Neutron-Induced Fission Cross Section Measurements for Uranium Isotopes and Other Actinides at LANSCE.
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Published: 2012
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Published: 2012
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Published: 2010
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DOWNLOAD EBOOKFission cross sections of a range of actinides have been measured at the Los Alamos Neutron Science Center (LANSCE) in support of nuclear energy applications in a wide energy range from sub-thermal energies up to 200 MeV. A parallel-plate ionization chamber are used to measure fission cross sections ratios relative to the 235U standard while incident neutron energies are determined using the time-of-flight method. Recent measurements include the {sup 233,238}U, 239−242Pu and 243Am neutron-induced fission cross sections. Obtained data are presented in comparison with ex isting evaluations and previous data.
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Published: 1976
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DOWNLOAD EBOOKA procedure, called the threshold cross section method was applied to our experimental data involving four uranium (233U 234U, 236U, and 238U) and five plutonium (239Pu, 24°Pu, 241Pu, 242Pu, and 244Pu) isotopes to determine ratios of fission cross sections relative to 235U. The data were gathered using ionization fission chambers and the time-of-flight technique at the LLL 100-MeV electron linear accelerator: measurements span the neutron energy range of 0.001 to 30 MeV. Experimental uncertainties common to past measurements were either eliminated or significantly reduced in this study by use of the threshold method, thereby making higher accuracies possible. The cross section ratios are absolute in the sense that they do not depend on the work of others. Results from our ratios involving 233U, 235U, 238U, and 239Pu are used to illustrate this method.
Author: Gordon Douglas James
Publisher: Pergamon
Published: 1981
Total Pages: 304
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DOWNLOAD EBOOKNuclear Fission and Neutron-Induced Fission Cross-Sections is the first volume in a series on Neutron Physics and Nuclear Data in Science and Technology. This volume serves the purpose of providing a thorough description of the many facets of neutron physics in different fields of nuclear applications. This book also attempts to bridge the communication gap between experts involved in the experimental and theoretical studies of nuclear properties and those involved in the technological applications of nuclear data. This publication will be invaluable to those interested in studying nuclear fis.
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Published: 2010
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DOWNLOAD EBOOKFission cross sections of a range of actinides have been measured at the Los Alamos Neutron Science Center (LANSCE) in support of nuclear energy applications. By combining measurement at two LANSCE facilities, Lujan Center and the Weapons Neutron Research center (WNR), differential cross sections can be measured from sub-thermal energies up to 200 MeV. Incident neutron energies are determined using the time-of-flight method, and parallel-plate ionization chambers are used to measure fission cross sections relative to the 235U standard. Recent measurements include the {sup 233,238}U, {sup 239,242}Pu and 243Am neutron-induced fission cross sections. In this paper preliminary results for cross section data of 243Am and 233U will be presented.
Author: Anthony Lloyd Hutcheson
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Published: 2008
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DOWNLOAD EBOOKPrecision measurements of 238U(n, n'g) and 235,238U(n,2ng) partial cross sections have been performed at Triangle Universities Nuclear Laboratory (TUNL) to improve crucial data for the National Nuclear Security Administration's (NNSA) Stockpile Stewardship Program. Accurate neutron-induced reaction cross-section data are required for many practical applications, including nuclear energy and reactor technology, nuclear transmutation, and explosive nuclear devices. Due to the cessation of underground nuclear testing in the early 1990s, understanding of the performance of nuclear devices is increasingly dependent on precise model calculations which are, in turn, themselves reliant on accurate reaction data to serve as benchmarks for model codes. Direct measurement of (n, n') and (n,2n) reaction cross sections for uranium is extremely difficult due to large neutron background from fission and very close nuclear level spacing. Previous direct measurements of the cross sections are incomplete and/or discrepant over the energy range of interest. However, the (n, n'g) and (n,2ng) partial gamma-ray cross-section data obtained in the present work can be combined with model calculations to infer total (n, n') and (n,2n) reaction-channel cross sections. A pulsed and monoenergetic neutron beam was used in combination with high-resolution gamma-ray spectroscopy to measure these partial cross sections for incident neutron energies between 5 and 14 MeV. Gamma-ray yields were measured with high-purity germanium (HPGe) clover and planar detectors. Neutron fluxes were determined from the well-measured 2+ -> 0+ transition in 56Fe to be on the order of 10^4 n/cm^2/s. Detector efficiency and attenuation of gamma rays in the target were simulated using the MCNPX Monte-Carlo radiation transport code. Measured partial cross sections were compared with previous measurements and calculations from GNASH and TALYS Hauser-Feshbach statistical-model codes. Results are generally in good agreement with existing data and provide cross-section data for transitions in energy regions where none previously existed. Total reaction-channel cross sections are inferred from statistical-model calculations and compared with existing direct measurement data.
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Published: 1982
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DOWNLOAD EBOOKThe neutron-induced fission cross sections of /sup 242m/Am and 245Cm have been measured over an energy range of 10−4 eV to approx. 20 MeV in a series of experiments at three facilities during the past several years. The combined results of these measurements, in which only sub-milligram quantities of enriched isotopes were used, yield cross sections with uncertainties of approximately 5% below 10 MeV relative to the 235U standard cross section used to normalize the data. We summarize the resonance analysis of the /sup 242m/Am(n, f) cross section in the eV region. Hauser-Feshbach statistical calculations of the detailed fission cross sections of 235U and 245Cm have been carried out over the energy region from 0.1 to 5 MeV and these results are compared with our experimental data.
Author: R. L. Henkel
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Published: 1957
Total Pages: 28
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Published: 1986
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DOWNLOAD EBOOKThe measurement of the fission cross section ratios of nine isotopes relative to 235U at an average neutron energy of 14.74 MeV is described with particular attention to the determination of corrections and to sources of error. The results are compared to ENDF/B-V and to other measurements of the past decade. The ratio of the neutron induced fission cross section for these isotopes to the fission cross section for 235U are: 23°Th - 0.290 +- 1.9%; 232Th - 0.191 +- 1.9%; 233U - 1.132 +- 0.7%; 234U - 0.998 +- 1.0%; 236U - 0.791 +- 1.1%; 238U - 0.587 +- 1.1%; 237Np - 1.060 +- 1.4%; 239Pu - 1.152 +- 1.1%; 242Pu - 0.967 +- 1.0%. 40 refs., 11 tabs., 9 figs.
Author: David T. Goldman
Publisher:
Published: 1968
Total Pages: 680
ISBN-13:
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