New methods for the determination of total radiative thermal neutron capture cross sections

R. B. Firestone, M. Krticka, D. P. McNabb, B. Sleaford, U. Agvaanluvsan, T. Belgya, Zs Revay

Research output: Conference contribution

9 Citations (Scopus)

Abstract

Precise gamma-ray thermal neutron capture cross sections have been measured at the Budapest Reactor for all elements with Z= 1-83,92 except for He and Pm. These measurements and additional data from the literature been compiled to generate the Evaluated Gamma-ray Activation File (EGAF), which is disseminated by LBNL and the IAEA. These data are nearly complete for most isotopes with Z<20 so the total radiative thermal neutron capture cross sections can be determined directly from the decay scheme. For light isotopes agreement with the recommended values is generally satisfactory although large discrepancies exist for 11B, 12,13C, 15N, 28,30Si, 34S, 37Cl, and 40,41K. Neutron capture decay data for heavier isotopes are typically incomplete due to the contribution of unresolved continuum transitions so only partial radiative thermal neutron capture cross sections can be determined. The contribution of the continuum to the neutron capture decay scheme arises from a large number of unresolved levels and transitions and can be calculated by assuming that the fluctuations in level densities and transition probabilities are statistical. We have calculated the continuum contribution to neutron capture decay for the palladium isotopes with the Monte Carlo code DICEBOX. These calculations were normalized to the experimental cross sections deexciting low excitation levels to determine the total radiative thermal neutron capture cross section. The resulting palladium cross sections values were determined with a precision comparable to the recommended values even when only one gamma-ray cross section was measured. The calculated and experimental level feedings could also be compared to determine spin and parity assignments for lowlying levels.

Original languageEnglish
Title of host publicationCOMPOUND-NUCLEAR REACTIONS AND RELATED TOPICS - Proceedings of the 2007 International Workshop onCompound-Nuclear Reactions and Related Topics(CNR 2007)
Pages26-29
Number of pages4
DOIs
Publication statusPublished - máj. 21 2008
Event2007 International Workshop on Compound-Nuclear Reactions and Related Topics, CNR 2007 - Yosemite National Park, CA, United States
Duration: okt. 22 2007okt. 26 2007

Publication series

NameAIP Conference Proceedings
Volume1005
ISSN (Print)0094-243X
ISSN (Electronic)1551-7616

Other

Other2007 International Workshop on Compound-Nuclear Reactions and Related Topics, CNR 2007
CountryUnited States
CityYosemite National Park, CA
Period10/22/0710/26/07

ASJC Scopus subject areas

  • Physics and Astronomy(all)

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    Firestone, R. B., Krticka, M., McNabb, D. P., Sleaford, B., Agvaanluvsan, U., Belgya, T., & Revay, Z. (2008). New methods for the determination of total radiative thermal neutron capture cross sections. In COMPOUND-NUCLEAR REACTIONS AND RELATED TOPICS - Proceedings of the 2007 International Workshop onCompound-Nuclear Reactions and Related Topics(CNR 2007) (pp. 26-29). (AIP Conference Proceedings; Vol. 1005). https://doi.org/10.1063/1.2920738