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Transition from collective to noncollective rotation at high spin in N approx. = 87 nuclei

Description: The systematics of the (E2) ..gamma.. ray transition energies and the available lifetime data are used to characterize the excitation modes of the light rare-earth nuclei (N greater than or equal to 82) at different spins. The results, which include our recently obtained data on /sup 149/Gd, /sup 154/Ho, /sup 155/Er, /sup 157/Yb and /sup 158/Yb nuclei, indicate that, at low spins, the nuclear excitation mode (shapes) change from single-particle excitations (weakly oblate) in N less than or equal to 85 nuclei to quasi-vibrational (soft triaxial) in N = 86, weakly rotational (prolate) in N = 87, and rotational (prolate) in the N greater than or equal to 88 systems. At higher angular momenta, all these nuclei show a general tendency to traverse the (epsilon,..gamma..) plane towards the oblate axis, and to eventually adopt the aligned coupling mode of excitation.
Date: January 1, 1982
Creator: Baktash, C.
Partner: UNT Libraries Government Documents Department

Physiopathology of blood platelets and development of platelets substitutes. Progress report, August 1, 1976--October 31, 1977. [/sup 51/Cr]

Description: Progress is reported on the following research projects: the effect of estrogen on platelet aggregability and thrombus formation; the antithrombotic effect of platelet inhibiting agents in a bench model of artificial kidney; the arrest of hemorrhage in severely alloimmunized thrombocytopenic patients; and in vivo elution of /sup 51/Cr from labeled platelets induced by antibody. (HLW)
Date: July 31, 1977
Creator: Baldini, M G
Partner: UNT Libraries Government Documents Department

Fission product retention in TRISCO coated UO sub 2 particle fuels subjected to HTR simulated core heating tests

Description: Results of the examination and analysis of 25,730 individual microspheres from spherical fuel elements HFR-K3/1 and HFR-K3/3 are reported. The parent spheres were irradiated in excess of end-of-life exposure and subsequently subjected to simulated core heating tests in a special high-temperature furnace at Forschungszentrum, Juelich, GmbH (KFA). Following the heating tests, the spheres were electrolytically deconsolidated to obtain unbonded fuel particles for Irradiated Microsphere Gamma Analyzer (IMGA) analysis. For sphere HFR-K3/1, which was heated for 500 h at 1600{degree}C, only four particles were identified as having released fission products. The remaining particles from the sphere showed no statistical evidence of fission product release. Scanning Electron Microscopy (SEM) examination showed that three of the defect particles had large sections of the TRISO coating missing, while the fourth appeared normal. For sphere HFR-K3/3, which was heated for 100 h at 1800{degree}C, the IMGA data revealed that fission product release (cesium) from individual particles was significant and that there was large particle-to-particle variation in retention capabilities. Individual particle release (cesium) averaged ten times the KFA-measured integral spherical fuel element release value. In addition, the bimodal distribution of the individual particle data indicated that two distinct modes of failure at fuel temperatures of 1800{degree}C and above may exist. 6 refs., 6 figs., 4 tabs.
Date: November 1, 1990
Creator: Baldwin, C.A. & Kania, M.J.
Partner: UNT Libraries Government Documents Department

Kinetics of stimulated Moessbauer emission in neutron-pumped krypton-83

Description: Using an idealized kinetic model for a gamma-ray laser system pumped by a spatially uniform delta-function burst of fast neutrons, a computer study has been made of the growth, decay, and attenuation of resonant 9.3-keV recoil-less gamma radiation from /sup 83/Kr, as a function of neutron-burst intensity, gamma-ray linebreadth, temperature, dilution of krypton in a beryllium host, and nonresonant absorption coefficient of the host. The isomer is formed by neutron capture in a 40-eV resonance, and the 144-ns transition lifetime is short in comparison with the time for neutrons to moderate. The kinetic behavior of this system is therefore determined largely by the time dependence of the neutron spectrum and only slightly by the reciprocal linebreadth of the graser transition. Because the lower state is stable, inversion is rapidly lost, so that, for observable gain, an unrealistically high source intensity is needed. Use of a beryllium host, which increases the Debye temperature, is negated by its parasitic absorption. Although this transition is unsuitable for a graser, these findings help to illustrate useful properties of nuclear isomers and solid hosts for which stimulated emission might be observable.
Date: November 1, 1977
Creator: Baldwin, G.C. & McNeil, L.E.
Partner: UNT Libraries Government Documents Department

