood and trimmed appropriately, the remaining three magnets will b« assembled in a similar fashion.~~

• During spring 1985, the magnets will be assembled to form the spectrometer, and we will characterize and optimize the performance of this system. This procedure will predominantly involve minimizing the TOF spread through the spectrometer for a particle with a given mass- to-charg'> »~atio. NUCLEAR STRUCTURE AND REACTIONS 147

The first experiment is scl. duled for summer/fall 1985; it will (1) further test and optimize TOFI with low-Z, neutron-rich fragmentation products and (2) study the rapid onset of prolate deformation tbc't has been observed in the neutron-rich sodium region.151-1''2

~~LEAF AT LOS ALAMOS~~

~~Jan G. Boissevain (P-2), Malcolm M. Fowler, Avigdor I. Gavron (P-2), Darleane C. Hoffman,* Patrick Lysaght, and Jerry B Wilhelmy~~

LEAP (Large Einsteinium Activation Program) is a joint proposal by Lawrence Berkeley Laboratory, Oak Ridge National Laboratory, Los Alamos National Laboratory, and Lawrence Livermore National Laboratory to use a special large-production source of 254Es i~40 ug) for a variety of nuclear and chemical studies. The main objectives center on studies of the nuclear properties of neutron-rich heavy elements, studies of the chemical properties of elements with Z > 100, and attempts to produce superheavy elements. The Los Alamos effort will focus on nuclear studies. The LEAP program can be expected to produce many as yet undiscovered neutron-rich isotopes in the Z = 100 to 106 region through transfer reactions. The decay properties of these isotopes will supply crucial information about the fission process. As was previously pointed out,153 what little we know about this region indicates rapidly changing fission properties with respect to half-lives, kinetic energy releases, and mass distributions. One of the main challenges of the LEAP program will be to elucidate the fission properties of the very-difficullt-to-produce, neutron-rich heavy- element isotopes. When designing experiments to study these isotopes, one must contend with several difficulties: (1) small-production cross sections, (2) a nonspecific reaction mechanism, (3) a variety of recoil angles and energies from the transfer reactions, and (4) an enormous range of half-lives, including short-lived spontaneous fission decay. It has been shown that transfer reactions in actinides and preactinides (Refs. 154 and 155, respectively), have nanobarn to microbarn cross sections for production of the desired nucleon transfers. (For a 1-nb cross section ?nd a 400 ug/cm2 target, a 1- particle-uA beam will produce 0.4 atom/minute.) Clearly, efficient detection techniques are required. The transfer reactions ha^e broad excitation functions and are rather nonselective in the isotopes produced. Therefore, we need a detection system that can sort out the desirable isotopes from the multitude produced. The transfer reaction mechanism creates another difficulty in that the desired products are not the result of full momentum transfer of the beam. One or more light ejecliles are associated with the reaction, and these carry off an appreciable amount of the beam momentum and contribute to a broadening of the heavy-element angular distribution. This precludes the use of traditional velocity filter systems that rely on well-focused reaction products. Because of the wide range of half-lives for the decay of the heavy elements, a variety of techniques are required to efficiently perform the identification. For long-lived species (tl/2 > seconds), traditional chemistry probably offers the highest selectivity and sensitivity. Mechanical transport systems coupled with helium jets, direct kinematic recoil collection, or gas separator techniques can operate down to the millisecond range and offer the advantage of moving the products out of

~~"Lawrence Berkeley Laboratory 148 NUCLEAR STRUCTURE AND REACTIONS~~

\he primary reaction chamber. This still leaves a large range of half-lives that should be investigated. We propose to construct a detection system that could provide information down to the nanosecond level and thus bt complementary to the other proposed detection systems. Several of the potentially produced even-even elements of Z ~ 100 to 104 could have half-iives in the nanosecond to millisecond range.156 In general, the theoretical undei standing of the fission process will be maximized by studying the even-even products, so it is important to gain information on these isotopes. Our proposed detection system (HEFT - heavy-element fission tracker) will consist of an array of self-contained detector modules. The goal of the system is to identify the charge and mass of the fission products resulting from the spontaneous fission decay of the heavy element. By thus characterizing the iwo Fission products, we can determine the identity of the heavy element. Each module {Fig. 8.4) consists of four components. The first is a gridded multiwire detector operating in the double-avalanche mode, which provides fast timing (~200 picosecond) and an x-y position signal (through delay line propagation). The second region is a low-pressure ionization chamber ~20 cm in depth, which serves to measure ihe dE/dx of transversing fission products. The third region is a larger multiwire detector similar to the first, which again records the time of signal arrival and the x-y position. These first three regions operate in the same gas volume at a pressure of —2 T isobutane. There is only one window for these detectors, an ~40-|ig/cm2 polypropylene toil in front of the first multiwire; this will minimize any extraneous energy loss or straggling caused by window effects. The last component is a segmented ionization chamber of ~20-cm depth; it will operate with sufficient isobutane pressure to stop the fission products (~40 T) and provide a residual energy signal. Fission product mass information is thus obtained through an Et2 measurement, and the nuclear charge is extracted from the dE/dx determination. Over the last few years, we have designed and fabricated a variety of gas detection systems. Although we have not produced the complete HEFT composite system that we propose for the LEAP project, we have constructed modules similar to those used for each of the regions. The multiwire systems have evolved through several iterations,157"16" and we believe that they can be designed and produced to meet the specifications for LEAP. We have performed Monte Carlo simulation studies using realistic resolution responses for individual modules. These calculations showed that the resolution is insufficient to make a definitive assignment to the decaying isotope from a single observation of a coincident fission

~~TOP START SH3NAL, QfMDDED MULTIWIRE X-Y (3 cm x 16 cm)~~

~~LOW-PRESSURE ION COUNTER (2-T ISOBUTANE)~~

~~- GADDED MULTiWRE (16 cm x 16 cm)~~

~~""-PRESSURE WWDOW~~

~~(16 cm x 16 cm x 20 cm)~~

Fig. 8.4. Schematic of ihe composite detector system HEFT. NUCLEAR STRUCTURE AND REACTIONS 149 fragment pair. However, if we can overcome systematic uncertainties, we could probably make an assignment by detecting between 10 to 100 fission decays of the isotope. These calculations must be verified experimentally by scattering elements in the fission product range (Z = 30 to 60) at energies of about 1 MeV/nucleon into our HEFT prototype system. After we have successfully characterized the detector module, we propose to build an array of these systems for efficient detection of the short-lived spontaneous fission isotopes produced in :54Es bombardments. The detector modules are designed so that, for high efficiency, 10 systems can be placed in a ring (Fig. 8.5) that will be perpendicular to the beam axis. This complete system would not look directly at the target because the prompt reactions would clearly overwhelm the counting capabilities of the system. Instead, we envision two modes of operation. The first would be a recoil shadow technique: the prompt reactions would be shadowed from ihe detector, and we would look at the residual recoils emerging from the system to study the prompt decay in flight. This technique has been successfully used in many fission isomer studies. With our expected recoil energies, this method would be useful for half-lives in the 1- io 100-nanosecond region. The second technique would be to collect the reaction recoils on a thin downstream foil and look for spontaneous fission decay between beam bursts. This technique would have an operational limit

~~20 cm—~~

Fig. 8.5. (a) Proposed ring containing 10 detector modules for high-efficiency measurement, as viewe'l looking in the direction of the beam, (b) Detector cross section, as viewed perpendicular to the beam. ISO NUCLEAR STRUCTURE AND REACTIONS

for half-lives in the 10-nanosecond to 1-millisecond range. In principle, there is no upper limit; however, background build-up and the viability of the competing gas and mechanical transport techniques for half-iives greater than 1 millisecond would make these the techniques of choice. We have performed an initial proof-of-concept test using the design criteria of HEFT. The test detector (Fig. 8.6) consisted of two multiwire components separated by an ~20-cm-long drift ionization region. Fission products like heavy ions were produced at the Los Alamos Van de Graaff Facility and scattered into the detector array. We obtained position and timing informalion

~~GRIDDED MULTIWIRE (x.y.t)~~

~~LOW-PRESSURE IONIZATION CHAMBER (AE) . CSIODED f MULTIWIRE (x.y.t)~~

~~Fig. 8.6. Schematic of test detector system consisting of two multiwire components separated by a drift ionization region.~~

from the multiwire components and a AE signal from the ionization region. For individual heavy ions transversing the detector, we measured a timing response of a < 200 picoseconds. In Fig. 8.7, the two-dimensional correlation of flight time and energy loss for icns is presented. For the adjacent elements tellurium and iodine, at approximately the same energy per nucleon, separation of the me^n values is clearly observed. However, the dashijd line shows the FWHM for these distributions, and it is evident that substantial overlap occurs for the adjacent elements. The effective Z/AZ resolution is ~25 in this test system and would require detection of 10 to ICO events to make a high-confidence assignment to a specific element for a fissioning system. NUCLEAR STRUCTURE AND REACTIONS 151

~~I !7I(93M»V) (0.732 MaV/u)~~

~~\130T«v'8&a5M«Vj (0.656 MaV/u)~~

~~I -•— TIME (CHANNEL NUMBER)~~

Fig. 8.7. The AE vs liming correlation for scattered heavy ions into test detector. Solid lines show distribution of measured centroids, and dashed lines indicate measured FWHM for the individual ions.

~~DEVELOPMENT OF FAST NEPTUNIUM CHEMISTRY AND THE SEARCH FOP. NEW ISOTOPES OF NEPTUNIUM~~

Malcolm M. Fowler, Hans R. von Gunten,* and the SISAK Collaboration**

The lack of suitable nuclear reactions to produce neutron-rich actinides has prevented the production and study of many of these nuclides. Most of the known neutron-rich actinide nuclides have been produced through neutron capture, light-ion stripping, or direct reactions with exotic targets. All of these reactions limit the range of products that can be produced. Complete fusion reactions with heavy ions have small cross sections and produce neutron-poor actinides because of the bend in the valley of beta stability toward higher neutron proton ratios. At present, the only hope of producing new, beta-decaying actinides is through transfer reactions that use heavy ions with neutron-rich actinide targets.

•Eidgenossisches Institut fur Reaktorforschung, Wfirenlingen, Switzerland and Anorganisch-Chemisches Institut, University of Bern, Bern, Switzerland **W. Briichle, M. Brugger, H. Gaggeler, K. Moody, M. Schadel, and G. Wirth, Gesellschaft fiir Schwenonerforschung, Darmstadt, Germany; G. Herrmann, N. Kafrell, P. Hill, J. V. Kratz, J. Rogowski, H. Tetzlaff, and N. Trautmann, Institut fur Kernchemie, Johannes Gutenberg University, Mainz, Germany; J. Alstad, Department of Chemistry, University of Oslo, Oslo, Norway; and G. Skarnemark and M. Skalberg, Department of Nuclear Chemistry, Chal.ners University of Technology, Guteborg, Sweden 152 NUCLEAR STRUCTURE AND REACTIONS

Extrapolation of results from irradiations of !4!Cm and 249Cf targets with '36 Xe beams (Refs. 161 and 162, respectively) indicates that the new nuclides 243Np and 244Np should be produced from 244Pu with significant cross sections (>0.1 mb). In an attempt to produce these new isotopes of neptunium, we formed a collaboration to combine the fast chemical separation methods developed at Mainz with gas jet transport of recoil products and targetry at the UNILAC at GSI. At the UNILAC, we irradiated thin targets of 244Pu with 136Xe ions to produce neptunium isotopes by transfering protons from the target to the projectile. The products of the reactions recoiled out of the target and were tnermalized in nitrogen gas loaded with potassium chloride aerosol particles. The products became attached to the aerosol particles and were transported to the chemistry laboratory for chemical processing. The total time from production to delivery at the chemistry laboratory was about 40 seconds, and the efficiency was around 40%. We chose the SISAK method161 for the neptunium chemistry because it is fast and has good chemical yields. This technique involves a continuous solvent extraction of the element of interest. Phase separation during the extraction is effected by high-speed centrifuges that use continuous flow. Several extraction/back-extraction steps are usually needed to ensure the required purity of the final product. The effluent from the SISAK system is transported through small-bore tubing to a detector system. In most cases, the detector is a shielded high-resolution Ge(Li) photon spectrometer. The major disadvantages of the SISAK system are the large volumes of extraction solutions required and the relatively short time that the product stream is near the detector. In preliminary work at Mainz, two methods for separating nep'.unium were developed for the SISAK system. Both methods relied on the differential extraction of neptunium in various oxidation states. In the first method, the aerosols containing neptunium were dissolved in dilute nitric acid; the neptunium was oxidized to the +6 state with eerie ion and then reduced to the +5 state with HNO:. This solution was extracted with HDEHP in CC14 to remove most fission products and actinides. The aqueous solution containing the neptunium was again treated with eerie ion for reoxidation of the neptunium to the +6 state, and the solution was again extracted with HDEHP. Finally, the neptunium was back-extracted from the HDEHP by reducing the neptunium to the +5 state with either H:O2 or HNO:. The second method, outlined in Fig. 8.8, starts with the dissolution of the aerosols containing neptunium in 0.6 N HC1 containing 0.3% TiCl3. In this step, the neptunium is reduced to the +3 state. The aqueous solution is extracted with HDEHP in CC14 to remove some fission products, and the neptunium is oxidized to the +4 state with dilute nitric acid. The neptunium is then extracted into HDEHP and finally back-extracted with 15% H,PO4 at 50°C. Both HDEHP- containing solutions are recycled and the second one is washed with 2 N HC1 during recycling. We ran a series of tests at the reactor to test both methods for separation from fission products, chemical yield, and holdup time. In these tests, we used reactor-produced 2"Np as a tracer and chemical-yield monitor with fission products from a 2"Pu target in the reactor. We finally chose the second method for the actual experiments because the reduction of neptunium in the last step of the first method was too slow. We found that with the second method the overall chemical yield was a suprising 70 to 75% and that the holdup time was or.ly about 10 seconds. The decontamination from other unwanted products was excellent. In the actual experiments at GSI, we made a series of irradiations at two different energies. We collected gamma s;pectra of the products from the SISAK system for periods of a few hours at each irradiation energy. The gamma rays associated with the decay of the isotopes of neptunium were identified using previously determined level schemes for the beta-decay daughter products.164165 We estimated the half-lives of :4'Np and 244Np by adding a delay loop in the delivery lube going from the SISAK system to the gamma detector. We normalized the data obtained with and without the loop to reproduce the known half-life of 242Np (5.5 minute), and we applied this normalization to the data for the other neptunium isotopes. A crude idea of how the excitation function was shaped was also inferred from the two irradiation energies. NUCLEAR STRUCTURE AND REACTIONS 153

~~Waste 5% HDEHP in gases 7% HDEHP in CCI4 CC1~~

~~2N HCt Waste~~

~~Delay loop~~

~~[Detector~~

~~N2 + KCI Aerosol from target chamber~~

~~Fig. 8.8. Schematic of SISAK system for neptunium separations.~~

We are still evaluating the results of the experiments, but it seems that we have observed both :41Np and :44Np for the first time. Preliminary results from the experiments are summarized in Table 8.1. The measured half-lives are somewhat shorter than predicted,166 whereas the cross sections are about the size expected. It is now clear that if one is to make more detailed measurements, the only way to increase the counting rate is to increase the detection efficiency, and we are evaluating several methods to accomplirh this task. The most promising method seems to be collecting the neptunium on an absorbing bed or column in front of the detection system.

TABLE 8.1. Half-Lives and Cross Sections for Neptunium Isotope Production from Bombardment of 244Pu with 136Xe Ions Production Cross Section9 Nuclide Gamma Energy Half-Life 10.2 MeV/u 10.56 MeV/ub (KeV) (seconds) (mb) (mb) 242Npt 159 330 0.46 0.96,0.64d 243Np 287.5 50 ±20 0.28 0.56, 0.53d 244Np 162 22 ±11 0.64 1.0, 1.2d

'Assuming that the detected gamma ray was 100% abundant. •The l36Xe bombarding energy. 'Reference nuclide used to normalize runs. "•Results from duplicate runs. 154 NUCLEAR STRUCTURE AND REACTIONS

~~LAMPF He-JET COUPLED MASS SEPARATOR PROJECT~~

~~Merle E. Bunker, Willard L. Talbert, Jr., Hermann Wollnik, and John W. Starner~~

Introduction We are investigating the technical feasibility of using a He-jet coupled on-line mass-separator system at LAMPF to study nuclei far from stability. The He-jet activity transport approach, used in conjunction with a target chamber placed in the LAMPF main beam, has two main attractions: (1) it provides access to isotopes of a number of elements that cannot be efficiently extracted for study at any other type of on-line facility, either existing or proposed, and (2) low cost. Our studies have shown that essentially all elemental species produced in spallation and fission reactions (except for the gaseous products) can be transported through a 22-m-long capillary from a target chamber in the LAMPF beam with absolute efficiencies of about 60%. Also, we have found that the transport time is short enough to allow studies of activities with half-lives as short as 300 milliseconds. Because the He-jet technique requires targets thin enough to allow a large fraction of the reaction products to recoil out of the target foils, a very large incident beam current, comparable to that available at LAMPF, is needed to produce sufficient yields of individual radioisotopes for detailed nuclear studies. The separated ion beams extracted from the proposed separator would be directed to various experimental devices that are capable of determining basic nuclear properties such as half-life, spin, nuclear moments, mass, and nuclear structure. The data acquired would have broad application to theories of nuclear matter and to such related topics as nucleosynthesis of the elements. We estimate that several hundred previously unobserved nuclei, both neutron-deficient and neutron-rich, would become available for study. These prospects would inevitably attract a sizable international users group. This project was initiated in FY 1981 with a proposal to conduct experiments at LAMPF. Two sets of experiments, carried out in FY 1982 and FY 1983, have demonstrated the feasibility of the He-jet activity transport approach. In FY 1984, we performed additional experiments at the OWR using fission products of :35U to study and optimize the target chamber design and to quantify the relative performance of different aerosols.

New Results The target chamber constructed for studies at the OWR simulated the one to be used in the main beam at LAMPF. The chamber had a diameter of 7.6 cm and a thickness of 4 cm. A neutron beam of diameter 7.6 cm, extracted from the thermal column of the OWR, was directed through the chamber. The beam could be interrupted by a fast-acting cadmium shutter, which permitted accurate timing measurements. Using aerosols of NaCl, K.C1, and PbCl2, we determined relative transport efficiencies by monitoring the activity transported through the capillary. These studies determined that PbCl, v.as the most efficient transport aerosol: about 20% better ihan K.C1 and about 50% better thar NaCl. The use of PbCl2 also offers possible advantages in the He-jet skimming operation (because of the high molecular weight) and in ion-source tolerance (because of the lower vaporization temperature). These considerations strongly support the use of PbCl2 in the proposed LAMPF system. The target chamber used at OWR could be configured to vary the number of inlet and outlet lines to study tlie dependency of transient activity build-up upon the number and orientation of inlets and outlets. We found that two inlets (at ± 135° to the central outlet capillary) gave the optimum rate of activity build-up and that using up to five outlet capillaries improved the flow of activity from the target chamber very little, if any, compared to the use of a single outlet capillary. We have concluded that the target chamber configuration for LAMPF should have two inlets, one outlet capillary of 2.4-mm inside diameter, and a target chamber pressure of 250 to 350 kPa. For these conditions, the activity transported in the OWR experiments reached about 50% of the equilibrium value within 600 milliseconds. NUCLEAR STRUCTURE AND REACTIONS ISS

With the assistance of MP Division, two target chambers have been designed, one for fission targets and one for spallation targets. These chambers, which are designed for remote servicing, will be located at the end of a vertical shield plug that will be incorporated in the LAMPF A-6 beam-stop area. The target chambers will incorporate the inlet and outlet geometries determined from the OWR experiments a ad will feature double containment to allow use of actinide targets. The shield plug is designed to be remotely raised and lowered to move the target in and out of the LAMPF beam. To define more accurately the boundaries of the mass regions that could be accessed with the proposed He-jet coupled isotope separator system, we have estimated production cross sections for both neutron-rich and neutron-deficient nuclei far from stability for 800-MeV proton reactions. We estimated the spallation-product cross sections through use of the Rudstam systematic*.l6' For estimation of the fission-product cross sections, however, there is no established, similar approach. Thus, we took an empirical approach in which two overlapping Gauss' < distributions were fitted to existing rubidium and cesium isotopic distributions obtained"1816" al (56 MeV to 1 GeV—one Gaussian for the neutron-rich portion of the distribution and one for the neutron-deficient portion. The parameters of the Gaussians were then varied with A and Z to account for mass-yield variations and other differences between the rubidium and cesium data. We adjusted the cross- section distributions to 800 MeV by interpolating existing data obtained with protons of energy 156 MeV, 170 MeV, and 1 GeV. The results of these cross-section estimates are shown in Figs. 8.9 and 8.10 for spallation and fission reactions, respectively. In these figures, the solid outline indicates a boundary beyond which the nuclear half-lives are predicted by the gross theory of beta decay170 to be <300 milliseconds. If we assume that 1000 atoms/second of a mass-separated radionuclide are needed for spectroscopic measurements and that the mass separator system has only a 1% overall efficiency, a partial cross section of about 0.7 ub is required for the nuclide in question if we assume a LAMPF beam intensity of 800 uA. According to our cross-section estimates, essentially all neutron- deficient nuclei with half-lives >300 milliseconds will be produced in 800-MeV spallation with a

~~Contours 1 ub - 10 mb~~

Fig. 8.9. Chart of nuciides showing contours of calculated spallation production cross sections. The targets used are aluminum, scandium, iron, germanium, molybdenum, tin, lanthanum, terbium, tungsten, bismuth, and uranium. The dashed line is the limit of known decay schemes. 156 NUCLEAR STRUCTURE AND REACTIONS

~~100 T T~~

~~60-~~

~~40- • Target nucleus Contours 1 fib - 10 mb 20-~~

~~0 20 40 GO 80 100 120 140 160 180~~

~~Fig. 8.10. Chart of nuclides showing contours of calculated 238U(p,f) production cross sections.~~

cross section of > 1 ub (assuming the use of at least 10 different target materials). Interesting nuclear regions that could be reached include 7flSr and lll0Sn. On the neutron-rich side of stability, most nuclei with half-lives >300 milliseconds and mass 60 to 135 can be reached in high-energy fission of :1SU with a cross section of >1 ub.BetweenA= 135and 160, the 1-ub contour does not reach all the way to the 300-millisecond limit, but there are many neutron-rich nuclei within this contour that have not yet been observed. Depending on the type of nuclear property, the numbers ot nuclei between known limits and the 300-millisecond or 1-ub limit that are not yet studied (and in most cases, not available elsewhere) are presented in Table 8.2. Clearly, much "territory" in the chart of nuclides remains to be explored. We estimate that at least half of the hundreds of unstudied nuclei in Table 8.2 can be accessed only with a He-jet on-line separator system. We have obtained an isotope separator from LBL that had been placed on the surplus equipment list. This separator, designed and built by Maynard Michel, is superbly engineered, and its acquisition will decrease the cost of our proposal accordingly. The separator has been received and is presently in storage; it will not be reassembled until we are assigned space in the new LAMPF staging area building. Ion-optical designs, based on use of the 90°-sector field magnet obtained from Berkeley, have been made for the proposed LAMPF on-line separator system. The designs take into account problems that arise from changes in the ion-source plasma surface, incomplete space-charge compensation in regions of intense beam-current densities, and effects of beam-limiting slits. The designs will provide compensation for ion-source and beam fluctuations and minimize cross- contamination of the separated beams caused by residual gas scattering, charge exchange during acceleration, or undesirable isobaric components. The design employs a beam transfer section before the first separation stage to form an intermedia! i' image of the ion source object; this provides compensation for ion-source changes by adjusting th. transfer section parameters. Incomplete space-charge compensation is mitigated by using an astig natic lens in the transfer section, thereby avoiding the high ion densities caused by concurrent focusing in tvo dimensions. Beam-limiting slits are used only to limit tails of the unseparated beam, unless they are needed for high-resolution operation after the main separator stage. NUCLEAR STRUCTURE AND REACTIONS 157

TABLE 8.2. Numbers of Nuclei Between Known Limits and Estimated Production Limits (Z = 10 Through m. Spallation Property Products "*U(p,f) Spin-parity 646 401 Mass 436 281 Decay schemes 630 243 Half-Jife 198 170

Cross-contamination is avoided by employing tandem magnetic stages and either an electrostatic sector or an elevated potential for (one of) the magnetic stage(s). In addition, the system can be constructed to increase vacuum pumping speed in the acceleration region. Isobaric contaminants can be removed by selective ionization or high mass resolution (10 000 to 30 000). The separator designs also take into account third-order aberrations and employ correction octupole and hexapole fields. The transfer secuon has been designed as a quadrupole triplet. All elements except the main separator field are electrostatic and should be adequate for currents from the ion source of a few milliamperes. Later, a 55" preseparator magnetic sector could be added to improve discrimination against rest-gas scattering contamination. An ultimate mass resolution of 30 000 has been calculated for this two-stage system, at a cost in transmission of appro-'imatclv 75%. "

Status and the Future We are preparing a proposal to DOE/HENP for funding of this project. Outside interest in a He- jet coupled on-line isotope separator at LAMPF has been high; forty experimentalists and 15 theorists, representing i7 other institutions, have expressed their intent to part.cipate in the associated research program. There may be additional users if a proposed on-line separator system at TRIUMF is not built. The He-jet approach for on-line separator systems has been pursued at other laboratories171 on a scale much more modest than that proposed at LAMPF. Because of the historical difficulty in coupling a separator ion source to the He-jet transport line, overall system efficiencies have generally been quite low. We plan to redesign the generally used hollow-cathode ion source and test its performance with the on-line He-jet system at Idaho Nuclear Engineering Laboratory (INEL) vhere it is used to transport and separate :5:Cf fission products. In addition, we are studying novel i source approaches (as applied to mass separators) such as the cusp-field source, which may o r stable performance, high efficiency, and high tolerance to "background" helium. If such an approach appears feasible, we plan to test it at INEL. 158 NUCLEAR STRUCTURE AND REACTIONS

~~LOS ALAMOS MESON PHYSICS FACILITIES~~

~~DIRECT MASS MEASUREMENTS IN THE LIGHT NEUTRON-RICH REGION BY USING A COMBINED ENERGY AND TOF TECHNIQUE~~

Chandra Pillai,* David J. Vieira, Gilbert W. Butler, Jan M. Wouters, Sayed H. Rokni,** Kamran Vaziri,** and Louis P. Remsberg*

Of approximately 300 new atomic masses reported since 1975, the most important" measurements taken to test atomic mass models have been those involving a concentrated set of measurements that extend far from beta-stability.l7: Two excellent examples are the isotopic series of mass measurements carried out on the alkali elements173'5 and the alpha-decay chain Q value measurements originating from l76l78Hg (Refs. 176 and 177). Both provided extensive sets of new data that helped to reveal systematic deficiencies in a variety of atomic mass models. But extensive as these measurements were, each was limited by what could be measured (that is, a particular isotopic sequence or a particular decay chain). In the experiment described here, we attempted to further extend mass measurement capabilities by developing a more general approach in which a whole array of nuclei that lie far from stability can be measured simultaneously, independent of both N and Z. We demonstrated that direct mass measurements can be performed for fast- recoiling nuclei by using a combined energy and time of flight (TOF) technique.

Experimental Method and Results The experimental setup is shown in Fig. 8.11. We used LAMPFs high-intensity 800-MeV proton beam to bombard a thin uranium target (300 to 450 ng/cm:) that was supported on a backing of pyrolytic carbon (0.6 to 1.1 mg/cnr). Reaction products resulting from the fragmentation of uranium (or the spallation of carbon) were detected in the 45° flight tube of the thin target experimental area. The detection system consisted of (1) two secondary-electron, channel-plate (CP), fast-ciming detectors'78 (~25-|.ig/cnr carbon/Formvar foils) located approximately 285 and 468 cm from the target and (2) a gas ionization counter, specially designed for this experiment,l79 to obtain good energy and Z resolution. The counter operated with CF4 gas at 35-torr pressure and had a stretched polypropylene isolation window of ~70 ug/cm2; it provided the following energy

~~INCIDENT FAST TIMING GAS IONIZATION BEAM DETECTORS COUNTER~~

~~rX \. TARGET COLL CP1 CPZ 1 CATHODE 1 —1 ! H 1~~

~~X &E, AEj E E,sl /^\ WINDOW~~

~~Fig. 8.11. Schematic of the experimental layout.~~

~~"Oregon -State University "Utah Slate University tBrookhaven National Laboratory NUCLEAR STRUCTURE AND REACTIONS 159~~

signals: AE1. AE2, E, and Erej. Data acquisition was triggered by a CP1 • CP2 • AE1 • AE2 • E • Erej coincidence. A total of 17 parameters were recorded with each event, of which 4 were primary parameters [TOF(CP1-CP2), AE1, AE2, and E] and 13 were secondary parameters. We subsequently used the secondary parameters during data analysis to stabilize or to correct the data and to reject misidentified or unusual events. The experiment ran for 4 months during which ~ 50 million events were recorded for 60 different runs; the integrated beam current on the target was ~4000 Coulombs. We determined ihe Z of each event by using a AE2-E or AE2-TOF table look-up method after corrections were made for gas density variations and mass dependences. The mass was calculated from the total energy, TOF, and flight-path distance. The total energy was determined by summing the energy deposited in the ion counter (that is, AE1 + AE2 + E) and the energy lost in the CP1/CP2 foils and gas isolation window. The latter energy losse\ were calculated using a method for which the AE2-E table served as a dE/dx table. The TOF used in the mass determination was thai derived from the target-to-CP2 timing, for which a beam pickoff method was employed.'80 Although the TOF(CP1-CP2) measurement had a timing uncertainty of ~ 300 picoseconds, a slightly improved velocity measurement could be obtained from target-to-CP2 timing because of its longer flight path. An effective timing and energy uncertainty of 700 picoseconds and 400 keV, respectively, was deduced for "Ne over a target-to-CP2 (light path distance of 468 cm. The mass resolution was typically 1.0 to 1.2% at the collimator setting, which gave the best mass measurement accuracy per unit time. For all but the highest energy ions, the mass resolution was limited by the energy resolution. Figure 8.12 shows the final mass spectra for nitrogen and fluorine. The centroid (more specifically, the arithmetic mean) of each mass line was determined using a moments analysis approach. Figure 8.13 shows a plot of the difference between the known mass176 and the extracted mass centroid (that is, 5 = massinnwn — mean) vs the mass number for the range of nuclei measured in this experiment. We observe a smoothly varying surface of differences ranging from —0.15 amu for l50 to -i-0.11 amu for :"Ne. These experimental deviations result from the difficulty of correctly determining the energy and TOF on an absolute scab over a broad range of Z, A, and energy.

~~o —~~

~~M 00 18 00 22.00 15 00 19.00 2 3 00 2 7 00 MASS((-"LUOR,NE )~~

~~Fig. 8.12. The mass spectra for (A) nitrogen (Z = 7) and (B) fluorine (Z = 9) isotopes. 160 NUCLEAR STRUCTURE AND REACTIONS~~

~~1 T ~l 1 1 1 1 i 1 015 6 = U -MEAN 010 / /'\ N= .i-;,, 0.05 N=15~~

~~0.1)0 /•' ^N=14 N=IO N=13~~

~~-0.05 - N=9 '••••-/ X 8 - •'* '•-••'' N=12 \ -0.1.0 N=7 N=1 1 " \ " )••• z=u~~

~~Z=6 / Z=10 / • •••' -0.15 Z=3 1=3 /' Z=fl 1 1 1 1 1 1 1 1 i 12 14 18 IB 20 22 24 28 MASS NUMBER~~

Fig. 8.13. The measured mass deviation vs mass number. Isotonic and isotopic members are connected by dashed lines and labeled according to their N or Z. Errors are contained wuhin the size of the data points unless otherwise indicated.

To evaluate how fundamentally limiting these experimental deviations are to this technique, we attempted to fit and extrapolate these deviations as a function of A or Z. For isotopic sequences, a quadratic expression in A described the data well. In general, isotonic and isobaric sequences did not have as many nuclidcs as did the isotopic series, and they were difficult to fit and extrapolate. Instead, the difference between adjacent isotonic or isobaric members was fit as a simple linear function of A. For each nuclide of interest, all three methods extrapolated to the same value within their respective errors. In Table 8.3 (column 2) the weighted average of the three extrapolated deviations is given for several neutron-rich light nuclei. Comparing these to the known deviations (column 3), we find good agreement in every case. We determined the masses of several neutron-rich light nuclei by adding the extrapolated deviation to the measured mass centroid. These masses are quoted as mass excesses in column 4. Although the error bars are relatively large (2.6 to 8.0 MeV) for these measurements, we found excellent agreement with the known masses (column 5). In all cases, errors were limited by the statistical uncertainty of the IT ass line centroid, not by the extrapolation error. For the first time, the experimental masses of the previously unmeasured nuclei, 20N and 24F, were determined. These agree well with the systematic mass predictions of Wapstra and Audi.176

Summary In this experiment, we have demonstrated that direct mass measurements can be performed (albeit they are of low precision in this first attempt) by means of a combined energy and TOF method. This technique has the advantage that many particle-bound nuclei produced in fragmentation reactions can be measured simultaneously, independent of their particular N or Z. The main disadvantage of this approach is that both the energy and the TOF must be measured accurately on an absolute scale. Although small deviations of the mass centroids as a function of N and Z were < bserved in this experiment, these uncertainties were largely removed by extrapolation of the NUCLEAR STRUCTURE AND REACTIONS 161 smooth dependence observed for known nuclei that lie closer to the valley of beta-stability. We performed mass measurements for several neutron-rich light nuclei ranging from I8C to 26Ne. In all cases, these measurements agree with Wapstia and Audi's latest mass compilation.'76 The masses of :"N and -4F were determined for the first time. A report on this work was presented at the 7th International Conference on Atomic Masses and Fundamental Constants (AMCO-7) (Ref. 181), and a separate manuscript is being prepared for publication. This research represents the major part of the Ph.D. thesis work of Chandra Pillai from Oregon State University.

TABLE 8.3. Comparison Between Extrapolated and Measured Mass Deviation; Determined vs Known Mass Excess for Light Neutron-Ricl:i Nuclei Extrapolated Measured Measured Known A, Deviation" Deviation1" Mass Excess0 Mass Excess Sc«( amui sobsi(amu) (MeV) (MeV) I7C -0.0107 (±0.0030) -0.0118 (±0.0044) 20.0 (±4.9) 21.025 (±0.035) 18C 0.0187 (±OJ041) 0.0211 (±0.0076) 22.7 (±8.0) 24.890 (±0.150) l9N -0.0046 (±0.1020) -0.0029 (±0.0026) 14.3 (±3.0) 15.867 (±0.047) 2UN 0.0288 (±0.J033) .... — 21.9 (±5.7) 22.10d — 210 0.0267 (±0.4018) 0.0261 (±0.0028) 8.7 (±3.1) 8.127 (±0.052) 22O 0.0634 (±0.1)033) 0.0632 (±O.G059) 9.7 (±6.3) 9.443 (±0.087) aF 0.0609 (±0.0023) 0.0597 (±0.0024) 4.5 (±3.1) 3.354 (±0.170) d l' 0.1018 (±0.11027) — — 8.3 (±4.5) 8.75 — 25Ne 0.0734 (±0.0020) O.d735 (±0.0034) -2.2 (±3.6) -2.1S6 (±0.091) 26 Ne 0.1114 (±0.11023) 0.1122 (±0.0054) —u.f (±5.5) 0.440 (±0.'072) "Weighted average of three independent extrapolation methods (see text). b = 80&s massim,,,,., — mean. TVIeasured mass •= mean + 5eX(. ''Systematic mass predictions taken from Ref. 176. 162 NUCLEAR STRUCTURE AND REACTIONS

~~PION NUCLEUS DOUBLE-CHARGE EXCHANGE AT LOW ENERGIES~~

Michael J. Leitch, Eliazer Piasetzky (MP-4), Helmut W. Baer (MP-4), J. David Bowman (MP-4), Robert L. Burman (MP-4), Bruce J. Dropesky, Peter A. M. Gram (MP-4), Farokh Irom (MP-4), Donald Roberts (MP-4), Glen A. Rebka, Jr.,* Jim N. Knudson,** Joseph R. Comfort,** Virginia A. Pinnick,** Dennis H. Wright/ and Stephen A. Wood.*

Picm double-charge exchange (DCX) is particularly interesting to study because it must involve two nucleons and thus is sensitive to correlations among nucieons. At pion energies near 50 MeV, a unique situation occurs. The cross section at forward angles for pion single-charge exchange (SCX) to the isobaric analog state (IAS) on light nuclei is vanishingly small.1" This is a result of a near cancellation of the s- and p-wave amplitudes for SCX on the nucleon; this effect persists for SCX on light nuclei. Consequently, the contribution of two sequential SCX scatterings to DCX is expected to be suppressed. Optical model calculations confirm this behavior, generally giving a flat cross section with angle. Thus, at energies near 50 MeV, the DCX reaction to the double isobaric analog state (DIAS) has an enhanced sensitivity to nucleon correlation effects. Recently, Miller181 proposed that explicit quark effects play a strong role in DCX near 50 MeV. His model assumes that pairs of nucleons, each a collection of three quarks, sometimes form a six- quark cluster in a nucleus. This cluster can then contribute to pion DCX and produce a strong forward peaking in the cross section. Other standard mechanisms, Miller claims, do not produce this large forward angle DCX cross section while still giving a small SCX cross section at forward angles. The oniy previous DCX data at this energy'84 could not confirm nor deny this feature because of the data's large error bars and the instrumental limitation of only a 50° forward angle. To establish the shape of the angular distribution and »hus investigate these correlations or possible six-quark bag effects, we have measured the cross section for 14C(jt+,7T)l40 (DIAS) at 50 MeV for scattering angles between 20 and 130° with a relative accuracy of ±10%. (Details of the experiment are contained in a recent paper.185 The results show a strong forward peaking of the cross section and are consistent with prior measurements.184 In Fig. 8.14, the DCX angular distribution at 50 MeV is shown with the SCX data for 15N(rc+,7i°)l5O (IAS). The I5N data, where one valence neutron is involved in the reaction, have been multiplied by 2 to approximate the analogous cross section for the two valence neutrons involved in the SCX reaction on 14C. One can see that the DCX cross section at forward angles is nearly as large as that for SCX. The solid curve is Miller's six-quark calculation, which predicts too high a cross section at. forward angles but which Miller claims will be lowered when absorption is treated correctly. The dashed line through the data was used to determine the angle-integrated cross section of 15.3 ± 1.6 mb and to extrapolate to the zero-degree cross section of \9 ±0.5 ub/sr. In Fig. 8.15, the energy dependence of the zero-degree cross section is shown. One can see that the SCX and DCX cross sections approach each other in magnitude near 50 MeV (both the SCX data above 80 MeV and the DCX data are published;166187 the lower energy SCX data are preliminary). Also, the DCX cross section at 50 MeV is about the same size as that at 300 MeV. The existence cf a six-quark cluster mechanism for DCX is supported but not proven by our measurements. More traditional models are also being developed to explain these data, and they have met with some success. To distinguish between these various mechanisms, ° will make further measurements to establish the systematics of low-energy DCX with energy ana with target nucleus or A. Nevertheless, it is clear that these measurements have a strong sensitivity to nucleon correlation phenomena and are an important step toward understanding the nature and importance of the various reaction mechanisms.

