β decay of100In

Abstract

The \ensuremath{\beta} decay of ${}^{100}\mathrm{In},$ the one proton hole and one neutron particle neighbor to ${}^{100}\mathrm{Sn},$ was investigated at the GSI on-line mass separator by using germanium detectors and a NaI total-absorption spectrometer. On the basis of \ensuremath{\beta}\ensuremath{\gamma}\ensuremath{\gamma} coincidences, the ${}^{100}\mathrm{In}$ decay scheme was established for the first time. The ground-state spin and parity for ${}^{100}\mathrm{In}$ are discussed by investigating \ensuremath{\beta} feeding of levels in ${}^{100}\mathrm{Cd}$ and $\ensuremath{\beta}$-delayed proton emission to ${}^{99}\mathrm{Ag}.$ The half-life was remeasured and found to be 5.9(2) s. The ${Q}_{\mathrm{EC}}$ value was determined from the measured $EC/{\ensuremath{\beta}}^{+}$ ratio for the \ensuremath{\beta}-delayed protons to be 10.08(23) MeV. The main fraction of the \ensuremath{\beta} feeding was established to populate the region of 6 MeV excitation energy, which corresponds to a total Gamow-Teller (GT) strength of 3.9(9) and a centroid at 6.4 MeV. Large-scale shell-model calculations employing a realistic interaction are used to assign configurations to states in ${}^{100}\mathrm{In}$ and ${}^{100}\mathrm{Cd}.$ The GT \ensuremath{\beta}-decay strength distribution measured in the total absorption experiment is compared to shell-model predictions. The deduced overall hindrance of the GT strength agrees with the values predicted for the ${}^{100}\mathrm{Sn}$ GT decay.