Decays ofMn58,Mn57, andMn56

Abstract

We have measured with high accuracy the $\gamma$ rays from 66-sec ${}_{}{}^{58}{}_{}{}^{}\mathrm{Mn}$, 1.6-min ${}_{}{}^{57}{}_{}{}^{}\mathrm{Mn}$, and 2.6-h ${}_{}{}^{56}{}_{}{}^{}\mathrm{Mn}$. Thirty-seven $\gamma$ rays were observed from ${}_{}{}^{58}{}_{}{}^{}\mathrm{Mn}$ decay which were incorporated into a ${}_{}{}^{58}{}_{}{}^{}\mathrm{Fe}$ level scheme with 17 excited states below 4.9 MeV. Present evidence favors a $3^{+}$ assignment for the ${}_{}{}^{58}{}_{}{}^{}\mathrm{Mn}$ ground state, but the $\beta$ decays to low-lying $2^{+}$ states are hindered. Additional weak $\gamma$ transitions giving rise to new $\beta$-decay modes were observed from ${}_{}{}^{57}{}_{}{}^{}\mathrm{Mn}$ and ${}_{}{}^{56}{}_{}{}^{}\mathrm{Mn}$ decays.