Stellar β- Decay Rates for 63Co and 63Ni by the Projected Shell Model

beta- decay for Co-63-Ni-63-Cu-63 region nuclei play important roles in core-collapse supernovae and the slow neutron-capture (s) process. In this work, the stellar beta(-) decay rates for Co-63 and Ni-63 are studied within the projected shell model where the effects of thermally populated parent-nucleus excited states are analyzed. For Co-63, the calculated stellar beta(-) decay rates are lower than the results of the conventional shell model. For the s-process branching point Ni-63, the beta(-) decay rate under a terrestrial condition is well described, and the calculated stellar beta(-) decay rates in the s-process condition turn out to increase with stellar temperature due to the contribution from parent-nucleus excited states.

Automated summary

In this study, the beta(-) decay rates for Co-63 and Ni-63 were investigated, and the calculated results were compared with the conventional shell model. It was found that the calculated beta(-) decay rates for Co-63 were lower than the conventional results. For Ni-63, the beta(-) decay rate under terrestrial conditions was well described, and the calculated beta(-) decay rates under s-process conditions were found to increase with stellar temperature due to the contribution from parent-nucleus excited states.