Determininig the (n,{gamma}) cross section of {sup 153}Gd using surrogate reactions

Journal Article · Thu Apr 17 04:00:00 EDT 2008 · AIP Conference Proceedings

DOI:https://doi.org/10.1063/1.2920710· OSTI ID:21143131

Scielzo, N D; Bernstein, L A; Bleuel, D L; Burke, J T; Lesher, S R; Norman, E B; Sheets, S A; Basunia, M S; Clark, R M; Fallon, P; Gibelin, J; Lyles, B; McMahan, M A; Moretto, L G; Phair, L W; Rodriguez-Vieitez, E; Wiedeking, M; Allmond, J M; Beausang, C W ^[1]

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1. Lawrence Livermore National Laboratory, 7000 East Avenue, Livermore, CA 94550 (United States)

The astrophysical s-process is responsible for the synthesis of many of the nuclei heavier than iron through a series of low-energy (n,{gamma}) reactions and {beta}-decays. For nuclei for which the neutron capture and {beta}-decay rates are comparable, the branching is crucial for tests of s-process models. Direct measurements of (n,{gamma}) cross sections for these nuclei are extremely challenging due to the inherent difficulties associated with radioactive targets and the low intensity of available neutron beams. The surrogate reaction technique can be used to circumvent these difficulties by creating the same compound nucleus through light-ion reactions on a stable target. The cross section can be determined by combining optical model calculations for the formation of the compound nucleus with the measured exit channel probability for {gamma}-ray emission. We have collected data to determine the low-energy (n,{gamma}) cross section for the unstable nucleus {sup 153}Gd by bombarding a stable {sup 154}Gd target with protons from the 88-Inch Cyclotron at the Lawrence Berkeley National Laboratory to create the desired {sup 154}Gd* compound nucleus. The STARS/LiBerACE silicon and clover germanium detector arrays were used to detect {gamma}-rays in coincidence with the scattered protons. Additional cross section measurements using {sup 156}Gd and {sup 158}Gd targets will be compared to direct measurements of the (n,{gamma}) cross sections for {sup 155}Gd and {sup 157}Gd. The current status of the analysis is summarized.

• OSTI ID: 21143131
• Journal Information: AIP Conference Proceedings, Journal Name: AIP Conference Proceedings Journal Issue: 1 Vol. 1005; ISSN APCPCS; ISSN 0094-243X
• Country of Publication: United States
• Language: English

Related Subjects

73 NUCLEAR PHYSICS AND RADIATION PHYSICS
ASTROPHYSICS
BETA DECAY
BRANCHING RATIO
CAPTURE
COMPOUND NUCLEI
CROSS SECTIONS
GADOLINIUM 153
GADOLINIUM 154 TARGET
GADOLINIUM 155 TARGET
GADOLINIUM 157 TARGET
GAMMA RADIATION
GE SEMICONDUCTOR DETECTORS
NEUTRON BEAMS
NEUTRON REACTIONS
NUCLEOSYNTHESIS
OPTICAL MODELS
PROTONS
S PROCESS
STATISTICAL MODELS