Moessbauer-Borrmann superradiance

Description: The kinetic behavior of a gamma-ray laser is comprised of an array of isomeric nuclei located at regular lattice sites in a perfect single crystal of dimensions and structure so chosen as to favor anomalous emission into that Borrmann mode having the maximum possible number of component Bragg-reflected beams, which greatly reduces the excitation requirements. The analysis of several hypothetical systems shows that superradiance, rather than amplified spontaneous emission, will then be the preferred mode of deexcitation, provided the nuclei can be pumped rapidly to a short-lived Moessbauer level while preserving crystal integrity. This warrants a search for solutions to the major problems: candidate nuclides, preparation of a storage isomer, and interlevel transfer from storage to lasing state. 10 refs., 8 figs., 2 tabs.
Date: January 1, 1986
Creator: Baldwin, G.C.; Feld, M.S.; Hannon, J.P.; Hutton, J.T. & Trammell, G.T.
Partner: UNT Libraries Government Documents Department

Recent studies of the gamma-ray laser problem. Addendum to LA-UR-80-96

Description: The possibility of extending the laser principle into the hard x-ray region above a few keV depends upon the ability of a pump to create the critical density of population inversion for which gain overcomes loss by absorption. Although this critical density decreases with the wavelength of the radiation to be stimulated, the power required to generate it depends upon the lifetime of the state being pumped. The lifetimes of inner-shell vacancies of atoms are very short. Nuclear states, on the other hand, have much longer lifetimes, ranging from fractions of picoseconds to millennia. Moreover, in the so-called recoilless or Moessbauer transitions of nuclear isomers, it was observed that the resonance cross section often exceeds the nonresonant absorption cross section by several orders of magnitude: just the condition for lasing in an inverted population. If, other things being equal, the absorber foil of a Moessbauer experiment contained an excess of excited states, then, instead of the absorption dip normally observed at resonance, there would be an increase of intensity, and amplification by stimulated emission would be achieved. The problem in making a gamma-ray laser is, therefore, simply that of obtaining an inverted population without inhibiting the Moessbauer effect. Research on this problem is reviewed.
Date: January 1, 1980
Creator: Baldwin, G.C.; McNeil, L.E.; Solem, J.C. & Suydam, B.R.
Partner: UNT Libraries Government Documents Department

Radiochemical examination of Peach Bottom HTGR component samples

Description: This document describes the results of a program conducted at General Atomic (GA) to radiochemically examine primary coolant circuit components of the Peach Bottom HTGR. The purpose of this program was to provide (1) absolute values of plateout activity in the primary coolant circuit, (2) fission gas release data for fuel compacts, (3) sorption data for cesium on fuel element graphite (spine and sleeve), and (4) diffusion coefficient data for cesium in fuel element graphite (spine and sleeve). The resulting plateout data consist of specific activities for Sr-90, Cs-134, and Cs-137. These were the only reportable activities found. Iodine was below the limits of detection by neutron activation analysis. The Sr-90 activity ranged from about 5 to 10/sup -4/ to 9 x 10/sup -4/ ..mu..Ci/cm/sup 2/ in the cold duct and 2 x 10/sup -3/ to 9 x 10/sup -3/ ..mu..Ci/cm/sup 2/ in the steam generator. The strontium found was orders of magnitude lower than the Cs-137 values of about 0.8 to 4 ..mu..Ci/cm/sup 2/ in the cold duct and 2 to 12 ..mu..Ci/cm/sup 2/ in the steam generator. Additionally, it was found that the Cs-134 activity was, in general, higher than the Cs-137 activity throughout the primary helium coolant circuit. Post irradiation fission gas release tests on driver fuel element compacts gave R/B values for krypton and xenon somewhat higher than measured reactor values. It was determined by metallographic examination that the small failed fraction at end-of-life was appreciably hydrolyzed after the fuel was removed from the core. This explains the relatively high R/B values found in the postirradiation tests. Failure fractions determined by metallography are in good agreement with values determined by hot-chlorine leaching experiments at ORNL.
Date: August 1, 1978
Creator: Baldwin, N.L.; Norman, B.L. & Bell, W.E.
Partner: UNT Libraries Government Documents Department