~~'University of Wyoming ••Arizona State University 'Virginia Polytechnic Instil ilu and Stale University *Tel Aviv University, Tel AVJV, Israel NUCLEAR STRUCTURE AND REACTIONS 163~~

~~zoo i I I I I~~

~~100 -~~

~~l5N(ir>*)l5O(IAS) 48 MeV x£~~

Fig. 8.14. The angular distributions of the cross section for 50-MeV pion single- and double-charge exchange to the isobaric analog state. The "N SCX cross 10 sections have been multiplied by 2 to approximate the MC SCX cross section.

~~JO a.~~

~~G O(DIAS) •a~~

~~i.o~~

~~20 40 60 80 iOO ISO 140~~

~~&m(deg.)~~

~~Fig. 8.1S. The zero-degree cross section for pion single- and double-charge exchange vs energy showing the dramatic behavior in both near 50 MeV.~~

~~1 i~~

~~I i * :"C(TT->-)"1O{DIAS) I p.co~~

~~_l L_ 100 200 Tjr (MeV) 164 NUCLEAR STRUCTURE AND REACTIONS~~

~~SINGLE-PION PRODUCTION BY FAST PIONS~~

Bruce J. Dropesky, Gregg C. Giesler, Shuheng Yan,* Lon-Chang Liu, Rajeev S. Bhalerao,** and Yoshitaka Ohkubo*

In our continuing program to investigate the interactions of pions with complex nuclei, we have completed a study of the (JC,2JI) reaction employing activation techniques. W; know that pion- induced single-pio.n production on a nucieon dominates pion-nucleon inelastic reactions for energies between the (3,3) resonance (180 MeV) and about 1 GeV (Ref. 188). Thus, the investigation of (7c,2n) reactions in nuclei is an imponant extension of current pion-nucleus studies, whi:h are mainly concentrated at energies below about 300 MeV. Theoretical interest in this class of pion reaction is evidenced by recent papers by Eisenberg'*'1 a ad Rockmore.1'1" The only experimental work reported on the (rc,27t) reaction in complex nuclei is a measurement of the cross section ofthe(rc" ,)tT7i+) reaction from 210 to 375 MeV in emulsion nuclei (silver and bromine) by a Soviet group in 1969 (Ref. 191). They observed a total cross section of about 0.4 ub at 350 MeV, which is the energy used in our study. We carried out a study of this interesting and relatively unexplored reaction by measuring the cross sections for the reactions :7Al(rt\ 27t+):7Mg (9.45 minutes), 51V(jt\ 2rc+)5lTi (5.75 min), 45Sc(7i", 27t~)4iTi (3.1 hours), and "!Cu(rc, 27T)wZn (38 minutes). Pions of 350 MeV were selected as a compromise between an expected rising cross section and a declining pion beam intensity with increasing energy. The two (7iT.27r+) reactions yielded products that could be measured by means of a characteristic gamma ray associated with each (9.45-minute :7Mg and 5.75-minute 51Ti). High-resolution Ge(Li) gamma spectrometers were used to make these measurements. The two (K~,2K~) reactions, on the other hand, gave products that could only be measured by means of their decay by p+ emission, and thus, radiochemical separation and purification were required to observe the 3.1-hour 45Ti and 38- minute MZn products. We determined the P+ decay of these samples by counting the coincident 511-keV p"1 annihilation radiation using a pair of Nal(Tl) scintillators. Except for the aluminum targets, which served as their own beam monitors, target foils were sandwiched with external monitor foils: thin plastic scintillators with the vanadium targets and thin aluminum foils with the scandium and 61Cu targets. We converted the m jasured reaction product yields to cross sections by using the established cross section of the beam monitor reactions i:C(7t+,7iN)"C (20.4 minutes) (Ref. 192)and ^Al^.x^Na (15 hours) (Ref. 193). This study was complicated by the fact that the products from (K+,2K+) and (n',2iz') reactions are identical to those from (n,p) and (p,n) reactions, respectively. The latter reactions are brought about by secondary neutrons and protons that are produced by pion interactions in the necessarily thick targets. Thus, the yields of the reaction products must be measured as a function of target thickness and then the values must be extrapolated to zero thickness to determine the contribution from the (it,2it) reaction only. Figures 8.16 and 8.17 show the results of our measurements on the (7i+,2n+) reactions in 27A1 and "V, respectively. Cross sections for the sum of the (7C\2JI+) and (n,p) reactions are plotted against the average path length 5 for secondary neutrons. Remsberg and others developed the formalism for calculating 8, namely 8 = t/2[3/2 In (t/r)], where t is the target thickness and r is the radius of the target disk.1 "4 A least squares fitting of the measured points yields a zero-thickness intercept for the '"Al(7r',27rf )"Mg reaction of 14 ± 5 ub and for the 5lV(^+,27i+)5lTi reaction of 13 ± 8 ub.

""Institute of Atomic Energy, Peking, People's Republic of China **Tata Institute of Fundamental Research, Bombay, India institute of Physical and Chemical Research, Saitama, Japan NUCLEAR STRUCTURE AND REACTIONS 165

~~AIITT+, 2TT+) +(n,p) Mg(9.5min.)~~

~~50 100 150 200 250 300 350 400 Average Path Length £ (mg/cm )~~

~~Fig. 8.16. Cross section for the (7t+.2n+) reaction in : 'Al as a function of average path length K.~~

~~!40 1 1 1 r 1 1 1 i 1 1 1 1 1 h sl BIV(Tr*,ZirH ) • (n,p) Ti(5.75min.) 120 [350 MeV~~

~~100~~

~~BO io n 4- o - so 60 in in~~

~~oe 40 -~~

~~20 <*- 13± 8/it~~

~~0 ' ' ' j_. 1 1 i 1 1 1—1—1—1— 0.2 0.4 0.6 0.8 1.0 1.2 1.4 Average Path Length J(g/cm2)~~

~~Fig. 8.17. Cross section for the (ji+,27r+) reaction in 51v as a function of average path length 8. 166 NUCLEAR STRUCTURE AND REACTIONS~~

Unfortunately, analysis of the (K ,2n") data is much more complicated because the short range of secondary' protons in the target material means that the thickness dependence of the (p,n) reaction is nonlinear. To establish the shape of this function, we calculated the secondary (p,n) cross sections. The formalism for this calculation was developed by J. J. Berlijn* and the computer programming and calculations were carried out by W. R. Gibbs.** Input for these calculations consisted of the flux of secondary protons from 350-MeV pion interactions, calculated with our intranuclear cascade plus evaporation codes (ISOBAR'97DFFI%), and the experimental cross section vs energy data for the (p,n) reactions in 45Sc and h3Cu. By assuming that the calculated shape of the (p,n) vs target thickness is correct, we carried out a weighted linear regression calculation for the set of measured cross sections vs target thickness to arrive at a cross section value for zero thickness. Table 8.4 shows the results of these calculations for the (ii~,2ii~) reactions and our cross sections for the (rc\2jr) reactions. These experimental values are compared with theoretical cross sections for both the reactions that lead to particle-bound states (the only cross sections we determine experimentally) and the inclusive reactions.

TABLE 8.4. Experimental and Preliminary Theoretical Cross Sections for the (TC,2TC) Reactions at 350 MeV To Particle-Bound States Inclusive Reaction Experimental Theory Theory (ub) (ub) (mb) -7AK7c\2ir.+)27Mg 14±5 7.8 1.9 5IV(7c+,27i+)5ITi 13±8 4.6 2.2 45Sc(jr,27O45Ti 28 ±19 7.8 2.6

We calculated the (7i,2rc) reaction cross sections using a distorted-wave impulse approximation. In the calculations, the nuclei were described by the Fermi gas model, and the fundamental nN —- 1 7 TUTN amplitudes were computed from the Weinberg theory, " normalized to yield the correct production cross sections: on a free nucleon. To obtain cross sections for A(JI,2K)B reactions leading to all particle-bound states, we require that the excitation energies of the residual nuclei are below the threshold of particle emission so that the final nuclei remain particle stable. For the calculation of cross sections for the inclusive reaction A(n,27t)X, we removed this upper limit on excitation energies. Because of various approximations, these calculated cross sections should be considered preliminary. We see in Table 8.4 that although the uncertainties in our measured cross sections are large, the cross sections for the (7t,2jt) reactions to the particle-bound states studied here art very small and are consistent with the model calculations. On the other hand, we note that the inclusive cross sections are many hundredfold larger (several millibarns). Also, processes in which the produced pion has a charge onposite that of the incident pion have substantially larger cross sections than those we studied here. All of which indicates that in-beam experiments with large solid-angle detectors for the coincident outcoming pions should be feasible. We are encouraged by the results of this activation study and intend to pursue the investigation of these important (7I,2JC) reactions by using such techniques.

*From information received from J. J. Berlijn (Group X-8). """Information provided by W. R. Gibbs (Group T-5). NUCLEAR STRUCTURE AND REACTIONS 167

~~A UNITARY OFF-SHELL MODEL FOR THRESHOLD PIONIC ETA PRODUCTION AND ETA-NUCLEON SCATTERING~~

~~Rajeev S. Bhalerao* and Lon-Chang Liu~~

Pion-induced r\ production on a single nucleon is an important TIN reaction at energies above the much-studied (3,3) resonance region but below a pion kinetic energy of Tn = 1 GeV. In terms of the magnitude of the cross section, it is the second most important nN reaction in this energy region—second oniy tc rc-induced 7t production. The (n,r|) reactionsin nuclei are also of great interest. In the SU(6) model, T) differs from 7t° by having an additional ss quark-antiquark pair in its wave function. The systematics of r|N and n°N scatterings could yield information on the dynamic role of this ss pair in meson/baryon interactions. Like (y,n,) and other model of nuclear n, productions, (jt,n,) reactions will allow us to study n,N scattering. Hadronic and electromagnetic T)- production processes are different; however, the details of n,N scattering extracted from these different types of nuclear reactions will complement each other. Because TC° and r| do not beiong to the same isospin multiples comparative studies of A(n,T|)B and A(7i*,jr°)B reactions are also of interest. To date, little is known about nuclear (rc,n,) reactions, either theoretically or experimentally. In this report, we take a first step by presenting an off-shell model for the jtN —* r|N T-matrix, which can readily be used in nuclear (7t,r|) calculations. We recall that the off-shell domain is a kinematic region where the energy and momentum of an interacting particle (pion, nucleon, or eta in the present case) are not related to its nhysical mass by the usual relation M: = E; — p" of a noninteracting particle. This domain, though inaccessible by a free particle, is reached by all the collision partners in a nuclear reaction. Consequently, only models with off-shell dynamics explicitly taken into account could provide useful analyses of nuclear reactions. Our model will find immediate applications in the interpretation of A(7i±,r|)B data that will become available at LAMPF in the near future.1"" The threshold for the reaction Tip —- rjn on a free nucleon is at Tn = 561 MeV or a total cm. energy \Js = 1488 MeV. The total production cross section rises rapidly with pion energy and reaches a maximum (~2.5 mb) at Tn = 661 MeV or \/s — 1550 MeV (Ref. 199). For simple kinematic reasons, pionic reproduction in a nucleus is possible at much lower pion energies, In the forthcoming LAMPF experiments, pions of energies Tn = 500 to 550 MeV will be used. In this energy region, the basic nN —• rjN process is subthreshold with respect to rj production on a free nucleon. Existing theoretical models200 for the 7iN — r)N amplitu ie are based either on the K- matrix approach or on Breit-Wigner-type parameterization of the amplitude; the masses and the partial widths of various resonances are determined by fitting the experimental ^-production cross sections. However, these models are not suitable for calculating (it,r|) cross sections in a nucleus because they do not contain form factors to allow a physically meaningful extrapolation of the KN —» r|N amplitude to the off-shell domain. They also cannot predict the n,N elastic scattering amplitude, a quantity indispensable for evaluating the final-state interaction in A(7t,r|)B reactions. The theoretical model presented here overcomes these weaknesses. For the energy region in which we are interested (\/l < 1600 MeV), there are only three important reaction channels in 7iN collisions: the 7tN elastic scattering, the single-pion production ;iN — 7TTCN, and the eta production KN — r)N. Our model for these reactions is illustrated by the diagrams in Figs. 8.l8(a-c). Specifically, we assume that the basic reactions proceed through formation of an isobar. Because the r|N system has isospin 1/2, it can only couple to the isospin 1/2 isobars N* or to the nucleon N. For the 7tN — KKN process, we follow Ref. 201 and assume that it proceeds according to 7tN — N* (or A) —• 71A — 7i7tN. Here, A denotes the isospin 3/2 isobar corresponding to the rcN resonance at \/s — 1232 MeV.

~~Tata Institute of Fundamental Research, Bombay, India 168 NUCLEAR STRUCTURE AND REACTIONS~~

~~j ^ j \ / / t N a A N N a K N a N (a) (b) (c)~~

~~Fig. 8.18(a-c). Schematic representation of the separable interaction matrix elements.~~

In summary, we have included the vertices of the isobar formations: TIN <=* A, 7tA & A, JIN +± N*, itA <=* N*, and T|N <=* N*; N* are SI 1(1535), PI 1(1440), and D13(1520) nucleon resonances. However, we did not include the nN <=* N coupling because the energy region in which we are interested ( \/l = 1488 to 1600 MeV) is far away from the nucleon mass (939 MeV). Further, a recent experiment has indicated that this coupling constant is nearly zero.202 To conserve the total Slux of particles distributed among all the channels, we unitarized our model by solving a coupled- channel relativistic Lippmann-Schwinger equation based on these interactions. This coupled- channel approach gives reaction amplitudes for 7cN — 7tN, T|N —* r)N, rcN —• rarN, nN — K7tN, and TCN — T|N processes in a single calculation. We determined the coupling constants and the range parameters of the vertices and the energy dependences of the mass and width of the isobars A and N* by separately fitting the JIN (complex) phase shifts in the P33 A channel and in the S11, P11, and D13 N* channels (Ref. 203 and Arndt**). In general, we found two solutions for each of these N* channels. However, one of them could be readily eliminated because it led to N* —» TIN and N* —• TJN branching ratios that are incompatible with the measured values. Satisfactory fits were obtained in all cases; as an example, Fig. 8.19 displays our fit for the P33 and SI 1 channels. The parameters of the model are summarized in Table 8.5. Using these quantities determined from 7cN scattering, we have predicted the cross sections for jt"p — r|n. Theoretical results are compared with the experimental data of Ref. 199 in Fig. 8.20. The agreement is excellent and lends support to the validity of our model. We have noted that, because of combined spin-flip and nonspin-flip contributions, the cross section based on SI 1 or PI 1 channel alone is angle independent, whereas that based on D13 channel alone has a minimum at 9 = 90°. Further, the differential cross section calculated with SI 1 and PI 1 but without D13 can depend only linearly on cos9, making it obvious that the structure in the experimental cross section reflects the presence of the Dl 3 channel. This contrasts with the conclusion drawn in Ref. 198 that below \JT, = 1670 MeV, only S and P waves need be considered. Our model predicts an attractive S-wave interaction for low-energy n-nucleon scattering. The validity of this prediction will be checked with forthcoming A(n,r|)B data.198 We note that nN phast shifts generated by both the CERN theoretical group203 and Arndl have led to different values for \ arious coupling constants, range paramete- s, and energy dependences of the isobars. However, both efforts have yielded rc~p —• x\n cross sections that are compatible with experimental data. Because different coupling constants, range parameters, and energy dependences of the isobars imply different off-she!! interaction behavior, we believe future studies of nuclear A(jr,r|) reactions with our model will let us differentiate the qualities of rcN phase shifts given by the CERN theoretical group21", Arndt, and other research groups.

~~•From information provided by R. Arndt, Virginia Polytechnic Institute NUCLEAR STRUCTURE AND REACTIONS 169~~

~~TTN—«-TTN~~

~~£•- 80- 160~~

~~Sfeo •a rO ro 80 a. CO~~

~~1100 1200 1300 WOO 1500 1600 ()~~

Fig. 8.19. The TtN scattering phase shifts 5 (in deg.) and inelasticity parameter n vs y's. The SI! data of Ref. 203 ( ). Arndt's Sll data (•), and the P33 daia of Ref. 203 (A) and Arndt (*•) are compared with !he calculations shown, respectively, as the solid, dashed, and dot-dashed curves.

TABLE 8.5. Coupling Constants g, Range Parameters A (in MeV/c), and Bare Masses mu (in MeV)» Coupling to — P33 g (2.347) (1.247) m,, = (1323.5) A (331.0) (264.9) _-_ Sll g 1.384(1.301) 3.509 (7.080) 0.616 (0.769) m,, = 1608.1 (2088.0) A 344.3 (435.2) 203.3 (376.6) 465.1 (1503.0) Pll g 1.814(1.988) 5.019 (4.989) 0.267 (0.305) mn= 1588.6(1664.9) A 568.9 (573.5) 110.4(159.8) 207.1 (187.9) D13 g 3.073 (3.037) 1.411 (1.404) 0.334 (0.327) m,, = 1579.3 (1567.8) A 268.0 (289.5) 267.6 (250.1) 115.3(156.2)

~~"Numbers with and without parentheses are the results of ^N phase shifts of Arndt and of Ref. 203, respectively. 170 NUCLEAR STRUCTURE AND REACTIONS~~

~~0.5 1511 MeV 0.2~~

* 5

~~v/s • 1542 MeV~~

~~0 1572 MeV y 0.2~~

~~0.1~~

~~-1.0 -0.6 -0.2 0.2 0.6 1.0~~

Fig. 8.20. Differential cross section for ri'p — nn vs cosine of the production angle in the cm. frame Dashed and solid curves are obtained with parameters of Table 8.5, based on itN phase shifts of Ref. 203 and Arndt, respectively. Data are from Ref. 199.

~~NUCLEONS, DELTAS, AND OTHER BARYONS AS NONTOPOLOGICAL SOLITONS~~

~~Rajeev S. Bhalerao,* Jutta Kunz,** and Lon-Chang Liu~~

Understanding the nature of the strong interaction that is responsible for binding the nucleons in nuclei has been of prime interest in physics since the 1930s. Recent discoveries of many new particles in high-energy particle physics indicate that quarks and antiquarks are the building blocks of strongly interacting mesons and baryons. It is now established that there are at least six different types (flavors) of quarks (u,d,s,c,b,t) and antiquarks (u,d,s,c,b,t). Each of these types can exist in three color states. They interact through the exchange of gluons, and each gluon can exist in eight different color states. The microscopic theory for this strong interaction is termed in the literature "quantum chromodynamics" or QCD. The QCD theory may explain the fact that qjarks, antiquarks, and gluons have not been detected in isolation.

~~Tata Institute of Fundamental Research, Bombay, India "University of Giessen, Federal Republic of Germany NUCLEAR STRUCTURE AND REACTIONS 171~~

Although QCD is believed to be the theory for strong interactions, exact calculations based on this theory remain impractical because of its complexity. Many phenomenologiical models have been proposed to approximate the QCD. Among them are "bag" models in which the physics inside the bag involves explicitly the quark-gluon degrees of freedom. On the other hand, the bag confines the quarks and gluons so that they cannot exist in isolation. In the Ml T bag model204 and the chira! bag models/"5:"" a sharp bag surface was imposed in Ihe theory to produce the desired confinement. There is another class of model known as the soliton model, which does not have a sharp boundary separating the inner frorr. the outer region, and the confinement arises self consistently from the interactions. The soliton models that have received wide attention are the Skyrme solitons:" and the nontopological solitons of Friedberg and Lee.:"!i Wilets et alr[n first applied Friedberg and Lee's model to the modeling of nucleons and deltas. The mode! was extended to the studies of pions and other mesons with a simplified interaction by Shakin et a/." This latter group claimed that modification of the quark/quark interaction by the nuclear medium is responsible for the larger nucleons inside a heavy nucleus than inside a light nucleus.'" However, the authors of Rets. 209 and 210 restricted their studies to those ground-state mesons and baryons thai are composed of onlv two types of quarks and antiquarks (u,d,u, and d). We have generalized the Friedberg-Lee equation to include the s quark so that one can study baryons with nonzero strangeness as well. Our results for baryon masses are given in Table 8.6. As one can see, the theoretical predictions are in satisfactory agreement with the experimental results. Our calculations also led to the masses mu = rads0 and rn, = 350 MeV, which are compatible with currf "tly accepted values for quark masses. As i.r.is work continues, our main efforts are to introduce forces resulting from 1-gluon exchange to lift the degeneracy of the masses among the baryons of the same row in Table 8.6.

TABLE 8.6. Baryon Masses Given by the Nontopologkal Soliton Model Ave.age Masses (MeV) No. of Strange Particles Quarks Experiment Theory p,n, A+',A+,A",A- 0 1134 1139 A', v f v v - l 1265 11285 Y*+ V" V-

~~Z, i — , — , i 2 1426 1447 Or 3 1671 1617 172 NUCLEAR STRUCTURE AND REACTIONS~~

~~LAMPF NUCLEAR CHEMISTRY DATA ACQUISITION SYSTEM~~

~~Gregg C. Giesler~~

The data acquisition system (DAS) is a PDP-11/44 computer-based system that is used for data acquisition and analysis at the LAMPF Nuclear Chemistry Laboratory (NCL). Nuclear chemistry experiments are conducted at LAMPF using either the direct proton beam or any of the secondary beams of muons, pions, or neutrons. In activation experiments, the targets irradiated in any of these beams are transported to the NCL where they are analyzed. Because these targets decay by one or more modes, we need the capability to count whatever decay mode is most favorable for the particular sample. Therefore, in addition to a number of Ge(Li) and high-purity germanium gamma-ray and x-ray spectrometer systems, we have counting systems for alpha- and beta-particle and positron decays. The experiments run by local and external users require that the various counting systems be operated as stand-alone manual or semi-automatic counting systems; that is, without direct access to the computer, as well as computer controlled for automatic counting. To reduce the load on the computer, all counting systems are connected to the computer by a CAMAC branch highway, and their acquisition capabilities are either internal or in the associated CAMAC module. Each of our three counting rooms has a CAMAC crate and a computer terminal to provide experimental control and user interaction. The center of the DAS is the PDP-11/44 computer with 512-kilobyte memory and a floating point processor. This computer is used both to control the various counting systems in automatic mode and to process the data acquired either with it or elsewhere in on-line experiments. In addition to the microprogrammed branch driver that connects the computer to the CAMAC branch highway, the DAS has several disk and tape drives and a number of terminals. There is a terminal in each counting room, and several other terminals are available for data analysis and software development. Figure 8.21 shows a schematic of the DAS. Last year, to handle the ra -idly increasing number of data files, we installed a 205-megabyte RA60 disk system to replace the old 40-megabyte system. This in turn forced us to replace the operating system and FORTRAN compiler we had been using for the previous 6 years. Although users find the systems very similar, the system manager knows that they are very different. As a result, the conversion has been slower than we planned. The conversion has also been delayed by our need to process acquired data.

~~PARAMETER YIME-Of-Tl SC UER SAMPLE INPUT MCA DATA fur'"'' I r'^Ro" i! * - l lUtSITION CHANGER o.a SEC, Tl INTERFACES ACQI CONTROL :cnis.J | QSTWT || »»is I SYSTYSTELE .~~

~~Fig. S.21. A schematic of the NCL DAS. NUCLEAR STRUCTURE AND REACTIONS 173~~

Whenever a new version of a compiler is used, a problem arises in that the code produced by the new compiler takes more memory than that of the previous version; the conversion from FORT RAN IV-PLUS to FORTRAN-77 was no exception. Some of the data analysis programs we use must be rewritten; they no longer fit within the maximum allowed memory size because the system software has grown. We are using this conversion as an opportunity to improve the error handling and to make the analysis programs easier to use. In the coming year, we will complete the conversion and improvements in the analysis programs. We also plan to connect all the counting systems to the DAS for fully automatic operation. We would like to add a 6250-bpi tape drive to our 800/1600-bpi tape drives to reduce the number of tapes used, especially for backing up disks and storing data. We will also connect the DAS to the LAMPF computer network and, thereby, to the Laboratory computer network. This will allow us to transfer data directly to larger computers when necessary for data processing, instead of using the current method of transfer via magnetic tape.

~~NUCLEAR FISSION~~

~~FISSION OF:5"56Es, 25S-2S7Fm, AND 258Md AT MODERATE EXCITATION ENERGIES~~

~~H. Chip Srilt (P-2), Darleane C. Hoffman,* Hans van der Plicht,** Jeiry B. Wilhelmy, Eli Cheifetz.t R. Jean Dupzyk,t and Ronald W. LougheedJ~~

The fission decay of heavy actinides has shown anomalous properties lor mass and kinetic energy distributions. A dramatic shift toward highly symmetric mass division accompanied by high kinetic energy release has been observed for the spontaneous fission of 25"Fm and 25l)Fm (Refs. 212 and 213, respectively). These results differ from the extrapolations that are based on the lighter actinide systems.31"1-115 In contrast, the spontaneous fission of 25*Md (Ref. 216) apparently has a mixture of fission decay properties. It gives, as do the N > 158 fermium nuclei, a symmetric mass distribution, but it has a total kinetic energy release that is substantially lower and more consistent with the phenomenological systematics derived from lighter actinides. The only other N > 158 nucleus whose fission properties have been determined is 356Cf (Ref. 212); its uiass and kinetic energy distributions are more consistent with systematics observed for lighter actinides. The limited data available217-18 on the fission decay properties of even higher Z nuclides (though for more neutron-deficient cases) also show no apparent anomalous behavior. Therefore, we have a situation in which, for spontaneous fission, strong deviations from systematic actinide properties occur in a limited region near Z = 100 with N > 158. Unfortunately, this region is experimentally very difficult to access unambiguously. For the neutron-rich heavy actinides, the information on fission in excited nuclei has been limited to (n,f) studies on :54Es, 256Fm, and :57Fm (Refs. 215, 219, and 220, respectively). For the fission of :v>Fm, an increase in excitation energy brought about through neutron capture results in an observed asymmetric spontaneous fission mass distribution that progresses toward a broad symmetric division.:'g For :3"Fm, the trend with excitation energy is from a higher symmetric mass

*Lawrence Berkeley Laboratory **Michigan State University tWeizmann Institute of Science, Rehavot, Israel ^Lawrence Livermore Laboratory 174 NUCLEAR STRUCTURE AND REACTIONS distribution for spontaneous fission212 to a distribution that, though still peaking at symmetry, shows shoulders that indicate significant yield for asymmetric division. Thus, on both 256Fm and :58Fm, the trend is to mix symmetric and asymmetric fission with increasing excitation energy from the more pure distribution observed in spontaneous fission. To obtain more data in this interesting region and overcome the excitation energy limitations imposed by spontaneous and (n,f) studies, we performed direct and capture reaction studies on an 254Es target. We have studied the fission of -5S 25flEs,255 257Fm, and J58Md in the excitation energy range from threshold to 25 MeV. A target of 254Es was used in the direct reaction studies (d,p), (t,pf), (3He,df), (3He,pf), and in the compound induced-fission reactions formed with p, d, t, and a projectiles. In the direct reaction studies, coincident fission fragment energies were recorded with the outgoing light charged particle. The mass and kinetic energy distributions were studied as a function of nuclear excitation energy. The observed bulk properties were consistent with established systematics in that they exhibited an asymmetric mass distribution and a phenomenologically consistent total kinetic energy. However, the systems demonstrated a fission decay mode that we ascribe to high-energy symmetric fission decay. Figure 8.22 presents the total kinetic energy (TKE) vs mass yield for -54Es('He,d)-i5Fm* fission decay. The distribution is peaked for asymmetric mass division, but a substantial high-energy symmetric yield is also observed. Though the current measurements do not show significant deviations in the average TKE, they do have a substantial yield of "high-energy symmetric fission" (HESF). To observe this distribution as a function of nuclear excitation energy, we have arbitrarily chosen the following definition of HESF: TKE > 210 MeV and E, - E: < 20 MeV. With this definition, in Fig. 8.23 we show the

~~160 -~~

~~150 130 170~~

Fig. 8.22. Contour plot of heavy fragment yield vs preneutron emission TKE for the reaction 254Es(3He,d);!55Fm. The data are summed over all excitation energies (3 to 23 MeV). Contours are labeled by the number of observed counts. NUCLEAR STRUCTURE AND REACTIONS 175 yield of HESF as a function of excitation energy for the direct reaction cases. For ail systems studied, the yield of this component is in the 8 to 24% range per fission. There is a general decrease in this yield with increasing excitation energy but, for a given excitation energy, an increase in nuclear charge and neutron number results in an increased yield.

~~. "-'Fm 256,Fm~~

~~0 5 10 15 0 io -fe-io- 25 Ex (MeV) Fig. 8.23. High-energy symmetric fission yield as a function of excitation energy for the indicated systems.~~

The heavy fermium region is of interest for theoretical reasons. The outer fission barrier is decreasing in magnitude and approaching a configuration that has a minimum potential energy for a symmetric shape. Analyses based on barrier properties"1 have reproduced the dramatic half-life change in the heavy fermium isotopes by predicting that the outer fission barrier has fallen below the ground state energy. This causes an abrupt decrease in the tunneling requirement and a corresponding decrease in the spontaneous fission half-life. These calculations predict that the change should occur between 25aFm and 26UFm, wiiereas in the experimental data,222 the abrupt change occurs between 256Fm and 258Fm (the half-life changes by a factor of 3 X 10"8). The fission mass distribution properties may also be influenced by the rapidly decreasing outer barrier and its trend toward a mass symmetric shape. Analysis that is based on the mass distribution being determined by saddle point properties223 h2s been moderately successful in predicting trends. However, the more quantitatively successful approaches use an asymmetric, two-center-shell model analysis224 or a scission point model,225 which emphasizes the potential energy surface near the scission configuration. These models have demonstrated that shell effects in the forming fragments play an important role in determining fission observables. It is an interesting coincidence that analyses based on either barrier properties or fragment shells are indicating rapidly changing effects in the heavy fermium region. Most of the predictions are for spontaneous fission properties. The general trend indicates that the shell effect will become less important as excitation energy is added to the fissioning system. Our observations imply that we have a mixture of fission modes in all the heavy-element cases studied. Figure 8.24 presents contour diagrams of yield vs TKE and heavy fragment mass for 256Fm at three different excitation energies. The spontaneous fission results show an asymmetric system whose bulk properties are well reproduced by fission phenomenology. However, even for this case there is an indication of a large variance in the TKE release near symmetric division. As the excitation energy is increased to the (nlh,f) region, an increase in yield for symmetric division is observed. Also, there is now significant yieid in the high-energy symmetric fission region. As the excitation energy is increased further through the 254Es(3He,p)256Fm reaction, we observe a continued evolution of the system. Now the mass yield has be ome symmetric and broad. However, the TKE distribution, though it is broad, no longer seems to have a distinct tendency toward a two-component distribution. The high-energy symmetric fission yield is not readily 176 NUCLEAR STRUCTURE AND REACTIONS discernable under these conditions. For the :"Fm nucleus, the increasing excitation energy at first increases the HESF yield, but this effect is washed out at yet higher energies. These changes with excitation energy are indicating the importance that shell effects in the potential energy iurface have in determining fission properties. As stated by Mustafa and Ferguson,"4 the preference for asymmetry is very slight in the :56Fm system at the deformation considered (the neck radius D = 4 fm). With the •-•-6 MeV of excitation energy brought about through neutron capture, the system would be expected to sample the symmetric distribution with some appreciable yield. However, population in the symmetric component at this specific deformation cannot ensure that there will be appreciable yield for final symmetric division as the system evolves toward fission. The dynamical effects associated with the movement toward scission cou'd provide substantial variation from the adiabatic conditions implied by the potential energy surface analysis. The observed high TK.E associated with some of the symmetric yield points toward a more compact scission configuration for these decays. Our observations would be more consistent with a distinct potential energy minimum nearer the scission configuration. The subsequent disappearance of observed HESF at energies reached with the (3He,p) reaction would also be more consistent with a scission analysis in which increasing intrinsic temperature results in a washing out of shell effects"5 and an eventual broad, symmetric fragment mass distribution.

~~REL. INTENSITY (SF) 47 366 Events Ex=O~~

~~(n,0 172 B81 Events E*=6.4 MeV~~

~~(3He.p) R092 Events Ex=17.5MeV CfE>-2.7 MeV~~

~~13C, 140 150 160 170 Heavy Fragment Mass (AMU)~~

Fig. 3.24. Contour plots of heavy fragment yield vs TKE for :'6Fm fission. The top figure is the preneutron emission masses and kinetic en^rgie'i for spontaneous fission decay and is taken from Ref. 226. The middle J5? figure (taken from Ref. 219) is for Fm(n,h,f) provisional masses and kinetic energies. The bottom figure 2: 1 presents the " Es('He,p) reaction summed over all measured excitation energy (Ex = 17.5 MeV, aE = 2.7 MeV) and is also for provisional masses and kinetic energies. NUCLEAR STRUCTURE AND REACTIONS 177

~~MEASUREMENT OF NEUTRONS EMITTED IN FISSION OF 1S8Er~~

Avigdor Gavron (P-2), Jan G. Boissevain (P-2). H. Chip Britt (P-2)., E. Cheynis,* Robert L. Ferguson,* Arie Gayer,** Felix Obenshain.* G. A. Pettit,t Franz Plasil.* Jerry B. Wilhelmy, and Glenn R. Young*

When one reviews existing neutron data for fission of actinide nuciei at moderate and high excitation energies"7"11 along with recent results for fission of 170Yb (Ref. 230), one finds that the number of prefission neutrons observed is significantly greater than indicated by the results from statistical model calculations. A possible explanation for this discrepancy is that the excess neutrons are emitted during the transition from the saddle point to scission point. Given the neutron evaporation time, which is obtained from statistical model calculations, the excess neutrons can serve as a "clock" to time the fission process. In particular, they may allow us to test models of fission dynamics. To be able to determine the fission time scale, we measured the neutrons emitted in the fission of "*Er at different excitation energies. The following systems were studied:

~~21S MeV *Ti + ""Pd Ex = 70.9 MeV 180 MeV ' :S + -Te Ex = 92.3 MeV 174 MeV :4Mg+IMBa Ex =109.6 MeV 208 MeV 16O+u:Nd Ex =161.2 MeV~~

The experiments were performed at the Oak Ridge Holifield Heavy Ion Research Facility (HHIRF). The experimental set-up was similar to that described in Ref. 231, except that the fission fragments were detected by two multiwire proportional counters (MWPC). For the first two reactions, we used a small, low-pressure MWPC as a START detector for the time of flight measurement of the fragments and the neutron;;. For ihe last two reactions, the START signal was obtained from the cyclotron radio frequency signal. The data for the first two reactions have already been analyzed, and the analysis of the data for the last two reactions is in progress. Figures 8.25 and 8.26 present typical neutron spectra for the 180-MeV "S on i:6Te reaction. The dashed lines are the results of the simulation calculations used to separate the contribution of prefission and postfission neutrons. Table 8.7 summarizes the results for the number of prefission and postfission neutrons emitted in the first two reaciions as well as the appropriate statistical model calculations. We see that for low excitation energies, the number of prefission neutrons is in agreement with the calculations. From the present resuks, we draw the tentative conclusion that no excess neutrons are emitted as long as the neutron evaporation time is 10":n seconds or longer. We expect that the results for the other two reactions will provide more stringent limits to the fission time scale.

*Oak Ridge National Laboratory **Soreq Nuclear Research Center, Israel tGeorgia State University 178 NUCLEAR STRUCTURE AND REACTIONS

~~i ' r •1e 180'MeV =~~

K)1 r x10 »•». • 10*

~~10s \O iv~~

~~'1 10'~~

10° 0 0 2.0 4.0 8.0 B.O 10.0 Fig. 8.25. Neutron spectra in the various detectors for the 180 MeV ''Sf ':''Te reaction. The dashed lines are fits obtained by a simulation calculation. (*.= 17°(D) = 32°, (•) = 58°, (O) = 75°, (•) = 151°.

~~e 10 I I S- fiei tooMe1V | : xiop A - 6 10 r A~~

~~X1O • D~~

•

~~: *-•' i" 0 -^ ** t 10' r- "~ -^ o t _ : s 0 > 0 "--^ I a 10 •s \ i s 1 1^ : -I ) _ -4 10' L. \\ 1 t \ V - - i \ i. \ \ 10° 1 0.0 2.0 4.0 6.0 8.0 1G.0 ENERGY (MeV)~~

~~Fig. 8.26. As in Fig. 8.25, but lor liie detectors at the right side to th. !ieam. (A = 14° (D) = 31°. (II) = 60°, (O) = 105°. (•)= 146". NUCLEAR STRUCTURE AND REACTIONS 179~~

TABLE i1.7. Neutron Yields Excitation Energy Experimental Statistical Reaction (MeV) Results" Mode! HIH *n + pd 70.9 vh = 0.00 ± 0.20 vb = 0.34 vH = 0.90 ±0.10 923 v, - 0.75 ± 0.20 vb--=0.8S v,--= 1.40 ±». ifl ;4Mg+'-uBa 109.6 Nd 161.2 "Subscript j indicates before fission; 1' imik'HSes after fission. , •!

