HEDL Evaluation of Actinide Cross Sections for ENDF/B-V.
Author: Frederick M. Mann
Publisher:
Published: 1977
Total Pages: 92
ISBN-13:
DOWNLOAD EBOOKRead and Download eBook Full
Author: Frederick M. Mann
Publisher:
Published: 1977
Total Pages: 92
ISBN-13:
DOWNLOAD EBOOKAuthor:
Publisher:
Published: 2004
Total Pages: 7
ISBN-13:
DOWNLOAD EBOOKOur Nuclear Physics Group has worked over the last several years to improve the ENDF/B actinide cross sections, especially as measured against the famous series of fast-spectrum critical experiments performed at Los Alamos under such names as Godiva, Jezebel, the Flattops, and Bigten. The new evaluations include changes in the high-energy fission cross sections, nubar, elastic scattering, inelastic scattering, fission spectra, and delayed neutrons that combine to significantly improve the calculated results for the Los Alamos critical assemblies. As a happy byproduct of this work, we found that the new evaluations also removed about half of a long-standing discrepancy in calculations of thermal-reactor critical experiments using lattices of low-enriched uranium oxide rods. In the meantime, work at the Oak Ridge National Laboratory has resulted in new proposed resonance parameters for U238. When these low-energy data are combined with the new high-energy data from Los Alamos, they have the effect of removing most of the rest of the problem for thermal lattices. Although more work will be done at both Los Alamos and Oak Ridge, including making the evaluations consistent with the new standards, the results presented in this talk provide promise that ENDF/B-VII will result in good improvements for users at both high and low neutron energies.
Author: D. A. Brown
Publisher:
Published: 2004
Total Pages: 7
ISBN-13:
DOWNLOAD EBOOKThe Livermore Computational Nuclear Physics group is charged with producing updated neutron incident cross section evaluations for all the actinides in the coming year, concentrating on neutron induced fission, neutron capture and (n,2n) cross sections. We attack this daunting task either by adopting other recent evaluations or by performing our own. Owing to the large number of nuclei involved, we seek to automate this process as much as possible. For this purpose, we have developed a series of computer codes: x41, an interface to the EXFOR database, fete, a code that translates ENDF/B formatted evaluations into a computationally convenient form, and da{_}fit, a fitting code that takes all relevant EXFOR data for a reaction or set of reactions and performs a generalized least square fit to them, subject to various constraints and other prior information.
Author: S. Tagesen
Publisher:
Published: 1981
Total Pages: 84
ISBN-13:
DOWNLOAD EBOOKAuthor: D. C. Irving
Publisher:
Published: 1970
Total Pages: 13
ISBN-13:
DOWNLOAD EBOOKThe neutron cross sections for iron have been evaluated and placed in the ENDF/B format with the material (MAT) number 1101. The total cross section was evaluated from recent experimental measurements and is compatible with measurements from very thick sample penetration made at the Tower Shielding Facility. Other data were taken from evaluations by J.J. Schmidt as contained in the UKAEA Nuclear Data File, DFN 64. (Author).
Author:
Publisher:
Published: 1997
Total Pages: 135
ISBN-13:
DOWNLOAD EBOOKSeparate evaluations have been done for the three stable isotopes of silicon for ENDF/B-VI. The evaluations are based on analysis of experimental data, supplemented by results of nuclear model calculations. The computational methods and the parameters required as input to the nuclear model codes are reviewed. Discussion of the evaluated data given for resonance parameters, neutron induced reaction cross sections, associated angular and energy distributions, and gamma-ray production cross sections is included. Extensive comparisons of the evaluated cross sections to measured data are shown in this report. The evaluations include all necessary data to allow KERMA (Kinetic Energy Released in MAterials) and displacement cross sections to be calculated directly. These quantities are fundamental to studies of neutron heating and radiation damage.
Author: Savannah River Laboratory
Publisher:
Published: 1979
Total Pages: 32
ISBN-13:
DOWNLOAD EBOOKAuthor:
Publisher:
Published: 2004
Total Pages: 7
ISBN-13:
DOWNLOAD EBOOKThe authors discuss the possibilities and limitations of the use of theory as a tool in the evaluation of actinide fission and capture cross-sections. They consider especially the target 235U as an example. They emphasize the roles of intermediate structure in the fission cross-section and of level width fluctuations in both intermediate structure and fine structure, noting that these lead to a breakdown of Hauser-Feshbach theory at sub-barrier and near barrier energies. At higher energies (where fluctuation-averaged Hauser-Feshbach theory is applicable) semi-quantitative and intuitive representations of transition state spectra and barrier level density functions have to be tested against experimental data wherever these are available. Adjustment of the fission cross-section against inelastic scattering to the much better known levels of the residual nucleus should then lead to a fairly sound estimate of the capture cross-section. They compare such estimates with evaluated and experimental data for 235U.
Author:
Publisher:
Published: 1989
Total Pages: 9
ISBN-13:
DOWNLOAD EBOOKIsotopic evaluations for {sup 50,52,53,54}Cr, {sup 54,56,57,58}Fe, {sup 58,60,61,62,64}Ni, {sup 63,65}Cu, and {sup 206,207,208}Pb are included in ENDF/B-VI for the first time. These general purpose files, all by the ORNL evaluation group, include many activation cross sections. In this review, the 34 activation reactions for these materials in the priority-I CSEWG list were checked for their presence and contents in the general purpose files. These cross sections are reviewed in terms of the experimental data base and the evaluation methods. Most of them have been significantly improved over ENDF/B-V through the improved data base and the use of advanced codes such as SAMMY for resonance analysis, GLUCS for handling ratio data and covariances, and TNG for cross-section shape and for extracting individual cross sections from the measured particle spectrum. 18 refs., 1 fig., 1 tab.
Author: D. C. Irving
Publisher:
Published: 1970
Total Pages: 17
ISBN-13:
DOWNLOAD EBOOK