Matter oscillations: Neutrino transformation and regeneration in the earth

Description: Transformation and regeneration phenomena are calculated to result from transmission through the Earth of neutrinos with E(MeV)/..delta..m/sup 2/(eV)/sup 2/ in the vicinity of 10/sup 6/ to 10/sup 7/. As a result, large time-of-night and seasonal variations are predicted for various solar neutrino experiments in this parameter range. Analagous effects are predicted for terrestrial cosmic ray and accelerator experiments.
Date: January 1, 1987
Creator: Baltz, A.J. & Weneser, J.
Partner: UNT Libraries Government Documents Department

Factors affecting the rate of hydrolysis of phenylboronic acid in lab-scale precipitate reactor studies

Description: Removing aromatic carbon from an aqueous slurry of cesium-137 and other alkali tetraphenylborates by acid hydrolysis will be an important step in preparing high-level radioactive waste for vitrification at the Savannah River Site's Defense Waste Processing Facility (DWPF). Kinetic data obtained in bench-scale precipitate hydrolysis reactors suggest changes in operating parameters to improve product quality in the future plant-scale radioactive operation. The rate-determining step is the removal of the fourth phenyl group, i.e. hydrolysis of phenylboronic acid. Efforts to maximize this rate have established the importance of several factors in the system, including the ratio of copper(II) catalyst to formic acid, the presence of nitrite ion, reactions of diphenylmercury, and the purge gas employed in the system.
Date: January 1, 1992
Creator: Bannochie, C. J.; Marek, J. C.; Eibling, R. E. & Baich, M. A.
Partner: UNT Libraries Government Documents Department

Leach behavior and mechanical-integrity studies of irradiated Epicor-II waste products

Description: The leachability of Cs and Sr from cement solidified ion exchange media claimed to be representative of the Epicor-II prefilters (D-mix) is presented. The Cs and Sr release is significantly lower than that typically observed for organic ion exchange resin/cement composites. The effect of radiation up to a total dose of 10/sup 7/ Gy upon the leachability and mechanical integrity (as measured by MCC-11) of D-mix/cement composites has been investigated. No deleterious effects were found. 6 figures.
Date: January 1, 1982
Creator: Barletta, R.E.; Swyler, K.J.; Chan, S.F. & Davis, R.E.
Partner: UNT Libraries Government Documents Department

Decomposition of sodium tetraphenylborate

Description: The chemical decomposition of aqueous alkaline solutions of sodium tetraphenylborate, NaTPB, has been investigated. The focus of the investigation is on the determination of components which influence NaTPB decomposition. Copper(II) ions, solution temperature, and solution pH (hydroxide ion concentration) have all been demonstrated to affect NaTPB stability. Their relationship with each other and the stability of NaTPB has been determined. Based upon this knowledge, a method for stabilizing NaTPB was determined. Decomposition of a NaTPB solution was delayed with the addition of sodium hydroxide. In additional work, the elimination of oxygen from the reaction environment did not prevent NaTPB decomposition in the presence of copper(II) ions but did, however, affect the course of decomposition.
Date: January 1, 1990
Creator: Barnes, M.J.
Partner: UNT Libraries Government Documents Department