~~4 • r~~

~~Omega West Reactor 183~~

~~Hi IRRADIA TWN FA CILIT1ES 183~~

~~OMEGA WEST REACTOR~~

~~Herbert T. Williams, Alvin R. Lyle, Michael M. Minor, and Merle E. Bunker~~

The Omega West Reactor (OWR) provides Los Alamos experimenters and scientists from other laboratories with an intense flux of thermal and epithermal neutrons. The OWR is operated at a higher power level than any other research reactor in the western US. At its normal power level of 8 MW, the maximum available thermal flux is 9 X 10" n/cnrs. Nine beam tubes, fourteen rabbit systems, and a number of removable graphite "'stringers" provide access to the neutron flux. The reactor facilities are used for radioisotope production, neutron-diffraction and -absorption experiments, in-core irradiation of instrumented capsules, neutron radiography of assemblies, neutron- capture prompt-gamma-ray studies, neutron cross-section measurements, and neutron-activation trace-element assay measurements. The numerous Laboratory programs that make use of the OWR were listed in the INC-Division FY 1983 annual report/12

Operations FY I9S4 In FY 1984, personnel from 24 Los Alamos groups and 9 outside laboratories used the reactor. There was an almost constant demand for neutron irradiation of materials, including such diverse substances as rock, soil, human urine, human teeth, animal bones, elk hair, wild plants, bees, honey, coal, crude oil, volcanic debris, and a variety of pure materials used in basic radiochemical research. Over 17 000 samples were irradiated in FY 1984, and approximately 2000 experiment hours were logged. Table 9.1 lists the organizations that obtained sample irradiations, and a summary of other experimental usage is shown in Table 9.2. Additional highlights concerning the year's reactor operation include:

• Sixty new OWR fuel elements were acquired from Babcock & Wilcox Corp. through a contractual agreement with Oak Ridge National Laboratory. These elements represent a 6- year supply at the present rate of consumption.

• A facility for irradiating samples with fission-spectrum neutrons, which will be used in radiochemical diagnostic work, has been completely designed. This assembly will be installed in the OWR thermal column.

~~» The 3-axis neutron-diffraction spectrometer was significantly upgraded during the year through installation of new gear drives and new electronic controls.~~

~~» A new boron-shielded water-cooled epithermal-neutron rabbit facility was installed in one of the through-ports that pass tangent to the reactor core.~~

• A new. large (l.O-in.-diam) thermal-neutron rabbit facility was installed in the thermal column. The rabbit tube terminates in a counting room located 160 ft east of the reactor. Further discussion of this facility is presented in the following section.

Neutron Activation Analysis Activities In trr past 2 years, there has been an increasing demand for neutron-activation analysis (N AA) to analyze for trace elements in materials collected on air filters used in environmental and other atmospheric studies. These analyses present a challenge because the filter papers are typically quite large, but the amount of material on the filters is quite small. Also, it is essential to avoid 184 IRRADIATION FACILITIES

TABLE 9.1. OWR Irradiations in FY 1984 Organization No. of Samples Los Alamos National Laboratory CHM-l 238 CHM-6 27 CMS 10 Ell 4 ESS-1 165 ESS-2 626 ESS-4 HSE-5 2692 IISE-9 -4866 INC-DO 152 INC-3 48 1NC-4 25 INC'-5 1022 INC-7 5114 INC-11 1542 MST-NMO 3 MST-5 304 MST-10 1 P-3 3 P-10 21 Q-1 17 WX-5 8 Patrick Air Force Base 31 Shell Oil, Offshore 50 South Dakota School of Mines 2 I'niversity of California, Berkeley 3 I'niversity. of California, Davis 5 University of California, Los Angeles 76 I'niversity of New Mexico 76 TOTAL 17133

vAirLinciuis surface contamination of the tillers. These considerations have led to the design and installation of a new large rabbit lacilin at the OWR. 1 he rabbit line, which accommodates National Bureau ot Standards irradiation \ials. extends from the reactor to a receiving station adiacent to the sue I \-2 clean room, located 160 ft east of the OWR. The irradiation vial can accommodate samples of 1 -in. diameter and 3-in. length and can be transferred to and from the roster tlv.-nnal column in approximate^ 1 seconds. Four lit'nuim-driftcd-germanium gamma-ray detectors and a microcomputer-controlled data acquisition system have been installed for use with this svsicm fo facilitate a more complete ink' -element assa\ of the material collected on air filters, the soltvvare lor the N \ \ swems has been modified to enable the detection and analysis of very short lived neutron-induced activities, such as 1 1-second '"F. This capabilily is especially important in atmospheric studies because several of the elements of greatest interest, such as fluorine, yield only short-lived activities when bombarded with neutrons. The software modifications allow any time sequence ol irradiation and counting to be performed Alternative counting sequences are set UD by altering external tables that are accessed by the main programs. Filter analyses are typically IRRADIATION FACILITIES 185 performed by irradiating the samples for 30 seconds and delivering each sample immediately to a gamma-ray detector, where the sample is counted for 30 seconds after a 10-second decay. The sample is then counted for 2 minutes after a total decay time of 2 minutes. Sample transit times are sufficiently short that the first count could be started 3 seconds or less after the end of the irradiation. However, many of the air filters have been treated with 7LiOH, and the high-energy beta rays from the decay of "Li (844 milliseconds) produce an unacceptably large background for approximately 10 seconds after the irradiation. In addition to fluorine, oxygen (via 27-second "O), scandium(v/a 19-second 46mSc), selenium (via 17-second 77mSe), and hafnium (via 19-second l7titanium, vanadium, manganese, copper, gallium, bromine, indium, tin, and iodine is made in the second count. Approximate detection limits for these elements on filter papers are shown in Table 9.3. During FY 1984, 12 554 samples from 14 Laboratory groups and 5 outside organizations were analyzed by gamma-ray NAA and delayed-neutron counting (DNC) at the OWR. Some of the projects for which sizeable groups of samples were measured are as follows:

~~• 4892 urine and environmental samples were assayed for fissile material by the DNC technique for the Health. Safety, and Environment Division.~~

• In collaboration with the Isotope Geochemistry Group (INC-7), 750 air-filter samples collected during the recent Kilauea and Mauna Loa volcanic eruptions were subjected to multielement analysis by NAA (see Sec. 5 for further discussion of this project).

TABLE 9.2. Experiments at OWR in FY 1984 Experiment Organization Experiment Hours WX-3/INC-5 Neutron Radiography 22 WX-5 Neutron-Diffraction Studies of 370 Eu, Pu, and U Tritides WX-5 Retention of 3He in Tritides 90 HSE-1 Neutron Dosimeter Calibrations 3 HSE-9 Neutron-Capture Gamma-Ray Measurements 161 INC-7 Neutron-Capture Gamma-Ray Measurements 553 P-DO/INC-5 Neutron-Capture Gamma-Ray Measurements 119 P-8 Neutron Detector Calibrations 50 INC-5 He-Jet Transport of Fission Products 206 INC-11 24-keV Neutron Irradiations 53 INCH Neutron Flux Measurements 12 Q-l Spent Fuel Element Measurements 61 Q-2 Gamma Detector Calibrations 56 Washington U./ INC-11 Fission Yield Measurements 7 TOTAL 1763 TOTAL HOURS OF OPERATION 1666 186 IRRADIATION FACILITIES

535 stream sediment and beach sand samples collected throughout the Caribbean island St. Lucia were analyzed by NAA as part of a reconnaissance-scale geochemical survey organized by the Geology/Geochemistry Group (ESS-1) under the auspices of the US Agency for International Development, the Caribbean Development Bank, and the Government of St. Lucia. The main purpose of the survey was to identify areas favorable for exploration of metallic mineral resources. Of the several metallic-element anomalies found, the only one that seemed worth further investigation was a significant gold anomaly in the northern part of the island.-0

600 rock samples were analyzed by NAA for a Laboratory-supported research project concerned with geochemical anomalies at "biological crisis zones" in the fossil record (see Sec. 12 for a discussion of this project).

TABLE 9.3. Approximate Detection Limits for Elements Typically Observed in Material Collected on Air Filters Approximate Detection Limit Element (Pi) Br 0.4 Ca 50 Cl 9" Cn 1 F 1 Ga 10 Hf 0.0015 In 0.01 Mn 0.04 Na T S 500 Sc 0.001 Se 0.010 Sn 25 V 0.04 "Limited by filter blank. w % c < , ^ ,. - *» ^ **- "* ^ "^ - Ve •• •• ' .^ - fr* • • VJ "' ,, *• • i- .,»• -^i

~~v <* '' * r'r J-L (3 •.^ -,5*/, n d~~

~~•i - -»'i~~

~~B W ^«if "• m~~

~~613 ADVANCED ANALYTICAL TECHNIQUES: DEVELOPMENT AND APPLICATIONS 189~~

~~SOLID STATE NMR STUDIES OF ADSORPTION AND ACID SITES IN Y-ZEOLITE~~

William L. Earl, Paul O. Fritz,* and Jack H. Lunsford**

Over the nast few years, we have been studying vhe adsorption of NH3 on various preparations of y-zeolite with the intention of characterizing the number and location of the acid sites. The acidity and catalytic behavior of the zeolite are intimately related. Calcined y-zeolite is the primary cracking catalyst for gasoline production throughout the world and is the sole catalyst used in the US for this purpose. The zeolite samples are prepared from a commercial Linde NH4 y-zeolite. Commerciallv, the catalyst is synthesized in the Na" form and then the N.V is ion exchanged out by NHj. Usually, about 80 to 85% of the Naf is replaced. The commercial preparation is heated under vacuum, in our laboratory, to several temperatures for varying times to drive both the water and NH out of thj zeolite and produce Hy-zeoiite. Different time/temperature conditions produce different conditions of acidity. After thermal treatment, "N-enriched bases (approximately 99 at.% I5N) are added to the sample. To date, we have used NH, and N(CH,j, as probe bases. The kinetic diameters of these molecules arc such that NH, can enter all pores in the zeolite but N(CH,), can oniy enter the large cavities. The '"N NMR spectra of the final preparations are diagnostic of the different acid sites. One expects a separate resonance peak for ammonia adsorbed on each different acid site. Samples prepared in this manner can also be subjected to heating for various times under vacuum to desorb the base from the weaker sites. This is a crude version of temperature-programmed desorption. The NMR spectra of the resulting samples are diagnostic of the more acidic sites Four or five aisu:H: rites have been identified in zeolite samples heated to 673 K for 1 hour. (The fifth site i' at low concentration and gives a weak NMR resonance that is partially buried under a stronger resonance and thus is not always conclusively present.) The I5N resonances obtained are in the chemical shift region characteristic of the protonated base, that is, NHt not NH,. Very mild desorption conditions (heating to 353 K. for 10 minutes) eliminate the resonances for three of the sites, leaving one site that is heavily populated and another that is weakly populated. More severe conditions (heating to 453 K for 2 hours) result in a single "N NMR resonance, which indicates that there is only one site populated. The NMR resonance lines obtained in these experiments are relatively narrow, that is, less than 50 Hz, indicating that each acid site is magnetically monodisperse. A variety of similar but slightly different sites would result in a multitude of overlapping NMR resonances that would look like a single broad line. It should also be pointed out that the NMR experiment is sensitive to moiecular motion; the NHt ions discussed above are attached to the zeolite framework in some fashion. It is also possible to obtain an NMR signal from NHJ ions that are free to move in the pores of the zeolite; in that case, the final spectrum is a linear combination of the following: a broad resonance caused by mobile molecules and a set of narrow resonances caused by the attached molecules. Adsorption of N(CH,), gives somewhat different results. In this case, the molecule is too large to enter the small pores of the zeoli'e, so one expects to probe only those sites in the large pores. The "N spectrum of enriched N(CH,), saturated in the zeolite is a single, rather broad resonance. After thermal desorption treatment, the resonance narrows somewhat. This result indicates that there may be more than one site in the large pores but the N(CH,), does not adsorb homogeneously on each site, as NH, does, because of its much larger kinetic diameter. The single, slightly narrowed resonance remains after heating to 453 K. for 2 hours, which indicates that the site in the large pores is the most acidic site.

~~'Associated Western Universities summer graduate student "Texas A&M Universitv 190 ADVANCED ANAL YTICAL TECHNIQUES: DEVELOPMENT AND APPLICATIONS~~

Finally, we have attempted to produce Lewis acid sites in the zeolite. These are formed by healing to about 873 K; under these conditions, defects are created in the framework such that A. atoms (Lewis acids) are accessible to the base. In all cases attempted, we ha\'e only obtained very broad I5N resonance lines that do not give any interesting chemical information. To understand Lewis sites requires a study of a series of model Lewis acid adducts and repetition of the zeolite adsorption studies with a larger variety of bases.

~~THE INSIDE-OUT HELMHOLTZ: A UNILATERAL MAGNET FOR NMR~~

Eiichi Fukushima, Alan Rath,* and Stephen B. W. Roeder*

Some applications of NMR are either difficult or impossible because the magnet that provides the static field is not large enough to contain f'.ie sample, regardless of how small the region of interest is—and there is a practical limit to how large a magnet can be. For example, in whole-body NMR, a cylindrical magnet capable of accepting the entire body inside the annular space has been used to study a smaller region inside the body. The disadvantage to this scheme is that the currently used geometries (superconducting solenoid and composite resistive Helmholtz coils) encircle the patient so that, at best, the access to the patient is awkward and, at worst, the patient may refuse to be inserted into the apparatus for psychological reasons. We have designed a magnet that generates a uniform and unilateral magnetic field, that is, a magnet that creates a uniform field somewhere outside the magnet. It is a modification of the Helmholtz coil in which the two loops are located asymmetrically so that the uniform field region is created on one side of both loops. Because of its functional similarity with the Helmholtz pair, we call our coil the inside-out Helmholtz (IOH). Other unilateral magnets exist but they do not produce uniform fields. The IOH magnet is suited to in-vivo imaging and possibly to topical NMR at low fields; it will also allow us to study objects that previously were considered too large (or are immovable) for intact study. An interesting application of this magnet is as a part of an NMR apparatus to operate with a glove box for NMR studies of reactive or corrosive materials. The magnet would be placed behind a nonmagnetic glove box with the NMR probe inside the box. Conventional probes could be used to examine small samples, or remote sensing coils might be used to study larger samples. With current superconductivity technology, it is possible to conservatively design an IOH magnet with an outer coil diameter of 176 cm and an inner coil equal to one-half the outer coil. The two coils will be separated by 22 cm, and the region of uniformity will be centered 22 cm from the smaller coil on the cylindrical axis. The larger loop can consist of about 7500 turns of niobium- titanium wire and the smaller iocf will be one quarter that number. If the larger loop has a cross section 5.6 cm on a side, the current density will be approximately l.S X 104 A/cm2. The uniform field region, centered 22 cm from the smaller loop (in the direction away from the larger loop), will be no smaller than a sphere of 3.3-cm diameter for an inhomogeneity of 100 ppm. The corresponding sphere for 1 ppm wouid have a diameter of 0.7 cm. We have applied for US patent and have written a general article on magnets (discussing the IOH as a special case).234

*San Diego State University ADVANCED ANAL YTICAL TECHNIQUES: DEVELOPMENT AND APPLICA TIONS 191

~~ACCELERATOR-BASED MASS SP^.CTROMETRY OF METHANE~~

~~Malcolm M. Fowler, William B. Ingalls (P-9), Patrick Lysaght, Joseph Tesm- (P-9), and Jerry B. Wilheliny~~

Several steps have been made toward our goal of using the Los Alamos vertical Van de Gr?afT as an accelerator-based mass spectrometer. The initial application would be the analysis of muss-21 methane, nCDj, a highly desirable tracer for high-sensitivity studies of atmospheric dynamics and for monitonng environmentai air quality. We are pursuing an analytical approach in which positively charged methane ions are accelerated to energies of 6 to 8 MeV, which will allow us to detect and identify them by nuclear counting techniques. The use of ion energies that arc much higher than in conventional mass spectrometry is CGupIed with particle identification techniques to reduce background interferences and ultimately improve the detection sensitivity by 2 to 3 orders of magnitude. In addition, the detection technique provides information about the constituents of accelerated molecular ions so that one can separate ions of similar mass but different structure. The effort to implement a system that offers; the required analytic capability has resulted in several innovations. The zero-degree beam line from the vertical electrostatic accelerator at the ion beam facility has been upgraded to include decking on all sides for easy access and stability. Additional space has been provided for work and spare-part storage. A turbomolccular high-vacuum pumping system that features an ultimaie operational pressure of 5 X 1CT8 torr has been installed on the beam line. The vacuum system is modular and is composed of a 5OO-8/s turbopump backed by a large direct-drive forepump, control electronics, and an electrically controlled, pneumatically operated high-vacuum valve. Although the vacuum system is self-contained, the normal "house" roughing vacuum is also available for initial pumping. The vacuum system exhaust is filtered, in accordance with the requirements for trapping possible tritium contamination. House chilled water cools the vacuum pumps and the beam- defining slits. Several safety interlocks protect the turbopump in the event of power failure or failure of the cooling-water supply. In either case, the high-vacuum valve closes to isolate the beam line and the forepump is vented to prevent back contamination of the turbopump. A simplified schematic of the new vacuum system and beam line is shown in Fig. 10.1.

~~EXPERIMENT-SCATTERING CHAMBER FARADAY CUP~~

~~TURBO MOLECULAR PUMP ANALYZING MAGNET~~

~~hlQH-VACUUM VALVE~~

~~ROTARY VANE FOREPUMP QfiECT DfiiVE~~

~~Fig. 10 I. Vacuum system and beam line for methane mass spectrometry. 192 ADVANCED ANALYTICAL TECHNIQUES: DEVELOPMENT AND APPLICATIONS~~

In addition to constructing the beam line and pumping system, we have developed a housing for an electron-bombardment ion source that will mate to the exi?ting extractor plate in the terminal of the vertical Van de Graff. We plan to use the existing extractor electrode to provide an electrostatic field that will withdraw the positively charged methane ions from the ion source and accelerate them into the main acceleration tube of the Van de Graaft. The actual operation of the electron- bombardment ion source is regulated by an ionizer controller. We arc repackaging a standard controller, lik* 'be one we used for laboratory tests, in a configuration dictated by space available in the terminal of the accelerator. There are currently seven parameters for operating the ion source, which we feel should be remotely controlled and monitored. For this requirement we will usr ^xtra channels in the accelerator telemetry system. Because the telemetry system accepts single-ended signals in the range of 0 to 10 V, we are developing signal-conditioning isolation amplifiers to be incorporated in the ionizer controller. Through a number of tests on the electron-bombardment ion source and ionizer controller, we have determined the operating conditions for the best production of methane ions. In addition, we •neasured the source's gas consumption under these conditions to estimate both the size of samples that will be necessary and the overall ion source efficiency. Our tests have shown that ionization efficiency for the production of methane ions is highest at bombarding-electror. energies of about 37 eV and that ihe efficiency slowly drops with increasing electron energy. The production of CH} and CH^ ions is nearly equal at al! but the lowest electron energies and then the CHJ is favored. In general, the CHt ion intensity is about 25% of the total ion production. For the ion source we are currently using, we cannot achieve the desired electron emission with only 37 eV of electron energy: we need around 60 eV to achieve 25-mA electron emission. With an ionizing current of about 25 mA and an electron energy of 65 eV, we can produce an extracted and analyzed methane beam of 6 to 7 X 10" ions/s. Under these conditions, the ion source consumes 2.0 STP cm' of methane per hour, which corresponds to an overall efficiency of 4 X 10~5. In 1 hour of operation, 2 X lO" ions would ue produced, and if the ratio of mass-21 methane to mass-16 methane were 1 X 10 i:, one would expect to detect 2000 mass-21 ions. This is an easily measured rate of 0.6 ion/s and corresponds to a detection sensitivity about 10 times better than that obtainable with conventional mass spectrometry. We believe we will demonstrate operation at this level within the next several months. Trace-Element Composition of Volcanic <5ases From the 1984 Eruptions of

~~Kilauea and MaiinaLoa Volcanoes 19S~~

~~First Antarctic Tracer Experiment Results', 201~~

~~Variations ofStratospheric Nitric Acid Concentrations 1971-1983: Revisited 203 ATMOSPHERIC CHEMISTRY AND TRANSPORT 195~~

~~TRACE-ELEMENT COMPOSITION OF VOLCANIC GASES FROM THE 1984 ERUPTIONS OF KILAUEA AND MAUNA LOA, HAWAII~~

Bruce M. Crowe, Eug.ene J. Mroz, David L. Finnegan, and William H. Zoller*

A volcanic gas sampling system developed by Zoller and students at the University of Maryland2"2'" has been used to sample trace constituents of volcanic gases during active eruptions. Particulates and trace constituents of the gases are collected on a series of filters contained in a polycarbonate canister. A vacuum that is produced by a portable electric pump pulls the gases through the filters. The first filter in ttn. canister is a paniculate filter; it efficiently collects ash particles greater than 0.01 urn in diameter as well as the trace constituents of the gases that are absorbed on the particles. The remaining filters are impregnated with 7LiOH, which acts as a potent base and absorbs acidic gas species (such as SO:, HO, and HF). The filters, after exposure to volcanic gases, are analyzed by nondestructive neutron activation techniques. Quantitative results can be obtained for a suite of about 35 trace elements. During this year, we upgraded the sampling system and sampled gases during eruptions at Kilauea and Mauna Loa Volcanoes in Hawaii, O

~~(1) sample volcanic gases during the complete cycle of an Hawaiian volcanic eruption~~

~~(2) verify the presence of high concentrations of iridium in the volcanic gases as first reported by Zoller el al.ni~~

(3) examine the enrichment patterns for a suite of trace metals during (a) individual cycles of single eruptions, (b) separate eruptions at the same volcanic vent, and (c) eruptions from separate volcanoes.

Kilauea, a shield volcano in southeast Hawaii, began an eruptive cycle in January 1983; it was characterized by 2 to 3 days of fouiitaining and lava emission followed by a repose period of about 3 to 4 weeks. Eruptions from the Pu'u O vent, about 20 km from the summit caldcra of Kilauea and along the east rift zone, have continued throughout 1983 and 1984. We sampled volcanic gases during two eruptions of the Pu'u O vent once in November 1983 and once in January 1984. During the November event, we arrived &t the close of the eruption, when glowing, cooling lava was still visible in the vent. We collected gas samples above the vent for periods of 10 to 30 minutes Th_ temperature of the emitted gases was greater than 600°C at that time. In January, we arrived at Kilauea within 23 hours after the eruption began (phase 13), while it was still in the fountaining phase (Fig. 11.1). For 2 days, we sampled volcanic gases in the plume by using fixed- wing aircraft several kilometers downwind of the vent. After fountaining and lava extrusion stopped on the third day of the eruption, we collected gases above a sequence of cooling lavas north of the main lava channel at a lava breech in the east wall of the Pu'u O spatter cone. On the fifth day, we were able to enter the spatter cone centered at the vent to collect gas samples from the mild spatter activity that was confined within the vent. We sampled gases continuously for 5 hours at two sites immediately above the spatti ing lava column (Fig. 11.2). On March 25, 1984, a long-expected flank eruption of Mauna Loa volcano began; it lasted for 22 days. The activity started approximately 500 m below the summit caldera, and during the first 15 hours it migrated down the east rift ^f the volcano to about 2830-m elevation; fissure activity localized at this lower site for the rest cf the eruption (Fig. 11.3). Plume gases and particulates were collected at a permanent atmospheric sampling station at the Mauna Loa Observatory at the start of the eruption. This sampling continued for 2 days, until the rapidly spreading lava flows severed

~~'University of Washington 196 A TMOSPHERIC CHEMISTR Y AND TRANSPORT~~

Fig. 11.1. This aerial view ofKiiauea Volcano was taken during overflights to collect gas samples from the plume. Note the scoria bomb (small red projectile) to the left of the vent area. We took gas samples from the ground immediately below this bomb at the source of the lava channel. The rough texture visible on the flank of the magma inside the vent resulted when the surface chilled and solidified basaltic glass. The darker area on the flow surface in the channel is a similar feature. At lower left, the lava spilled over the channel walls and fed thin driblet flows.

Fig. : 1.2. We sampled gases where iava spilled over the edges of the channel and created lava levees. The thin red-orange line is the still-molten interior (910°C) of the cooling lava flow. At the end of the rod. the white polycarbonate cannister holds particulate and base-treated filters that collect volcanic gases. ATMOSPHERIC CHEMISTRY AND TRANSPORT 197

11.3. Inside the Pu'u O vent. The lighter grey scoria zone circling the vent is the result of the highly acidic (HF) veru gases etching the glassy scoria surfaces. Dark bands inside the vent are lava lobes from previous eruption cycles.

the power lines to the Observatory. Approximately 5 days into the eruption, we completed multiple sampling flights in the gas plume downwind of the 2830-m eruption site. The following dav. we set up ground-based sarnpling sites adjacent to and downwind of the fissure vents (Fig. 1! .4) and continued sampling for several days. As soon as the eruption ceased in April, we collected samples of the final gases emitted from the cooling fissure vents. We have completed neutron activation analyses of selected filters from all the sampling missions. These analyses measure the absolute abundance of trace constituents on the filters. Because collection times are variable and the gases are diluted with differing amounts of air, true comparisons cannot be made between measured trace elements. To effect these comparisons, we must normalize the elements to an immobile phase by using the formula

Ep = (X/Al) sample bhv" (X/Al)bhvo " where X is the measured concentration of an element of interest on the filters and in some reference material. Currently, the reference material used for the studies is the US Geol' iucil Survey Hawaiian basalt standard (BHVO-1); we use the elemental concentrations reported by Gladney and Goode.'17 After they are analyzed, spatter samples of lava erupted contemporaneously with the sampled gases at the Mauna Loa and Kilauea eruptions will be used for the elemental normalizations. It is critically important that the element chosen for normalization is not fractionated between the gas and magma. Altnough aluminum and scandium have both been used for the normalization, the most consistent enrichment patterns are obtained with aluminum. Scandium is strongly partitioned into olivine, and it is likely that inconsistent results with scandium are related to the varying contents of olivine microlites in the collected particulates. 198 ATMOSPHERIC CHEMISTRY AND TRANSPORT

Fig. 11.4. On Mauna Loa, we collected samples of spatter erupted from the elongate fissures and samples of gases from plumes and downwind of plumes. Note the lava flows (ribbons of red) that snake down the walls of these two fissures along the rift zone. Velocities of fountain-fed lava flows ranged from 30 to 60 km/hour, and maximum lava effusion was about 106 m3/hour.

~~Figures 11.5 to i 1.7 show trace-dement enrichment factors for analyzed gases. Some significant features of these data a'e outlined below.~~

(1) We noted enrichment factors of greater than 104 for arsenic, silver, cesium, iridiurn, cadmium, and selenium. Copper, potassium, zinc, antimony, tin, and tugsten show enrich- ments of greater that 10:.

(2) We obtained reproducible analytical results from gases in the separate eruptions of Kilauea and Mauna Loa. These data are consistent for both the relative degree of enrichment and the ordering of enriched elements. ATMOSPHERIC CHEMISTRY AND TRANSPORT 199

~~(3) Gases emitted from the cooling lava flows are markedly less enriched in the more volatile phases when compared with gases released during ihe eruption.~~

(4) Gases emitted from subsurface lava below cooling vents of Kilauea volcano have highly variable trace-element contents. Some trace elements are depleted relative to those in eruption gases, whereas others are enriched. These variations are caused in part by precipitation and dissolution of gas-borne trace constituents as the gases cool and react with wall rock-processes thai, under ideal conditions, could lead to formation of ore deposits. Systematic variations through tim^ in the ratios of trace elements are probably caused by ihe influx of new batches of magma into an inferred, shallow magma beneath the Pu'u O vent. It thus appears that sampling and measurement of trace elements in gases may provide a new and previously unsuspected technique for monitoring the subsurface movement of magma

~~AIRCRAFT SAMPLES~~

~~MAUNA LOA~~

~~10% ENRICHMENT FACTORS KILAUEA~~

~~10?•~~

~~-102~~

~~icN~~

~~10° "1 I I 1 I I 1 1 1 1 1 Cl K Cu Zn Mo Sb Ai Ir Au Cd So~~

~~Fig. 11.5 Enrichment factors fcr volcanic gases collected in the gas plume downwind of the vent for Mauna Loa and Kilauea volcr.noes. 200 ATMOSPHERIC CHEMISTRY AND TRstNSPORT~~

~~10%~~

~~ICT-a MAUNA LOA VENT~~

~~10% ENRICHMENT FACTORS 103 KILAUEA VENT~~

~~102 KILAUEA COOLING LAVA 10'~~

~~10° I i II I I \ i II 1 I T I I Th No Cu K Zn Sn W As Ag Cs Ir Au Cd S«~~

~~Fig. 11.6. Enrichment factors for volcanic gases collected in the vents of Mauna Loa and Kilauea Volcano and above a cooling lava flow about 1 km from the vent.~~

~~IU 5 +~~

~~10S + 5 10 | KILAUEA VENTy ENRICHMENT - FACTORS 10% — KILAUEA COO 10%~~

~~itfj y" + 10%~~

~~10°- I 1 1 1 1 1 1 ! 1 Ha Cu K Zn Sn W As Ag Cs Ir Au Cd S«~~

~~Fig. 11.7. Enrichment factors for volcanic gases collected in the vent during eruptive activity and approximately 5 days after the eruption. ATMOSPHERIC CHEMISTRY AND TRANSPORT 201~~

~~FIRST ANTARCTIC TRACER EXPERIMENT RESULTS~~

Allen S. Mason, Mohammed Alei, John H. Cappis, Paul R. Guthals, Eugene J. Mroz, Donald J. Rokop. and Elmer Robinson*

Our efforts to better understand the transport of trace substances to Antarctica have begun to yield results. A continental-scale experiment, involving five nations operating eight sampling stations and using logistics airplanes and helicopters, has been under way since 1982 (Ref. 238). The keys to the experiment are INC-7*s state-of-the-art mass spectrometry and INC-4's capability to separate isotopes of carbon and use these isotopes to synthesize gases essentially absent from the atmosphere. These gases are detectible in exceedingly low concentrations; thus, small quantities released far from Antarctica can be detected despite the dilution that occurs during their transport to the continent.

Releases Two release missions were carried out during FY 198<1, and one more during the first month of FY 1985. On January 9. 1984, our field party made the first release from a National Science Foundation-US Navy LC-130 ski-equipped logistics airplane enroute from Christchureh, New Zealand to McMurdo Station, Ross Dependency, Antarctica. Figure 11.8 shows a scnematic representation of the release, the anticipated path cf the gas, and the sampling stations. The 1-kgof "CD4 was released at 55°OO'S. 167° 47'E. Following the release, the ground stations sampled for 60 days; each sample contained a 3-day accumulation. The Los Alamos field party obtained 99 samples while flying aboard the logistics airplanes on their scheduled missions around Antarctica and to and from New Zealand.

~~HEAVf METHANE TRACER GAS~~

~~WEDDELL SEA~~

~~ATLANTIC OCEAN~~

~~INDIAN OCEAN~~

Fig. 11.8. An airplane releases the heavy methane tracer for the Antarctic Tracer Experiment. The sampl. ig sites are indicated by the national flags cf the participating agencies. Expeditions Polares Francaises, British Antarctic Survey. National Institute of i'olar Research (Japan). Australian Antarctic Research Division, and the National Science Fourdation Division of Polar Programs (USA).

~~•National Oceanic and Atmospheric Administration 202 ATMOSPHERIC CHEMISTT ¥ AND TRANSPORT~~

The second release was made June 8, 1984, from a US Air Force WC-135 weather reccnnaisance airplane. This date fell during the austral winter when no aircraft landings are possible on the Antarctic continent. The Air Force permitted our experimenter to accompany the airplane on a. scheduled rest :n:h mission and diverted one flight to the desired point at 59° 40'S, 160° 45'W, 13 where again 1 kg of CD4 was released. The ground stations sampled for 60 days as for the earlier release, but no airplane sampling was possible, as noted above. The third release was more complex. Whereas both the previous releases were of a single gas and took place at the midtroposph°ie level of 500 mbar or 18 OOQ-ft altitude, this time two gases were released at widely different ai'ttudes but in the same genera! location. A kilogram of "CD4 was released at 64° 55'S, 174° 58'E, 840 mbar or about lOOO ft above the sea surface. A much larger |: amount of CD4 (20 kg) was released at 62° 15'S, 172° 10'E, 500 mbar. The two altitudes were chosen to eli-cidate differences between transport near the surface and at niidtroposphere. The >: larger amount of CDA was necessary because there is lower analytical sensitivity for that substance. This release was made from a US Air Force Military Airlift Command C-141B transport airplane; again the Air Force accommodated our representative and di\erted the flight toward the most favorable meteorological conditions. The first release pany included our meteorologist consultant, who was assisted by the US Navy weather office at Christchurch, New Zealand. For each subsequent release, the US Navy Fleet Numerical Oceanography Center, Monterey, California, provided him the most extensive data suite and computational capability available. However, even with the best data available, calculation of the trajectory of an air parcel containing our tracer in the high latitudes of the southern hemisphere is a highly uncertain matter. Figure 11.9 shows four possible trajectories calculated for the January yih lelease. The numbers along the trajectories indicate the calculated position at the end or'that number of days. Trajectories A, B, and C were all calculated from one data set by the British Antarctic Survey and illustrate the sensitivity of such calculations to small changes in assumptions concerning the initial conditions at the release point. Trajectory D, showing much slower movement, was calculated from a somewhat different data base by the US Air Force.

Fig. 11.9. Forecast iraccr trajectories following the January ^. 1984 release. The numbers represent the days aftc- [he release and indicate the calculated position of the tracer. ATMOSPHERIC CHEMISTRY AND TRANSPORT 203

Analytical Results Transportation of samples from non-US stations in Antarctica requires several months because most of their trip is made by surface shipping. Therefore, analytical efforts to date have been concentrated on airplane samples from the January release. The preliminary resi Its on those samples indicate that the tracer arrived over the continent in less than the predicted time—perhaps as little as 2 to 4 days. This finding, if confirmed, will again demonstrate the problem inherent in attempting trajectory forecasting for a data-sparse region. Our efforts in the near term svill be concentrated on analysis and interpretation of data from the first three releases. We will determine what additional releases may be required to better define the problems of trajectory prediction and sampling of trace substances in the high latitudes of the southern hemisphere.

~~VARIATIONS OF STRATOSPHERIC NITRIC ACID CONCENTRATIONS 1971-1983: REVISITED~~

William A. Sedlacek, Eugene J. Mroz. Allan L. Lazrus,* and Bruce W. Gandrud*

In the FY 1982 INC Division Annual Report, we presented preliminary results from 11 years of stratospheric nitric acid measurements.'11 Since that time, analyses of three additional sampling series have been completed (see Fig. ! 1. i 0}. Our explanation of the 11-year rise and fall in stratospheric nitric acid that is apparent in our data is now generally accepted. The primary source of this variation, which is in the region of the atmosphere between the tropopause and 20-km altitude, is the ionization of oxygen and nitrogen by galactic cosmic rays. Our data agree with nitric acid concentrations predicted by theoretical models. The concentration variation also has the correct phase relationship to modulations of galactic cosmic-ray fluxes that are c:.used by the 11-year solar semicycle, as indicated by stratospheric ionization measurements and theoretical models. However, the 6 X 10''-molecule excess nitric acid we observed in spring 1977 following the November 17, 1976, 4-ivIt Chinese nuclear test has frequently been questioned. This excess indicates an injection of odd nitrogen oxides that is about an order of magnitude greater than that predicted by mathematical models. Although the models do not tak^ into account several possible nitrogen oxide production terms from an atmospheric nuclear detonation, it is unlikely viiat they are in error by a factor of 10. We have subjected the spring 1977 data to a number oft-, ots for validation and find that they are quiie defensible. A sampl'.-by-sample plot of borrb-produced radioactivity vs nitric acid (Fig. 11.11) shows a very high degree of association between these species. Although we admit t'xat such a correlation does not prove that the nuclear test was the source of the excess nitric acid, certainly the data strongly suggest it. As we consider the apparent discrepancy between observations and th^ model, we ask ourselves if something could have been different in the stratosphere in spriitg 1977 to cause the samplers to behave differently. We believe that under normal circumstances, stratospheric nitric acid exists in the vapor state. 4" During the sampling process, as air passes through the filters, vapor phase HNO, molecules become attached to filter fibers. At the lower air velocities used with balloon-borne

*National Center for Atmospheric Research, Boulder, Colorado 204 ATMOSPHERIC CHEMISTRY AND TRANSPORT samplers, this, process is nearly 100% efficient, but for the aircraft-borne samplers, collection efficiencies between 40 and 80% are more common. However, both balloon and aircraft samplers are 100% efficient for aerosols. Therefore, if the nitric acid present in spring 1977 were attached to aerosols because of ultracold —80°C stratospheric temperatures of the polar stratospheric night, it would be sampled more efficiently than normal and show a rnuch larger than expected apparent increase, as seen in Fig. 1 i.10. (Summertime polar stratospheric temperatures are about —45CC.) Fortunately, for the spring 1976, spring 1977, and summer 1977 sampling, we used filters of which a portion was impregnated with tetrabutyl ammonium hydroxide (TBAH). The TBAH- impregnated filters are essentially 100% efficient for acidic vapor phase molecules as well as 100% efficient for aerosols. The TBAH data for these three sampling series are shown in Fig. 11.10 by a dotted line. The same spring 1977 incr -ase appears in ihe TBAH data; however, the increase is not quite as large, and because we now have 100% sampling efficiency, it is not further enhanced by the efficiency factor. This means that instead of a factor of 10 inconsistency with the model, the difference is at most a factor of 4 or 5. In fact, when all the data (except spring 1977) are corrected for efficiency and the TBAH value is used for spring 1977. that period's excess HNO, is only slightly greater than the excesses observed in 1972, 1974, and 1978-79.

