Spectroscopic studies of neutron-rich ${}^{129}$In and its ${\hat{I}}^2$-decay daughter, ${}^{129}$Sn, using the GRIFFIN spectrometer

Abstract

The ${\hat{I}}^2$-decay of neutron-rich ${}^{129}$In into ${}^{129}$Sn was studied using the GRIFFIN spectrometer at the ISAC facility at TRIUMF. The study observed the half-lives of the ground state and each of the ${\hat{I}}^2$-decaying isomers. The level scheme of ${}^{129}$Sn has been expanded with thirty-one new ${\hat{I}}^3$-ray transitions and nine new excited levels, leading to a re-evaluation of the ${\hat{I}}^2$-branching ratios and level spin assignments. The observation of the ${\hat{I}}^2$-decay of the (29/2${}^{+}$) 1911-keV isomeric state in ${}^{129}$In is reported for the first time, with a branching ratio of 2.0(5)$\%$.