Radionuclide reactions with groundwater and basalts from Columbia River basalt formations

Description: Chemical reactions of radionuclides with geologic materials found in Columbia River basalt formations were studied. The objective was to determine the ability of these formations to retard radionuclide migration from a radioactive waste repository located in deep basalt. Reactions that can influence migration are precipitation, ion-exchange, complexation, and oxidation-reduction. These reactions were studied by measuring the effects of groundwater composition and redox potential (Eh) on radionuclide sorption on fresh basalt surfaces, a naturally altered basalt, and a sample of secondary minerals associated with a Columbia River basalt flow. In addition, radionuclide sorption isotherms were measured for these materials and reaction kinetics were determined. The radionuclides studied were /sup 137/Cs, /sup 85/Sr, /sup 75/Se, /sup 95m/Tc, /sup 237/Np, /sup 241/Am, /sup 226/Ra and /sup 237/Pu. The Freundlich equation accurately describes the isotherms when precipitation of radionuclides does not occur. In general, sorption increased in the order: basalt < altered basalt < secondary minerals. This increase in sorption corresponds to increasing surface area and cation exchange capacity. The Eh of the system had a large effect on technetium, plutonium, and neptunium sorption. Technetium(VII), Pu(VI), and Np(V) are reduced to Tc(IV), Pu(IV), and Np(IV), respectively, under Eh conditions expected in deep basalt formations. The kinetics of radionuclide sorption and basalt-groundwater reactions were observed over a period of 18 weeks. Most sorption reactions stabilized after about four weeks. Groundwater composition changed the least in contact with altered basalt. Contact with secondary minerals greatly increased Ca, K, and Mg concentrations in the groundwater.
Date: June 1, 1981
Creator: Barney, G.S.
Partner: UNT Libraries Government Documents Department

Identification of key radionuclides in a nuclear waste repository in basalt

Description: Radionuclides were identified which appear to pose the greatest potential hazard to man during long-term storage of nuclear waste in a repository mined in the Columbia Plateau basalt formation. The criteria used to select key radionuclides were as follows: quantity of radionuclide in stored waste; biological toxicity; leach rate of the wastes into groundwater; and transport rate via groundwater flow. The waste forms were assumed to be either unreprocessed spent fuel or borosilicate glass containing reprocessed high-level waste. The nuclear waste composition was assumed to be that from a light water reactor. Radionuclides were ranked according to quantity, toxicity, and release rate from the repository. These rankings were combined to obtain a single list of key radionuclides. The ten most important radionuclides in order of decreasing hazard are: /sup 99/Tc, /sup 129/I, /sup 237/Np, /sup 226/Ra, /sup 107/Pd, /sup 230/Th, /sup 210/Pb, /sup 126/Sn, /sup 79/Se, and /sup 242/Pu. Safety assessment studies and the design of engineered barriers should concentrate on containment of radionuclides in this list.
Date: May 1, 1980
Creator: Barney, G.S. & Wood, B.J.
Partner: UNT Libraries Government Documents Department

Pion charge exchange and nuclear structure: II, Nuclear structure calculation

Description: Whereas the nuclear charge distribution, essentially determined by the protons, has been studied for decades in elastic electron scattering, a study of the neutron distribution in nuclei has only recently become possible through pion charge-exchange experiments. The excitation of the isobaric analog state (IAS) in pion single-charge-exchange reactions is one of the most prominent candidates for such an investigation which will be especially interesting for strongly deformed nuclei which can be aligned in magnetic fields. This contribution concentrates on calculations related to such a reaction for the rare-earth nucleus Ho-165. 8 refs., 3 figs.
Date: January 1, 1987
Creator: Bartel, J.; Johnson, M.B. & Singham, M.
Partner: UNT Libraries Government Documents Department