~~5.0 10.0 15.0 20.0 NITRIC ACID (ng) / AIR (g)~~

Fig. in.10. Nitric acid burden measured in ihc stratosphere from 80°N to !he equator, between the troposphere and 20 km. The dashed line is ihe variation in ionization caused by galactic cosmic rays. Vectors proportional to their yields indicate stratospheric injections by northern hemisphere atmospheric nuclear tests larger than 2 Mt. The time is also indicated for an injection from above by a major solar proton evem (just after the conclusion of our fall 1972 sampling). A calculated value for the above ambient nitric acid that should have been expected if only dynamical removal processes were acting (as traced by bomb-produced 95Zr) is compared with the measured value for the TBAH-impregnated filters in spring 1977. A TMOSPHERIC CHEMISTR Y AND TRANSPORT 205

~~15 8 m m TBAH IMPREGNATED FILTERS O * WINTER + SPRING NEUTRAL FILTERS. NOT CORRECTED FOR EFFICIENCY X x SUMMER Q ° FALL O 10- CALCULATE!"! VALUE 5 MEASURED VALUE E-~~

~~o 5-~~

~~3 o T I—T" 1— 1 1970 1971 1972 1973 19"» 1075 1976 1977 1978 1979 1930 1981 1982 1983~~

Fig. 11.11. Co'-rclation plot for bomb debris gamma activity and nitric acid measured on each filter for the spring 1477 sampling. The slope is 100 times higher than a similar plot for spring 1976. The correlation coefficient is 0.90.

A corollary question must be addressed. Why do we not observe a similar effect for the period when th? stratospheric aerosol .concentration was very high: in spring 1975 following the October 1974 eruption of Volcan Fuego or in the springs of 1981, 1982, and 1983 following eruptions of Mount St. Helens. Alaid. Pagan, the mystery volcano, and El Chichon? One difference may be in the nature of the stratospheric aerosol. Following large volcanic eruptions, the aerosol is primarily droplets of about 75% H:SO4 and 25% H^O. Following a nuclear test, the aerosol in the debris cloud will be primarily vaporized metallic bomb case materials and possibh crustal silicate minerals (if the fireball touched the ground or entrained crustal dust into the rising cloud). If we invoke condensation on bomb debris particles but not on HrSO4 aerosols, then the release mechanism to produce the decrease we observed between spring and summer 1977 becomes crucial. Some of that decrease can be accounted for by dynamical removal processes. This is illustrated in Fig. 11.10, which compares a calculated HNO, concentration that is based on atmospheric dynamics, as traced by radioactive bomb debris, to the measured value for the summer 1977 TBAH-impregnated filters. However, the remainder of the decrease must be caused by some physical or photochemical change in the state of the nitric acid. Although Rosen and :j| Hofmann reported that they observed evaporation and recondensation of volcanic H:SO4 aerosol, such a phenomenon is certainly not possible with refractory materials vaporized in the bomb fireball. If HNO, reacts with metallic debris particles to form a salt, it would not have been released in summer 1977 by a photochemical mechanism. Only if the HNO, attachment to debris particles were a physical surface absorption or if sufficient acid, H2SO4 or HNO,, were attached to the metallic particles to make an acidic droplet would release in the summer of 1977 have been feasible. Other possible explanations require the introduction of some other fortuitously coincident episodic source of odd nitrogen oxides or the adoption of photochemical schemes that are beyond our present knowledge. 12.

~~Geochemical Anomalies at Biological Crisis Zones in the Fossil Record 209~~

~~The Molybdenum Solar Neutrino Experiment 212~~

~~Variations in Activities of Cosmogeaic Radionuclides Over a Solar Cycle 215~~

~~Cosmogenic Nuclides in the SNC (Martian?) Meterorites 217~~

~~Boron Cosmochemistry 219~~

~~»^ EARTH AND PL4NETAR Y PROCESSES 209~~

~~GEOCHEMICAL ANOMALIES AT BIOLOGICAL CRISIS ZONES IN THE FOSSIL RECORD~~

Charles J. Orth, James S. Gilmore, Leonard R. Quintana, Petrita Q. Oliver, and Jere D. Knight*

In a recent paper, Raup and Sepkoski242 concluded that extinctions of terrestrial life have occurred with a periodicity of 26 million years—at least during the last 245 million years. This important conclusion has sparked renewed interest in large-body/earth impacts and their association with global biological crises such as the event hypothesized by Alvarez et al.M that marks the terminal Cretaceous Period, 65 million years ago. Through statistical analysis, several in- vestigators2445 have found indications that the age distributions of terrestrial impact craters are also periodic and roughly synchronous with the extinction pattern. Our search for geochemical anomalies at extinction boundaries is providing chemical and physical evidence to test both these hypotheses and recent suggestions that periodic comet swarms, resulting from several possible astronomical mechanisms,244246" are responsible for the periodic extinctions and crater-age distributions. Comets, like meteorites and asteroids, should have brought in large amounts of platinum-group elements such as iridium, which we can detect with very high sensitivity (about 1 ppt). Therefore, comet showers should have left their signature as an increase in the concentration of iridium in sedimentary rocks laid down at the time of collision. In this work, we measure concentrations of osmium, iridium, platinum, and gold by neutron activation of the rock samples ; we perform radiochemical separations to increase the sensitivity. We also submit duplicate samples to the Los Alamos Reactor Group (Group INC-5), who use their automated neutron activation analysis system240 to provide us with abundances for about 30 other chemical elements. A global extinction -of marine animals occurred at the end of the Frasnian Age of the Late Devonian Period (- 365 million years ago). In earlier work, we have found no evidence for excess indium in samples collected across this Frasnian/Famennian (F/F) boundary at three localities in New York and at another near Sinsin, Belgium.2''" It was possible that the absence of geochemical anomalies in these sections was the result of local preservation factors, so we decided to test another locality where the marine sediments were laid down under quiescent deepwater conditions and where a thin fallout bed might be preserved. In collaboration with Australian and Canadian paleontologists and stratigraphers, we located, sampled, and analyzed an idefl sedimentary sequence in the Canning Basin of Western Australia (Fig. 12.1). Precisely at the stratigraphic level assigned as the F/F boundary (on the basis of fossil evidence), we detected a moderate iridium anomaly that reached 320 ppt over the local background of about 15 ppt. Other elements such as platinum, cobalt, arsenic, nickel, copper, lead, rare earths, vanadium, and thorium were also in higher abundances at the boundary, as shown in Fig. 12.2. Particularly striking is the cerium pattern, which shows a two- to fourfold increase in its ratio to the other rare earths at the boundary. The elemental ratios, taken in total, are not representative of any known class of meteorite. The fossil iron cyanobacterium Frutexites occurs in abundance at the boundary' as bundles of filaments covered by micritic envelopes. Analysis of the fossil material and adjacent matrix that were extracted with a microdrill shows that the anomalous elements are concentrated by fa ors of 2 to 5 in the fossil material. We cannot say whether biological mechanisms were the sole cause of the anomalies, or whether the organisms were only able to accumulate these elements to such a degree because of abnormally high concentrations in seawater at that time: we suspect the former. In addition, we do not know whether the concentrating mechanism was biochemical, mechanical, or even diagenetic. The cause ol the massive F/F extinction remains a mystery.

*Los Alamos National Laboratory consultant 210 EARTH AND PLANETARY PROCESSES

~~DEVONIAN REEF COMPLEXES McWHAE RIDGE~~

~~CANNING BASIN~~

~~Fig. 12.1. Map of Frasman/Famcnnian extinction boundary sampling locality at McWhae Ridge, Western Australia.~~

A team of Russian investigators2''1 has reported an iridium anomaly at a marine Precam- brian/Cambrian (P/C) boundary section at a locality near Yakutsk, Siberia. They observed an iridium spike that reached 160 ppt over local backgrounds of ~ 10 ppt. We obtained duplicate samples and measured 35 ppt at the boundary' over a local background of ~6 ppt. Furthermore, several elements, for example, aluminum, vanadium, arsenic, antimony, rare earths, and uranium, which are not associated with meteorite sources, are also enriched at the boundary. Because the concentration of iridium is simply proportional to the clay content in this marine carbonate sequence, we find no reason to associate an impact with the P/C boundary at this locality. According to paleontologists, the greatest extinction in the fossil record occurred at the end of the Permian Period (P/T boundary) about 245 million years ago. In earlier work, Asaro et al.2'2 found no evidence for an iridium anomaly at this boundary at two localities in China. However, about 1 year ago, several Chinese teams reporied:3i:v) strong iridium anomalies at two P/T localities separated by 1100 km; one locality is the same measured by Asaro el al. Recently, in collaboration with Keith Rigby, a recognized paleontologist at Brigham Young University, we measured elemental abundances in a P/T boundary sample that he collected at a new locality near Lichuan in Hubei Province, China. We found a mere 1.3 ppt of iridium in a boundary clay sample that appeared to be the alteration product (now illite) of ash from an acidic (explosive) volcano. The trace-element patterns we observed were identical to those reported earlier by Asaro et al.:>1 To resolve this problem, we are attempting to obtain duplicate samples from the Chinese. Either they have established a new stratigraphic level for the boundary that contains an iridium anomaly, or their measurements are in error. In the FY 1983 annual repoit. we presented preliminary results that indicated an absence of an iridium anomaly at the Ordovician/Silurian (O/S) boundary exposed on Anticosti Island, Quebec."' That work is now compete and the conclusions remain the same. In collaboration with UC Berkeley paleontologists, we have examined samples collected from the O/S boundary at the type locality at Dob's Linn, Scotland; the iridium levels are somewhat high (100 to 175 ppt), possibly because of extremely slow rates of sedimentation. We are now doing further, more detailed sampling. Thus far, our measurements in sedimentary rocks older than 65 million years have not turned up any convincing evidence to support the suggestions that biological extinctions are caused by periodic cometary impacts. EARTH AND PLANETARY PROCESSES 211

~~+ V5- + 1 -~~

~~8-1- i~~

~~-2-~~

~~-3-~~

~~0 320 C 64 0 0 32 0 20 0 50 0 64 0 26 -4 Ir(ppi) Pt(ppb) Au (ppb) Fe!%) Co (ppm) Ni(ppm) Cr(ppm)~~

~~• 1-5- •O -~~

~~-2-~~

~~-3-~~

~~-4- 0 64 0 26 0 100 0 80 0 320 0 16 0 2 Cu (ppm) As (ppm) Pb (ppm) La (ppm) Ce (ppm) Th (ppm) U (ppm)~~

~~+ 1-5- • 1 -~~

~~-2-~~

~~-3-~~

-4- ° 13 4 "66118 3 2 54 200 6 Ct%.) 6B0(%.) Ca(%) ' ° ° ° V(ppm) Mn tppm) Fig. 12.2, Abundance patterns for some significant elements and isotope ratios for carbon and oxygen at the Frasnian/Famennian extinction boundary exposed in northwestern Australia. The sampled section ranged from 1.5 m above 10 4 m below the boundary (0) that was established on the basis of fossil evidence. 212 EARTH AND PLANETARY PROCESSES

~~THE MOLYBDENUM SOLAR NEUTRINO EXPERIMENT~~

Kurt Wolfsberg, Donald J. Rokop, Charles M. Miller, Kathryn S. Daniels, Nicholas S. Nogar (CHM-2), Stephen W. Downey (M-4), Vicki G. Niesen, E. A. Bryant, George A. Cowan (ADCEL), and Wick. C. Haxton*

The measurement of "*Tc produced from molybdenum by solar neutrinos is one application of our program2""1 to develop a mass-spectrometric technique for measuring sub-picogram levels of iechnetium isotopes. The goal of the molybdenum solar neutrino experiment257 is to deduce the aB solar neutrino flux, averaged over the past several million years, from the concentration of ''"Tc in a deeply buried molybdenum deposit. The experiment is very important for understanding stellar processes; it will shed light on the discrepancy between theory and observations in the chlorine solar neutrino experiment.2^ Since 1970, an average neutrino capture rate of 0.3 per day in 615 tons of perchloroethylene has been observed; the result is more than a factor of 3 lower than the value predicted by the standard -our model. Reasons for the discrepancy may lie in the properties of neutrinos (neutrino oscillations) or in deficiencies of the standard solar model. The chlorine experiment only measures the SB neutrino flux in current times and cannot address possible temporal variations in the interior of the sun4 (these variations are also not considered in the standard model). In the molybenum experiment, we plan to measure g8Tc (4.2 million years), also produced by 8B neutrinos, and possibly "7Tc (2.6 million years), which is produced by lowei energy neutrinos. We anticipate a capability of measuring 107 atoms** of''"Tc by a mass spectrometric method. To obtain this number of atoms, we will require about 2600 tons of ore, which contain 13 tons of molybdenite, from a deeply buried deposit."157 Our problem, then, is to chemically isolate a trace quantity of technetium for mass spectrometry from such a large quantity of material. Fortunately, some of the work is done for us in the commercial processing of molybdenum by the AMAX Corporation during the production of molybdenum oxide.f Rotation separation at the Henderson molybdenum mine in Colorado produces a concentrate that is 90 to 99% molybdenite. The concentrate is shipped to the AMAX roasting plant at Ft. Madison, Iowa, where MoS: is converted to MoO<. There are two roasters at the plant, each with a capacity of up to 50 tons of concentrate per day; our experiment requires only part of a day's production. A schematic of the plant is presented in Fig. 12.3. The MoS: concentrate is in the roaster about 8 hours at temperatures from 740 to 615°C. The exhaust gas, containing principally SO: and SO,, is treated for dust removal and is then cooled, scrubbed, and converted to sulfuric acid. The scrub operation removes fluorides, chlorides, some of the sulfur gases, selenium, and rhenium from the gas stream before it enters the sulfuric acid plant. In the scrub stream, the last traces of molybdenum dust are filtered out, selenium is precipitated (probably as the metal) for environmental reasons, and li;ne is added to precipitate sulfates and sulfites.

"Unwersiiy of Washington, Seattle **Note in proof: We have learned that the cross section calculated for the '"Motv.i, /"Tc reaction from recently determined Gammow-Tcller strengths in excited states of ^Tc is a factor of 3.5 higher than previously estimated. This fact, and our anticipated ability to be able to process 50 tons of molybdenite concentrate rather than the 13 ions as originally planned, may allow us to separate a sample containing 108 atoms of'sTc and will relax the detection requirement by an order of magnitude. tThe rrahagement of the AMAX Molybdenum Division of the Climax Molybdenum Company has been most gracious in allowing us to pursue the possibility of this experiment. In particular, we are indebted to T. Reams, R. H. Calc. and their stali'at the plant in Ft. Madison Iowa. EARTH AND PLANETAR Y PROCESSES 213

To infer the fate of technetium during the process, we have been relying largely on our measurements of its chemical homolog rhenium, which has similar properties. The boiling points of Re:O7 and Tc:O7 are 360 and 31 PC, respectively; the redox potentials for the ReO^/ReO, and TcO;/TcO: couples are 0.510 and 0.738 V, respectively. The MoS2 concentrate that is fed into the roaster typically contains 7 ppm rhenium, whereas the MoO3 product contains <0.1 ppm rhenium; this indicates that rhenium is volatilized in the roaster. Molybdenum dust recycled from the precipitators contains about 6 ppm rhenium, which tells us there is no sink for that element in xhe hot gas exhausi line before the acid scrub. Rhenium is condensed in the acid scrub (fluoride tower) and is found at concentrations of about 6 ppm immediately ahead of and following the molybdenum dust filtei and the selenium filter. Only about 10% of the rhenium is in the selenium filter, Re:S, is not precipitated quantitatively because H?S cannot be added in excess as a result of the large amount of H:SO, in the scrub stream. It was necessary to develop a process to remove technetium and rhenium from this acid scrub stream, preferably ahead of the H:S addition. It was also desirable that this process cause minimum disruption in the commercial operation of the plant. An ion exchange process appeared to be a good choice. Commercial columns of the type used for de-ionizing or softening water are rated for flow rates of up to 30 8/minute. Perrhenate and pertechnetate are strongly absorbed on anion-exchange resin, and our experiments showed that many commercial resins work well. However, technetium does not sorb well out of H2SOj solution, probably because it is reduced to a neutral or cationic species; rhenium still absorbs strongly. We solved the problem by oxidizing the solution with NaOCl, the addition of which is acceptable to the AM AX plant management. Laboratory experiments with H2SO4-H2SO3 solutions oxidized with NaOCl, in which only the column diameter was scaled down, indicated that 98% of the technetium could be retained for a half-day run at the plant. We conducted a similar experiment at the plant, using actual plant-stream solution and a small-diameter column but a realistic linear flow rate through a 95-cm-long column; we found that 87% of the rhenium was captured on the column. We have now designed these modifications at the plant to remove technetium and rhenium from the acid scrub stream. In Fig. !2.3, the dashed lines indicate addition of NaOCl to an existing storage tank and location of a by-pass loop to be constructed for the ion-exchange columns. The plan for this loop, shown in Fig. 12.4, allows for the interception of all or part of the stream through anion-exchange columns. Our plan for a large-scale experiment requires that these columns be returned to Los Alamos for continued purification of the techntiium. The next step is to recover the technetium from the — 100 5 of resin in a relatively small volume. Pertechnetate has a very high distribution coefficient on anion-exchange resin, and we investigated methods for stripping technecium that involved reduction to nonsorbing species. It appears that after TCO4 sorbs on the resin it is very difficult to reduce, and none of the reducing agents we investigated was successful. At the present time, we propose to ash the resin at ~420°C for ~ 1 day. Tests have shown only minor loss of technetium, and the residue is soluble. We are developing additional purification steps before mass-^pec- trometric measurement. We still must develop methods to separate the technetium from rhenium (~ 100 g), molybdenum (an overall decontamination factor of 1021 is required!), and other impurities such as selenium. We are investigating both thermal-ionization and laser resonance-ionization methods to measure the technetium mass spectrometrically at the levels required. The principal goal is to achieve high ionization efficiencies and acceptably low levels of interference from molybdenum isobais. For thermal ionization, we start with filaments made from zone-refined rhenium metal and heat them at 2300°C for 30 to 50 minute. Filaments that exhibit low molybdenum signals at 1900°C are hand pijked from these. To date, the resin-bead method has given the best results for both high ionization efficiency and low isobaric interference from the sample itself. In the last chemical manipulation, technetium is loaded from NH^OH onto a single ~200-um bead of anion-exchange resin that is subsequently washed with HCl. The bead is then put onto the rhenium canoe filament 214 EARTH AND PLANETAR Y PROCESSES for mass spectroscopy in a tandem-magnet spectrometer At the present time, we can typically achieve ionization efficiencies of 8 X 10"' for samples containing 50 pg (3 X 10" atoms) of ""Tc, although efficiencies as high as 7 X 10"1 have been achieved. To perform the experiment, we must be able to routinely achieve an efficiency of about 5 X 10~4 to 10" \ this will give a count rate of 10 to 20 counts per second above a similar background. We are investigating the bead-loading and filament parameters involved in this process as well as schemes such as negative thermal ionization. Resonance ionization is a laser-based ionization technique that allows discrimination against unwanted atoms in the sample.2*" For technetium, we have explored a variety of two-color, three- photon resonance ionization schemes that greatly reduce the problems associated with molybdenum contamination.:M To date, however, we have not demonstrated sufficient efficiency for the solar neutrino measurements; in this phase of the work, we are also concentrating our efforts to increase the yields. Technetium-99 will be present at several orders of magnitude greater than l"*Tc as a spontaneous fission product of the :18U in the molybdenite. The experiment requires demonstration of secular equilibrium for "uTc. We will use artificially produced "7Tc to trace wTc in smaller samples. The known concentration of ""Tc can then be used as a tracer for "sTc in the large-sample experiments.

~~Scrubbed flue gases Lo aulfuric acid plant.~~

~~Proposed ^.. .. f Tc loop Recycled Proposed Se filler Lime .10% NaOCl addition ~3.B tpm~~

~~Fig. 12.3. Schematic of a molybdenum roasting plant. EARTH AND PLANETARY PROCESSES 215~~

~~Proposed 3" Khsdula at CPVC pipa 1 1/7' outlet schedule 80 CPVC pipe~~

~~To existing storage lank before Se iilter~~

~~Fiberglass ion exchange columnlumr s 1?' dlamelilei r~~

~~Legend Quik Connect~~

~~Pressure gauge~~

~~Globe valve~~

~~Check valve~~

~~Fig. 12.4. Schematic of the by-pass loop to remove technetium from acid scrub stream.~~

~~VARIATIONS IN ACTIVITIES OF COSMOGENIC RADIONUCLIDES OVER A SOLAR CYCLE~~

~~Robert C. Reedy~~

The sun emits a variety of plasmas, magnetic fields, and energetic particles into the solar system. The fluxes of the galactic-cosmic-ray (GCR) particles are modified as they enter the solar system by scattering on the interplanetary magnetic and electric fields that come from the sun.262 The amount of solar activity, which varies with time and location in the solar system, determines how much the fluxes of GCR particles are modulated. Almost all the cosmic-ray-produced nuclides observed in meteorites or deep in lunar samples are made by GCR particles.:w:w We have calculated how much the activities of these cosmogenic nuclides change because of variation in solar activity. The time between peaks or valleys in solar activity is usually about 11 years, and the period between two consecutive solar minima is called a solar cycle. The integral fluxes of GCR particles with energies above I GeV/nucleon during solar minimum are about twice those during periods of maximum solar activity.:M The fluxes of GCR particles with energies below 1 GeV/nucleon also are reduced considerably during solar maximum.262 Because the GCR particles are modulated by the changing activity of the sun, the production rates of cosmogenic nuclides vary by factors of about 2.5 over the period of a solar cycle. This variation in production rates was calculated from the modulated spectra of GCR particles264; it also was observed in the activities of short-lived radionuclides that were measured in meteorites falling during different parts of the solar cycle.265 216 EARTH AND PLANETARY PROCESSES

For most cosmogenic radionuclides, this variation in production rates is unimportant: their half-lives are much longer than the 11-year activity cycle of the sun and their radioactivities are not changed much by production or decay over such a relatively short period. However, for half-lives of about 11 years or less, such as 12.33-year 3H, 5.27-year 60Co, 2.6-year ~Na, 312-day 54Mn, 84-day lhSc, and 16-day 48V, the measured radioactivities will vary during the 11-year solar cycle. These variations were calculated using two analytic expressions for the change in the production rates during a solar cycle: a cosine curve and a saw-toothed function. Several indicators of solar activity, such as sunspot numbers, follow curves shaped like cosines over a solar cycle. For the saw-toothed function, the production rate drops linearly over 5.5 years from peak value to minimum, then immediately increases linearly to maximum. This saw-toothed function was used because the counting rates of cosmic-ray-produced neutrons at the earth's surface frequently have such a shape during parts of a solar cycle—often at the maximum or minimum. Table 12.1 gives the calculated radioactivity variations for these two product! in-rate profiles and for several radionuclides or half-lives. The cosmogenic-nuclide production rates over an 11- year cycle were assumed to vary by a factor of 2.5. The values of the maximum activity divided by the minimum activity and of the offsets of the extremes in activity after the extremes in the production rates are given for different radionuclide half-lives and for the two profiles (a cosine and a saw-toothed function) used for the production rates. The magnitude of variation between extremes in the activities and time of the extreme activities varied with the half-life. Very short lived radionuclides follow the production profile. Very long lived species have very little activity change over a solar cycle, and their radioactivity extremes are 2.75 years after the peak or valley in the production profile. The offsets of maximum radioactivity relative to the peak production rate were less for the saw-toothed function than for the cosine because the saw-toothed function drops faster just after the peak rate. Thus for the saw-toothed production profile, the radionuclide has less time to build its radioactivity to a maximum, and the maximum/minimum ratio is less than for the cosine profile. The real variations in solar activity over a solar cycle and in the production rates of cosmogenic nuclides are a complicated function that varies considerably within and among solar cycles. The two functions used here are roughly extremes to the observed profiles, so the variations that should be observed for radioactivities of short-lived cosmogenic nuclides would usually be between the viiues given in Table 12.1. The calculated offsets and ranges of the radioactivities in the table for 2:Na, '4Mn, 4(1Sc, and 48V are similar to those observed in meteorites that fell during different parts of a solar cycle.:M

~~Table 12.1. Changes in the Activities of Short-Lived Radionuclides Over an 11-Year Solar Cycle"~~

~~Cosine Saw-Tooth~~

Radionuctide Half-Life Max/Min Offset Max/Min Offset (years) (years) (years) 100.0 1.01 2.73 1.01 2.73 'H 12.33 1.09 2.58 1.07 2.54 60Co 5.27 1.21 2.35 1.16 2.26 22Na 2.60 1.44 1.99 1.34 1.82 1.50 1.74 1.56 1.57 1.34 5JMn 0.856 2.08 1.08 1.85 0.84 J6Sc 0.229 2.45 0.33 2.29 0.23 J8V 0.044 2.50 0.06 2.46 0.04 0 010 2.50 0.01 2.49 0.01 EARTH AND PLANETARY PROCESSES 217

~~COSMOGENIC NUCLIDES IN THE SNC (MARTIAN?) METEORITES~~

~~Robert C. Reedy~~

Characteristics of the four Shergottite, three Nakhlite, and Chassigny (SNC) meteorite family indicate that they have unique origins. Chemical, petrological, and chronological measurements for the SNC meteorites imply that they came from a large parent body.266267 The noble gases and nitrogen trapped in Shergottite EETA79001, which was found near Elephant Moraine in Ant- arctica, resemble the gises in the atmosphere of Mars.268 However, it seems unlikely that these meteorites could hav? been ejected from a large body like Mars without resetting various isotopic ratios and producing other observable shock effects.276-m Knowing what happened to these very unusual meteorites in space would help us understand their origins, so I calculated the production rates of cosmogenic nuclides in several SNC meteorites and studied their cosmic-ray records. The basic calculation for the production rate of a cosmogenic nuclide is the same as that used previously for the moon270 and meteorites.271 The production rate for product j at depth d in a meteorite of preatmospheric radius R, Pj(R,d) is

~~Pj(R,d) = I, Ni / F(E,R,d)~~

where N; is the chemical abundance of element i; F(E,R,d) is the flux of cosmic-ray particles as a function of energy E, radius R, and sample depth d; and o^E) is the cross section for making product j from element i as a function of energy. The flux model for stony meteorites used for F(E,R,d) and the cross sections used for most of the cosmogenic nuclides have been descrioed in earlier publications.270271 The chemical compositions of these differentiated meteorites vary widely, especially those for the target elements that make such important cosmogenic nuclides as 2lNe, 26A1, 16C1,3iAr, and krypton and xenon isotopes. I used the chemical compositions that were measured267272273 or estimated (for example, zirconium using hafnium and yttrium from dys- prosium) for six different SNC chemistries. The shapes of the production-rate profiles as a function of the meteorite's preatmospheric radius and a sample's depth in the meteorite are generally similar to those calculated for L-chondrites;271 the 38Ar in the calcium-rich compositions is one of the most dissimilar profiles. These production rates can vary considerably with radius and depth, and the production profiles for a high-energy product like 3He are different than those for a low-energy one like 2;Ne. The calculated ratio 3He/2'Ne for Shergotty, shown in Fig. 12.5 is a fairly sensitive indicator of a meteorite's preatmospheric radius and a sample's depth. However, the magnitude of most production rates varies considerably with chemical composition; the smallest variations are for 3He and 10Be, which are made mainly from oxygen. (See Table 12.2 for a summary of six different SNC chemistries). The ratio of the production rates in these SNC chemistries to those in L-chondrite chemistries are often depth dependent. Several groups of researchers have recently measured cosmogenic noble gases or radionuclides in the SNC meteorites. These cosmic-ray records can be used to determine the length of time that these objects were exposed to cosmic rays in space, the terrestrial residence time of the two Antarctic Shergottites (ALHA77005 and EETA79001), and the meteorites' approximate preatmospheric sizes. The integral cosmic-ray exposure ages inferred from the noble-gas concentrations form three groups: the Nakhlites and Chassigny, Shergottite EETA79001, and the other three Shergottites.274 Cosmogenic radionuclides provide additional constraints on the exposure histories of the SNC meteorites. Preliminary measurements* of 1.6-million-year l0Be in the SNCs are consistent with the three groups of noble-gas exposure ages.

*From information provided by Gregory Herzog, Rutgers University. •""Information received from John Evans, Battelle Pacific Northwest Laboratories, and Rolf Sarafin, University of Cologne, Federal Republic of Germany. 218 EARTH AND PLANETARY PROCESSES

~~50 100 150 200 250 300 DEPTH (g/cm2)~~

Fig. 12.5. The calculated 3He/2lNe ratios are shown as a function of Shergotty's possible preatmospheric radii (g/cnv) and sample depth. Production by solar cosmic rays was not considered. The ratio marked with an x in the upper left corner is for primary particles in the galactic cosmic rays and is the ratio expected for a very small object.

The cosmogenic nuclide data do not imply any unusual exposure geometries in space for the SNC meteorites, but they are consistent with those of other typically sized meteorites. For example, the 3Her'Ne ratio measured2"8 in a sample of EETA79001 is 7.62 ± 0.72, which according to calculated ratios similar to those in Fig. 12.5, corresponds to a sample depth of less than 25 cm. Activities of 0.7-million-year -bAl in EETA79001 imply its terrestrial residence time was only a few hundred thousand years;** thus its shorter exposure age relative co the other Shergottites is not caused by a long terrestrial age, but by ejection from a much larger body later than the other Shergottites. Because no cosmogenic nuclides from this earlier exposure geometry were detected in EETA79001, the parent body for EETA79001 must have been at least many meters in radius, and EETA79001 was deeply buried in it. These results for cosmogenic nuclides imply that the Shergottites would have to have been ejected from Mars (or their ultimate parent body) by two events, or EETA79001 was ejected inside a very large object that was broken apart about a million years ago. Both of these scenarios for the Shergottites appear to disprove the martian origin hypothesis; they would imply either two impacts in the same region of Mars within a very short period of time or the ejection of a very large object, both of which are unlikely, h ieasurements of additional cosmogenic nuclides, including some made by neutron-capture reactions, and measurements of heavy cosmic-ray nuclei tracks in the SNC meteorites will put more constraints on their cosmic-ray exposure histories and their possible origins. EARTH AND PLANETAR Y PROCESSES 219

Table 12.2 Ratios of Cosmogenic-Nuclide Production Rates of SNC Meteorites to Those in L-Chcndrites* Isotope Shergotty ALHA77005 EETA79001A E TA79001B Nakhla Chassigtiy 3He 1.04-1.03 1.04-1 05 1.05-1.05 1.04-1.03 1.04-1.02 1.03-1J4 10Be 1.05-1.08 1.09-1.11 1.07-1.09 1.04-1.07 1.©2 1.05 1.07-1.08 21Ne 0.76-0.53 1.13-1.13 0.91-0.76 0.74-0.48 0.75-0.53 1.18-1.24 26A1 1.48-1.54 1.10-1.11 1.36-1.40 1.57-1.67 1.21-1.20 0.91-0.89 36C1 2.6-3.6 1.1-1.3 1.9-2.5 2.7-3.8 3.5-4.9 0.7-0.5 18Ar 3.4-5.1 1.4-1.8 2.5-3.6 3.7-5.6 4.7-7.3 0.6-0.4 78Kr 9.8-9.2 2.8-2.6 4.8-4.5 9.9-9.3 3.4-3.5 8lKr 7.4-6.6 2.0-1.8 3.3-2.8 6.7-5.8 3.65-3.65 "First ratio is for low shielding geometry in spar e (small objee or near surface). Second ratio isi for heavy shielding (deep inside large object.)

~~BORON COSMOCHEMISTRY~~

~~David B. Curtis~~

Introduction Several years ago, we published the results of analyses for boron in 86 pieces that represent 44 different chondritic meteorites. ' Seventy-two of these pieces were analyzed as we received them from the curatorial facilities Each of the 86 was an observed fall, but otherwise its history in the terrestrial environment was unspecified; these were called "unknown" samples. Sixteen of these 86 samples were specifically extracted from the interior of observed falls. A comparison showed that the mean value of boron abundances in interior pieces was significantly less than that in the unknown samples. We concluded that boron in chondritic meteorites is extremely susceptible to terrestrial contamination and that any cosmochemical inferences regarding this element should be based on the results from only interior samples. Our value for the cosmic abundance of boron was calculated from such results and, consequently, was at least three times less than any previous meteorite-based estimate. It was also in good agreement with spectroscope-based estimates of boron abundance in the sun. In a recent evaluation of the cosmic abundances of the elements, Anders and Ebihara27" considered our data275 in detail. They concluded that the cosmic abundance of boron should be about three times greater than the value we determined. The discrepancy between these conclusions arises from differences in assumptions about the cosmochemical character of boron. Seeing no systematic relationship between the boron content and -.hondritic type, we assumed that each interior sample was representative of the primordial abundance of the element; we calculated the cosmic abundance from a simple average of the log of abundance in each piece. Using the results of thermodynamic considerations of the phase relationships of boron in a cooling solar nebula,277 Anders and Ebihara assumed that boron was a "moderately volatile" element.27'1 According to the theory propounded by Larimer and Anders,278 the measured abundance of such an element in different chondrite types represents its cosmic complement diluted by different proportions of a component that is barren of volatile elements. Therefore, to obtain the true solar proportion of boron, measured abundances must be corrected for dilution by this component. Anders and Ebihara estima^d the degree of dilution by consider- ing the abundances of other moderately volatile elements in the same meteorites, or meteorites of the same type, and corrected the boron abundances accordingly.276 220 EARTH AND PLANETAR Y PROCESSES

To resolve this discrepancy in interpretation, we analyzed boron in 37 interior samples representing 23 different chondrites. In addition, we measured the abundance of the major elements silicon, sulfur, aluminum, sodium, and manganese in the same samples. Silicon and sulfur are of particular interest. Silicon is the element to which all others are normalized when we determine cosmic abundances and identify systematic differences between the composition of different chondrite types. Sulfur is a moderately volatile element; silicon-normalized abundances of sulfur and boron should correlate if boron is a moderately volatile element. We analyzed boron, silicon, sulfur, and aluminum by a specialized type of neutron activation analysis in which samples are bombarded with neutrons and concurrently, the collimated beam of gamma rays emitted from the sample is analyzed by a Ge(Li) spectrometer. We determine element quantities by directly comparing the results from samples with those from appropriate standard materials. Detailed discussions and evaluations of the methods are found in Refs. 275 and 279-233. We determined sodium abundances by the standard neutron activation analysis technique.

Results and Discussion Figure 12.6 is a plot of the silicon-normalized abundances of boron vs sulfur in chondrites of petrologic types 1 to 4. Data is plotted on this diagram without regard to chemical type; it includes results from both carbonaceous and ordinary chondrites. The data in the figure are identified with (1) interior, (2) "unknown," or (3) low-sodium samples. With the exception of those samples distinguished by low sodium, interior pieces of low-petrologic-type chondrites contain covarying quantities of sulfur and boron. However, only 3 of the 13 unknown samples show this same regular relationship between the 2 elements. (Five samples contained such large quantities of boron that they were not included in Fig. 12.5.)

