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Thermal neutron calibration of a tritium extraction facility using the /sup 6/Li(n,t)/sup 4/He//sup 197/Au(n,. gamma. )/sup 198/Au cross section ratio for standardization

Description: Absolute tritium activities in a neutron-activated metallic lithium samples have been measured by liquid scintillation methods to provide data needed for the determination of capture-to-fission ratios in fast breeder reactor spectra and for recent measurements of the /sup 7/Li(n,n't)/sup 4/He cross section. The tritium extraction facility used for all these experiments has now been calibrated by measuring the /sup 6/Li(n,t)/sup 4/He//sup 197/Au/n,..gamma..)/sup 198/Au activity ratio for thermal neutrons and comparing the result with the well-known cross sections. The calculated-to-measured activity ratio was found to be 1.033 +- 0.018. 2 figures, 20 tables.
Date: August 1, 1980
Creator: Bretscher, M.M. & Smith, D.L.
Partner: UNT Libraries Government Documents Department

Nuclear structure and reactions studied with the Darmstadt-Heidelberg crystal ball

Description: Angular momentum distribution in compound nuclei have been derived from ..gamma..-ray multiplicities and angular distributions measured with the Darmstadt-Heidelberg crystall ball. The influence of dynamic barrier fluctuation on the amount of angular momentum absorbed in the fusion process is discussed. Entrance channel effects have been observed which result in different decay paths for compound nuclei at the same excitation energy and spin in different target-projectile combinations. The ..gamma..-decay of resonances in the /sup 12/C + /sup 12/C system has been investigated. The measured ..gamma..-ray yields are consistently smaller than expected for collectively enhanced E2 transitions in a deformed and rigidly rotating intermediate system. The order of magnitude of the experimentally observed ..gamma..-intensity is, however, reproduced in theoretical calculations of nuclear bremsstrahlung, using realistic wave functions of the scattering states. 29 references, 10 figures.
Date: January 1, 1984
Creator: Metag, V.; Fischer, R.D.; Koch, G.; Kuehn, W.; Muehlhans, R.; Novotny, R. et al.
Partner: UNT Libraries Government Documents Department

Intermediate structure in unresolved resonances of fissile and fertile nuclides

Description: Evidence for the existence of intermediate structure in the unresolved resonance fission and capture cross sections of /sup 235/U and in the capture cross section of /sup 238/U is reviewed. Certain of the statistical tests that have been used are known to be compromised by finite resolution when applied to unresolved resonance data, but it is concluded that over most of the energy range the test results are valid. Parity assignments for the structure in /sup 238/U(n, ..gamma..) suggest that s-wave neutron absorption is responsible for much of the structure. If this is the case, the cross section fluctuations are most likely due to fluctuations in the radiative capture width, rather than in the neutron width. Finally, the practical effect of the possible presence of width correlations in fertile and fissile nuclides is addressed. 1 figure, 1 table.
Date: January 1, 1980
Creator: Moore, M.S.
Partner: UNT Libraries Government Documents Department

Experiments with. lambda. hypernuclei

Description: Recent observations of hypernuclear bound states in experiments at the Brookhaven National Laboratory Alternate Gradient Synchrotron are described. Gamma rays from hypernuclei have been observed in coincidence with a (K/sup -/,..pi../sup -/) energy difference spectrum. The energy resolution and purity of the (K/sup -/,..pi../sup -/) spectrum demonstrates the hypernuclear origin of the gamma rays. The case of /sub ..lambda..//sup 7/Li is discussed in detail as it represents the first successful application of the technique. Experiments of this kind can benefit greatly from the increased kaon beam intensity that will be available at LAMPF II.
Date: January 1, 1982
Creator: May, M.
Partner: UNT Libraries Government Documents Department

Comparison of late effects of single x-ray exposure, chronic tritiated water ingestion, and chronic cesium-137 gamma exposure in mice

Description: There is concern over the possible late effects resulting from chronic exposure to tritiated water, a primary by-product of power reactors. We are comparing the genetic and somatic effects of tritiated water ingestion to acute x-ray or chronic cesium-137 gamma-ray exposures. Eight week old mice were maintaned on tritiated water in concentrations of 0.3, 1.0, and 3.0 ..mu..Ci/ml. Identical animals received cesium-137 gamma exposures equivalent to that from the tritiated water. At 4 week intervals, animals were sacrificed and the hematopoietic stem cell content and cellularity of the bone marrow determined. For comparison of acute and chronic effects, one group of mice received a single whole-body x-ray exposure of 525 rads. The x-irradiated animals showed an immediate sharp decrease in marrow cellularity followed by gradual return to normal levels, with a lifelong reduction in number of marrow stem cells. Animals exposed to the two higher concentrations of tritiated water showed only slight reductions in marrow cellularity, with a lifelong reduction in hematopoietic stem cells in the bone marrow. Comparison of the external gamma exposures to chronic tritiated water ingestion indicates similar patterns. Maintenance of normal cellularity with a reduced number of stem cells in x-rayed animals was shown by tritiated thymidine cytocide to be due to the reduction in number of stem cells in the resting G/sub O/ stage. At this time it is not possible to determine whether there is a significant difference in relative biological effectiveness of tritiated water compared to cesium-137 gamma rays; however, indications are that they are similar.
Date: January 1, 1979
Creator: Carsten, A.L. & Cronkite, E.P.
Partner: UNT Libraries Government Documents Department