Determination of iodine-129 in mixed fission products by neutron activation analysis

Description: This report describes an improved method for analyzing /sup 129/I in fission product mixtures originating from fuel reprocessing studies. The method utilizes conventional iodine valence adjustment and solvent extraction techniques to chemically separate /sup 129/I from most fission products. The /sup 129/I is then determined by neutron irradiation and measurement of the 12.4-h /sup 130/I produced by the neutron capture reaction. Special techniques were devised for neutron irradiation of /sup 129/I samples in the pneumatic tube irradiation facilities at the High Flux Isotope (HFIR) and Oak Ridge Research (ORR) reactors. Chemically separated /sup 129/I is adsorbed on an anion exchange resin column made from an irradiation container. The loaded resin is then irradiated in either of the pneumatic facilities to produce /sup 130/I. Sensitivity of the analysis with the HFIR facility (flux: 5 x 10/sup 14/ neutrons cm/sup -2/s/sup -1/) and a 100-s irradiation time is approximately 2 ng. Samples up to 250 mL in volume can be easily processed. The method has been in routine use for about two years and has given good results on samples of reactor fuel solutions and off-gas traps.
Date: October 1, 1980
Creator: Bate, L. C. & Stokely, J. R.
Partner: UNT Libraries Government Documents Department

Iodine-129 separation and determination by neutron activation analysis

Description: A method is described for analysis of /sup 129/I in fission product mixtures originating from fuel reprocessing studies and low-level wastes. The method utilizes conventional iodine valence adjustment and solvent extraction techniques to chemically separate /sup 129/I from most fission products. The /sup 129/I is determined by neutron irradiation and measurement of the 12.4 h /sup 130/I produced by the neutron capture reaction. Special techniques were devised for neutron irradiation of /sup 129/I samples in the pneumatic tube irradiation facilities at the High Flux Isotope (HFIR) and Oak Ridge Research (ORR) Reactors. Chemically separated /sup 129/I is adsorbed on an anion exchange resin column made from an irradiation container. The loaded resin is then irradiated in either of the pneumatic facilities to produce /sup 130/I. Sensitivity of the analysis with the HFIR facility (flux: 5 x 10/sup 14/ n/cm/sup 2//sec) and a 100-second irradiation time is approximately 0.03 nanograms. Samples up to 250 ml in volume can be easily processed.
Date: January 1, 1981
Creator: Bate, L.C. & Stokely, J.R.
Partner: UNT Libraries Government Documents Department

Measurement of Leaching From Simulated Nuclear-Waste Glass Using Radiotracers

Description: The use of radiotracer spiking as a method of measuring the leaching from simulated nuclear-waste glass is shown to give results comparable with other analytical detection methods. The leaching behavior of /sup 85/Sr, /sup 106/Ru, /sup 133/Ba, /sup 137/Cs, /sup 141/Ce, /sup 152/Eu, and other isotopes is measured for several defense waste glasses. These tests show that radiotracer spiking is a sensitive, multielement technique that can provide leaching data, for actual waste elements, that are difficult to obtain by other methods. Additionally, a detailed procedure is described that allows spiked glass to be prepared with a suitable distribution of radionuclides.
Date: September 1982
Creator: Bates, J. K.; Jardine, L. J. & Steindler, M. J.
Partner: UNT Libraries Government Documents Department

