The stellar (n. gamma) cross sections of Br-79, Br-81, Rb-85, and Rb-87 have been determined by a series of ten activation measurements in a quasistellar neutron spectrum corresponding to a thermal energy of kT = 25 keV. The final uncertainties between 3 and 10% were dominated by the gamma-ray intensities in the decay of the respective reaction products. All other uncertainties were significantly reduced through variation of the experimental parameters. The consequences of these results for s-process nucleosynthesis of Brand Rb, and in particular of the local s-only isotopes Kr-80.12 and Sr-86.87, are discussed with respect to the branching points at Se-79 and Kr-85. The contributions of both the main s component from thermally pulsing low mass asymptotic giant branch stars and the weak s component from massive stars are considered in this analysis.
Stellar (n, gamma) cross sections for Br and Rb: Matching the weak and main s-process components
GALLINO, Roberto;BISTERZO, SARA;
2008-01-01
Abstract
The stellar (n. gamma) cross sections of Br-79, Br-81, Rb-85, and Rb-87 have been determined by a series of ten activation measurements in a quasistellar neutron spectrum corresponding to a thermal energy of kT = 25 keV. The final uncertainties between 3 and 10% were dominated by the gamma-ray intensities in the decay of the respective reaction products. All other uncertainties were significantly reduced through variation of the experimental parameters. The consequences of these results for s-process nucleosynthesis of Brand Rb, and in particular of the local s-only isotopes Kr-80.12 and Sr-86.87, are discussed with respect to the branching points at Se-79 and Kr-85. The contributions of both the main s component from thermally pulsing low mass asymptotic giant branch stars and the weak s component from massive stars are considered in this analysis.
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