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New fit of thermal neutron constants (TNC) for 233,235U, 239,241Pu and 252Cf(sf): Microscopic vs. maxwellian data

Pronyaev, Vladimir G.; Capote, Roberto; Trkov, Andrej; Noguere, Gilles; Wallner, Anton

Description

An IAEA project to update the Neutron Standards is near completion. Traditionally, the Thermal Neutron Constants (TNC) evaluated data by Axton for thermal-neutron scattering, capture and fission on four fissile nuclei and the total nu-bar of 252Cf(sf) are used as input in the combined least-square fit with neutron cross section standards. The evaluation by Axton (1986) was based on a least-square fit of both thermal-spectrum averaged cross sections (Maxwellian data) and microscopic cross...[Show more]

dc.contributor.authorPronyaev, Vladimir G.
dc.contributor.authorCapote, Roberto
dc.contributor.authorTrkov, Andrej
dc.contributor.authorNoguere, Gilles
dc.contributor.authorWallner, Anton
dc.contributor.editorPlompen, A.
dc.contributor.editorHambsch, F.-J.
dc.contributor.editorSchillebeeckx, P.
dc.contributor.editorMondelaers, W.
dc.contributor.editorHeyse, J.
dc.contributor.editorKopecky, S.
dc.coverage.spatialBruges, Belgium
dc.date.accessioned2019-12-18T03:52:45Z
dc.date.available2019-12-18T03:52:45Z
dc.date.created11 September 2016 through 16 September 2016
dc.identifier.isbn9782759890200
dc.identifier.urihttp://hdl.handle.net/1885/195745
dc.description.abstractAn IAEA project to update the Neutron Standards is near completion. Traditionally, the Thermal Neutron Constants (TNC) evaluated data by Axton for thermal-neutron scattering, capture and fission on four fissile nuclei and the total nu-bar of 252Cf(sf) are used as input in the combined least-square fit with neutron cross section standards. The evaluation by Axton (1986) was based on a least-square fit of both thermal-spectrum averaged cross sections (Maxwellian data) and microscopic cross sections at 2200 m/s. There is a second Axton evaluation based exclusively on measured microscopic cross sections at 2200 m/s (excluding Maxwellian data). Both evaluations disagree within quoted uncertainties for fission and capture cross sections and total multiplicities of uranium isotopes. There are two factors, which may lead to such difference: Westcott g-factors with estimated 0.2% uncertainties used in the Axton's fit, and deviation of the thermal spectra from Maxwellian shape. To exclude or mitigate the impact of these factors, a new combined GMA fit of standards was undertaken with Axton's TNC evaluation based on 2200 m/s data used as a prior. New microscopic data at the thermal point, available since 1986, were added to the combined fit. Additionally, an independent evaluation of TNC was undertaken using CONRAD code. Both GMA and CONRAD results are consistent within quoted uncertainties. New evaluation shows a small increase of fission and capture thermal cross sections, and a corresponding decrease in evaluated thermal nubar for uranium isotopes and 239Pu.
dc.format.mimetypeapplication/pdf
dc.language.isoen_AU
dc.publisherEDP Sciences - Web of Conferences
dc.relation.ispartofseries2016 International Conference on Nuclear Data for Science and Technology, ND 2016
dc.rights© 2017 The Authors
dc.rights.urihttps://creativecommons.org/licenses/by/4.0/
dc.sourceND 2016: International Conference on Nuclear Data for Science and Technology
dc.titleNew fit of thermal neutron constants (TNC) for 233,235U, 239,241Pu and 252Cf(sf): Microscopic vs. maxwellian data
dc.typeConference paper
local.description.notesImported from ARIES
local.description.refereedYes
local.identifier.citationvolume146
dc.date.issued2017-09-13
local.identifier.absfor020202 - Nuclear Physics
local.identifier.absfor029904 - Synchrotrons; Accelerators; Instruments and Techniques
local.identifier.ariespublicationa383154xPUB9116
local.publisher.urlhttps://www.epj-conferences.org
local.type.statusPublished Version
local.contributor.affiliationPronyaev, Vladimir G., Private Institution "Atomstandart" at State Corporation "Rosatom"
local.contributor.affiliationCapote, Roberto, International Atomic Energy Agency
local.contributor.affiliationTrkov, Andrej, NAPC-Nuclear Data Section
local.contributor.affiliationNoguere, Gilles, CEA
local.contributor.affiliationWallner, Anton, College of Science, ANU
local.bibliographicCitation.startpage1
local.bibliographicCitation.lastpage4
local.identifier.doi10.1051/epjconf/201714602045
dc.date.updated2019-08-04T08:17:20Z
local.identifier.scopusID2-s2.0-85030483088
dcterms.accessRightsOpen Access
dc.provenanceThis is an Open Access article distributed under the terms of the Creative Commons Attribution License 4.0, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
dc.rights.licenseCreative Commons Attribution License 4.0
CollectionsANU Research Publications

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