~~VK. 1HTEHGB 'uwuiowr LOW Hi C-l • o I ' 1 C-2 A A 40 __ A C-3 • D K.LLL-3.4* 0 - O - 30 — 9 o A A 20 - PRECISION © OF - RESULTS - V I 10 - ^ A CD k~~

~~1 0 1 -1 L 1 , 10 20 30 40 50 S/Si(aton»/I02 atoms)~~

Fig. 12.6. Con elated variations in the silicon-normalized abundances of boron and sulfur as a function of chondrite class in interior pieces of low petrologic types indicate that boron, like sulfur, is a moderately volatile element. EARTH AND PLANETAR Y PROCESSES 221 We reiterate our conclusion from the previous paper75 that boron data from unknown pieces of meteorites are unreliable and should not be used without some evidence that they are representative of uncontaminated material. We consider the agreement between results from interior samples and those from unknown pieces of Murray, Bali, and Allende to be such evidence and therefore will include results from these three in subsequent considerations of indigenous meteoritic boron. In most instances, the sodium abundance is quite consistent between different samples of the same meteorite. However, three pieces of type 2 carbonaceous chondrites contain less than half the sodium found in other samples of the same type. All pieces of the low-sodium type deviate from the observed covariance between boron and sulfur. The pieces with small sodium abundances contain large quantities of boron. Some proportion of sodium in this type of chondrite is water s Juble (Jarosewich, as reported in Ref. 284). Anomalously low sodium and anomalously high boron may be signatures of leaching in the terrestrial environment, or they could be the result of preterrestrial hydrous alterations. In either case, we will assume that the deficiency of this alkali element is diagnostic of secondary alteration of boron and will exclude these samples when we consider its cosmochemistry. Both the covariance of boron abundance and its regularity as a function of chondritic type suggest that boron is indeed moderately volatile, as suggested by Anders and Ebihara.27* Conse- quently, we have re-evaluated the meteorite-based cosmic abundance of boron using their method. Measured abundances were corrected to account for dilution by the volatile-poor component. The proportion of this component in individual meteorites was taken from the work of Takahashi et a/.;ss and Wolfe/ a/.286 When data was not available for individual chondrites, we assumed the proportion 0.55 for type C-2,0.75 for type C-3, and 0.81 for ordinary chondrites. The average of the log of these corrected abundances in individual pieces of chondrites of petrologic types 1 to 4 is, thus, taken to be the cosmic abundance of boron. This value is 21*' atoms B/10+6 atoms silicon. In ordinary chondrites, copper and gallium, two other moderately volatile elements, show little variation in abundance as a function of meteorite type.287 Our own data for sulfur also show a very narrow distribution in ordinary chondrites; analyses of 22 interior pieces of ordinary chondrites of petrolog-c types 3 to 6 produced results with a standard deviation that is only 11% of the mean. Boron in ordinary chondrites does not show such consistency. Figure 12.7 is a histogram of boron abundances in interior pieces of ordinary chondrites. Data from the lower petrologic types 3 and 4 are distributed about a value that we assume represents the solar proportion of boron in this type of meteorite. However, the higher petrologic types 5 and 6 define a bimoda) distribution at the extremes of this value. The distinction between the distribution defined by the iower petrologic types and the two modes defined by the higher petrologic type is clearly defined. The five type 3 and 4 samples define an extremely narrow distribution that includes only one of the higher petrologic types. The higher petrologic types 5 and 6 delineate two well-defined modes on the histogram shown in Fig. 12.7. The low-abundance mode has an average of 3.4 atoms B/106 atoms silicon with a range of 2.2 to 4.0. The high-abundance mode has an average of 11.5 atoms B/106 atoms silicon with a range between 7 and 27. There is a hiatus between 4 and 7. Neither mode is exclusively populated by either a single chemicF.l or a single petrologic type of chondrite. In fact, one piece of Leedey falls in the Sow-abundance mode and another in the region of high abundance. One piece of Manor., Iowa, contains more than twice as much boron as is contained in two other pieces of the same meteorite. Given the care with which the samples were prepared and the regularity of the data, it seems unlikely that the distinction between the boron content in lower petrologic types and that in higher petrologic types can be attributed to terrestrial weathering. We suggest that the bimodal distribution of boron in types 5 and 6 ordinary chondrites is a unique manifestation of metamorphic processes in the chondritic parent bodies. 222 EARTH AND PLANET AR Y PROCESSES

~~ORDINARY CHONDRfTES~~

~~10 12 >12 B/si(atoms/i06 atoms)~~

F;g. 12.7. The hisiogram demonstrates the distinction between the tightly defined distribution of boron in low-pelrologic-iype ordinarv chondiiies and the bimodal distribution of boron in high petroiogic types. \ Advisory Committee Diviii^^DiJnareandip mot

~~V C « APPENDIX: DIVISION PERSONNEL 225~~

~~LIST OF DIVISION PERSONNEL BY GROUP~~

INC-DO (667-4457) Deborah S. Ehler Buildings RC-29 and 34, TA-48 Scolt A. Ekberg *P. Gary Eller * Donald W. Barr, Division Leader James A. Fee, Project Leader t*Oarleane C. Hoffman, Division Leader tEKzabelh M. Foltyn "James E. Sattizahn, Deputy Division Leader *Eiichi Fukushima t*Nicholas A. Matwiyoff, Coord. Nud. Med. Michael G. Garcia *Bruce R. Erdal, Associate Division Leader John L. Hanners Helen A. Lindberg, Assistant Division Leader •Judith C. Hulsosi Barbara J. Anderson "Gordon D. Jarvenin Joann W Brown "Llewellyn H. Jones (Laboratory Fellow) Audrey L. Giger tToby E. Kain iody H. Heiken Jean K-ing Janey Howard "Scott kinkead Richard J. Kissane "Gregory J. Kubas INC-3 (667 4675) Charles A. Lehman, Jr. Building RC-34 and Radiochemistry Bu'ding. TA-48 t*Robert E. London *B. B. Mclnteer, Project Leader *Harold A. O'Brien, Jr., Group Leader Raymond C. Medina *David C. Moody, III. Deputy Group Leader "Thomas R. Mills •John W. Barnes Joe G. Montoya t*Glenn E. Bentley John D. Purson "Janet A. Mercer-Smith Ramon Romero Martin A. Oit Kenneth V. Salazar Karen E. Peterson "Alfred P. Sattelberger Neno J. Segura Frances A. Schmahl Franklin H. Seurer "Clifford J. I'nkefer *F. J. Steinkruger *Pat J. Unkefer *Zita V. Svitra tRaymond C. Vandervoort Wayne A. Taylor "William E. Wageman t*K^nneth A. Thomas "Thomas E. Walker *Philip M. Wanek "William H. Woodruff t*D. Scott Wilbur

INC-5 (667-4151) INC-4 (667-6045) Omega Site, TA-2 Buildings 3 and 150. TA-21; Building 88. TA-46 "Merle E. Bunker, Group Leader "Basil I. Swanson, Group Leader "Michael M. Minor, Deputy Group Leader t*Robert A. Penneman, Group Leader tBruce P. Eide "Robert R. Ryan, Deputy Group Leader "Sammy R. Garcia "Stephen F Agnew Michael D. Kaufman *Dale E. Armstrong "Alvin R. Lyle "Lamed B. Asprey Janet S. Newlin "James R. Brainard t*Josef R. Parrington Michelle L. Brewer Danny O. Ramsey F. Ruth Capron Thomas C. Robinson "Don T. Cramer Cathy J.Schuch "William L. Earl "John W. Starner Douglas G. Eckhart "Herbert T. Williams 226 APPENDIX: DIVISION PERSONNEL

INC-7 (667-4498) Michael R. Cisneros RacHochemistry Building. TA-4S •David D. Clinton Kay L. Coen •Ernest A. Bryant. Grouj. Leader Joy Drake •Alexander J. Gancarz. Jr.. Depuly Group Leader •Bruce J. Dropesky Ruben D. Aguilar *D. Wes Efurd •Mohammed Alei Patricia A. Elder Joseph C. Banar •Martha L. Ennis t*Barbara P. Bayhurit •Malcolm M. Fowler Gregory' K.. Bayhurst •James D. Gallagher •Timothy M. Benjamin Carla E. Gallegos *Irwin Binder •Gregg C Geisler •John H. Cappis •James S. Gilmore •Robert W. Charles Gary T. Hansen t*George Corchary •S:>ra B. Helmick •Bruce M. Crowe •David F. Hobarl •David B. Curtis Merlyn E. Holmes Kathrvn S. Danieis Gregory M. Kelles •Clarence J. Dully •(••Thomas A. Kelk-\ Suzann Dye Jack H. Knight Ruth A. Fuvat •Sylvia D. Knight •Paul R. Guihals •Gordon M. Knobeloch Deva E. Handel Marcella L. Kramer Julia M. Jaramillo Marjorie E. Lark Kathleen S. Kelly •Francine O. Lawrence •Allen S. Mason •Michael J. Leitch •.Vend Meijer. Project Leader Shari Lermuseaux •Charles M. Miller Lelia Z. Liepins Lia M. Mild,ell •Lon-Chang Liu •Eugene J. Mroz Calvin C. Longmire •A. Edward Norris Patrick S. Lysaght •Thomas L. Norris Sixto Maestas •Allen E. Ogard +E. Loretta McCorkle •Richard E. Pcrrin Alan J. Mitchell •JaneC. Poths Thomas A. Myers •Pamela Z. Rogers •Thomas W. Newton •Donald J. Rokup Glcnda E. Oakley C. Elaine Roybal Petrita Q. Oliver •William A. Sedlacek •Charles J. Orth (Laboratory Fellow) t*Rosemary J. Vidale Phillip D. Palmer Patsy L. Wanck t^RcncJ. Preslwood •Kurt Wollsberg Tony Racl •Robert C Reedy •Robert S. Rnndbcrg INC-11(667-4546) t*Virginia L. Rundberj" Radiochemistry Building. T.A-48: Raymond G. Schofield LAMPF Building. TA-53 Richard I. Stice •Willard L. Talbert. Jr. •William R. Daniels. Group Leader •Kimberly W. Thomas •Gcnevifve F. Grisham. Depuly Group Leader •Joseph L. Thompson tVoncille M. Armijo Larry S. Ulibarri •John P. Balagna Lcvi Valencia •Gary' S. Benson •David.'. Vieira Roland A. Bibeau •Jerry B. Wilhclmy (Laboratoi. .'(.-.'.) •Gilbert W. Butler •Jan M. Wouters •Edwin P. Chamberlin t*Alfrcd H. Zcltmann APPENDIX: DIVISION PERSONNEL 227

~~Long- Term Hsiting Staff Members~~

~~tRaajev S. Bhalerao. INC-11 tNathan Bower, 1NC-7 tWilliam H. Zoller. 1NC-7~~

~~Postdoctoral Appointees~~

M. Pamela Bumsted. INC-4 Ci. Langhorne Farmer, 1NC-7 David L. Finnegan. INC-7 Steve D. Figard. INC-3 + HerberlA. Fry, INC-4 David E Morn,. 1NC-4 tYoshiiakaOlikubo, INC-11 + R,i>mondS. Rogers. INC-3 ~Harvey J. Wasserman, 1NC-4 Debra A. WroblesM. 1NC-4

~~Graduate Research Assistants~~

tSharon L Blaha, INC-11 tCarol J. Burns, INC-4 tBridgel R. Burris. INC-7 .lames F. Conner, INC-7 tBrian T. Foley. INC-7 tSusan L. Fraser. INC-i 1 MarkL. Giger, INC-4 + -\mina Guessous, INC-1 1 Roger A. Henderson, INC-' 1 Steven Kidman. INC-7 tRonald Kuse. INC-4 Douglas Manatt, INC-4 Vicki Niesen, INC-7 tElizabeth M. Overmyer. INC-4 Leonard R. Quintana. INC-11 tLarry Robinson. INC-11 Jamal Sandarusi. INC-7 tMark Schafmer. INC-11

~~Undergraduate Assistants~~

~~Cindy L. Jaramillo. INC-1 I CaliC. Matheny. INC-4 Lorraine M. Schlosser. INC-DO John S. Wilson. INC-4~~

*StafT Member tNo longer working in INC Division 228 APPENDIX: PUBLICA TIONS

~~PUBLICATIONS~~

~~INC-3~~

5. L. Waters, K. R. Butler, J. C. Clark, P. L. Horlock, M. J. Kensett, I. W. Goodier, J. Makepeace, D. Smith, M. J. Woods, J. W. Barnes, G. E. Bentley, P. M. Grant, and H. A. O'Brien, Jr., "Radiosssay Problems Associated with the Clinical Use of a Rubidium-82 Radionuclide Generator." Int. J. Nucl. Med. Biol. 10(2/3), 69-74 (1983).

J. H. Patterson, F. J. Steinkruger, G. M. Matlack, R. C. Heaton, K. P. Coffelt, and B. Herrera, "Plutonium Release from Pressed Plutonium Oxide Fuel Pellets in Aquatic Environments," Los Alamos National Laboratory report LA-9962-MS (December 1983).

~~J. A. Mercer-Smith and D. C. Mauzerall, "Photochemistry of Porphyrins: A Model for the Origin of Photosynthesis," Photochem. Photobiol. 39(3), 397-405 (1984).~~

R. Quinn, J. A. Mercer-Smith, J. N. Burstyn, and J. S. Valentine, "The Influence of Hydrogen Bonding on the Properties of Iron Porphyrin Imidazole Complexes: An Internally Hydrogen Bonded Imidazole Ligand," J. Am. Chem. Soc. 106( 15), 4136-4144 (1984).

F. T. Avignone, C. W. Barker, H. S. Miley, H. A. O'Brien, Jr., F. J. Steinkruger, and P. M. Wanek, "Absolute Pair Production Cross Section Measurements in Z = 1.077 MeV Photons," Phys. Let. 104A(3), 143-145 (1984).

~~F. J. Steinkruger, G. M. Matlack and R. J. Beckman, "The Half Life of Pu-240 Determined by Alpha Activity Measurement," Int. J. Appl. Radiat. Isotop. 35(3), 171-172 (1982).~~

K. E. Peterson, M. A. Ott, F. H. Seurer, and K. E. Thomas, "INC-3 Isotope Production Activities in FY 1983," in "Isotope and Nuclear Chemistry Division Annual Report FY 1983," Los Alamos National Laboratory report LA-10130-PR (May 1984), pp. 82-84.

S. Yan, H. A. O'Brien, F. J. Steinkruger, and W. A. Taylor, "Recovery of ^Ti From a Proton-Irradiated Vanadium Target Development of a 44Ti -> 44Sc Generator," in "Isotope and Nuclear Chemistry Division Annual Report FY 1983," Los Alamos National Laboratory report LA-10130-PR (May 1984), pp. 87-89.

J. W. Barnes, M. A. Ott, K. E. Thomas, and P. M. Wanek, "Iodine-123," in "Isotope and Nuclear Chemistry Division Annual Report FY 1983," Los Alamos National Laboratory report LA-10130-PR (May 1984), p. 85.

F. J. Steinkruger and G. E. Bentley, "Production and Recovery of 52Fe From an Irradiated Nickel Target," in "Isotope and Nuclear Chemistry Division Annual Report FY 1983," Los Alamos National Laboratory report LA-10130-PR (May 1984), pp. 79-80.

K. E. Thomas and W. A. Taylor, "Progress With Isotope Production From Molybdenum Targets," in "Isotope and Nuclear Chemistry Division Annual Report FY 1983," Los Alamos National Laboratory report LA-10130-PR (May 1984), pp. 80-81.

G. E. Bentley and P. M. Wanek, "Characterization of LAMPF-Produced Radiohalogens," in "Isotope and Nuclear Chemistry Division Annual Report FY 1983," Los Alamos National Laboratory report LA-10130- PR (May 1984), pp. 85-87.

G. E. Bentley, F. J. Steinkruger, and W. A. Taylor, "Applications of Electrochemistry to Isotope Production," in "Isotope and Nuclear Chemistry Division Annual Report FY 1983," Los Alamos National Laboratory report LA-10130-PR )May 1984), pp. 90-91. APPENDIX: PUBLICATIONS 229

~~R. S. Rogers, "Antibody Radiolabeling," in "Isotope and Nuclear Chemistry Division Annual Report FY 1983," Los Alamos National Laboratory report LA-10130-PR (May 1984), pp. 91-93.~~

D. S. Wilbur, "Studies of Radiohalogenations Using Trimethylsilyl Intermediates: Radiohalogenations of Amines for ,Brain Studies," in "Isotope and Nuclear Chemistry Division Annual Report FY 1983," Los Alamos National Laboratory report LA-10130-PR (May 1984), pp. 93-102.

D. S. Wilbur and Z. V. Sivtra, "Studies Toward Radiohalogenuiions of Fatty Acids: Radiopharmaceuticals for Evaluating the Heart," in "Isotope and Nuclear Chemistry Division Annual Report FY 1983," Los Alamos National Laboratory report LA-10130-PR (May 1984), pp. 104-106.

~~INC-4~~

S. F. Agnew, B. I. Swanson, L. H. Jones, R. L. Mills, and D. Schiferl, "Chemistry of N:O4 at High Pressure: Observation of a Reversible Transformation between Molecular and Ionic Crystalline Forms," J. Phys. Chem. 87, 5065-5068 (1983).

R. L. Blakley, L. Cocco, J. A. Montgomery, C. Temple, Jr., B. Roth, S. Daluge, and R. E. London, "Catalytic Site of Dihydrofolate Reductase," in Chemistry and Biology of Pteridines, J. A. Blair, Ed. (Walter DeGreuter and Co., Berlin, 1983), pp. 215-221.

J. R. Brainard, I. Y. Hutson. R. E. London, and N. A. Matwiyoff, "l3C-Enriched Substrates for in Situ and in Vivo Metabolic Profiling Studies by "C NMR," in Stable Isotopes in Nutrition, ACS Symposium Series No. 158, i. R. Turnlund and P. E. Johnson, Eds. (American Chemical Society, Washington DC, 1984), Chap. 11, pp. 157-174.

J. R. Brainard, R. D. Knapp, J. D. Morrisett, and H. J. Pownall, "I3C NMR Studies of the Thermal Properties of a Model High Density Lipoprotein: Apolipoprolein Al-Dimyristoylphosphatidylcholine Complex," J. Biol. Chem. 259 (16), 10340-10347 (1984).

L. Cocco, B. Roth, C. Temple, Jr., J. A. Montgomery, R. E. London, and R. L. Blakely, "Protonated State of Methotrexale, Trimethoprim and Pyrimethamine Bound to D:hydrofolate Reductase," Arch. Biojhem. Biophys. 226, 567-577(1983).

~~D. T. Cromer, R. R. Ryan, and D. Scott Wilbur, "Structure of l//-Azepine-2,5-dione 5-(O-Methyloxime), C7H8N:O:," Acta Cryst. C40, 301 -303 (1984).~~

~~W. L. Earl, "Hidden Signals and Lineshapes in High Resolution Solid State NMR.," Texas A&M University NMR Newsletter 306, 42 (1984).~~

~~W. L. Earl, "Improvements for Cross Polarization NMR (Especially on Bruker CXP's)," Texas A&M University NMR Newsletter (1984).~~

~~P. Gary Eller and P. J. Vergamini, "Nuclear Magnetic Resonance and Chemical Studies of Uranium(V) Alkoxides," Inorg. Chem. 22. 3184-3189 (1983).~~

~~H. A. Fry, L. H. Jones, and J. E Barefield, "Observation and Analysis of Fundamental Bending Mode of T:O." J. Mol. Spectrosc. 103, 41-55 (1984).~~

~~H. A. Fry, L. H.Jones, and B. I. Swanson, "High Resolution Spectra of i( 1,1) — 0(0,0) Rotational Tradition of H:O in Argon and Krypton Matrices," Chem. Phys. Lett. 105, 517-550 (1984).~~

~~E. Fukushima, "Radiofrequency and Magnet Technology in Medical NMR," in Proc. 1SE/IEL.E Symposium, 1984, pp. 64-68. 230 APPENDIX: PUBLICA TIONS~~

~~G. D. Jarvinen and R. R. Ryan, "Reaction of SO2 with Transition Metal Hydrides: Synthesis and Structure of (H-H):(CO)io(n-S02)," Organometallics 3 (9), 1434-1438 (1984).~~

~~L. H. Jones and B. I. Swanson. "Quantification of Orientational Ordering of SF6 in Solid Xenon Matrices," J. Chem. Phys. 80(6), 2980-2982 (1984).~~

~~L. H. Jones and B. I. Swanson, "Orientational Ordering and Site Structure for CCI4 in a Krypton Matrix," J. Chem. Phys. 80(7), 3050-3053 (1984).~~

~~L. H. Jones, B. 1. Swanson, and S. A. Ekberg, "Orientational Ordering and Site Selective Photochemistry of UFh Isolated in Argon Matrices," J. Phys. Chem. 88 (7), 1285-1286 (1984).~~

~~O. L. Keller, Jr.. D. C. Hoffman. R. A. Penneman, and G. R. Choppin, "Accomplishments and Promise of Transplutonium Research," Physics Today 37 (3), 35-41 (1984).~~

G. J. Kubas and R. R. Ryan, "Reduction of Sulfur Dioxide by Cp:MH: (M = Mo, W) to Cp:M(S;O,) and Water: Molecular Structure and Reaction with Acids of an Organometallic Molybdenum-Thiosulfate Complex," lnorg. Chem. 23 (20), 3181 -3183 (1984).

G. J. Kubas, R. R. Ryan, B. I. Swanson, P. J. Vergamini, and H. J. Wasserman, "Characterization of the First Examples of Isolable Molecular Hydrogen Complexes, M(COb(PR3):(H2) (M = Mo, W; R = Cy, i-Pr). Evidence fora Side-on Bonded H: Ligand," J. Am. Chem. Soc. 106, 451-452 (1984).

G. C. Levy, D. J. Craik, A. Kumar, and R. E. London, "A Critical Evaluation of Models for Complex Molecular Dynamics: Application to NMR Studies of Double and Single Stranded DNA," Biopolymers 22, 2703-2726(1983)

R. E. London, "Carbon-13 Labeling Strategies in Macromolecular Studies: Application to Dihydrofolate Reductase," in Topics in Carbon-13 NMR Spcctroscopv, Vol. 4, G. C. Levy, Ed. (Wiley & Sons, New York, 19841, pp. 53-90.

~~J. G. Malm, P. Gary Eller, and L. B.. Asprey. "Low Temperature Synthesis of Plutonium Hexafluoridc Using Dioxygen Difluoride," J. Am. Chem. Soc. 106 (9), 2726 (1984).~~

~~D. C. Moody and R. T. Paine. "Low Valent Actinides as Hydrogenation Catalysts," J. Catal. 85, 536-537 (1984).~~

~~E. J. Peterson, E. M. Foltyn. and E. 1. Onstott, "Thermochemical Splitting of Sulfur Dioxide with Cerium(IV) Oxide," J. Am. Chem. Soc. 105 (26), 7572-7573 (1983).~~

P. E. Pfeffer, K. B. Hicks, M. H. Frey, S. J. Opella. and W. L. Earl, "'-^-"C Dipolar Interactions Provide a Mechanism for Obtaining Resonance Assignments in Solid State "C NMR Spectroscopy," J. Magn. Reson. 55,344.346(1983).

P. E. Pfeffer, K. B. Hicks, M. H. Frey, S. J. Opclla, and W. L. Earl, "Complete Solid State I3C NMR Chemical Shift Assignments for a-D-Glucose. a-D-Glucose'H^O and (3-D-Glucose," J. Carbohydrate Chem. 3 (2), 197-217(1984).

~~John M. Ritchey and David C. Moody, "Platinum(O) Complexes with Bulky Phosphines: Trinuclcar SO-, and CS: Complexes," Inorg. Chim. Acta 74. 271-274 (1983).~~

~~S.B.W. Roeder, E. Fukushima, and A.A.V. Gibson, "NMR Coils with Segments in Parallel to Achieve Higher Frequencies or Larger Sample Volumes." J. Magn. Reson. 59, 307-317(1984).~~

~~G. Selvaduray, L. B. Asprey, and M. W. Asprey, "Decontamination Requirements for FBR- and LWR- Derived Plutonium," Trans. Am. Nuclear Soc. 45, 135-136 (1983). APPENDIX: PUBLIC A TIONS 231~~

~~C. .1. Unkefer, R. M. Blazer, and R. E. London, "//? vivo Determination of the Pyridine Nucleotide Reduction Charge by Carbon-13 Nuclear Magnetic Resonance Spectroscopy," Science 222, 62-65 (1983).~~

C I. Unkefer and R. E. London, "In vivo Studies of Pyridine Nucleotide Metabolism in Escherichia coli and Saccharomyces cerevisiae by Carbon-13 NMR Spectroscopy," J. Biological Chem. 259 (4), 2311 -2320 (1984).

C .1. Unkefer, R. D. Walker, and R. E. London, "Hydrogen-1 and Carbon-13 Nuclear Magnetic Resonance Conlbrmational Studies of the His-Pro Peptide Bond: Conformational Behavior of TRH," Int. J. Peptide Protein Res. 22, 582-589(1983).

~~la T E. Walker and M. Goldblatt, "The Synthesis of Oxyg. n-18 Enriched Phenol and Naphthol from O}," J. Labelled Compd. Radiopharm. 21 (4), 353-361 (1984).~~

~~H. J. Wasserman, D. C. Moody, R. T. Paine, R. R. Ryan, and K. V. Salazar, "Tetrahydroborate Complexes of Uranium with 2-(Diphenylphosphino)pyridine," J. Chem. Soc. Chem. Commun. 8, 533-534 (1984).~~

H. J. Wasserman, D. C. Moody, and R. R. Ryan, "Tertian.1 Phosphine Complexes of Trivalent Uranium: Preparation and Structure olU(BH4),(dmpe): (dmpc = MeiPCH:PMe:)," J. Chem. Soc. Chem. Commun. 8, 532-533(1984).

H. J. Wasserrr.an, A. J. Zozulin, D. C. Moody, R. R. Ryan, and K. V. Salazar, "Crystal and Molecular 5 Structure of Tricyclopentadienyltetrahydrofuranuranium(III), (r| -C5H5hU OC4HS," J. Organomel. Chtm. 254.305-311(1983).

W. H. Woodruff, K. A. Norton, B. 1. Swanson, and H. A. Fry, "Temperature Dependence of the Resonance Raman Spectra of Plastocyanin and Azurin Between Cryogenic and Ambient Conditions," Proc. Natl. Acad. Sci. USA 81 (4), 1263-1267(1984).

~~INC-5~~

M. E. Bunker, W. L. Talbert, Jr., and R. C. Greenwood. "Helium-Jet Transport of Fission and Spallation Reaction Products," in "Progress at LAMPP, January—December 19T3," Los Alamos National Laboratory report LA-10070-PR (April 1984). pp. 125-128.

~~S. Raman. «•'. r^iynski. E. T. Jurney, M. E. Bunker, and J. W. Starner, "3(IS (n.y) "S Reaction with Thermal Neutrons, and Decay of "S to Levels in "Cl," Phys. Rev. C 30. 26 (1984).~~

W. L. Talbert, Jr.. and M. E. Bunker. "Expectations for Radioactive Beams at a Proposed ISOL Facility at LAMPF," in "Proceedings of the Workshop on Prospects for Research with Radioactive Beams from Heavy Ion Accelerators," Lawrence Berkeley Laboratory report LBL-18187-UC-34A (April 1984), pp. 59-70.

W. L. Talbert, Jr., M. E. Bunker, and J. W. Starner, "A He-Jet System to Study Short-Lived Fission Product Nuclei at LAMPF," in "Proceedings of the NEANDC Specialists Meeting on Yields and Decay Data of Fission-Product Nuciides." Brookhaven National Laboratory report BNL-51778 (1983), pp. 331-336.

~~INC-7~~

~~D. R. Janecky and W. E. Seyfried. Jr., "Magnetite-Hematite-NaCl-HiO Reactions at 300°C," T.-ans. Am. Geophys. Union 15. 603 (1983).~~

~~T. L. Norris, A. J. Gancarz. D. J. Rokop, and K. W. Thomas, "Half Life of 2flAl," J. Geophys. Res. 88 (15), B331-B333 (1983).~~

R. M. Zimmerman. R. D. Young. J. L. Younker. el ai. "Test Plan for Exploratory Shaft at Yucca Mountain," US Department of Energy Nevada Operations Office report NVO-244 (November 1983). 2 32 APPENDIX: PUBLIC A TIONS

R. Brandt, G. Fiege, T. Lund, D. Molzahn, D. C. Hoffman, S. J. Knight, A. J. Gancarz, G. W. Knobeloch, and F. O. Lawrence, "Upper Limits for the Concentration of the Potential Superheavy Elementary Particle (247Cm X") in Atlantis II Salt Brines" (abs.), Radiochim. Acta 34, 163-164 (1983).

~~A. S. Mason and H. G. Ostlund, "Stratospheric Tritium Sampling October 1979—August 1980." Los Alamos National Laboratory report LA-9874-PR (December 1983).~~

A. E. Ogard, K. Wolfsberg, and D. T. Vaniman, Comps., "Research and Development Related to the Nevada Nuclear Waste Storage Investigations, April 1—June 30, 1983," Los Alamos National Laboratory report LA-9846-PR (December 1983).

~~H. G. Ostlund and A. S. Mason, "'Commments on Natural Tritiated Moisture Levels in Air Vary with Atmospheric Pressure" (Letter-to-the-Editors), Int. J Appl. Radi.u. isot. 35 (2), 143 (1984).~~

T. M. Benjamin, C. J. Duffy, P. S, Z. Rogers, C. J. Maggiore, D. S. Woolum, D. S. Burneit, and M. T. Murell, "Microprobe Analyses of Rare Earth Element Fractionation in Metecritic Minerals," Nucl. Instrurn. Methods 231, 677-680 (1984).

~~D. B. Curtis, Book Review of The Origin of the Chemical Elements and the Oklu Phenomenon, by P. K. Kuroda, Geochim. Cosmochim. Acta 48, 601-602 (1984).~~

W. R. Daniels and J. L. Thompson, Comps., "Laboratory and Field S udies Related to the Radionuclide Migration Project, Annual Report, October 1, 1982—September 30, 1983," Los Alamos National Laboratory report LA-10121-PR (April 1984).

E. S. Gladney, D. B. Curtis, and D. R. Perrin, "Determination of Boron in 35 International Geochemical Reference Materials by Thermal Neutron Capture Prompt Gamma-Ray Spectrometry," Oeos'.nnd. Newsl. 1 (8), 43-46(1984).

~~P. S. Z. Rogers, C. J. Duffy, T. M. Benjamin, and C. J. Maggiore, "Geochemical Applications of Nuclear Microprobes," Nucl. lnstrum. Methods 231, 671-676 (1984).~~

K. Wolfsberg, K. S. Daniels, S. L. Frascr R. S. Rundberg, P. L. Waneic, J. L. Thompson, W. R. Daniels, H. W. Bentley, D. Elmore, L. E. Tubbs, and J. Fabryka-Martin, "The Migration of 1-129 and Cl-36 from an Underground Nuclear-Explosion Cavity Under Forced Conditions" (abs.), Program of the 187th American Chemical Society National Meeting, Division of lndwstrial and Engineering Chemistry (April 1984).

D. S. Woolum, R. Brooks Cochrane, D. Joyce, A. El Goresy, T. M. Benjamin, P. S. Z. Rogers, C. M. Maggiore, and C. J. Duffy, "Trace Element PIXE Studies of Qinzhen (EH3) Metal and Sulfides" (abs.), in Lunar and Planetary Science XV(Lunar and Planetary Institute, Houston, 1984), pp. 935-936.

D. L. Bish, D. T. Vaniman, R. S. Rundberg, K. Wolfsberg, W. R. Daniels, and D. E. Broxton, "Natural Sorptive Barriers in Yucca Mountain, Nevada, for Long Term Isolation of High Level Wastes" (abs.), in Radioactive Waste Management, Vol. 5 (IAEA, Vienna, 1984), pp. 415-432.

D. C. Hoffman, W. R. Daniels, K. Wolfsberg, J. L. Thompson, R. S. Rundberg, S. L. Fraser, and K. S. Daniels, "A Review of a Field Study of Radionuclide Migration from an Underground Nuclear Explosion Cavity at the Nevada Test Site" (abs.), in Radioactive Waste Management, Vol. 5 (IAEA, Vienna, 1984), pp. 241-257.

~~A. S. Mason, "Stratospheric Tritium Sampling April 1982—March 1983," Los Alamos National Laboratory report LA-9988-PR (May 1984).~~

T. L. Norris, A. J. Gancarz, D W. Efurd, T E. Perrin, G. W. Knobeloch, P. Q. Oliver, G. F. Grisham, R. J. Prestwood, I. Binder, G. W. BuUer, W. R. Daniels, and D. W. Barr, "14McV (n,2n) Neutron Cross Sections of 2"'Am and 243Am," in "RTNS-II 1983 Annual Report—Irradiations at the Rotating Target Neutron Source- II," Lawrence Livermore National Laboratory report UCID-19837-83 (May 1984). APPENDIX: PUBLICA TIONS 233

~~R. W. Charles and G. K. Bayhurst, "Reaction of Calcite Veined Granodiorite Reservoirs with a Dilute Aqueous F- '• An Expenmental Approach" (abs.), Trans. Am. Geophys. Union 64 (45), 879 (1984).~~

~~D. J. DePaolo and G. L. Fanner, "Isotopic Data Bearing on the Origin of Mesozoic and Tertiary Granite in the Western United States," Phil. Trans. R. Sec. Lond. A310, 743-753 (1984).~~

S. W. Downey, N. S. Nogar, and C. M. Miller, "Multiwavelength Resonance lonization of Technetium," in Proceedings oj the 32nd Annual Conference on Mass Spectrometry and Allied Topics (American Society for Mass Spectrometry, 1984), pp. 370-371.

~~S. W. Downey, N. S. Nogar, and C. M. Miller, "Resonance lonization Mass Spectrometry of Technetium," Int. J. Mass Spectrom. Ion Proc. 61, 337-345 (1984).~~

~~S. W. Downey, N. S. Nogar, and C. M. Miller, "Resonance lonization Mass Spectrometry of Uranium with Intracavity Laser Ionization," Anal. Chem. 56, 827-828 (1984).~~

C. M. Miller, N. S. Nogar, and S. W. Downey, "Analytical Developments in Resonance Ionization Mass Spectrometry," in Proceedings of the 32nd Annual Conference on Mass Spectrometry and Allied Topics (American Society for Mass Spectrometry, 1984), pp. 368-370.

~~E. J. Mroz and M. Alei, "Tracking Antarctic Winds," Antarc. J. U. S. 1983 Rev. XVIII (5), 235 (1984).~~

N. S. Nogar, S. W. Downey, and C. M. Miller, "Analytical Capabilities of RIMS: Absolute Sensitivity and Isotopic Analysis," in Resonance lonization Spectroscopy 1984 (Institute of Physics, Boston, 1984), pp. 91-95.

N. S. Nogar, S. W. Downey. R. A. Keller, and C. M. Miller, "Resonance Ionization Mass Spectrometry at Los Alamos National Laboratory," in AnalyiLul Spectroscopy, W. S. Lyon, Ed. (Elsevier Science Publishers, Amsterdam, 1984), Symp. Series Vol. 19. pp. 155-160.

~~R. E. Perrin, G. W. Knobeloch, V. M. Armijo. and D. W. Efurd, "High-Precision Isotopic Analysis of Nanogram Quantities of Plutonium," Los Alamos National Laboratory report LA-10013-MS (June 1984).~~

~~M. Reagan and A. Meijer, "Geology and Geochemistry of Early Arc Volcanic Rocks from Guam," Bull. Geol. Soc. Am. 95, 701-713(1984).~~

~~W. A. Sedlacek, A. L. lazrus, and B. W. Gandrud, "Measurements of Stratospheric Bromine," J. Geophys. Res. D3 (89), 4821-4825 (1984).~~

~~W. E. Seyfhed. Jr., D. R. Janecky. and M. J. Mottl, "Alteration of the Oceanic Crust Implications for Geochemical Cycles of Lithium and Boron," Geochim. Cosmochim. Acta 48, 557-569 (19S4).~~

~~R. J. Vidale and R. W. Charles, Book review oTGeothermal Systems: Principles and Case Histories, L. Rybach and L. J. P. Muffler, Eds., Am. J. Sci. 284, 795-796 (1984).~~

~~R. J. Vidale, "Some Aspects of the Information Onslaught in Geosciencs," in Science, Computers, and the Information Onslaught, D. Kerr et al., Eds. (Academic Press, Inc., 198-1), pp. 103-110.~~

D. L. Bish, A. E. Ogard, and D. T. Vaniman, "Mineralogy-Petrology and Geochemistry of Yucca Mountain Tuffs," in Scientific Basis for Nuclear Waste Management VII, G. L. McVay, Ed. (North Holland, New York, 1984). pp. 284-291.

E. A. Bryant and D. T. Vaniman, Comps., "Research and Development Related to the Nevada Nuclear Waste Storage Investigations, July 1—September 30, 1983," Los Alamos National Laboratory report LA-10006-PR (July 1984).

G. P. Ford, K. Wolfsberg, and B. R. Erdal, "Independent Yields of the Isomers of'"Xe and 135Xe for Neutron Induced Fission of 233U. 235U, 238U, 239Pu, and :42Amm," Phys. Rev. C 30 (I), 195-213 (1984). 234 APPENDIX: PUBLIC A riONS

A. E. Ogard, K. Wolfsberg, R. S. Rundberg, W. R. Daniels and B.J. Travis, "Retardation of Radionuclides by Rock Units Along the Path to the Accessible Environnu m," in Scientific Basis for Nuck'tir Waste Manage- ment VIIG. L. McVay, Ed. (North-Holland, New York. 1984), pp. 329-336.

K. Wolfsberg and D. T. Vaniman, Comps., "Research and Development Related to the Nevada Nuclear Waste Storage Investigations October 1—December 31, 1983," Los Alamos National Laboratory report LA- 10032-PR (August 1984).

E. J. Mroz, M. Alei, W. Efurd, P. R. Guthals, and A. S. Mason, "Heavy Methane Tracer Studies in Antarctica" (abs.). Program of the 188th American Chemical Society National Meeting, Division of Nuclear Chemistry and Technology (September 1984).

R. J. Prestwood, D. B. Curtis, D. J. Rokop, D. R. Nethaway, and N. L. Smith, "The Determination of the Cnr s Section for 15"Tb(n,2n)'58Tb and the Half-Life of l58Tb" (abs.), Phys. Rev. C 30 (3), 823-825 (1984).

~~W. A. Sedlacek, "Volcanism: S0: & SCV' (abs.). Program of the 188th American Chemical Society National Meeting, Division of Nuclear Chemistry and Technology (September 1984).~~

L. X. Trocki, D. B. Curtis, A. J. Gancarz, and J. C. Banar, "Ages of Major Uranium Mineralization and Lead Loss in the Key Lake Uranium Deposiv, Northern Saskatchewan. Canada," Econ. Geol. 79. 1378-1386(1984).

~~INCH~~

D. Ashery. D. F. Geesman, R. J. Holt. H. F. Jackson, J. R. Specht, K. E. Stephenson, R. E. Segel, P. Zupranski, H. Baer, J. D. Be. nan, M. D. Cooper. M. Leitch, A. Erel, J. Comuzzi, R. P. Redwine, and D. Tieger, "Inclusive Pion Single Charge Exchange Reactions," Phys. Rev. C 30, 946 (1984).

H. Backe, P. Sc.iger, W. Bonin, E. Kankeleit, M. Kramer, R. Kries, V. Metag, N. Trautmann, and J. B. Wilhelmy. "Estimates of the Nuclear Time De)qy in Dissipative U + U and U + Cm Collisions Derived from th" Shape of Positron and 5-Ray Spectra," Phys. Rev. Lett. 50, 1838 (1983).

~~J. Y. Bourges, B. Guillaume, G. Koehly, D. E. Hobart, and J. R. Peterson, "Coexistence of Americium in Four Oxidation States in Sodium Carbonate-Sodium Medium," Inorg. Chem. 22, 1179 (1983).~~

E. Bretthaner, F. Grossman, W. Efurd, G. Douglas, A. Smith, W. Corkern, and M. Bills, "Environmental Radioactivity at the TMI, Venting Phase," Environmental Protection Agency report EPA-600/4-81 (1984).

M. E. Bunker, W. L. Talbert, Jr., and R. C. Greenwood, "Helium-Jet Transport of Fission and Spallation Reaction Products," in "Progress at LAMPF 1983," Los Alamos National Laboratory report LA-10070-PR, (April 1984), p. 127.

M. D. Cooper, H. W. Baer, R. Bolton, J. D. Bowman, F. Cverna, N. S. P. King, M. J. Leitch, J. Alster, A. Doran, A. Erell, M. A. Moinester, E. Blackmore. and E. R. Siciliano, "Angular Distribution for l5N(7c',7i°).l5O (g.s.) at Trc=48 MeV," Phys. Rev. Lett. 52, 1100-1103 (1984).

J. L. Clark, P. E. Haustein, T. J. Ruth, J. Hudis, and A. A. Caretto, Jr., "Energy Deposition Accompanying Pion Double Charge Exchange: Radiochemical Study of the 2O9Bi(7t+,;c"xn)2O9"xAt Reactions," Phys. Rev C 27,1126(1983).

W. R. Daniels and J. L. Thompson, Comps., "Laboratory and Field Studies Related to the Radionuclide Migration Project, October 1, 1982—September 30, 1983," Los Alamos National Laboratory' report LA-10121-PR(Aprill984).

