Abstract
The astrophysical origin of a rare isotope remains an open question. An isomer () in is an -process branching point from which a nucleosynthesis flow reaches . The -process abundance of depends on the isomer production ratio in the reaction. However, the ratio has not been measured in an energy region higher than the thermal energy. We have measured rays following neutron capture reactions on using two cluster high-purity germanium (HPGe) detectors in conjunction with a time-of-flight method at J-PARC. We have obtained the result that the relative -ray intensity ratio of the isomer is almost constant in an energy region of up to 5 keV. This result suggests that the -process contribution to the solar abundance of is minor. We have found that the ratio of a resonance at 737 eV is about 1.5 times higher than other ratios. This enhancement can be explained by a -wave neutron capture. This result suggests measurements of decay rays to isomers are effective to assign the spin and parity for neutron capture resonances.
1 More- Received 28 July 2016
DOI:https://doi.org/10.1103/PhysRevC.94.055803
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