Gamow-Teller decay ofZn80: Shell structure and astrophysical implications

Gamow-Teller β decay of ${}_{}{}^{80}{}_{}{}^{}\mathrm{Zn}$ to levels in ${}_{}{}^{80}{}_{}{}^{}\mathrm{Ga}$ has been calculated from a random-phase-approximation shell model with Nilsson model wave functions. The predicted features are compared to existing experimental results. Gross β-decay properties as well as quasiparticle structure indicate shape coexistence for ${}_{}{}^{80}{}_{}{}^{}\mathrm{Ga}$. This result implies a rather rapid weakening of the shell strength far from β stability above ${}_{28}{}^{78}{}_{}{}^{}\mathrm{Ni}_{50}^{}{}_{}{}^{}$. The nuclear properties of ${}_{}{}^{80}{}_{}{}^{}\mathrm{Zn}$ as an astrophysical ‘‘waiting-point’’ nucleus suggest that the r-process scenario which is responsible for the solar r abundances has attained an (n,γ)-(γ,n) equilibrium.