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Author Kaeppeler, F. ♦ Toukan, K. A. ♦ Schumann, M. ♦ Mengoni, A.
Source United States Department of Energy Office of Scientific and Technical Information
Content type Text
Language English
Subject Keyword PHYSICS ♦ CAPTURE ♦ CROSS SECTIONS ♦ CERIUM ISOTOPES ♦ NEUTRONS ♦ BERYLLIUM 7 ♦ LITHIUM 7 TARGET ♦ NEUTRON SPECTRA ♦ PRASEODYMIUM ISOTOPES ♦ PROTON REACTIONS ♦ S PROCESS
Abstract The neutron capture cross sections of the stable cerium isotopes 136, 138, 140, and 142 have been measured relative to that of gold by means of the activation method. The samples were irradiated in a quasistellar neutron spectrum for {ital kT}=25 keV using the {sup 7}Li({ital p},{ital n}){sup 7}Be reaction near threshold. Variation of the experimental conditions in different activations and the use of different samples allowed for the reliable determination of corrections and the evaluation of systematic uncertainties. The resulting stellar cross sections can be given with uncertainties between 3{percent} and 7{percent}. The present data for {sup 136}Ce and {sup 138}Ce are the first experimental information in this mass region of relevance for {ital p}-process studies to our knowledge, whereas the new {sup 142}Ce cross section allowed to resolve a previous discrepancy. The experimental results are complemented by a set of calculated cross sections for all cerium isotopes from {sup 132}Ce to {sup 142}Ce as well as for {sup 141}Pr, {sup 142}Pr, and {sup 143}Pr. The improved cross sections were used in an updated {ital s}-process analysis of the Ce-Pr-Nd region that included the small branchings at {sup 141}Ce and {sup 142}Pr. The consequences of the resulting {ital s} abundances are discussed with respect to isotopic anomalies in meteoritic neodymium as well as for the {ital r}- and {ital p}-process residuals. {copyright} {ital 1996 The American Physical Society.}
ISSN 05562813
Educational Use Research
Learning Resource Type Article
Publisher Date 1996-03-01
Publisher Place United States
Journal Physical Review, C
Volume Number 53
Issue Number 3


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