Shell-Model Half-Lives forN=82Nuclei and Their Implications for therProcess

Abstract

We have performed large-scale shell-model calculations of the half-lives and neutron-branching probabilities of the $r$-process waiting-point nuclei at the magic neutron number $N\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}82$. We find good agreement with the measured half-lives of ${}^{129}\mathrm{Ag}$ and ${}^{130}\mathrm{Cd}$. Our shell-model half-lives are noticeably shorter than those currently adopted in $r$ process simulations. Our calculation suggests that ${}^{130}\mathrm{Cd}$ is not produced in $\ensuremath{\beta}$-flow equilibrium with the other $N\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}82$ isotones on the $r$-process path.