Program overview: Remedial actions at Oak Ridge National Laboratory

Description: Research on and development of civilian and defense uses of nuclear materials and technologies have occurred at Oak Ridge National Laboratory (ORNL) since its creation as part of the World War II Manhattan Project in 1943. A diverse legacy of contaminated inactive facilities, research areas, and waste management areas exists; many are candidates for remedial action. Most attention is focused on waste management sites which contain the bulk of ORNL's environmental contamination. A wide variety of liquid and solid wastes, primarily radioactive wastes or mixed wastes in which radioactivity was the principal hazardous constituent, have been disposed of on-site in the past 45 years. One potential approach to remedial problems at ORNL is to design primarily for control and decay in situ (during an institutional control period of 100 years or more) of intermediate-lived wastes such as /sup 3/H, /sup 90/Sr, and /sup 137/Cs. Passive measures designed to provide greater long-term confinement (for example, in situ vitrification) could be exercised at sites contaminated with TRU wastes or high concentrations of hazardous constitutes. This approach would (a) provide a period sufficiently long for evaluation of the effectiveness of environmental processes and passive remedial measures in controlling the migration of long-lived materials, (b) allow additional time needed for development of new technologies for more permanent site stabilization, and (c) reduce the need for immediate implementation of the more-expensive exhumation and disposal option.
Date: July 27, 1988
Creator: Bates, L.D. & Trabalka, J.R.
Partner: UNT Libraries Government Documents Department

Radiological effects of SRS operations, 1988

Description: A discussion of the offsite effective dose equivalents reported for 1988 SRS releases serves as the basis for this report. Detailed analyses of atmospheric and liquid release trends and their consequences in terms of relative importance among facilities, radionuclides, and exposure pathways have also been included. Releases of radioactivity to the atmosphere were generally lower in 1988 than in 1987. No major unplanned tritium releases were recorded during the year. However, there were three inadvertent releases of Pu-238 from F Area in January, March and October of 160, 32 and 83 uCi, respectively. Radioactive releases to onsite streams from direct discharges and seepage basin migration decreased in 1988. However, as a result of a decrease in the flow rate of the Savannah River in 1988, higher offsite doses were reported. The maximum individual dose, conversely, was down from 1987. This decrease reflected the fact that the maximum individual dose is most significantly affected by the cesium concentration in fish. In terms of largest contributors to dose, the releases were dominated by tritium, Cs-137 and to a much lesser extent Sr-90. With respect to the offsite population, doses from atmospheric releases are generally higher than those from liquid releases, and this trend continued in 1988. Analyses of 1988 data and the data for the preceding decade suggest that radioactive releases from the SRS during this period have not significantly impacted the offsite population.
Date: October 25, 1989
Creator: Bauer, L.R.
Partner: UNT Libraries Government Documents Department

Reactor operation environmental information document

Description: This volume is a reactor operation environmental information document for the Savannah River Plant. Topics include meteorology, surface hydrology, transport, environmental impacts, and radiation effects. 48 figs., 56 tabs. (KD)
Date: December 1, 1989
Creator: Bauer, L.R.; Hayes, D.W.; Hunter, C.H.; Marter, W.L. & Moyer, R.A.
Partner: UNT Libraries Government Documents Department

Neutron capture cross sections for /sup 86/Sr and /sup 87/Sr at stellar temperatures. Revision 1

Description: Recent work on s-process nucleosynthesis has focused attention on the investigation of capture cross sections for nuclei in the mass region near the N = 50 closed neutron shell. Of special astrophysical interest are (i) the analysis of the s-process branching through /sup 85/Kr as a monitor of stellar neutron density and temperature and (ii) the investigation of the possible chronometric pair /sup 87/Rb-/sup 87/Sr as an independent measure of the age of the galaxy. For both problems the capture cross sections of the two pure s-process nuclei /sup 86/Sr and /sup 87/Sr have to be known to an accuracy of 5% or better. The current investigation of the neutron capture cross sections for /sup 86/Sr and /sup 87/Sr was undertaken to extend recent measurements by Walter and Beer to energies below 3.5 keV, where strong resonances are known to exist, and to explore the discrepancy in the results of the Maxwellian averaged capture cross section of /sup 87/Sr at kT = 30 keV as reported by previous investigators. 9 refs., 1 fig.
Date: June 25, 1986
Creator: Bauer, R.W.; Mathews, G.J.; Becker, J.A.; Howe, R.E. & Ward, R.A.
Partner: UNT Libraries Government Documents Department