K. Eskola, P. Eskola, M. M. Fowler, H. Ohm, E. N. Treher, J. B. Wilhelmy, D. Lee, G. T. Seaborg. "Production of Neutron Rich Bi Isotopes by Transfer Reactions," Physical Review C 29, 2160 (1984). APPENDIX: PUBLICA TIONS 235

A. E. Evans and P. J. Bendt, "Neutron Spectrum From an Iron-Aluminum-Sulfur Filter," in Proceedings of the American Nuclear Society 1984 International Conference, Washington, DC, November 11-16, 1984.

G. Feige, R. Brandt, T. Lund, D. Molzahn, D. C. Hoffman, S. D. Knight, A. J. Gancarz, G. W. Knobeloch, and F. O. Lawrence, "Upper Limits on the Concentra on of the Potential Superheavy Elementary Farticle (:47CmX~) and other Transuranium Nuclides in Salt Brines," Science (1983).

~~M. M. Fowler and S. Barr, "A Long Range Atmospheric Tracer Field Test," Atmos. Environ. 17 (9), 1677-1685(1983).~~

A. Gavron, P. Eskola, A. J. Sierk, J. Boissevain, H. C. Britt, K. Eskola, M. M. Fowler, H. Ohm, J. 8. Wiihelmy, S. Wald, and R. L. Ferguson, "New Evaluation of Fission-Fragment Angular Distributions in Heavy Ion Reactions." Phys. Rev. Lett. 52, 589 (1984).

~~J. S. Gilmore. J. D. Knight, C. J. Orth, C. L. Pillmore, and R. H. Tschudy, "Trace Element Patterns at a Non- Marine Cretaceous-Tertiary' Boundary," Nature 307, 224-228 (1984).~~

R. G. Haire, H. E. Hcllwege, D. E. Hobart, and J. P. Young, "Synthesis, Lattice Parameters, and Absorption Spectra of the Orthophosphaics of the First Five Transplutonium Elements," J. Less-Comm. Metals 93, 358 (1983).

G. Himmele, H. Backe, P. A. Butler, D. Habs, V. Metag, H. J. Specht, and J. B. Wilhelmy, "Measurement of Nuclear Reaction Cross Sections for 18VI84W + :18U Near the Interaction Barrier," Nucl Phys. A404, 401 (1983).

~~D. E. Hobart. G. M. Begun, R. G. Haire, and H. E. Hellwege, "Raman Spectra of the Transplutonium Orthophosphates and Trimetaphosphates," J. Raman Spectrosc. 14, 59 (1983).~~

D. E. Hobart and J. R. Peterson, "Physicochemical Properties of Berkelium," in The Chemistry of the Actinide Elements. 2nd Edition, J. J. Katz. G. T. Seaborg, and L. R. Morss, Eds. (Chapman and Hall, Ltd., London).

~~D. E. Hobart, G. M. Begun, R. G. Haire. and H. E. Heliwcge, "Characterization of Transplutonium Ortho- and Trimeta-Phosphates by Raman Spectroscopy." J. Less-Comm. Metals 93, 3:>9 (1983).~~

D. C. Hoffman. W. R. Daniels. K. Wolfsberg, J. L. Thompson, R. S. Rundberg, S. L. Fraser, and K. S. Daniels, "A Review of a Field Study of Radionuclide Migration from an Underground Nuclear Explosion," International Atomic Energy Agency report IAEA-CN-43/469 (1983).

~~J. R. Hurd. L. r. Bland. G. P. Gilfoyle, R. Gilman. G. S. Slephans, J. W. Sweet, and H. T. Fortune, i: I6 "Resonance with C>Cgr in C+ O." Phys. Lett. 134B, 166(1984).~~

M. ). Leitch, M. R. L. Burman, R.Carlini. S. Dam, V. Sandberg, M. Blecher. K. Gotow, R. Ng, R. Aublc, F. E. Bertrand. E. E. Gross, F. E. Obenshain, J. Wu, G. S. Blanpied, B. M. Preedom, B. G. Ritchie. W. Bertozzi, M. V. Hynes, M. A. Kovash. and R. R. Redwinc. "Pion-Nucleus Elastic Scattering at 80 MeV," Phys. Rev. C 29, 561-568(1984).

~~L.-C. Liu. "Diffraction Theory and the Double-Charge Exchange Reaction l8O(7C+,jt" l8Ne," Phys. Rev. C 27, 11611 (1983).~~

C. Madic, G. M. Begun, D. E. Hobart, and R. L. hdhn, "Rarnan Spectroscopy of Neptunyl and Plutony! in Aqueous Solutions: Hydrolysis of Np(VI) and Pu(VI) and Disproportionation of Pu(V)," Inorganica Chirnica Acta94, 100(1983),

C. Madic, G. M. Begun. D. E. Hobart, and R. L. Hahn, "Cation-Cation Complexes ol'Pentavalent Actinides- 111: Complexes Formed by NpOjor VOt with VOt in Aquc . ~ Perchlorate Solutions." Radiochim. Acta. 236 APPENDIX: PUBLICA TIONS

C. Madic, D. E. Hobart, and G. M. Begun, "Raman Spectrometric Studies of Actinide(V) and (VI) Complexes in Aqueous Sodium Carbonate Solution and of Solid Sodium Auinide(V) Carbonate Compounds," Inorg. Chem. 22, 1494(1983).

~~G. R. McGhee, j. S. Gilmore, C. J. Orth, and E. Olsen, "No Geochemical Evidence for an Asteroidal Impact at Late Devonian ulass Extinction Horizon," Nature 308, 629 (1984).~~

E. J. Mroz, M. Alei, J. H. Cappis, W. Efurd, P. Guthals, A. S. Mason, ana D. J Rokop, "Heavy Methane Tracer Studies in Antarctica," in Proceedings of the American Chemical Society Meeting, Philadelphia, Pennsylvania, August 27-31, 1984.

T. L. Norris, A. J. Gancarz, R. E. Perrin, I. Binder, D. W. Efurd, G. W. Knobeloch, P. Q. Oliver, G. F. Gnsham, R J. Prestwood, G. W. Butler, W. R. Daniels, and D. W. Barr "i4 MeV (n,2n) Neutron Cross Sections of 241Am and !4!Ara," in "Rotating Target Neutron Source (RTNS) Annual Report," Lawrence Livermort National Laboratory report UCID-19837-83 (June 1984).

I. Navon, M. J. Leitch, D. A. Bryman, T. Numao, P. Schlatter, G. Azuelos, R. Poutissou, J. A. Macdonald, J. E. Spuller, C. K. Hargrove, H. Mes, M. Blecher, K. Gotow, M. Moinester. and H. Baer, "Pion Double Charge Exchange at 50 MeV on I4C," Phys. Rev. Lett. 52, 105 (1984).

~~C. J. Orth, J. D. Knight, L. R. Quintana, J. S. Gilmore, and A. R. Palmer, "A Search for Indium Abundance Anomalies at Two Late Cambrian Biomere Boundaries in Western Utah," Science 233, 163 (1984).~~

~~R. E. Perrin, G. W. Knobeloch, V. M. Armijo, and D. W. Efurd, "High-Precision Isotopic Analysis of Nanogram Quantities of Plutonium," Los Alamos National Laboratory report LA-10013-MS (June 1984).~~

~~J. R. Peterson and D. E. Hobart, "The Chemistry of Berkelium," Adv. Inorg. Chem. Radiochem. 28, 29-72 (1984).~~

~~P. R. Playford, D. J. McLaren, C. J. Orth, J. S. Gilmore, and W. D. Goodfellow, "Iridium Anomaly in the Upper Devonian of the Canning Basin, Western Australia," Science 226, 437-439 (1984).~~

J. van der Plicht, H. C. Britt, M. M. Fowler, Z. Fraenkel, A. Gavron, J. B. Wilhelmy, F. Plasil, T. C. Awes, and G. R. Young, "Fission of Polonium. Osmium, and Erbium Composite Systems," Phys. Rev. C 28 (5), 20 22-2032(1983).

~~N. T. Porile, A. A. Careito, B. J. Dropesky, C. J. Orth, L.-C. Liu, and G. C. Giesler, "Recoil Study of the l2Qn±,7tN)"C Reaction Between 90 and 350 MeV," Phys. Rev. C 75, 2239 (1984).~~

~~R. J. Prestwood, K. W. Thomas, D. R. Nethaway, and N. L. Smith, '"Measurement of 14-MeV Neutron Cross Sections for 88Zr and 88Y," Phys. Aev. C 79 (3), 805-810(1984).~~

R. S. Rundberg, B. J. Dropesky, G. C. Giesler, G. W. Butler, S. B. Kaufman, E. P. Steinberg, "Excitation Functions of Pion Single Charge Exchange Reactions in 27A1, 45Sc, and 65Cu," Phys. Rev. C 30, 1597-1603 (1984).

M. E. Schulze, D. Beck, M. Farkhondeh, S. Gilad, R. Goloskie, R. J. Hclt, S. Kowalski, R. M. Laszewski, M. J. Leitch, J. D. Moses, R. P. Redwine, D. P. Saylor, J. R. Specht, E. .!. Stcphenson, K. Stephenson, W. Turchinetz, and B. Zeidman, "Measurement of the Tensor Polarization in Electon-Deuteron Elastic Scattering," Phys. Rev. Lett. 52, 597-600 (1984).

~~K. K. Seth, M. Kaletka, S. Iverson, A. Soha, D. Barlow, D. Smith, and L -C. Liu, "Core Excitation Effects in Pion Double Charge Exchange," Phys. Rev. Lett. 52, 894 (1984).~~

W. L. Talbert, Jr. and D. W. Barr, "Analysis of Selected Soviet Thermonuclear Events Fired in the Atmosphere (U)," Los Alamos National Laboratory report LA-10073-MIS (S) (August 1984). APPENDIX: PUBLICA TIONS 237

R. S. Tschudy, C. L. Pillmoie, C. J. Orth, J. S. Gilmore, and J. D. Knight, "Disruption of the Terrestrial Plant Ecosystem ai the Cretaceous-Tertiary Boundary, Western Interior," Science 225, 1030-1032 (1984).

C. Tuniz, C. M. Smith, R. K. Moniot, T. H. Kruse, W. Savin, D. K. Pal, G. F. Herzog, and R. C. Reedy, "Beryllium-10 Contents of Core Samples from the St. Severin Meteorite," Geochim. Cosmochim. Acta 48, 1867-1872(1984).

P. G. Varlashkin, D. E. Hobart, G. M. Begun, and J. R. Peterson, "Electrochemical and Spectroscopic Studies of Neptunium in Concentrated Aqueous Carbonate and Carbonate-Hydroxide Solutions," Radiochim. Acta. 35,91-96(1984).

D. J. Vieira and W. L. Talbert, Jr., "LAMPF II Nuclear Chemistry Working Group Report from the Nuclei- Far-From-Stability Section," in "Proceedings of the Third LAMPF II Workshop, Los Alamos, New Mexico, July 1983," Los Alamos National Laboratory report LA-9933-C, Vol. II (November 1983), p. 886.

J. B. Wilhelmy, R. R. Chasman, A. M. Friedman, and I. Ahmad, "Directions for Nuclear Research in the Transplutonium Element Region," in Opportunities and Challenges in Research with Transplutonium Elements (National Research Council, National Academy of Science Press, Washington, DC, 1983), pp. 181-230.

~~H. J. Ziock, C. Morris, G. Das, J. R. Hurd, R. C. Minehart, L. Orphanos, and K. O. H. Ziock, "A^+ Resonance in a " B Nucleus," Phys. Rev. C 30, 650 (1984).~~

~~INC-DO~~

~~D. W. Efurd, G. W. Knobelor.h, R. E. Perrin, D. W. Barr, "An Estimate of 237Np Production During Atmospheric Testing," Health Physics 47, 786 (1984).~~

~~W. L. Talbert, Jr., and D. W. Barr, "Analysis of Selected Soviet Thermonuclear Events Fired in the Atmosphere," Los Alamos National Laboratory report LA-10073-MS (1984).~~

T. L. Norris, A. J. Gancarz, R. E. Perrin, I. Binder, D. W. Efurd, G. W. Knobeloch, P. Q. Oliver, G, F. Grisham, R. J. Prestwood, G. W. Butler, W. R. Daniels, and D. W. Barr, "14MeV (n,2n) Neutron Cross Sections of 24'Am and 243Ani," Lawrence Livermore National Laboratory, Rotating Target Neutron Source (RTNS) Annual Report.

~~P. M. Grant, B. P.. Erdal, and H. A. O'Brien, Jr., "Medium-Energy Spallation Cross Sections. 2. Mo Irradiation with 800-MeV Protons," Int./J. Appl. Radiat. Isot. 34, 1631 (1983).~~

~~G. P. Ford, K. Wolfsberg, and B. R. Erdal, "Independent Yields of the Isomers of 1BXe and l35Xe for Neutron Induced Fission of :"U, 235U. :38U, B9Pu, and 242Amm," Phys. Rev. C30, (1984).~~

B. R. Erdal, D L. Bish, B. M. Crowe, W. R. Daniels, A. E. Ogard, R. S. Rundberg, D. T. Vaniman, and K. Wolfsberg, "Some Geochemical Considerations for a Potential Repository in Tuff at Yucca Mountain, Nevada," in "Proceedings of the US/FRG Bilateral Workshop on Standardization Methods for Measuring Migration of Radionuclides in Geomedia," US Department of Energy report TL-0-84-4 (1984).

Jody H. Heiken and Diane D. Norton, "Mechanized Editing: We Won't, We Can't, We Did!" in Proceedings of the 31st International Technical Communication Conference (Society for Technical Communication, Washington, DC, 1984), pp. WE-128-131.

R. Brandt, O Feige, T. Lund, D. Molzahn, Kemchemie, D. C. Hoffman, S. J. Knight, A. G. Gancarz, G. W. Knobeloch, F. O. Lawrence, "Upper Limit for the Concentration of the Superheavy Elementary Particle (24CmX"j in Atlantis-I! Hot Brines," Radiochimica Acta 34, 163-164 (1983). 238 APPENDIX: PUBLICATIONS

D. C. Hoffman, W. R. Daniels, K. Wolfsberg, J. L. Thompson, R. S. Rundberg, S. L. Fraser, and K.. S. Daniels, "A Review of A Field Study of Radionuclide Migration From an Underground Nuclear Explosion at the Nevada Test Site," Radioactive Waste Management, Vol. 5 (IAEA, Vienna, 1984).

Helen A. Lindberg, Marilyn M. Thayer, "Technical Writing for Teenagers: Achievement and Renewal," in Proceeding; of the 31st International Technical Communication Conference (Society for Technical Com- munication, Washington, DC, 1984), pp. RET 3-5.

John R. Cann, Robert E. London, Nicholas A. Matwiyoff, and John M. Stewart, "A Combined Spectroscnpic Study of the Solution Conformation of Bradykinin," Kinins—III, Pt. A., H. Fritz, N. Back, G. Dietze, and G. L. Haberland. Eds. (Plenum Press, London, 1983). pp. 495-500. APPENDIX: PUBLICA TIONS 239

~~PAPERS ACCEPTED FOR PUBLICATION INC-3~~

~~D. S. Wilbur. "Structural Determinations of Some Chloroazepin-2,5-Diones Using a Lanthanide Shift Reagent," J. Heterocyclic Chem. (in press).~~

D. S. Wilbur, S. R. Garcia, M. J. Adam, and T. .1. Ruth, "An Evaluation of the Introduction of Stable Nuclides of Bromine into High Specific Activity Radiobrominations," J. Label. Cmpds. Radiopharm. (in press).

~~D. S. Wilbur and Z. V. Svitra, "Electrophilic Radiobrominations of Hippuric Acid; An Example of the Utility of Arvlirimethylsilane Intermediates," J. Label. Cmpds. Radiopharm. (in press).~~

~~M. D. Hylarides. \. A. Leon. F. A. Mettler, and D. S. Wilbur, "Synthesis of 1-Bromo-estradiol," J. Org. Chem. (in press).~~

~~INC-4~~

~~S. F. Agnew, B. 1. Swanron, L. H. Jones, and R. L. Mills, "Disproportionation of Nitric Oxide at High Pressure," J. Phys. Chem.~~

M. Pamela Bumsted, "Human Variation: 5"C in Adult Bone Collagen and the Relation to Diet in an Isochronous Ct (Maize) Archaeological Population," Thesis, University of Massachusetts, 1984 (in press).

~~J. S. Dutcher. J. D. Sun, W. E. Bechtold, and C. J. Unkefer, "Excretion and Metabolism of 1-Nitropyrene in Rats after Oral or Intraperitoneal Administration," Fund. Appl. Toxicol.~~

~~L. H. Jones. S. A. Ekberg, and B. 1. Swanson, "Pulse Expansion Deposits and Orientational Ordering for Low Temperature Matrices," J. Chem. Phys.~~

~~L. H. Jones, B. !. Swanson, and S. A. Ekberg, "Isotope Shifts and Force Field for Carbon Tetrachloride in a Krypton Matrix." J. Phys. Chem.~~

~~L. H. Jones, B. I. Swanson. and S. A. Ekberg, "Orientational Ordering and Site Structure of SiF4 Trapped in Rare Gas Solids," J. Chem. Phys.~~

G. i. Kubas, H. J. Wasserman, and R. R. Ryan, "New Metal-Sulfur Complexes from SOi Reduction by 5 (n -C5H5)W(CO),H (R = H. Me): Structures of [CpW(CO)3]:(u-S) and [Cp*W(CO)2(u-S SO)|;, a Complex with Strong SOrSulfide Bonding," Organometallics.

~~B. B. Mclnteer, "The Isotopic Analysis of Dimethyl Selenide," Spectrosc. Int. J.~~

~~B. B. Mclnteer. J. G. Montoya. and E. E. Stark. Jr.. "An Automated Mass Spectrometer Grows Up," Spectrosc. Int. J.~~

~~A. Rath, S.B.W. Roeder, and E. Fukushima. "Opposed Coil Magnet Calculations for Large Sample and Unilateral NMR," Rev. Sci. Instrum.~~

J. M. Ritchey. A. J. Zozulin, D. A. Wrobleski. R. R. Ryan, H. J. Wasserman, D. C. Moody, and R. T. Paine, "An Organothorium-NicKel Phosphido Complex with a Short Thorium-Nickel Distance. The Structure of Th(C5Me,)2(n-PPh:);Ni(CO):." .1. Am. Chem. Soc.

~~C. J. Unkefer and W. L. Earl, "A Combination of Inadequate and Carbon-1? Saturation for Spectra! Simplification," J. Magn. Reson.~~

~~H. J. Wasserman. R. R. Ryan, and S. P. Layne, " Structure ofAcetanilide (CgH9NO) at 113 K," Acta Crys- tall. C. 240 APPENDIX: PUBLICATIONS~~

~~INC-5~~

W. L. Talbert, Jr., M. E. Bunker, and J. W. Starner, "Feasibility Studies of a Helium-Jet Coupled Isotope Separator at LAMPF," in "Proceedings of the Workshop on the Proposed TRIUMF-ISOL Facility," (in press).

~~INC-7~~

~~M. Alei Jr., W. E. Wageman, and L. O. Morgan, "An N-15 Study of Conplexation of Histidine by Zn(II) and Cd(II) in Aqueous Solution: The Histidine Amphion as a Complexing Ligand," Inorg. Chem.~~

T. M. Benjamin, P. S. Z. Rogers, E. J. Peterson, and L. E. Wangen, "The Application of the Los Alamos Nuclear Microprobe to the Characterization of Trace Element-Mineral Associations in Geologic Materials and Solid Wastes," Proceedings of the American Nuclear Society Fifth International Conference, Mayaguez, Puerto Rico, April 2-6, 1984 (in press).

~~B. M. Crowe, Comp., "Research and Development Related to the Nevada Nuclear Waste Storage Investiga- tions, January !—March 31, 1984," Los Alamos National Laboratory report LA-10154-PR (in press).~~

~~B. M. Crowe, "Volcanic Hazard Assessment for Disposal of High-Level Radioactive Waste," in Tectonics- Impact on Society (National Research Council, in press).~~

~~D. B. Curtis and E. S. Gladney, "Boron Cosmochemistry" tabs.) in Proceedings of the Meteoritical Society Meeting. Albuquerque, New Mexico, July 30 - Aug. 2, 1984 (in press).~~

~~D. W. Efurd, G. W. ICnobeloch, R. E. Perrin, and D. W. Barr, "An Estimate of 237Np Production During Atmospheric Testing," Health Phys.~~

F. Goff, R. Vidale, R. Charles, and J. Gardner, "Gas and Isotope Geochemistry of Sulphur Springs, Valles Caldera, New Mexico, and a Model of the Underlying Geothermal System," J. Volcanol. Geotherm. Res.

D. R. Janecky and W. E. Seyfried, Jr., "Formation of Oceanic Ridge Crest Massive Sulfide Deposits: Incremental Reaction Model for Mixing Between Hydrothermal Solutions and Seawater," Geochim. Cosmochim. Acta.

~~B. D. Marshall, G. L. Farmer, and D. J. DePaolo, "Calcium Isotopic Studies of Mesozoic and Tertiary Granitic Rocks from the Western United States," Trans. Am. G^ophys. Union.~~

~~D. C. Melchior, D. Langmuir, and P. S. Z. Rogers, "Chemical Modeling of Tenorite Solubility in Saline Waters" (abs.) in Proceedings of the 1984 Geological Society of America Meeting (in press).~~

~~C. M. Miller, "Resonance Ionization Mass Spectrometry for Isotopic Abundance," in Proceedings of the Workshop on Cosmogenic Nuclides. Los Alamos, New Mexico, July 26, 1984 (in press).~~

~~E. J. Mroz, A. S. Mason, K. Leifer, and Z. R. Juzdan, "Stratospheric Impact of El Chichon," Geofis. Int.~~

A. E. Ogard and J. F. Kerrisk, "Groundwater Chemistry Along Flow Paths Between a Proposed Repository Site and the Accessible Environment," Los Alamos National Laboratory report LA-10188-MS (in press).

R. E. Perrin, G. W. ICnobeloch, V. M. Armijo, and D. W. Efurd, "Isotopic Analysis of Nanogram Quantities of Plutonium by Using a SID Ionization Source," lint. J. of Mass Spectrom. Ion Phys. (in press).

R. S. Rundberg, A. E. Ogard, and D. T. Vaniman, Comps., "Research and Development Related to the Nevada Nuclear Waste Storage Investigations, April 1—June 30, 1984," Los Alamos National Laboratory report LA-10299-PR (in press). APPENDIX: PVBUCA TIONS 241

~~W. A. Sedlacek, E. J. Mroz, A. L. Lazrus, and B. W. Gandrud, "Variations of Nitric Acid Concentration in the Lower Stratosphere: 1971-1982," J. Atmos. Chem.~~

K. Wolfsberg, E. A. Bryant, K. S. Daniels, V. Niesen, C. M. Miller, D. J. Rokop, G. A. Cowan, S. W. Downey, N. S. Nogar, and W. C. Haxton, "The Molybdenum Solar Neutrino Experiment," in Proceedings of the Conference on Solar Neutrinos and Neutrino Astronomy, Lead, South Dakota, August 23-25, 1984 (in press).

~~D. S. Woolum, D. S. Burnett, C. J. Maggiore, and T. M. Benjamin, "REE Fractionation in St. Severin Phosphates: Implications for Pu-REE Coherence" (abs.) in Lunar and Planetary Science XIV{in press).~~

~~INC-11~~

~~D. W. Efurd, G. W. Knobeloch, R. E. Perrin, and D. W. Barr, "An Estimate of 217Np Production During Atmospheric Testing," Health Phys. (in press).~~

~~Y. Ohkubo, C. J. Orth, D. J. Vieira, and L.-C. Liu, "The (n.TtN) Reaction in 48Ca," Phys. Rev. C (in press). 242 APPENDIX: PRESENTA TIONS~~

~~PRESENTATIONS~~

~~INC-3~~

G. E. Bentley and W. A. Taylor, "Application of D.C. Plasma Emission Spectroscopy to the Production of Radioisotopes," 1983 Pacific Conference on Chemistry and Spectroscopy, Pasadena, California, October 26-28, 1983.

~~D. S. Wilbur and K. E. Thomas, "New Radionuclides with Potential for Use in Nuclear Medicine." Rocky Mountain Nuclear Medicine Conference, Park City, Utah, March 2-3, 1984.~~

~~D. S. Wilbur, "Synthesis and Radiobrominations of Some Trimelhylsilyphenethylamines," 31st Annual Society of Nuclear Medicine Meeting. Los Angeles, California, June 5-8, 1984.~~

F. J. Steinkruger, P. M. Wanek, and D. C. Moody, "'"Yd — llWmAg Biomedical Generator," poster session at the Fifth International Symposium on Radiopharmaceutical Chemistry, Tokyo, Japan, July 9-13, 1984.

G. E. Bentley and W. A. Taylor, "Electrolytic Isolation of Cu-67 from Proton Irradiated Zinc Oxide," poster session at the Fifth International Symposium on Radiopharmaceutical Chemistry, Tokyo, Japan, July 9-13, 1984.

J. A. Mercer-Srmih and D. C. Mauzerall, "Photochemistry of Porphyrins: Models for the Origin of Photosynthesis," Gordon Conference on The Origin of Life, New London, New Hampshire, August 19-24. 1984.

J. A. Mercer-Smith and D. C. Mauzerall, "The Ultraviolet Photochemistry of Uroporphyrinogen: A Model for the Origin of Photosynthesis," Gordon Conference on The Origin of Life. New London, New Hamphsire, August 19-24, 1984.

~~INC-4~~

Stephen F. Agnew, "Studies of Nitric Oxide and Dinitrogen Tetroxide at High Pressure," Seminar, Chemistry of High Explosives Technology Group, Lawrence Livermore National Laboratory, Livermore, California. January 30, 1984.

S. F. Agnew and B. I. Swanson, "Chemistry and Spectroscopy of Carbon Disulfide and Other Small Molecules at High Pressure," seminar. Chemistry Department, Washington State University, Pullman, Washington. July 25, 1984.

S. F. Agnew, B. I. Swanson, L. H. Jones, R. L. Mills, and D. Schiferl, "Disproportionation of Nitric Oxide at High Pressure," Gordon Conference on Research at High Pressure, Meridan, New Hampshire, June 25-29. 1984.

~~J. R. Brainard, "Metabolism as it Happens: A "C NMR Look at Liver and at Heart," Henry Ford Hospital, Detroit, Michigan. October 21-22, 1983 (invited talk).~~

J. R. Brainard, D. E. Hoekenga, J, Y. Hutson, C. J. Unkefer, D. S. Ehler, and R. E. London, "Carbon-13 Nuclear Magnetic Resonance Studies of Carnitine Metabolism in Isolated Perfused Guinea Pig Hearts." Society for Magnetic Resonance in Medicine, New York, New York, August 14-18, 1984.

M. Pamela Bumsted, "Better Prehistory Through Chemistry or What's a Nice Anthropologist Like You Doing in a Place Like This," Los A'amos Group CHM-1 seminar, January 30, 1984. APPENDIX: PRESENT A TIONS 243

P. Bumsted, T. W. Boutton, R. M. Barnes, K. Brendel, J. C. Lerman, and G. J. Armelagos, "Approaches for Analysis of Chemical Tracers of the Human Diet System," American Association of Physical Anthropologists, Philadelphia, Pennsylvania, April 13, 1984.

M. Pamela Bumsted, KJaus Brendel, and Thomas W. Boutton, "A Method for Separating Soil and Gelatin from Archaeological Bone for 5'3C Analysis," Gordon Conference on Diet and Human Evolution, Oxnard, California, 6-10 February 1984.

~~P. G Eller, L. B. Asprey, and J. G. Malm, "The Superoxidizer, Dioxygen Difluoride (FOOF)," Eighth Aciinide Separations Workshop, Boulder and Rocky Flats, Colorado, May 3O-3UJune 1, 1984.~~

~~E. Fukushima, "Radiofrequency and Magnet Technology in Medical NMR," Sixth Annual ideas in Science and Engineering Exposition and Symposium, IEEE. Albuquerque, New Mexico, May 2-4, 1984.~~

G. D Jarvinen, "Reduction of Sulfur Dioxide by Transition Metal Hydrides," poster session at the Florida Conference on Fundamental Steps in Catalysis, University of Florida, Gainesville, Florida, April 15-19, 1984.

C. T. Johnston and B. 1. Swanson, "Vibrational Spectroscopy of Acetanilide: Davydov Soliton or Fermi Resonance?" Gordon Research Conference on Vibrational Spectroscopy, Wolfesboro, New Hampshire, August 20-24, 1984.

~~G. J. Kubas, "Discovery and Characterization of the First Example of Molecular Hydrogen Bound to a Metal Complex," Texas A&M University, Co'lege Station, Texas, October 26, 1983 (invited seminar).~~

G. J. Kubas and R. R. Ryan, "Homogeneous Catalysis of Hydrogenation of SOs to Sulfur and Water by 5 Metallothiol Complexes, [r) -C5R5)Mo(u-S)(u-SH)]2," 1984 International Chemical Congress of Pacific Basin Societies, Honolulu, Hawaii, December 16-21, 1984.

G. J. Kubas, R. R. Ryan, P.J. Vergamini, H. .1. Wasserman, and B. I. Swanson, "Characterization of WtCObfPPr'^frp-H:), The First Example of a Molecular Hydrogen Complex," XXIII International Con- ference on Coordination Chemistry, Boulder. Colorado, July 29-August 3, 1984.

~~R. E. London, C. J. Unkefer, T. E. Walker, J. R. Bniinard. and J. Y. Hutson. "Studying Metabolic Regulation with I3C NMR Spectroscopy," FACSS Symposium, Philadelphia, Pennsylvania, September 1984.~~

~~B. B. Mclnteer, "The Isotopic Analysis of Dimethyl Selenide," Second International Conference on Mass Spectrometry and Gas Chromatography in Biomedical Sciences, Milan, Italy, June 18-20, 1984.~~

B. B. Mclnteer, J. G. Montoya, and E. E. Stark, Jr., "An Automated Mass Spectrometer Grows Up," Second International Confercnre on Mass Spectrometry and Gas Chromatography in Biomedical Sciences, Milan, Italy. June 18-20, 1984 (invited plenary lecture).

~~R. A. Penneman, "Bond Strengths i1 \ctinide Compounds; Applications to Mixed-Ligand Complexes," Eighth Actinide Separations Workshop, Boulder and Rocky Flats, Colorado, May 30-31 and June I, 1984.~~

A. Rath. S.B.W. RuL^r, and E. Fukushima, "The Inside-Out Helmholtz: A Unilateral Magnet for Large Sample NMR." 26th Rocky Mountain Conference sponsored by the Rocky Mountain Society for Applied Spectroscopy and the Rocky Mountain Chromatography Discussion Group, Denver, Colorado, August 5-9, 1984.

B. I. Swanson, "High Resolution Infrared Studies of Site Structure and Dynamics of Matrix Isolated Molecules," University ofTexas, Austin, Texas, November 28, 1983; University of Virginia, Charlottesville, Virginia. November 30. 1983; University of Florida, Gainesville, Florida, December 1, 1983.

~~B. I. Swanson, "Plutonium Fluorination Chemistry," Nuclear Programs Review, Los Alamos, New Mexico, January 18-19, 1984. 244 APPENDIX: PRESENTATIONS~~

~~B. I. Swanson, "Distillation Techniques," DOE meeting on Sulfur Isotopes in Environmental Studies, Washington, DC, February 22-23, 1984.~~

~~3.1. Swanson, "Chemistry at High Densities," Los Alamos Group CHM-2 seminar, April 4, 1984.~~

B. I. Swanson, "Chemistry at High Pressure: The Chemical Mechanism for Shock-Initiated Detonation of NO," US Army Armament, Research, and Development Center, Dover, New Jersey, May 18, 1984 (invited seminar).

B. I. Swanson, "Chemistry at High Pressure: The Chemical Mechanism for Shock-Initiated Detonation of NO," Workshop on Fast Reactions in Energetic Materials., US Army Research, Development, and Standard- isation Group (UK), London, England, May 21-24, 1984.

~~B. I. Swanson, S. F. Agnew, and L. H. Jones, "Time-Resolved UV-Visible Absorption Spectroscopy of the Pressure-Induced Nitric Oxide Reaction," Los Alamos Group M-1, April 18 i - '84.~~

C. J. Unkefer, "In Vivo Studies of Pyridine Nucleotide Metabolism in Esci*. ichia coli and Saccharomyces cerevisiaeby Carbon-13 NMR Spectroscopy," University of Texas, Dallas, Texas, October 26, 1983 (invited seminar).

~~C. J. Unkefer and W. L. Earl, "Inadequate and Carbon-13 Enriched Samples," 25th Experimental NMR Conference, Wilmington, Delaware, April 8-12, 1984.~~

C. J. Unkefer, D. S. Ehler, J. R. Brainard, J. Y. Hutson, D. S. Hoekenga, and R. E. London, "In Vivo Studies on L-[4-l3C]Carnitine in Saccharomyces cerevisiae by Carbon-13 NMR Spectroscopy," poster session at the American Society of Biological Chemists and the American Association of Immunologists, St. Louis, Missouri, June 3-7, 1984.

~~INC-5~~

~~M. E. Bunker, J. W. Starner, and S. Raman, "Decay of 37S," 1983 Fall Meeting of the Division of Nuclear Physics of the American Physical Society, Notre Dame, Indiana, October 13-15, 1983.~~

W. L. Talbert, M. E. Bunker, J. W. Starner, and M. E. Schaffner, "Target Design Studies for a He-Jet Activity Transport System," 1983 Fall Meeting of the Division of Nuclear Physics of the American Physical Society, Notre Dame, Indiana, October 13-15.

M. M. Minor and S. R. Garcia, "A Computer-Automated Neutron Activation Analysis System," Interna- tional Symposium on the Use and Development of Low and Medium Flux Research Reactors, Massachusetts Institute of Technology, Cambridge, Massachusetts, October .6-19, 1983.

A. R. Lyle, H. T. Williams, and M. E. Bunker, "The Los Alamos Omega West Reactor," International Symposium on the Use and Development of Low and Medium Flux Research Reactors, Massachusetts Institute ofTechnoiogy, Cambridge, Massachusetts, October 16-19, 1983.

W. L. Talbert, Jr., M. E. Bunker, and J. W. Starner, "A He-Jet System to Study Short-Lived Fission-Product Nuclei at LAMPF," Specialists Meeting on Yields and Decay Data of Fission-Product Nuclides, Brookhaven National Laboratory, October 24-27,1983.

~~W. L. Talbert, Jr., aau M. E. Bunker, "He-Jet Coupled On-Line Mass Separator at LAMPF for Studies of Nuclei Far From Stability," LAMPF Technical Advisory Panel Meeting, June 1, 1984.~~

W. L. Talbert, Jr., M. E. Bunker, and J. W. Starner, "Feasibility Studies of a Helium-Jet-Coupled Isotope Separator at LAMPF," TRIUMF-ISOL Workshop, Mont Rolland, Quebec, Canada, June 14-15, 1984. APPENDIX: PRESENTA TIONS 245

~~INC-7~~

~~B. M. Crowe, "Status of Volcanic Hazard Assessment for the Nevada Nuclear Waste Storage Investigations," Nuclear Regulatory Commission Geology Review Meeting, Denver, Colorado, October 4-6,1983.~~

M. M. Fowler and S. Barr, "A Long Range Atmospheric Tracer Field Test," Air Pollution Control Association Specialty Conference on Meteorology of Acid Deposition, Hartford, Connecticut, October 16-19, 1983.

~~C. M. Miller, "Mass Spectrometry in the Dark—Lasers and Resonance Ionization," National Bureau of Standards, Gaithersburg, Maryland, October 19, 1983.~~

N. S. Nogar, S. W. Downey, R. A. Keller, and C. M. Miller, "Resonance Ionization Mass Spectrometry at Los Alamos National Laboratory," 27th ORNL-DOE Conference on Analytical Chemistry, Knoxville, Ten- nessee, October 1983.

~~D. J. Rokop and C. M. Miller, "A Brief Review of What's Happening at 7000 Feet," National Bureau of Standards, Gaithersburg, Maryland, October 19, 1983.~~

~~D. L. Bish, A. E. Ogard, and D. T. Vaniman, "Mineralogy-Petrology and Geochemistry of Yucca Mountain Tuffs," Materials Research Society Meeting, Boston, Massachusetts, November 14-17, 1983.~~

A. E. Ogard, K. Wolfsberg, R. S. Rundberg, W. R. Daniels and B. J. Travis, "Retardation of Radionuclides by Rock Units Along the Path to the Accessible Environment," Materials Research Society Meeting, Boston, Massachusetts, November 14-17, 1983.

R. W. Charles and G. K. Bayhurst, "Reaction of Calcite Veined Granodiorite Reservoirs with a Dilute Aqueous Fluid: An Experimental Approach," American Geophysical Union Fall Meeting, San Francisco, California, December 5-9, 1983.

~~B. M. Crowe, "Volcanic Hazard Assessment for Disposal of High-Level Radioactive Waste," American Geophysical Union Fall Meeting, San Francisco, California, December 5-10,1983.~~

~~C. M. Miller, N. S. Nogar, R. A. Keller and S. W. Downey, "Developments in Resonance Ionization Mass Spectrometry," Los Alamos Group CHM-4 Seminar, December 7, 1983.~~

~~E. J. Mroz and P. R. Guthals, "Tracking Antarctic Winds," Science Lecture, McMurdo Station, Antarctica, January 1984.~~

~~R. J. Vidale, "Water-Rock Interaction in Pelitic Systems," Pennsylvania State University Geology Depart- ment, State College, Pennsylvania, January 31, 1984.~~

~~R. J. Vidale, "Water-Rock Interaction in Pelitic Systems," Geophysical Laboratory of the Carnegie Institu- tion of Washington, Washington, DC, February 24, 1984.~~

~~R. J. Vidale, "Water-Rock Interaction in Pelitic Systems," U. S. Geological Survey, Reston, Virginia, February 22, 1984.~~

~~A. E. Norris, "Large Block Sampling for 36C1 Dating of Pore Water," Nevada Nuclear Waste Storage Investigations Exploratory Shaft Plan Review Retreat, LaJolla, California, March 27-30, 1984.~~

~~A. E. Norris, "Diffusion Test," Nevada Nuclear Waste Storage Investigations Exploratory Shaft Test Plan Review Retreat, LaJolla, California, March 27-30, 1984.~~

D. S. Woolum, R. Brooks Cochrane, D. Joyce, A. El Goresy, T. M. Benjamin, P. S. Z. Rogers, C. M. Maggiore, and C. J. Duffy, "Trace Element PIXE Studies of Qinzhen (EH3) Metal and Sulfides," 15th Lunar and Planetary Science Conference, Houston, Texas, March 12-16, 1984. 246 APPENDIX: PRESENTA T1ONS

P. R. Guthals, "High Altitude Sampling Program (HASP)—Roles and Objectives—A Historical Review," SAR High Altitude Research Program (HARP) Working Group, National Science Foundation, Washington, DC, April 13, 1984 (invited presentation).