Gamma scattering in condensed matter with high intensity Moessbauer radiation

Description: We give a progress report for the work which has been carried out in the last three years with DOE support. A facility for high-intensity Moessbauer scattering is now fully operational at the University of Missouri Research Reactor (MURR) as well as a facility at Purdue, using special isotopes produced at MURR. High precision, fundamental Moessbauer effect studies have been carried out using scattering to filter the unwanted radiation. These have led to a new Fourier transform method for describing Moessbauer effect (ME) lineshape and a direct method of fitting ME data to the convolution integral. These methods allow complete correction for source resonance self absorption (SRSA) and the accurate representation of interference effects that add an asymmetric component to the ME lines. We have begun applying these techniques to attenuated ME sources whose central peak has been attenuated by stationary resonant absorbers, to more precisely determine interference parameters and line-shape behavior in the resonance asymptotic region. This analysis is important to both the fundamental ME studies and to scattering studies for which a deconvolution is essential for extracting the correct recoilless fractions and interference parameters. A number of scattering studies have been successfully carried out including a study of the thermal diffuse scattering in Si, which led to an analysis of the resolution function for gamma-ray scattering. Also studied was the anharmonic motion in Na and the satellite reflection Debye-Waller factor in TaS{sub 2}, which indicate phason rather than phonon behavior. We have begun quasielastic diffusion studies in viscous liquids and current results are summarized. These advances, coupled to our improvements in MIcrofoil Conversion Electron spectroscopy lay the foundation for the proposed research outlined in this request for a three-year renewal of DOE support.
Date: January 1, 1990
Partner: UNT Libraries Government Documents Department

JANUS neutron irradiation of a mouse cell line containing a shuttle vector plasmid

Description: The study presented here represents the initial steps of our attempt to characterize JANUS neutron induced mutagenesis in mammalian cells. The approach which we are taking is to use a mammalian cell system which allows one to determine the actual changes in DNA base sequence which occur when a gene mutates. Recently, several systems have been described which make possible the rapid and unambiguous determination of DNA base sequence changes in genes of eukaryotic cells. In some of these systems, a target gene is introduced into the mammalian cells as part of a shuttle vector which is capable of replication in both mammalian cells and bacteria. In this study we have used such a system for the analysis of neutron-induced mutations in the presence and absence of the radioprotector N-(2-mercaptoethyl)-1,3-diaminopropane, WR1065. 20 refs., 5 figs., 1 tab.
Date: January 1, 1989
Creator: Nagy, B. (Central Inst. for Tumors, Zagreb (Yugoslavia)); Grdina, D.J. (Argonne National Lab., IL (USA)) & Ashman, C.R. (Chicago Univ., IL (USA))
Partner: UNT Libraries Government Documents Department

Nondestructive assay of plutonium bearing scrap and waste with the advanced segmented gamma-ray scanner

Description: Assaying plutonium-bearing scrap and waste (S W) for plutonium content can be very difficult because of the heterogeneous nature of the items. We have characterized 25 S W items in three distinct S W categories to 2% or better. We used these items with fabricated calibration standards to evaluate the performance of the lump- corrected segmented gamma-ray scanner. We show that some difficult-to-measure S W samples can be assayed with less than 10% bias, but still suggest that each category of S W be individually evaluated for measurement bias. This paper describes the capability of the advanced segmented gamma-ray scanner (SGS) to measure a wide variety of plutonium-bearing scrap and waste. Real samples were obtained from operating facilities and subsequently carefully characterized. The samples include low-density plutonium bearing ash, high-density plutonium oxide, sand-slag crucibles (SSC), and salts generated from the molten salt extraction (MSE) process. This paper demonstrates that some of these process samples can be measured quite well with the state-of-the-art techniques on the SGS. 5 refs., 6 figs., 1 tab.
Date: January 1, 1990
Creator: Simmonds, S.M.; Sprinkle, J.K. Jr.; Hsue, S.-T. & Kellogg, M.P.
Partner: UNT Libraries Government Documents Department

Hanford Engineer Works Technical Manual: Section a, Metal Preparation

Description: Metal is used in the Hanford process in the form of short cylinders, or slugs, which are bonded to aluminum jackets. the jackets are necessary to prevent corrosion and the escape of radioactive materials. The bonding is required to provide adequate heat transfer. This section of the manual deals with the preparation of the jacketed slugs. 6 figs.
Date: January 1, 1967
Partner: UNT Libraries Government Documents Department

Recent experiences of scrap and waste assay using neutron coincidence counting of materials from F B-Line at the Savannah River Site

Description: The heterogeneous nature of scrap and waste poses unique problems for quantitative measurement. This is particularly true when the sample to be measured can have significant amounts of plutonium in addition to a variety of matrix components. One approach to addressing these difficulties is to combine gamma-ray and neutron counting techniques. A system combining a segmented gamma-ray scanner and neutron coincidence counter has recently been developed for the non-destructive assay of plutonium-bearing scrap and waste. Experience gained with the neutron coincidence counter portion of the system is described. Results obtained from the measurement of scrap and waste materials containing a few grams to a few hundred grams of plutonium are given. The effects of different matrices are evaluated and the role of special diagnostics is explored. 5 refs., 13 figs., 3 tabs.
Date: January 1, 1990
Creator: Baker, L.; MacMurdo, K. (Westinghouse Savannah River Co., Aiken, SC (USA)); Miller, M.C. & Bosler, G.E. (Los Alamos National Lab., NM (USA))
Partner: UNT Libraries Government Documents Department