Reassessment of data used in setting exposure limits for hot particles

Description: A critical review and a reassessment of data reviewed in NCRP Report 106 on effects of hot particles'' on the skin of pigs, monkeys, and humans were made. Our analysis of the data of Forbes and Mikhail on effects from activated UC{sub 2} particles, ranging in diameter from 144 {mu}m to 328 {mu}m, led to the formulation of a new model for prediction of both the threshold for acute ulceration and for ulcer diameter. A dose of 27 Gy at a depth of 1.33 mm in tissue in this model will result in an acute ulcer with a diameter determined by the radius over which this dose (at 1.33-mm depth) extends. Application of the model to the Forbes-Mikhail data yielded a threshold'' (5% probability) of 6 {times} 10{sup 9} beta particles from a point source on skin of mixed fission product beta particles, or about 10{sup 10} beta particles from Sr--Y-90, since few of the Sr-90 beta particles reach this depth. The data of Hopewell et al. for their 1 mm Sr-Y-90 exposures were also analyzed with the above model and yielded a predicted threshold of 2 {times} 10{sup 10} Sr-Y-90 beta particles for a point source on skin. Dosimetry values were employed in this latter analysis that are 3.3 times higher than previously reported for this source. An alternate interpretation of the Forbes and Mikhail data, derived from linear plots of the data, is that the threshold depends strongly on particle size with the smaller particles yielding a much lower threshold and smaller minimum size ulcer. Additional animal exposures are planned to distinguish between the above explanations. 17 refs., 3 figs., 3 tabs.
Date: May 1, 1991
Creator: Baum, J.W. & Kaurin, D.G.
Partner: UNT Libraries Government Documents Department

Release of volatile fission products from uranium dioxide

Description: Post-irradiation anneal experiments have been used to determine the release of iodine and tellurium from lightly irradiated UO/sub 2/ samples maintained at stoichiometry. The applicability of the equivalent-sphere model of diffusion to release of fission gases has been tested. Diffusion coefficients and activation energies have been evaluated. The diffusion coefficient of /sup 132/Te at 1400/sup 0/C was found to be of an order-of-magnitude larger than that of /sup 131/I. This result may be of importance for an understanding of the pellet-cladding interaction and for a better evaluation of the source term for fission-product release under accident conditions. Qualitatively, the influence of the stoichiometry on the release of /sup 133/Xe, /sup 131/I, and /sup 132/Te has been established.
Date: March 1, 1983
Creator: Bayen, D.
Partner: UNT Libraries Government Documents Department

Krypton entrapment in pulse biased sputter-deposited metals

Description: A supported gas discharge sputtering system was constructed to investigate krypton entrapment in high-rate sputter-deposited thick films. Krypton entrapment was studied as a function of substrate and target voltage for nickel, aluminum, titanium and iron deposits. Control of substrate and target voltages was achieved with pulse circuits capable of adjusting the pulse duration and repetition rate. A water-cooled cylindrical copper substrate 15 cm in diameter was used to collect the sputtered metal from a 9-cm diameter cylindrical target. To observe the immediate effect of changes in sputtering parameters on gas trapping, as well as measure the total gas trapped, a sensitive mass flow indicator was installed in the krypton supply of the dynamically pumped system. Data relating krypton content to substrate bias conditions and deposition rate are discussed in light of the theory of Carter, Colligon and Leck on ion absorption in the presence of sputtering. Krypton contents &gt; 2 at.% were found in the metals studied, all of which were deposited at rates exceeding 1 nm/sec. Computed krypton concentrations agreed with concentrations in samples that were analyzed chemically.
Date: January 1, 1978
Creator: Bayne, M. A.; Moss, R. W. & McClanahan, E. D.
Partner: UNT Libraries Government Documents Department