N. S. Nogar, S. W. Downey, and C. M. Miller, "Analytical Capabilities of RIMS: Absolute Sensitivity and Isotopic Analysis," Second International Symposium on Resonance Ionizatiun Spectroscopy and its Applica- tions, Knoxville, Tennessee, April 16-2i\ 1984.

G. A. Cowan, K.. S. Daniels, W. C. Haxton, D. J. Rokop, E. N. Treher, and K. Wolfsbcrg, "The Molybdenum Solar Neutrino Experiment." Second International Symposium on Resonance Ionization Spectroscopy and its Applications, Knoxville, Tennessee, April 16-20, 1984.

S. W. Downey. N. S. Nogar, and C. M. Miller, "Multiwavelength Resonance Ionization of Technetium," Thirty-Second Annual Conference on Mass Spectrometry and Allied Topics, San Antonio, Texas, May 27- Junel, 1984.

C. M. Miller, N. S. Nogar, and S. W. Downey. "Analytical Developments in Resonance Ionizuuon Mass Spectrometry," Thirty-Second Annual Conference on Mass Spectromctry and Allied Topics, San Antonio, Texas, May 27-June 1. 1984.

~~C. M. Miller, "Resonance Ionization Mass Spectrometry' for Isotopic Abundance Measurements." Workshop on Cosmogenic Nuclides, Los Alamos, New Mexico, July 26, 1984.~~

~~A. E. Norris, "16CI Experiment for the Exploratory Shaft," Nevada Nuclear Storage Investigations/Nuclear Regulatory Commission Workshop on Geochemistry, Los Alamos, New Mexico, July 10-12, 1984.~~

A. E. Norris, "Diffusion Experimeni for the Exploratory Shaft," Nevada Nuclear Storage Investiga- tions/Nuclear Regulatory Commission Workshop on Geochemistry, Los Alamos, New Mexico. July 10-12, 1984.

~~D. B. Curtis and E. S. Gladney, "Boron Cosmochemistry," Meteoritical Society Meeting, Albuquerque, New Mexico, July 30-August 2, !984.~~

~~Kurt Wolfsberg, "The Molybdenum Solar Neutrino Experiment," Conference on Solar Neutrinos and Neutrino Astronomy, Lead, South Dakota, August 23-25, 1984.~~

~~INCH~~

~~R. S. Bhalerao, "A Model for Threshold Pionic n Production on a Nucleon and n-Nuclcon Scattering." Los Alamos MP Division bag lunch seminar, June 11, 1984.~~

J. Bruckner, P. Englert, R. C. Reedy, H. Wanke, "Simulation Experiments for Gamma-Ray Mapping of Planetary Surfaces: Scattering of High-Energy Neutrons," Cosmogenic Nuclides Workshop, Los Alamos, New Mexico, July 26-27, 1984; and Lunar and Planetary Institute Technical Report Workshop.

J. Bruckner, R. C. Reedy, H. Wanke, "Neutron-Induced Gamma Rays from Thin Targets: Simulations for Planetary Spectroscopy," 15th Lunar and Planetary Science Conference, Houston, Texas, March 12-16, 1984.

J. Bruckner, P. Englert, R. C. Reedy, Heinrich Wanke, "High-Energy Neutron Induced Prompt Gamma Rays: Chemical Remote Sensing of Planetary Surfaces," 47th Annual Meeting of the Meteoritical Society, Albuquerque, New Mexico, July 30—August 2, 1984.

D. R. Davidson, R. C. Reedy, W. F. Sommer, and L. R. Greenwood, "Measured Radiation Environment at the LAMPF Irradiation Facility," 12th International Symposium on Effects of Radiation on Materials, Williamsburg, Virginia, June 18-20, 1984. APPENDIX: PRESENTATIONS 247

M. M. Fowler, "An Overview of the Isotope and Nuclear Chemistry Division of the Los Alamos National Laboratory," Johannes Gutenberg University, Nuclear Chemistry Seminar, Mainz, Federal Republic of Germany ,'july 18, 1984.

M. M. Fowler, "Heavy-Ion Research Program in the INC Division of the Los Alamos National Laboratory," Philipps University, Nuclear Chemistry Seminar, Morburg, Federal Republic of Germany, August 8, 1984.

~~G. C. Giesler, "LAMPF Nuclear Chemistry Data Acquisition System," 1983 Fall DECUS US Symposium, Las Vegas, Nevada, October 24-28, 1983.~~

G. C. Giesler, "Report on Experiment 728, Study of Pion Charge Exchange Mechanisms by Means of Activation Techniques," 17th Annual LAMPF Users Group Meeting, Los Alamos, New Mexico, November 7-8, 1983.

~~G. C. Giesler, "Conversion from RSX-1 ID to RSX-l 1M," 1984 New Mexico DECUS Symposium, Santa Fe, New Mexico. September 20-21. 1984.~~

D. E. Hobart, T. W. Newton, and V. L. Rundberg, "Carbonate Complexation of Americium(III): A Study of the Complex-Competition Reaction with Citrate Ions in Aqueous Solution," 1984 International Chemical Congress of Pacific Basin Societies, Honolulu, Hawaii, December 16-21, 1984.

~~M. J. Leitch, "Search for Six-Quark Clusters in Nuclei with Low-Energy DCX," Los Alamos MP Division colloquium, September 5, 1984.~~

~~L.-C. Liu, "Optical Model Theory for Pion Double Charge Exchange," LAMPF Low Energy Pion Physics Workshop, Los Alamos, New Mexico, Januan. 8, 1984.~~

L.-C. Liu, "Pion Single-Pion Production in Complex Nuclei," and "Pion-Induced r\ Production on a Nucleon and in Nuclei," 10th International Conference on Particles and Nuclei, Heidelberg, West Germany, Juh' 31, 1984.

~~L.-C. Liu, "Pion-Induced n. Production on Nucleons and in Nuclei," Seminar fit SIN, Villigen, Switzerland, July 19, 1984.~~

~~L.-C. Liu, "Contributions for Pair Correlations to Pion-Nucleus Double Charge Exchange," International Symposium on Nuclear Shell Model. Philadelphia, Pennsylvania, October 31-November 3, 1984.~~

~~T. W. Newton and V. L. Rundberg, "Disproportionation and Polymerization of Piu'.onium(IV) in Dilute Aqueous Solutions," Materials Research Society Annual Meeting, Eoston, Massachusetts (1983).~~

T. W. Newton and V. L. Rundberg, "The Pu(IV) Polymer: Its Formation and Chemistry in Dilute Aqueous Solutions," Materials Research Society Annual Meeting, Boston, Massachusetts, November 13-18, 1983.

Y. Ohkubo, "Report on Experimental Results and Model Calculations Related to Experiment 595, A Study of Pion-Induced Single Nucleon Removal Reactions in I2C and 48Ca," 17th Annual LAMPF Users Group Meeting. Los Alamos. New Mexico, November 7-8, 1983.

H. Ohm, J. Boissevain, H. C. Britt, P. Eskola, K. Eskola, M. M. Fowler, J. B. Wilhelmy, R. L. Ferguson, and F. Plasil. "Heavy Ion Induced Fission of Er, Os, Pb, Po, and Fm <""•->:,iposite Systems," Fall Meeting of the Division of Nuclear Physics, American Physical Society, Notre Dame, Indiana, October 13-15, 1983.

C. PiHai, "Update on Phase II of Experiment 308, An Attempt to Make Atomic IV iss Measurements in the Thin Target Area," 17th Annual LAMPF Users Group Meeting, Los Alamos, New Mexico, November 7-8, 1983.

C. H. Pillai, D. J. Vieira, G. W. Butler. J. M. Wouters, S. H. Rokni, K. Vaziri, L. P. Remsberg, "Direct Mass Measurements in the Light Neutron-Rich Region Using a Combined Energy and Time-of-Flight Technique," AMCO-7 Conference in Seeheim, Federal Republic of Germany, September, 1984. 248 APPENDIX:PRESENTATIONS

~~R. C. Reedy, "High-Energy Cosmogenic Neutrons in Extraterrestrial Matter," 15th Lunar and Planetary Science Conference, Houston, Texas, March 12-16,1984.~~

~~R. C. Reedy, "Calculated Production Rates of Noble Gases in the SNC Meteorites," 15th Lunar and Planetary Science Conference, Houston, Texas, March 12-16, 1984.~~

~~R. C. Reedy, "A Model for GCR-Particle Fluxes in Stony Meteorites and Production Rates of Cosmogenic Nuclides," 15th Lunar and Planetary Science Conference, Houston, Texas, March 12-16, 1984.~~

~~R. C. Reedy, "Cosmogenic Radionuclides and Exposure Histories of SNC Meteorites," 47th Annual Meeting of the Meteoritical Society, Albuquerque, New Mexico, July 30-August 20, 1984.~~

~~R. S. Rundberg, "The Kinetics of the Adsorption of Radionuclides on Tuff from Yucca Mountain," Materials Research Society Annual Meeting, Boston, Massachusetts, November 13-18, 1983.~~

~~R. S. Rundberg, "Tritium Modeling at Cambric," Radionuclide Migration Meeting, Los Alamos, New Mexico, January 17-18, 1984.~~

M. S. Spergel, R. C. Reedy, O. W. Lazareth, P. W. Levy, "Neutron Capture Production Rates of Cosmogenic Cobalt-60, Nickel-59, and Chlorine-36 in Stony Meteorites," Cosmogenic Nuclides Workshop, Los Alamos, New Mexico, July 26-27, 1984.

W. L. Talbert, Jr., M. E. Bunker, J. W. Starner, and M. E. Schaffner, "Target Design Studies for a He-Jet Activity Transport System," Fall Meeting of the Division of Nuclear Physics, American Physical Society, Notre Dame, Indiana, October 13-15,1983.

W. L. Talbert, Jr., M. E. Bunker, and J. W. Starner, "A He-Jet System to Study Short-Lived Fission Product Nuclei at LAMPF," OECD/NEA Nuclear Data Committee Meeting on Yields and Decay Data of Fission Product Nuclides, Brookhaven National Laboratory, October 24-27, 1983.

W. L. Talbert, Jr., and M. E. Bunker, "Expectations for Radioactive Beams at a Proposed ISOL Facility at LAMPF," Workshop on Prospects for Research with Radioactive Beams from Heavy Ion Accelerators, Washington, DC, April 26, 1984.

~~W. L. Talbert, Jr., "Feasibility of a He-Jet Coupled ISOL System at LAMPF," Physics Colloquium, Chalk River Nuclear Laboratory, Chalk River, Ontario, Ccnada, June 11, 1984.~~

~~W. L. Talbert, Jr., M. E. Bunker, and J. W. Starner, "Feasibility Studies of a Helium-Jet Coupled Isotope Separator at LAMPF," TRIUMF-ISOL Workshop, Mont Rolland, Quebec, Canada, June 15, 1984.~~

S. Theis, P. Englert, R. Michel, R. C. Reedy, J. R. Arnold, "Simulation of the Interaction of Galactic Cosmic Radiation with Matter Longlived Cosmogenic Nuclides Produced in Different Irradiation Experiments," 15th Lunar and Planetary Science Conference, Houston, Texas, March 12-16, 1984.

S. Theis, P. Englert, R. C. Reedy, J. R. Arnold, "Simulation of the Cosmic Irradiation Conditions in Thick Target Arrangements," Cosmogenic Nuclides Workshop, Los Alamos, New Mexico, July 26-27, 1984.

~~J. L. Thompson, "RNM Update—Cheshire," Radionuclide Migration Meeting, Los Alamos National Laboratory, Los Alamos, New Mexico, January 17-18, 1984.~~

P. G. Varlashkir., D. E. Hobart, and J. R. Peterson, "Electrochemical and Spectroscopic Studies of Neptunium and Plutonium in Concentrated Aqueous Carbonate and Carbonate-Hydroxide Media," 35th Southwestern Regional Meeting, American Chemical Society, Charlotte, North Carolina, November 9-11, 1983.

~~D. J. Vieira, "Progress Toward Making Direct Mass Measurements of Exotic Light Nuclei," Physics Colloquium, Utah State University, Logan, Utah, May 1, 1984. APPENDIX: PRESENTA TIONS 249~~

D. J. Vieira, J. M. Wouters, and G. W. Butler, C. Pillai, L. W. Swenson, K. Vaziri, S. H. Rokni, V. G. Lind, L. P. Remsberg, "Direct Mass Measurements in the Light Neutron-Rich Region Using a Combined Energy and Time-of-Flight Technique," AMCO-7, Seeheim, Germany, September 1984.

~~J. B. Wilhelmy, "New Directions in Radiochemical Detectors," Weapons Nuclear Physics Seminar, Los Alamos, New Mexico, November 14, 1983.~~

~~K.. Wolfsberg, "I29I and 36C1 Measurement," Radionuclide Migration Meeting, Los Alamos, New Mexico, January 17-18, 1984.~~

J. M. Wouters, D. J. Vieira, G. W. Butler, H. Wollnik, S. H. Rokni, K. Vaziri, V. G. Lind, D. S. Brenner, F. S. Wohn, L. P. Remsberg, "The Time-of-Flight Isochronous (TOFI) Spectrometer for Mass Measurements of Exotic Nuclei," AMCO-7, Seeheim, Germany, September 1984.

~~INC-DO~~

~~Jody H. Heiken and Diane D. Morton, "Mechanized Editing: We Won't, We Can't, We Did!" list International Technical Communication Conference, Seattle, Washington, April 29-May 2, 1984.~~

~~Darteane C. Hoffman, "Heavy Ion Reactions on Curium Targets," 1984 International Chemical Congress of Pacific Basin Societies, Honolulu, December 16-21, 1984.~~

Darleane C. Hoffman, M. M. Fowler, W. R. Daniels, H. R. von Gunten, D. Lfie, L. Moody, K. Gregorich, R. Welch, G. T. Seaborg, W. Bruchle, M. Brugger, H. Gaggeler, M. Schadel, K. Summerer, G. Wirth. T. Blaich, G. Herrmann, J. V. Kratz, M. L«rch, N. Trautmann, "Recent Results of Heavy Ion Reactions," International Conference on Nuclear and Radiochemistry, Lindau, Federal Republic of Germany, Oct. 8-12, 1984.

~~Helen A. Lindberg and Marilyn M. Thayer, "Technical Writing for Teenagers: Achievement and Renewal," 31st International Technical Communication Conference, Seattle, Washington, April 29-May 3, 1984.~~

~~APS Annuai Meeting~~

~~At the American Physical Society Annual Meeting in Washington, DC, April 23-26, 1984, the following papers were presented.~~

~~W. L. Talbert, Jr. and M. E. Bunker, "Production of Nuclei far from Stability at LAMPF'~~

~~R. S. Bhalerao and L.-C. Liu, "A Model for Threshold Pionic if Production on a Free Nucleon and in Nuclei"~~

M. J. Leitch, F. Irom, J. Comfort, M. D. Cooper, H. W. Baer, J. D. Bowman, E. Piasetzky, U. Sennhauser, H. Ziock, J. Alster, A. Erell, and M. Moinester, "Low Energy Pion Single Exchange Angular Distributions"

~~Y. Ohkubo, C. J. Orth, D. J. Vieira, L.-C. Liu, "Mechanisms for (7c,7tN) Reactions in the Mass Region 45-48"~~

C. H. Pillai, L. W. Swenson, D. J. Vieira, J. M. Wouters, G. W. Butler, K. Vaziri, "Progress Towards Making Direct Mass Measurements of Light Neutron-Rich Nuclei at LAMPF' 250 APPENDIX: PRESENTATIONS

~~187th National ACS Meeting~~

~~At the 187th American Chemical Society National Meeting held in St. Louis, Missouri, April 8-13, 1984, the following papers were presented.~~

~~J. A. Mercer-Smith, D. C. Mauzerall and A. Raudino, "The Ultraviolet Photochemistry of Urohex- ahydroporphyrin: A Mode! for The Origin of Photosynthesis"~~

~~S. Wilbur and Z. V. Svitra, "Reaction Variants in Scaling Radiobrominations from Stoichiometric Levels to No-Carrier-Added Levels"~~

~~H. A. O'Brien, Jr., and D. S. Wilbur, "A Review oi"77Bi and '^I Labeling Chemistries"~~

~~M. D. Hylarides, F. A. Mettler, and D. Scotl Wilbur, "Synthesis of 1-Bromoestradiol: incorporation of Bromine-82 and Bromine-77"~~

~~H. .'. Wasservnan, D. C. Moody, and R. R. Ryan, "Synthesis and Characterization of Some Uranium Complexes Containing Phosphine Ligands"~~

K.. Wolfsberg, K.. S. Daniels, S. L. Fraser, R. S. Rundberg, P. L. Wanek, J. L. Thompson, W. R. Daniels, H. W. Bentley, D. Elmore, L. E. Tubbs, and J. Fabryka-Martin, "The Migration of 1-129 and Cl-36 from an Underground Nuclear-Explosion Cavity Under Forced Conditions" (invited paper)

~~J. Dropesky, S. Yan, L.-C. Liu, R. S. Bhalerao, and G. C. Giesler, "Single Pion Production by Pions"~~

~~L.-C. Liu, "Probing Deuteron Clusters with (it.Kd) Reactions"'~~

~~J. Vieira, J. M. Wouters, G. W. Butler, C. Pillai, K. Vaziri, S. K. Rokni, and L. P. Remsberg, "Progress Toward Making Direct Mass Measurements of Light Neutron-Rich Nuclei at LAMPF'~~

~~Dar'.eane C. Hoffman, "Problems in Production and Detection of Superheavy Elements "~~

~~Seventh Rocky Mountain Regional Meeting of the ACS~~

~~Tne following papers were presented at the Seventh Rocky Mountain Regional Meeting of the American Chemical Society held in Albuquerque, New Mexico, June 6-8, 1984.~~

~~W. A. Taylor and G. E. Bentley, "Electrolytic Isolation of Cu-67 from Proton Irradiated Zinc Oxide"~~

~~F, J. Steinkruger, P. M. Wanek, and D. C. Moody, "A Separation Procedure for l(NmAg from logCd"~~

~~Z. V. Svitra, D. S. Wilbur, and R. S. Rogers, "Synthesis and Reactions of p-Trimethylsilylphenylpropionic Acid"~~

~~S. F. Agnew. B. I Swanson. and L. H. Jones. "Speclroscopic Studies of Oxygen above 100 kbar"~~

~~S. F. Agnew, B. i. Swanson. and L. H. Jones, "The Chemistry of Nitric Oxide at High Pressure"~~

~~P. G. Ellerand L. B. Asprey, "The Superoxidizer Dioxygen Difluoride (FOOF)"~~

~~P. G. Eller, G. D. Jarvinen, and R. A. Permeman, "Actinide Valence/Site Characterization in Advanced Nuclear Waste Forms"~~

~~G. J. Kubas, R. R. Ryan, and H. j. Wasserman, "Reactions of Sulfur Dioxide with Cyclopenta- dienyltricarbonylhydrides with Molybdenum and Tungsten"~~

~~B. I. Swanson, S. F. Agncw, and L. H. Jones, "Optical Studies of Chemistry at High Density" (invited) APPENDIX: PRESENTATIONS 251~~

~~14th end 15th Radiochemistry 1LVVOG~~

Weapons diagnostics and related subjects were discussed at the 14th and 15th Radiochemistry Inter- laboratory Working Group Meetings (ILWOG-14 and -15); participants were from McClellan AFB, Patrick AFB, Lawrence Livermore National Laboratory, and four divisions of Los Alamos. The following presentations were given by INC Division staff members at the ILWOG-14, Los Alamos, New Mexico, October 12-14, 1983.

~~T. M. Benjamin, "Application of the Los Alamos Nuclear Microprobe to Pie-Shot Weapons Diagnostics"~~

~~1. Binder, "Any New Radiochemical Detectors on '.he Horizon?"~~

~~D. B. Curtis, "Chtmical Procedures for Separating Rare Earth Elements for Mass Spectrometry"~~

~~A..!. Gancarz, '"Calibration of the Am-243 Detector and its Use at the NTS"~~

~~P. R. Guthals. 'Atmospheric Tracers and 'he September, 1979 Event"~~

~~T. L. Norris, "Mini .Idde"~~

~~D. 1. Rokop, "Mass Speclrometric Capabilities of INC-7 '~~

~~W. A. Sedlacek, "Computer Plotting of Pie Diagrams"~~

~~J. P. Balagna. "Experiences with Ions of the Other Kind"~~

~~D. W. Ban, "Test Results from the Los Alamos Fahada Event"~~

~~D. W. Barr, "Unexpected Phenomena in Nuclear Explosions as Revealed by Radiochemistry Diagnostics"~~

~~D. W. Barr, "The Determination of Ion Temperatures with Radiochemical Detectors"~~

~~G. Grisham. "Main Frame Computing: A Radiochemical Diagnostic Tool for Hypothetical Weapon Debris"~~

~~G. W. SCnobeloch, "Preliminary Results from Davis-i 2 Intercalibration"~~

~~R. J. Prestwood, "Thickness Corrections for Low Energy Gamma Rays"~~

~~The talks listed below were given by INC members attending the ILWOG-15 at Lawrence Liverrnore National Laboratory. Livermore, California, March 20-22, 1984.~~

~~D. W. Barr. "SABADO and TECH ADO Asymmetry Experiments: A Wedding of Prompt and Radiochemical~~

~~Diagnostics'1~~

~~W. Efurd. "Mass Spectromciri<- Determination of Thorium"~~

~~u. F. Grisham, "A Review of Isotope Produc'ion Code1; at Los Alamos"~~

~~T. A. Kellcy.' Future Plans for ihe Counting Room VAX at Los Alamos"~~

~~R. J. Prjsiwood. "Proposed Hf-l72(j),2n)Hf-I71 Cross Section Measurement"~~

~~R, C. Reedy, "Computer Analysis of Cm a;id Am Counting Data"~~

~~W. L. Talbert, 'Some Recent Studies of Debris Data Relating to FTD"~~

~~K. W. Thomas, "Progress Report on Carrier-Free Bismuth Chemistry" 252 APPENDIX: PRESENTA TIONS~~

~~Sixth Annual INC Division Information Meeting~~

~~The following talks were given at the Sixth Annual INC Division Information Meeting held in Los Alamos, September 12-14, 1984.~~

~~Stephen F. Agnew, "High Pressure Studies of Nitric Oxide and Carbon Disulfide: Comparison with Detonation and Shock-Induced Chemistry"~~

~~Donald W. Barr, "The Problem of Thermonuclear Fuel Burn and the Caprock Test"~~

~~Timothy M. Benjamin, "Having Fun With Weapons Using Panicle Beams"~~

~~Gary S. Benson, "TEX Formatter, a Tool to Move Reports and Journal Submissions Into the Computer Age"~~

~~Rajeev S. Bhalerao, "Quarks in a Bag as a Model for Nucleons"~~

~~Irwin Binder, "Iodine as a Radiochemical Detector"~~

~~Irwin Binder, "The Blue Flash—Cerenkov Counting"~~

~~James R. Brainard, "The Telltale Heart—with Apologies to Edgar Allen Poe"~~

~~Ernest A. Bryant, "The Molybdenum Solar Neutrino Experiment"~~

~~Merle E. Bunicer, "Review of OWR Operations"~~

~~Robert W. Charles, "Low Temperature Alterations of Acid Sulfate Waters from a Vapor Dominated Hydrothermal System"~~

~~Don T. Cromer, "Crystal Density Predictions and Electron Density Studies in Organic Explosives"~~

~~Bruce M. Crowe, "Trace Element Enrichment Patterns of Volcanic Gases During the January 1984 Eruption of the Puu O Vent, Kilauea Volcano"~~

~~David B. Canis, "Boron Cosmochemistry"~~

~~Bruce J. Dropesky, "An Activation Study of Pion Production by Pions"~~

~~Clarence J. Duffy, "Stability of Zeolites in Yucca Mountain"~~

~~Phillip G. Eller/Larned B. Asprey, "FOOF Chemistry,"~~

~~Malcolm M. Fowler, "Current Experimental Activities in Germany"~~

~~Eiichi Fukushima, "Innovations in Experimental NMR"~~

~~Arie Gayer, "Measurement of Neutrons in the Fission of' 58Er"~~

~~Genevieve F. Gr'sham. "INC-Division Computing: Introductory Remarks"~~

~~Sara B. Helmick, "Data Base Software and Applications"~~

~~David E. Hobart, "Precipitation, Dissolution, and Solubility of Colloidal Plutonium(IV)"~~

~~Scott Kinkead, "Synthesis and Reactions of Fluoro-Alkyl Fluorosulfates"~~

~~Michael J. Leitch, "Quark Effects in Low Energy Pion Double Charge Exchange" APPENDIX: PRESENTA TIONS 253~~

~~Leila Z. Liepins, "Separation of Pui.IV) from Orthophosphoric Acid Using a Cation-Exchange Resin"~~

~~Lon-Chang Liu, "Why Do We Need Quarks and Gluons If They Are Not Directly Observable?"~~

~~B. B. Mclnteer, "'Sulfur Isotope Separations—Application lo Acid Rain"~~

~~Janet Mercer-Smith, "Synthesis of a Copper-67 Labeled Chelate for the Monoclonal Antibody Project"~~

~~Eugene J. Mroz, "First Results from the INC Air Sampling Network"~~

~~Thomas A. Myers, " Local Area Networks at TA-58 and Beyond?"~~

~~Thorr.as L. Norris, "Noble Gas Weapons Diagnostics"~~

~~Allen E. Ogard, "Groundwater Chemistry at Yucca Mountain in the Nevada Test Site"~~

~~Charles J. Orth, "Anomalous Iridium Anomaly in Australia—Extinction Update"~~

~~Josef Parrington. "A New Large Pneumatic Rabbit Facility at the OWR"~~

~~Chandra Pillai, "Direct Mass Measurements in the Light Neutron-Rich Region Using a Combined Energy and Time-of-Flight Technique"~~

~~Robert C. Reedy, "Cosmic-Ray Exposure Histories of the SNC ("Martian") Meteorites"~~

~~Pamela Z. Rogers, "Nuclear Microprobe Characterization of Trace Elements in Oil Shale"~~

~~Robert S. Rundberg, "Measuring Submicron Particle Size Distributions by Dynanic Light Scattering or Inverting the Fredholm Integral of the First Kind"~~

~~Frederick J. Steinkruger, "Cadmium-10Q •» Silver-109m Biomedical Generator"~~

~~Kenneth E. Thomas, "Isotope Production From Zinc Oxide Targets"~~

~~Clifford J. Unkefer, "Stereospecific Synthesis of Stable Isotopically Labeled Compounds"~~

~~Patsy L. Wanek, "Mobile Laboratory Set-Up for Water Analysis a; Yucca Mountain"~~

~~Jerry B. Wilhelmy, "The LEAP Program"~~

~~William H. Woodruff, "Structures of Electronically Excited Transition Metal Complex in Solution"~~

~~Debra A. Wrobleski, "Bimetallic Actinide-Transition Metal Phosphido Complexes"~~

~~188th National ACS Meeting~~

~~The following papers were presented at the 188th American Chemical Society National Meeting in Philadelphia, Pennslyvania, August 26-31, 1984.~~

~~J. A. Mercer-Smith, D. C. Moody, H. A. O'Brien and W. A. Taylor, "Synthesis of Copper-67 Meso-Tetra(4- Carboxypheny!) Porphine"~~

~~H. A. O'Brien, Jr.. "Nuclear Medicine: A Challenging Field for Chemists" 254 APPENDIX: PRESENTATIONS~~

J. G. Malm, P. G. Eller, B. I. Swanson, L. R. Morss. and W. T. Camall, "Reactions of Nitric Oxide, Nitrosyl Oxide, and Nilryi Oxide with Actinide Hexafluorides: Properties of Nitrosonium and Nitronium Actinide(V) Hexafluorides"

~~K. V. Salazar, "The Characterization and Preparation of Some Trivalent Uranium Complexes"~~

~~Debra A. Wrobleski, K. V. Sala^ar, R. R. Ryan, and D. C. Moody, "Synthesis and Transition Metal Chemislry of Bis-(Tf-pentamethylcy(:lopentadienyl)thorium-bis(dialkylphosphide)"~~

~~C. M. Miller, N S. Nogar, S. W. Downey, and R. A. Keller, "Applications of Resonance Ionization Mass Spectrometry to Analytical Chemistiy and Spectroscopy,"~~

~~E. J. Mroz, M. Alei, J. H. Cappis, W. Efurd, P. Guthals, A. S. Mason, and D. J. Rokop, "Heavy Methane Tracer Studies in Antarctica"~~

~~W. A. Sedlacek, "Volcanism: SO: & SO=4"~~

~~G. C. Giesler, "LAMPF Nuclear Chemistry' Uata Aquisilion System"~~

~~R. S. Rundberg and B. J. Travis, "Computer Modeling of Radionuclidc Transport in Nevada Test Site Tuff" APPENDIX: ADVISOR Y COMMITTEE 255~~

~~ADVISORY COMMITTEES~~

~~VISITING COMMITTEE FOR NUCLEAR AND RADIOCHEMISTRY~~

Chairman: Gregory R. Choppin, Florida State University, Tallahassee, Florida, 1982-84. Donald S. Burnett, California Institute of Technology, Pasadena, California, 1983-85. Joseph Cerny, University of California, Berkeley, California, 1984-86. Richard L. Hahn, Oak Ridge National Laboratory, Oak Ridge, Tennessee, 1984-86. George E. Walker, Indiana University, Bloomington, Indiana, 1984-86.

~~LOS ALAMOS COMMITTEE ON MEDICAL RADIOISOTOPES~~

Sally J. DeNardo, M.D., Davis Medical Center, Sacramento, California, 1981-85. -vlfred P. Wolf, Brookhaven National Laboratory, Upton, New York, 1981-85. Henry N. Wagner, Jr., M.D.. Johns Hopkins University School of Medicine, Baltimore, Maryland, 1985-88.

~~STABLE ISOTOPES RESOURCE ADVISORY COMMITTEE~~

Chairman: Robert Barker. Cornell LIniversity, Ithaca, New York, 1975-84. Neal Castagnoli, University of California Medical Center, San Francisco, California, 1982-84. Harry Hogenkamp, University of Minnesota, Minneapolis, Minnesota, 1975-84. Oleg Jardetsky, Sianford University, Stanford, California, 1982-84. 256 APPENDIX: DIVISION SEMINARS

~~DIVISIONAL SEMINARS~~

~~•'Exploring Experimental Data With Pattern Recognition," Michael L. Parsons, Arizona State University, Tempe, Arizona, October 7, 1983.~~

~~"Adsorption Behavior and Use of 5-MnO: as a Resin in Trace Metal Speciation Studies," Simcha Stroes- Gascovne, Atomic Energy of Canada Limited, Pinawa, Manitobe, October 12, 1983.~~

~~"Recent Radionuchde Migration in Ancient Rocks Using Uraniurn-Series Disequilibrium Techniques," M. Gascoyne, Atomic Energy of Canada, October i4, 1983.~~

~~"Liquid Sodium Chemistry at the German Experimental LMFBR KNK-II at Karlsruhe," H. H. Slamm, Institut fur Radiochemie. Karlsruhe, Federal Republic of Germany. October 17, 1983.~~

~~"In Situ Gaseous Diffusion Tracer Tests at the Barnwell, S. C, Nuclear Waste Burial Facility," David K. Kraemer, University of Arizona, Tucson, Arizona, October 21, 1983.~~

~~"Laboratory and Field Studies of Water and Solute Movement in Soils," Robert S. Bowman, US Water Conservation Laboratory, Phoenix, Arizona, October 24, 1983.~~

~~"Chemistry of Volcanic Emissions," William Zoller, University of Maryland Silver Springs, Maryland, October 28, 1983.~~

"Geochemistry. Diagenesis, and Contaminant Transport of Uranium Tailings, Grants Mineral Belt, New Mexico," Patrick Longmire, New Mexico Environmental Improvement Division, Santa Fe, New Mexico, November?, 1983.

~~"Classical Model for Pion Production in High-Energy Heavy Ion Collisions," Jutta Kunz, T-9, November 4, 1983.~~

~~"Quinzhen, the Unique E3 Meteorite from China," Ahmed El Goresy, Max Plank Institut, Heidelberg, West Germany, November 15, 1983.~~

~~"Recycling Versus Juvenile Addition of Large-Ion Lithophile Elements to Crust in Young Volcanic Arcs," Arend Meijer, University of Arizona, Tucson, Arizona, November 18, 1983.~~

~~"In-Vivo P-31 NMR Spectroscopy. From Rats to Humans," Laurence Chan, University of Colorado School of Medicine, Denver, Colorado, November 29, 1983.~~

~~"Symmetric and Asymmetric Nuclear Deformations in the Mass-100 Region," Richard A. Meyer. Lawrence Livermore Laboratory', Livermore, California, December 1, 1983.~~

~~"The NRC Waste Management Geochemistry Research Program," George Birchard, Nuclear Regulator/ Commission. Washington. DC, December 6, 1983.~~

~~"Radiation Overexposure at Argentina Nuclear Facility," Tom McLaughlin, HSE-6, January 6, 1984.~~

~~"Nuclear Research at the Centre Regional D'Etudes Nucleaires de Kinshasa," Badimbayi Lumu, Kinshase, Ziare, January 9, 1984.~~

~~"Sources and Composition of Atmospheric Particles Over the Pacific," Josef R. Parrington, University of Maryland, Silver Springs, Marylard. January 11, 1984.~~

~~"Pre-Coiomfran Metallurgy in th So-thwest," Jay W. Palmer, Northwestern University, Evanston, Illinois, January 27. 1984. APPENDIX; DIVISION SEMINARS 257~~

~~"Applications of Optical Pumping in Molecular Spectroscopy," Mark Johnson, Joint Institute for Laboratory Astrophysics, Boulder, Colorado, March 15, 1984.~~

~~"Use of the Rare Gases as Tracers in the Continental Crust," William Rison, Scripps Institution of Oceanography, La Jolla, California, March 15, 1984~~

~~"'Application of Uraniu.n Series Disequilibrium Methods to the Study of Nuclide Migration in Natural Analogue Systems," Micro Ivanovich, Australian Atomic Energy Commission, March 23, 1984.~~

"Sorption-Desorplion Experiments with Cesium on Quaternary Swiss Sediments and Infiltration of Heavy Metals From a River Into Sea Sediments," II. R. von Gunten, University of Bern, Bern, Switzerland, April 4, 1984.

