β-decay half-lives of neutron-rich N=82,81 isotones by shell-model calculations

We perform large-scale shell-model calculations and successfully describe the low-lying spectra and half-lives of neutron-rich N = 82 and N = 81 isotones with Z = 42 − 49 in a unified way. Shell-model study shows that their Gamow-Teller strength distribution has a peak in the low-excitation energies, which significantly contributes to the half-lives. This peak is dominated by the ν0g7/2 → π0g9/2 transition and enhanced on the proton deficient side of these isotones due to the Pauli blocking effect and the change of the effective single-particle energy of the ν0g7/2 orbit.