Evaluation for ENDF/B-IV of the neutron cross sections for /sup 235/U from 82 eV to 25 keV
Abstract
Capture and fission cross sections for /sup 235/U in the ''unresolved resonance'' energy region were evaluated to permit determination of local-average resonance parameters for the ENDF/B-IV cross section file. Microscopic data were examined for infinitely dilute average fission and capture cross sections and also for intermediate structure unlikely to be reproduced by statistical fluctuations of resonance widths and spacings within known laws. Evaluated cross sections, averaged over lethargy intervals greater than 0.1, were obtained as an average over selected data sets after appropriate renormalization. Estimated uncertainties are given for these evaluated average cross sections. The ''intermediate'' structure fluctuations common to a few independent data sets were approximated by straight lines joining successive cross sections at 120 selected energy points; the cross sections at the vertices were adjusted to reproduce the evaluated average cross sections over the broad energy regions. Data sources and methods are reviewed, output values are tabulated, and some modified procedures are suggested for future evaluations. Evaluated fission and capture integrals for the resolved resonance region are also tabulated. These are not in agreement with integrals based on the resonance parameters of ENDF/B versions III and IV. 8 tables, 5 figures.
- Authors:
- Publication Date:
- Research Org.:
- Oak Ridge National Lab., Tenn. (USA)
- OSTI Identifier:
- 7189870
- Report Number(s):
- ORNL-4955; ENDF-233
TRN: 76-016730
- DOE Contract Number:
- W-7405-ENG-26
- Resource Type:
- Technical Report
- Country of Publication:
- United States
- Language:
- English
- Subject:
- 73 NUCLEAR PHYSICS AND RADIATION PHYSICS; NEUTRON REACTIONS; URANIUM 235 TARGET; URANIUM 235; CROSS SECTIONS; DATA ANALYSIS; RESONANCE INTEGRALS; GAMMA RADIATION; URANIUM 236; ACTINIDE ISOTOPES; ACTINIDE NUCLEI; ALPHA DECAY RADIOISOTOPES; BARYON REACTIONS; ELECTROMAGNETIC RADIATION; EVEN-EVEN NUCLEI; EVEN-ODD NUCLEI; HADRON REACTIONS; HEAVY NUCLEI; INTEGRALS; IONIZING RADIATIONS; ISOMERIC TRANSITION ISOTOPES; ISOTOPES; MINUTES LIVING RADIOISOTOPES; NUCLEAR REACTIONS; NUCLEI; NUCLEON REACTIONS; RADIATIONS; RADIOISOTOPES; TARGETS; URANIUM ISOTOPES; YEARS LIVING RADIOISOTOPES; 652026* - Nuclear Properties & Reactions, A=220 & above, Experimental- Spontaneous & Induced Fission- (-1987); 652025 - Nuclear Properties & Reactions, A=220 & above, Experimental- Nuclear Reactions & Scattering- (-1987)
Citation Formats
Peelle, R.W.. Evaluation for ENDF/B-IV of the neutron cross sections for /sup 235/U from 82 eV to 25 keV. United States: N. p., 1976.
Web. doi:10.2172/7189870.
Peelle, R.W.. Evaluation for ENDF/B-IV of the neutron cross sections for /sup 235/U from 82 eV to 25 keV. United States. doi:10.2172/7189870.
Peelle, R.W.. Sat .
"Evaluation for ENDF/B-IV of the neutron cross sections for /sup 235/U from 82 eV to 25 keV". United States.
doi:10.2172/7189870. https://www.osti.gov/servlets/purl/7189870.
@article{osti_7189870,
title = {Evaluation for ENDF/B-IV of the neutron cross sections for /sup 235/U from 82 eV to 25 keV},
author = {Peelle, R.W.},
abstractNote = {Capture and fission cross sections for /sup 235/U in the ''unresolved resonance'' energy region were evaluated to permit determination of local-average resonance parameters for the ENDF/B-IV cross section file. Microscopic data were examined for infinitely dilute average fission and capture cross sections and also for intermediate structure unlikely to be reproduced by statistical fluctuations of resonance widths and spacings within known laws. Evaluated cross sections, averaged over lethargy intervals greater than 0.1, were obtained as an average over selected data sets after appropriate renormalization. Estimated uncertainties are given for these evaluated average cross sections. The ''intermediate'' structure fluctuations common to a few independent data sets were approximated by straight lines joining successive cross sections at 120 selected energy points; the cross sections at the vertices were adjusted to reproduce the evaluated average cross sections over the broad energy regions. Data sources and methods are reviewed, output values are tabulated, and some modified procedures are suggested for future evaluations. Evaluated fission and capture integrals for the resolved resonance region are also tabulated. These are not in agreement with integrals based on the resonance parameters of ENDF/B versions III and IV. 8 tables, 5 figures.},
doi = {10.2172/7189870},
journal = {},
number = ,
volume = ,
place = {United States},
year = {Sat May 01 00:00:00 EDT 1976},
month = {Sat May 01 00:00:00 EDT 1976}
}
-
A discussion is given of the evaluation of neutron and gamma ray production cross sections of /sup 235/U from 10/sup -5/ eV to 20 MeV and the parts contributed by the author. All available new data are included in this evaluation, and the procedures adopted to assess the experimental data and adopt a set of recommended values are described. 22 figures, 10 tables.
-
Comments on the ENDF/B-VI evaluation for [sup 235]U in the neutron energy region from 1 to 20 eV
A discrepancy of 6% has been reported between the measured capture resonance integral of [sup 235]U and that calculated from the resonance parameters in ENDF/B-VI. This discrepancy may be due to the use of a value for the average radiation width which is too small. The possibility that small resonances whose widths are primarily capture were missed experimentally due to their proximity to resonances with large fission widths was also considered, but dismissed. Since accurate values of neutron widths, [Gamma][sub n] and total widths,[Gamma][sub T], of resonances can be determined from transmission data and are not dependent on any normalizationmore » -
Comments on the ENDF/B-VI evaluation for {sup 235}U in the neutron energy region from 1 to 20 eV
A discrepancy of 6% has been reported between the measured capture resonance integral of {sup 235}U and that calculated from the resonance parameters in ENDF/B-VI. This discrepancy may be due to the use of a value for the average radiation width which is too small. The possibility that small resonances whose widths are primarily capture were missed experimentally due to their proximity to resonances with large fission widths was also considered, but dismissed. Since accurate values of neutron widths, {Gamma}{sub n} and total widths,{Gamma}{sub T}, of resonances can be determined from transmission data and are not dependent on any normalizationmore »