~~"Cold Massive Transfer in the Reaction of 48Ca with ysCni," Heinz Gaggeler, GSI, Darmstadt, West Germany, April 4, 1984.~~

~~""Ion Exchange Properties of Zeolite;.," Howard S. Sherry, PQ Corporation, Valley Forge, Pennsylvania, May 16, 1984.~~

~~"A General Description of the J.R.C. Environmental Program Wilh a Particular Concern to Tracer Activity," Pietro Gaglione, Joint Research Centre, Ispra. Italy, May 29, 1984.~~

~~"Atmospheric Transport of Materials to Antarctica," Gerald Lambert, Centre des Faibles Radioactivites, Gif- Sur-Yvette, France, May 31, 1984.~~

~~"Environmental Technetium," Moses Attrep, Jr., East Texas State University, Commerce, Texas luly 16 1984.~~

~~" Oklo Symmetric Mass Region Fission Product Mobility," John R. de Laeter, Western Australian Institute of Technology, Bentlcy, Western Australia, July 20, 1984.~~

~~"Direct and Beta-Delayed Proton Emission in 58Ni-Induced Reactions," Per-Olof Larsson, Chalmers Univer- sity of Technology, Goteberg, Sweden. August 21, 1984.~~

~~DIVISIONAL COLLOQUIA~~

~~"The Study of Nitric Oxide and Dinitrogen Teirox.de at High Static Pressures," Steve Agnew, INC-4, November 18, 1983.~~

~~"The Future or the Omega West Reactor." John L. Yarnell and Merle E. Bunker, INC-5, January 20, 1984.~~

~~"In Vivo Metabolic Studies in Sar;haromyces, Cerevisiae Using Specific I3C Enrichment and ''C NMR Spectroscopy." Clifford J. Unkefe.. INC-4. February 17, 1984.~~

~~"Heavy Element Studies," Malcolm Fowler, INC-7. March 16. 1984.~~

~~"Fifteenth-Cemury Isoiopes, Diet, and Massacre," M. Pamela Bumsted. INC-4 and CHM-1, April 6, 1984.~~

~~""Pion-Nucleus Reaction Studies at LAMPF," Bruce J. Dropesky, INC-11, April 20, 1934.~~

~~"Experiments Probing the Limit of the Electric Field," Jerry Wilhelmy, INC-11. June 15, 1984. 258 IPPENDIX: PROGRAM FUNDING~~

~~ISOTOPE AND NUCLEAR CHEMISTRY (INC) DIVISION FY 1985 FUNDING PROFILE~~

~~OPERATING $22.6 M CAPITAL SUM~~

~~TOTAL $24.0 M~~

~~NUCLEAR WEAPONS DIAGNOSTICS AND R&D~~

~~ENERGY RESEARCH~~

~~INSTITUTIONAL SUPPORTING RESEARCH~~

~~5.0% OTHER AGENCIES OTHER DOE APPENDIX: PROGRA M FUNDING 259~~

~~MAJOR PROGRAM FUNDING FOR FY 1984~~

~~Program Strategic Funds Area Total $K $K~~

~~5-3. RADIOCHEMICA!. WEAPONS DIAGNOSTICS AND R&D 8207 (DOE/OMA) 7912 Test Analyses (DOD) 295~~

4. STABLE AND RADIOACTIVE ISOTOPE PRODUCTION, SEPARATION, AND APPLICATIONS 3460 1 'C-NMR and Metabolism (DOE/OHER) 635 Stable Isotopes Inventory (DOE/OHER) 665 National Isotopes Resource (NIH) 630 Medical Radioisotopes (DOE/OHER) 1200 Nuclear Medicine (1SR) 330

~~5. ELEMENT AND ISOTOPE TRANSPORT AND FIXATION 4766 Nevada Nuclear Waste Storage Investigations (DOE/NV) 3645 Geochemistry (DOE/OBES) 807 Defense Radionuclide Migration (DOE/NV) 314~~

~~6. ACTINIDE AND TRANSITION METAL CHEMISTRY 1804 Aclinide and SO: Chemistry (DOE/OBES) 495 Actinide and Fluorine Chemistry (1SR) 315 Laser Isotope Separation of Plutonium (DOE/ONMP) 994~~

7. STRUCTURAL CHEMISTRY, SPECTROSCOPY, AND APPLICATIONS 807 Crystal Density of Explosives (NSWQ 60 Vibralional Spectroscopy; X-Ray Diffraction Studies (ISR) 400 NMR Studies of Solids (ISR) 195 Inelastic Neutron Scattering Studies (ISR) 82 Fundamental Research on Explosives (ISR) 70

~~8. NUCLEAR STRUCTURE AND REACTIONS 1000 Nuclear Chemistry Research at LAMPF (DOE/OHENP) 676 Other Studies (ISR & OHLNP) 324~~

~~9. IRRADIATION FACILITIES 1216 Weapons Support (DOE/OMA) 780 Health and Environmental Support (LANL) 360 Irradiation Services (other institutions) 76~~

~~10. VDVANCEDANALYTICALTECKNIQUES 465 Accelerator-Based Mass Spectrometry Techniques (DOE/OHER) 125 Ultrasensitive Analysis Using Ion Accelerators (ISR) 65 Mass Spectrometer Development (DOE) 275~~

~~11. ATMOSPHERIC CHEMISTRY AND TRANSPORT 621 (DOE/OHER. NSF)~~

12. EARTH AMD PLANETARY PROCESSES 331 Search for Anomalous Iridium (ISR) 51 Lunar Geochemical Map (NASA) 43 Boron Cosmochemislry (NASA) 34 Solar Neutrino Flux (DOE/OHFNP) 150 IGPP 55 260 APPENDIX: FA CILITIES

~~ISOTOPE AND NUCLEAR CHEMISTRY DIVISION FACILITIES AND EQUIPMENT~~

~~GROUP CAPABILITY CONTACT~~

INC-3 Medical Isotopes Research Radioisolope Production Facility at the Los Alamos Meson Physics Harold A. O'Brien Facility, where large quantities of most radionuclides can be produced; includes: Hot cells for high-level gamma- and beta-active materials Purification and handling facilities

~~Analytical support capability for research, development, and quality control for radioactive isotopes in medicine; includes:~~

Dionex ion chromatograph Spectrametrics dc-coupled argon-plasma emission spectrometer Varian NMR spectrometer Model EM 360A Perkin-Elmer ir spectrometer Model 283 Hewlett-Packard gas chromulograph mass spectrometer Model 5992 Packard radiochromEtography scanner Model 7201 Three high-performance liquid chromatograpns (Waters) Animal counting system Picker gamma camera Model 4-11

~~INC-4 Isotope and Structural Chemistry Cryogenic Separation Facility for preparing large amounts of stable isotopes that can be used in other studies Thomas R. M;lls~~

~~TOF and automated nitrogen isotope ratio mass spectrometer B. B. Mclnteer~~

lr spectrometers for spectroscopic studies of small molecules in gas, liquid, and solid phases, including inert gas matrices and under extreme conditions of temperature and pressure (diamond anvil cells) and fingerprinting or" act -ide and transition-metal complexes; spectral range from 10 to 5000 en. temperature control down to 4 IC; includes: b JMEM DA3.002 Spectrometer Llewellyn H. Jones Perkin-Elmer Model 180 Pcrkin-Elmer Model 683 Nicolet FriR Model 7!9f- Digilab FTIR Model FTS-20C APPENDIX: FACILITIES 261

~~GROUP CAPABILITY CONTACT~~

Raman spectrometers for determining vibration spectra of solids, including explosives, phase transitions, pressure-induced chemistry of small molecules, copper blue proteins, actinide and t.ansition-metal complexes, solitons, spectral ranges from 2 to 10 000 cm"1, temperature control to 4 K, pressure control to 200 kbar (diamond anvil cells); includes: Two Spex 1403 monochromators Lasers for photochemistry and Raman spectroscopy; includes: Basil I. Swanson Spectra Physics Mode! 171 (argon ion) Spectra Physics Model 171 (krypton ion) Coherent Model 52G (argon ion) Lumonics Model TE431T-2 (Excimer) Lumonics Model EP033V (dye head) Coherent dye laser Tachists Model 215G (CO;, pulsed)

Apollo Model 570 (CO:, cw) NMR spectrometers for actinide and transition-metal complexes; studies Clifford J. Unkefer related*TO organ perfusion, metabolic pathways, and bio-organic synthesis; James R. Brainard structure and dynamics in organic explosives, polymers, and zeolites; includes: Bruker AM-200 Fourier transform multinuclear NMR spectrometer for solutions Bruker WM-300 wide-bore spectrometer for high-resolution, multinuclear NMR of liquids Bruker CXP-200 spectrometer for solid samples Varian EM-390 for |yF, "P, and 'H in solution (cw) Variable-frequency wide-line NMR apparatus (with 2.2 and 4.7 T magnets) for solid state studies Related equipment includes: Amplifier Research broadband amplifier (2 to 200 MHz, 200 W cw) Hewlett-Packard Model 4193 vector impedance meter Two Data General Nova-3 computer systems with magnetic tape, 10-Mbyte disks, and diskette drives

X-ray diffraction instrumentation for structural detennination of a large Robert R. Ryan class of materials, including actinide and transition-metal complexes, organic explosives, and small molecules at high pressures: single-crystal x-ray diffraction from -200 to 1000°C and in diamond anvil cells, precession and Weissenberg photography, powder diffraction; includes: Picker FACX1 single-crystal diffractometer Enraf Novius single-crystal diffraclometer Precession and Weissenberg single-crystal cameras Powder cameras 262 APPENDIX: FACILITIES

~~GROUP CAPABILITY CONTACT~~

"Hoi" laboratory capabilities foractinide and fluorine chemistry; includes: P. Gary Eller Aclinide glovebox lines for preparative work and interpretation; includes: Fluorine vacuum systems Nicolet SX-20 FT-1R with Csl optics Two Perkin-Elmer 330 UV-VIS-N1R spectrometers with data systems Preparative microwave systems X-ray powder diffraction system X-ray precession and Weissenberg cameras

Equipment for biochemical svnthcsis; includes: Thomas E. Walker Hewlett-Packard 571OA gas chromatograph with TC detector and HP 3390A integrator Hewiett-Packard 57IOAgaschrornatograph with FID detector and HP 3390A integrator

Extranuclear SpectrEL. quadrupole mass spectrometer with solid, gas, and GC imputs (used with HP 571OA instrument with FID detector); data system includes a Data General Nova 3 computer. Camac interface, and 10-Mbyte disk

Perkin-Elmer liquid chromatograph, including Scries 3B LC, LC-75 specirophotometric detector, and Sigma 15 data station Perkin-Elmer Model 297 ir spectrophotometer IBM UV-VIS spectrophotometer New Brunswick fermentors (5 and 28 i)

INC-5 Research R«actor OWR (8 MW); includes: Merle E. Bunker Fourteen thermal and epithermai rabbit facilities (maximum thermal flux 6X 10i: n/cm:s) In-core irradiation facilities (thermal flux 9 X 10" n/cnr s) Triple-axis neutron diffractomcter for neutron scattering studies Double-axis powder diffractometer for neutron transmission studies Neutron radiography facilities Tv.o neutron-capture gamma-ray facilities

~~Capability for producing relatively large quantities of radioisolopes by capture of thermal neutrons APPENDIX: FACILITIES 263~~

~~GROUP CAPABILITY CONTACT~~

~~Automated instrumental neutron-activation analysis for 46 elements; analy- Michael M. Minor sis of solids (soils, rocks, and paniculate filters) and liquids (up to 40 mi); includes:~~

Two automated and one semiautomaied neutron-activation systems with on-line data reduction; capable of handling up to 200 samples per day Delayed-neulron counting systems for determining fissile element, concentrations as low as several pans per billion Clean-room facilities for sample preparation Several Ge(Li) gamma-ray spectrometers tied to a local PDP-11/60 for data John W. Starner reduction

INC-7 Isotope Geochemistry High-precision mass spectrometry measurements for most elements; six David B. Curtis mass spectrometers; includes: Donald J. Rokop Two single-magnetic-stage instruments with pulse counting and/or Faraday cage ion detection; 10"'' to 10~':-g-sample size for plutonium, americium, and neptunium; 10 ' to 10H:-g-sample size for uranium Two instruments with two magnetic stages and pulse counting and/or Faraday cage ion detector; 0.2 to 1.0 standard cm' sample size for methane 10 " to 10 " g for terbium, bismuth, and technicium One resonance (laser) ionization (12 in., 90°) instrument with a single magnetic stage and pulse counting and/or Faraday cage ion detection; 10 ''to 10 "-g-sample size; includes argon ion and ring dye lasers One smgle-magnetic-stage instrument with pulse counting and/or Faraday cage ion detection; used for geochemistry studies on lead, uranium, neodymium, and strontium; 10"'' to 10 8-g-sample size One single-stage static (6 in., 90°) instrument with Faraday cage and multiplier detection; s 10 "' standard cm'; used for nobel gases

Anaerobic sampling of pumped groundvvaters and high-precision field and Allen E. Ogard laboratory analysis; trailer equipped for anion analysis by ion chromatography, cation analysis by atomic absorption spectrometry, alkalinity, dissolved oxygen, sulfide. Eh, and detergents; full laboratory analytical facilities

~~Atmospheric tracer experiments using an airborne platforn. (WB-57F) Paul R. Guthals (collaboration with National Aeronautics and Space Administration)~~

~~Physical and chemical characterization of aerosols in the stratosphere Allen S. Mason~~

Inorganic trace constituent analysis {in .v//« and laboratory) in upper Eugene J.Mroz troposphere and lower stratosphere: includes: Qtiadrupole mass spectrometer with gas chromatograph (masses to 1000)

~~Panicle-size and mass distribution analysis in atmosphere William A. Sedlacei< 264 APPENDIX: FACILITIES~~

~~GROUP CAPABILITY CONTACT Instruments for analysis and handling of samples; includes: Emest A. Bryant Perlcin-Elmer 404 atomic absorption spectrometer~~

~~Analysis of acids/air quality, SO; column density, volcanic gases David L. Finnegan~~

Nuclear microprobe for nondestructive, in situ materials analysis with Timothy M. Benjamin micron-scale spatial resolution using particle-induced x-ray emission, nu- Clarence J. Duffy clear reaction analysis (particle-induced gamma-ray and charged-particle Pamela S. Z. Rogers emission), and Rutherford backscattering techniques. Range of positive and negative particles available in the 1- to 40-MeV energy range. State-of-the- art software for data reduction using a VAX 730. Thick-target elemental detection limits in the 5-ppm range and thin-surface-coa!ing detection to 1/10 monolayer. Superconducting solenoid yields proton sample currents up to 200 pA/um: collaboration with Groups P-9 and E-l 1). Includes:

X-ray fluorescence spectrometer Chemical autoanalyzer used for atmospheric samples (Technicon Autoanalyzer II) Several high-performance liquid chromatographs (Waters and Spectron Physics) Two potentiostat-coulometers, PAR Model 173 Two Dionex anion chromatographs Rare-gas handling system for mass spectrometers Polarographic analyzer/strpping voltammer.er, PAR Model 264

~~Hydrothermal equipment; includes:~~

Cold seal rod vessels capable of duplicating conditions in the upper Robert W. Charles 2/3 of Earth's crust (750°C at 7 kb) Gold bag vessels for rock-solution studies to 2/3 kb and 400°C with corrosive solutions Large-volume circulation systems (700 m?) for studying natural aqueous systems under flowing conditions Solution calorimeter for measuring thermodynamic properties of aqueous solutions to 35O°C and 1/2 kb Laser RAMAN for investigating solution speciaf ;on to 4 kb and 6uO°C High-temperature furnace (155O°C) with controlled-atmosphere capabilities

~~Analytical equipment Dionex ion chromatography Spectrometrics plasma emission spectrometer Philips powder x-ray diffraction equipment~~

~~Gas-sampling trailer for collecting trace~~

~~GROUP CAPABILITY CONTACT~~

Extensive facilities for handling and chemically separating radioactive Gordon W. Knobeloch species; includes: re .lOtely controlled liquid-liquid extraction equipment ion exchange columns with automatic fraction collectors high-performance liquid chroma'ographic columns, presently used for iare earth separations "clean" chemical laboratories including quanz stills for preparation of "clean" acids facilities for handling alpha-emittting materials

~~Two magnetic deflection isotope separators John P. Balagna 90° medium current (500 uA) 55° double-focusing low current (20 uA)~~

~~Target irradiation facilities with 500- to 800-MeV protons, 0- to 500-MeV Bruce J. Dropesky pions, stopped and fast muons, and energetic neutrons~~

~~Pneumatic rabbit sytem for remote targeting in proton beam or neutron flux Facilities for handling and measuring radioactivity; includes:~~

~~automatic alpha-, beta-, and gamma-counting systems gam ma-ray spectrometers local computer-based data acquisition and processing system~~

~~Thin Target Area for on-line study of nuclear reactions induced by 800-MeV David J. Vieira protons~~

~~Transport line for studying fast-recoiling exotic nuclei produced in the Thin Target Area (in association with TOFI spf.ctrometer now being constructed)~~

~~He-jet activity transport system Willard L. Talbert 266 APPENDIX: FACILITIES~~

~~GROUP CAPABILITY CONTACT~~

INC-11 Nuclear and Radiochemistry Extensive facilities for quantitative measurement of radioactivity; includes: John P. B?.lagna James D. Gallagher 3 alpha counters (approximately 2 PI) 5 beta counters and data collection system 1 internal beta counter 2 trochoidal analyzers (positron counters) 11 Nal gamma spectrometers 9 Gel Li) automatic counters 3 Ge(Li) spectrometers 3 Gel Li) anticoincidence shielded well counters 1 low-energy x-ray Ge(Li) spectrometer 1 low-energy x-ray Si(Li) spectrometer 10 alpha spectrometers (Frisch grid and solid state) 2 data acquisition systems with 50 pulse height analyzers and PDP 11/60 computers

~~Data analysis system David D. Clinton VAX 780 and associated peripherals~~

Division-wide computing system Gary S. Benson Interactive VAX 780 system supporting programming for scientific applications and data processing, support of office automation, journal submissions, and internal publications

Integrated computer network access and peripherals Thomas A. Myers Access to both Laboratory open ICN through a jackfield with dedicated data lines and the secure partition through an encryption system, multiplexer, and jackfiekl with a Los Alamos coaxial cable data link; includes: line printer, laser printers, terminals, magnetic tape unit, card reader, disk drives with removable disk packs, terminal server, Ethernet, high-resolution color graphics

Detector development laboratory Malcolm M. Fowler Jointly implemented facility (INC and P Divisions) to develop special detectors; includes: vacuum chamber to simulate accelerator environment, multiwire proportional counters using thin polypropylene win- dows and fine wire grids, and a multisegmented system to detect and identify nuclear particles over a wide range of masses and energies

~~X-ray fluorescence spectrometer with dedicated computer for determining Charles J. Orth elemental concentrations in solids and liquids. 7, -I j- ."•"•'"»itfiv.^tMP»^ y?~~

\ *

~~1 !i~~

~~1 v f ^~~

~~^v-:.-- REFERENCES 269~~

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~~266. H. Y. McSween, "SNC Meteorites: Are They Martian Rocks?" Geology 12, 3-6 (1984).~~

~~267. H. Y. McSween and E. Jarosewich, "Petrogenesis of the Elephant Moraine A79001 Meteorite: Multiple Magma Pulses on the Shergottite Parent Body," Geochim. Cosmochim. Acta 47, 1501-1513 (1983).~~

~~268. RF. H. Becker and R. O. Pepin, "The Case fora Martian Origin of the Shergottites: Nitrogen and Noble Gases in EETA 7900!," Earth Planet. Sci. Lett. 69, 225-242 (1984).~~

~~269. L. E. Nyquist, "Do Oblique Impacts Produce Martian Meteorites?" J. Geophys. Res. 88, A785-A798 (1983).~~

~~270. R. C. Reedy and J. R. Arnold, "Interaction of Solar and Galactic Cosmic-Ray Particles with the Moon," J. Geophys. Res. 77, 537-555 (1972).~~

~~271. R. C. Reedy, "A Model for GCR-Particle Fluxes in Stony Meteorites and Production Rates of Cosmogenic Nuclides," J. Geophys. Res. (in press).~~

272. G. Dreibus, H. Paime, W. Rammensee, B. Spettel, G. Weckwerth, and H. Wanke, "Composition of Shergotty Parent Body; Further Evidence of a Two Component Model of Plant Formation," in Lunar and Planetary Science XIII (Lunar and Planetary Institute, Houston, 1982), pp. 186-187.

273. A. Burghele G. Dreibus, H. Palme, W. Rammensee, B. Spettel, G. Weckwerth, and H. Wanke, "Chemistery of Shergottites and the Shergottite Parent Body (SPB). Further Evidence of a Two Component Model of Planet Formation," in Lunar and Planetary Science XIV (Lunar and Planetary Institute, Houston, 1983), pp. 80-81.

~~274. D. D. Bogard, L. E. Nyquist, and P. Johnson, "Nobel Gas Contents of Shergottites and Implications of the Martian Origin of SNC Meteorites; Geochim. Cosmochim. Acta 48, 1723-1739 (1984).~~

~~275. D. Curtis, E. Gladney, and E. Jurney, "A Revision of the Meteorite Based Cosmic Abundance of Boron," Geochim. Cosmochim. Acta 44, 1945-1953 (1980).~~

~~276. E. Anders and M. Ebihara, "Solar System Abundances of the Elements," Geochim. Cosmochim. Acta 46,2363-2380(1982). 286 REFERENCES~~

~~277. A. G. Cameron, S. A. Colgate, and L. Crossman, "Cosmic Abundance of Boron," Nature 243, 204-207 (1973).~~

~~278. J. Larimer and E. Anders, "Chemical Fractionation in Meteorites—II Abundance Patterns and Their Interpretation," Geochim. Cosmochim. Acta 31, 1239-1270(1967).~~

~~279. E. Gladney, E. Jurney, and D. Curtis, "Nondestructive Determination of Boron and Cadmium by Thermal Neutron-Prompt Gamma-Ray Spectrometry," Anal. Chem. 48, 2139-2142 (1976).~~

~~280. E T. Jurney, D. B. Curtis, and E. S. Gladncy, "Determination of Sulfur in Environmental Materials by Thermal Neutron Capture Prompt Gamma-Ray Spectrometry," Anal. Chem. 49, 1741-1743 (1977).~~

281. E. S. Gladney, D. B. Curtis, and E. T. Jurney, "Multielement Analysis of Major and Minor Elements by Thermal Neutron Induced Capture Gamma-Ray Spectrometry," J. Radioanal. Chem. 46, 299-308 (1978).

~~282. D. B. Curtis, E. S. Gladncy, and E. T. Jurney, "Potential Interferences in the Determination of Sulfur by Thermal Neutron Induced Prompt Gamma-Ray Spectrometry," Anal. Chem. 51, 158 (1979).~~

283. E. S. Gladney, D. B. Curtis, and D. R. Perrin, "Determination of Boron in 35 International Geochemieal Reference Materials by Thermal Neutron Capture Prompt Gamma-Ray Spectrometry," Geostandards News). 8, 43-46(1984).

~~284. B. Mason, Data of Geochemistry Chapter B. Cosmochemisiry Part 1. Meteorites," Michael Fleischer, Ed., US Geological Survey paper440-B-l (1979).~~

~~285. H. Takahashi, M.-J. Janssens, J. W. Morgan, and E. Anders, "Further Studies of Trace Elements in C3 Chondrites," Geochim. Cosmochim. Acta 42, 97-106(1978).~~

~~286. R. Wolf, R. R. Gerhard. A. B. Woodrow, and E. Anders, "Chcm.ual Fractionation in Meteorites-XI C2 Chondrites," Geochim. Cosmochim. Acta 44, 711-717 (1980).~~

287. R. Kcays, R. Ganapathy. and E. Anders, "Chemical Fractionations in Meteorites—IV Abundances of Fourteen Trace Elements in L-chondritcs; Implications for Cosmothermometry." Gcochim. Cos- mochim. Acta 35. 337-363 (1971). •• ***** -T-.J. INDEX 289

~~INDEX OF AUTHORS~~

~~AGNEW, STEPHEN k High-Pressure Studies of Nitric Oxide and Oxygen 37~~

~~ALEI, MOHAMMED First Antarctic Tracer Experiment Results 201~~

~~ASPREY, LARNED B. Application of High-Energy Oxidizers to Strategic Nuclear Materials 107~~

~~BALAGNA, JOHN P. Electromagnetic Isotope Separators 30~~

~~BARNES, JOHN VV. Isotope Production Activities in FY 1984 66 Improved Targeting System for 12JXe --*• i:M Production and Recovery 71~~

~~BAYHURST, BARBARA P. Sorption Measurements on Yucca Mountain Tuff Samples 87~~

~~BAYHURST, GREGORY K. Acid Sulphate Alterations at Sulphur Springs, Valles Caldera, New Mexico 96~~

BENJAMIN, TIMOTHY M. Rutherford Backscattering Analysis of Heavy-Metal-Doped Light-Element Matrices 26 Particle-Induced X-Ray Emission Analysis of Metal Alloys 28 Nuclear Microprobe Characterization ofTrace Elements in Oil Shales 91

BHALERAO, RAJEEV S. Single-Pion Production by Fast Phns 164 A Unitary Off-Shell Model for Threshold Pionic Eta Production and Eta-Nucleon Scailering 167 Nucleons, Deltas, and Other Baryons as Nontopological Solitons 170

~~BIBEAU, ROLAND A. Electromagnetic Isotope Separators 30~~

~~BRAINARD, JAMES R. In Vivo NMR Study of the Metabolism of L-Carnitine 58 Pyruvate Metabolism in Perfused Heart 63~~

~~BRYANT, ERNEST A. The Molybdenum Solar Neutrino Experiment 212~~

~~BUNKER, MERLE E. Thermal Fission Cross-Section Measurement of :i5mU 34 LAMPF He-Jet Coupled Mass Separator Project 172 Omega West Reactor 133~~

~~BUTLER, GILBERT W. Time-of-Flight Isochronous (TOFI) Spectrometer 143 Direct Mass Measurements in the Lignt Neutron-Rich Region by Using a Combined Energy and TOF Technique 158 290 iNDEX~~

~~CAPPIS, JOHN H. Development of Surface-Ionization Diffusion-Controlled Ion Sources For Actinide Analysis 23 First Antarctic Tracer Experiment Results 201~~

~~C1IAMBERUN, EDWJN P. Electromagnetic Isotope Separators 30~~

~~CHARLES, ROBERT \V. Acid Sulphate Alterations at Sulphur Springs, Valies Caldera, New Mexico 96~~

~~CISNEROS, MICHAEL R. Sorpthn Measurements on Yucca Mountain Tuff Samples 87~~

~~CROMER, DON T. Density Prediction of Organic Explosives 37 Electron Density in Organic Explosives 43~~

~~CROWE, BRUCE M. Trace-Element Composition of Volcanic Gases From t'-ie 1984 Eruptions of Kilauea and Mauna Loa, Hawaii 195~~

~~CURTIS, DAVID B. Boron Cosmochemistry 2 19~~

~~DANIELS, KATHRYN S. The Molybdenurn Solar Neutrino Experiment 2 i 2~~

~~DROPESKY, BRUCE J. Pion Nucleus Double-Charge Exchange at Low Energies I 62 SingJe-F'ion Production by Fast Pions 164~~

DL'FFFY. CLARENCE J. Particle-Induced X-Ray Emission Analysis of Metal Alloys 28 Thermodynamics of Albite 86 Nuclear Microprobe Characterization of Trace Clemen's in Oil Shales 91 An Automated Calorimeter for Use at High Temperature and Pressure 98

~~EARL, WILLIAM L. NMR Studies of Organic Explosives 44 Solid State NMR Studies of Adsorption and Acid Sites in Y-Z~3liti: 189~~

~~EFURD, D. WESLEY Development of Curface-Ionization Diffusion-Controlled Ion Sources For Actinide Analysis 23 Neptunium-237 in Human Autopsy Tissues 47~~

~~EHLER, DEBORAH S. National Stable Isotopes Resource 54 In Vivo NMR Study of the Metabolism of L-C'arni'.ine 58~~

~~EKBERG, SCOTT A. High-Resolution Infrared Studies of Matrix-Isolated Molecules 111~~

~~ELLER, P. GARY Application of High-Energy Oxidizers to Strategic Nuclear Materials 107 Actinide Valence and Host Effects in Nuclear Waste Forms 119 INDEX 291~~

~~FINNEGAN, DAVID L. Trace-Element Composition of Volcanic Gases From the 1984 Eruptions of Kilauea and Mauna Loa, Hawaii 195~~

~~FOWLER, MALCOLM M. LEAP at Los Alamos 147 Development of Fast Neptunium Chemistry and the Search for New Isotopes of Neptunium 151 Accelerator-Based Mass Spectrometry of Methane 191~~

~~FUKUSHIMA, EIICHI The Inside-Out Helmholtz: An Unilateral Magnet for NMR ' 9"~~

~~GIESLER, GREGG C. Single-Pion Production by Fast Pions 164 LAMPF Nuclear Chemistry Data Acquisition System 172~~

~~GILMORE, JAMES S. Geochemical Anomalies at Biological Crisis Zones in the Fossil Record 209~~

~~GUTHALS, PAUL A. First Antarctic Tracer Experiment Results 201~~

~~MANNERS, JOHN L. National Siable Isotopes Resource 54~~

~~HOBART, DAVID E. The Effects of Alpha Self-Irradiation on Mixtures of Pu(IV)-Colloid, Pu(V). and Pu(Vl) 113~~

~~HOFFMAN, DARLEANE C. LEAP a! Los Alamos 147 Fission of:~ :5hEs,2i~~

~~HUTSON, JUDITH V. In Vivo NMR Study of the Metabolism of L-Carnkine 58 Pyruvate Metabolism in Perfused Heart 63~~

~~JARVINEN, GORDON D. Actinide Valence and Host Effects in Nuclear Waste Forms 119 The First Molybdenum Butterfly Cluster 124~~

~~JOHNSTON, CLIFFORD T. Vibrational Spectroscopic Studies of Acetanilide 130~~

~~JONES, LLEWELLYN H. High-Pressure Studies of Nitric Oxide and Oxygen 37 High-Resolution Infrared Studies of Matrix-isolated Molecules 111~~

~~KELLEY, GREG M. Electromagnetic Isotope Separators 30~~

~~KINKEAD, SCOTT A. Application of High-Energy Oxidizers to Strategic Nuclear Materials 107~~

~~KISSANE, RICHARD J. Application of High-Energy Oxidizers to Strategic Nuclear Materials 107 292 INDEX~~

~~KNIGHT, JERE O. Geochemical Anomalies at Biological Crisis Zones in the Fossil Record 209~~

~~KNIGHT, SYLVIA D. Sorption Measurements on Yucca Mountain Tuff Samples 87~~

~~KUBAS, GREGORY J. Reduction of SO: and Coordination of Molecular Hydrogen by Group VI-B Metal Complexes 109~~

~~LAWRENCE, FRANCINF. Sorption Measurements on Yucca Mountain Tuff Samples 87~~

~~I.EITCH, MICHAEL J. Pion Nucleus Double-Charge Exchange at Low Energies 162~~

LIU, LON-CHANG Single-Pion Production by Fast Pions 164 A Unitary Off-Shell Model for Threshold Pionic Eta Production and Eta-Nucleon Scattering 167 Nucleons, Deltas, and Other Baryons as Nonlopological Solitons 170

~~LONDON, ROBERT E. In Vivo NMR Study of the Metabolism of L-Carnitine 58~~

~~LYLE, ALVIN R. Omega West Reactor 183~~

~~LYSAGHT, PATRICK LEAP at Los Alamos 147 Accelerator-Based Mass Spectrornetry of Methane 191~~

~~MASON, ALLEN S. First Antarctic Tracer Experiment Results 201~~

~~McINTEER, B. B. Separation of Stable Isotopes—Production 51 Separation of Stable Isotopes—Research 53~~

~~MERCER-SMITH, JANET A. Synthesis of 67Cu A/eso-Tetra(4-Carboxyphenyl) Porphine for Conjugation to Monoclonal Antibodies 69~~

~~MILLER, CHARLES M. The Molybdenum Solar Neutrino Experiment 212~~

~~MILLS, THOMAS R. Separation of Stable Isotopes—Production 51 Separation of Stable Isotopes—Research IJ.~~

~~MINOR, MICHAEL M. Omega West Reactor 183~~

~~MITCHELL, ALAN J. Measuring Particle Size Distributions by Autocorrelator Photon Spectroscopy 82~~

~~MONTOYA, JOE G. Separation of Stable Isotopes—Production 51 Separation of Stable Isotopes—Research 53 INDEX 293~~

~~MOODY, DAVID C. Improved Targeting System for i:lXe — i:l! Produc.ion aiid Recovery 71 The "'"Cd — ""Agm Biomedical Generator 73 Actinide-Transition Metal Chemistry' 12"!~~

MROZ, EUGENE J. Trace-Element Composition of Volcanic Gases From the 1984 Eruptions of Kilauea and Mauna Loa Hawaii 195 First Antarctic Tracer Experiment Results 201 Variations of Stratospheric Nitric Acid Concentrations 1971-1783: Revisited 203

~~NEWTON, THOMAS W. The Effects of Alpha Seil-Irradialion on Mixtures of Pu( IV (-Colloid, Pu(V), and Pu(Vl) 113~~

~~NIESEN, VICKIG. The Molybdenum Solar Neutrino Experiment 212~~

~~O'BRIEN, HAROLD A. Improved Targeting System for ':lXe • i:'l Production and Recovery 71~~

~~OGARD, ALLEN E. Nevada Nuclear Waste Storage Investigations 81~~

~~OHKLBO. YOSHITAKA Single-Pion Production by Fast Pions 164~~

~~OLIVER. PETRITA Q. Geochemical Anomalies at Biological Crisis Zones in the Fossil Record 209~~

~~ORTH, CHARLES j. Geochemical Anomalies at Biological Crisis Zones in the Fossil Record 209~~

~~OTT, MARTIN A. Isotope Production Activities in FY 1984 6*i Improved Targeting System for i:'Xe — |:'I Production and Recovery 71~~

~~PALMER, PHILLIP D. The Effects of Alpha Self-Irradiation on Mixtures of Pu( I V)-Colloid, Pu(V), and Pu(VI) 113~~

~~PENNEMAN, ROBERT A. Low-Temperature X-Ra> Diffraction Structure of Uranyl Bis(Tri-Iso-Buiylphosphate)Nitrate 132~~

~~PERRIN, RICHARD F, Development of Surface-Ionization Diffusion-Controlled ion Sources For Actinide Analysis 23 Neptunium-237 in Human Autopsy Tissues 47~~

~~PETERSON, KAREN E. Isotope Production Activities in FY 1984 66~~

~~PILLAl, CHANDRA Direct Mass Measurements in the Light Neutron-Rich Region by Using a Combined Energy and TOF Technique 158~~

~~PURSON, JOHN D. Actinide Valence and Host Effects in Nuclear Waste Forms 119 294 INDEX~~

~~QUINT ANA, LEONARD R. Geochemical Anomalies at Biological Crisis Zones in the Fossil Record 209~~

~~REEDY, ROBERT C. Variations in Activities of Cosmogenic Radionuclides Over a Solar Cycle 215 Cosmogenic Nuclides in the SNC (Martian?) Meterorites 217~~

ROGERS, PAMELA S. Z. Rutherford Backseattering Analysis of Heavy-Metal-Doped Light-Element Matrices 26 Particle-Induced X-Ray Emission Analysis of Metal Alloys 28 Microprobe Characterization of Trace Elements in Oil Shales 9! An Automated Calorimeter for Use at High Temperature and Pressure 98

~~ROGERS, R. SCOTT Synthesis of h7Cu A/oo-Teira(4-Carboxyphenyl) Porphine for Conjugation to Monoclonal Antibodies 69 imaging and Biodistribution Capabilities at INC -3 76~~

~~ROKOP, ^ONALDJ. Development of Surface-Ionization Diffusion-Controlled Ion Sources For Actinide Analysis 23 First Antarctic Tracer Experiment Results 201 The Molybdenum Solar Neutrino Experiment 212~~

~~RUNDBEKG, ROBERT S. Measuring Particle Size Distributions by Autocorrelator Photon Spectroscopy 82~~

RvAN, ROBERT R. Density Prediction of Organic Explosives 37 Electron Density in Organic Explosives 45 Reduction ofSO: and Coordination of Molecular Hydrogen by Group VI-B Metal Complexes 109 Actinide Valence and Host Effects in Nuclear Waste Forms 119 Aciinide-Transition Metal Chemistry 122 The First Molybdenum B tterfly Cluster i 24 Low-Temperature X-Ray Diffraction Structure of Uranyl Bis(Tri-lso-Butylphosphate)Nitrate 1 32 Structure of Acetanilide at 113 K 129

~~SALAZAR, KENNETH V. Actinide-Transition Metal Chemistry' l-'-2~~

~~SEDLACEK, WILLIAM A. Variations of Stratospheric Nitric AciJ Concentrations 1971-1983: Revisited 203~~

SEGURA, NENOJ. Isotope Production Activities in FY 1984 66 Synthesis of (l7Cu A/esi>Tetra(4-Carboxyphenyl) Porphine for Conjugation to Monoclonal Antibodies 69 Improved Targeting System for i:iXe — m! Production ana Recovery 71

~~SEURER, FRANKLIN H. Isotope Production Activities in FY 19t54 66 Improved Targeting System for '"Xe — mI Production and Recovery 71~~

~~STARNER, JOHN W. Thermal Fission Cross-Section Measurement of :35mU 34 LAMPF He-Jet Coupled Mass Separator Project 154 INDEX 295~~

~~STEINKRUGER, FREDERICK J. Isotope Production Activities in FY 1984 66 The "NCd - l(l"Agm Biomedical Generator 73 Rubidium-86 Production 73~~

~~STICE, RICHARD L. Electromagnetic Isotope Separators 30~~

~~SVITRA, ZITA V. Imaging and Biodisinbution Capabilities al INC-3 76~~

SWANSON, BASIL I. High-Pressure Studies of Nitric Oxide and Oxygen 37 High-Resolution In fared Studies of Matrix-isolated Molecules 111 Vibrational Spectroscopic Studies ofAcctanilide 1 30 Resonance Raman Studies o! Blue Copper Proteins: Effects of Isotopic Substitutions and Temperature 134

~~I ALBERT, WIL1.ARD L., Jr. Thcrmai Fission Cross-Section Measurement of :Uml I 34 LAMPF He-Jet Coupled Mass Separator Ptoject 1 54~~

TAYLOR, WAYNE A. Isotope Production Activities in FY 1984 66 Synthesis of bXu .W«o-Tetra(4-Carboxyphenyl) Porphinc for Conjugation to Monoclonal Antibodies t>9 Improved Targeting System for l:'.\e - i:M Production and Recover. 71 Imaging and Biodistribution Capabilities at INC-3 76

~~THOMAS, KEN E. Isotope Production Activities in FY 1984 66~~

~~THOMAS, KIMBERLY \V. Sorplion Measurements on Yucca Mountain Tuff Samples 87~~

~~THOMPSON. .JOSEPH I.. Radiunuclide Migration at the Nevada Tesi Site 88~~

~~L NKEFER, CLIFFORD J. National Stable Isotopes Resource 54 In 1'iw NMR Study of the Metabolism of L-Carnitinc 58~~

~~VIDAl.E. ROSEMARY J. Acid Sulphate Alterations at Sulphur Springs, Valles Caldera. New Mexico 96~~

YIEIRA. DAVID,J. Electromagnetic Isotope Separators 3D nme-of-Flight Isochronous (TOFI) Spectrometer 143 Direct Mass Measurements in the Light Neutron-Rich Region by Using a Combined Energy and TOF Technique 158

~~WAGEMAN, WILLIAM E. National Stable Isotopes Resource 54~~

~~WALKER, THOMAS E. National Stable Isotopes Resource 54 296 INDEX~~

~~VVANEK, PHILIP M. isotope Production Activities in FY 1984 66 The IOTCd — m"Agm Biomedical Generator 73 Rubidium-86 Production 73 Imaging and Biodistributior. Capabilities at INC-3 76~~

WILHELMY, JERRY B. LEAP at Los Alamos 147 Fission of "55:56Es, ;"J)'Fm, and :5°Md at Moo rate Excitation Energies 1 73 Measurement of Neutrons Emitted in Fission of'""Er 177 Accelerator-Based Mass Speclromeiry of Methane 191

~~WILLIAMS, HERBERT T. Omega West Reactor 183~~

~~WOLFSBERG, KURT The Molybdenum Solar Neutrino Experiment 2 12~~

~~WOODRUFF, WILLIAM H. Resonance Raman Studies uf Blue Copper Proteins: Eflci ;•. nflsotopic Subslilulions and Temperature i 34~~

~~\VOUTERS,JAN M. Time-of-Flight Isochronous (TOFI) Spectrometer 143 D-rect Mass Measurements in the Light Neutron-Rich Region by Using a Combined En ;md TOF Technique 158~~

~~WROBLESKI, DEBRA A. Aciinide-Transition Metal Chemistry 122~~

~~YAN, SHUIII NG Singlc-Pion Production by Fast Pions 164~~