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

Abstract

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