β -decay half-lives of Sb134,134m and their isomeric yield ratio produced by the spontaneous fission of Cf252

Abstract

A number of fission products possess isomeric states which have a nuclear spin significantly different from that of the ground state. The yield ratio of these states following fission is influenced by the angular momentum present in the fissioning system. The $^{134m,134}\mathrm{Sb}$ yield ratio had not been previously measured in the spontaneous fission of $^{252}\mathrm{Cf}$; however, it had previously been observed to favor the (${7}^{\ensuremath{-}}$) isomer over the (${0}^{\ensuremath{-}}$) ground state in $^{235}\mathrm{U}({n}_{th},f$) and $^{232}\mathrm{Th}$(25 MeV $p,f$). Using a mass-separated beam of low-energy $^{134,134m}\mathrm{Sb}$ ions produced by $^{252}\mathrm{Cf}$ spontaneous fission at the CARIBU facility, $\ensuremath{\beta}$ particles and $\ensuremath{\gamma}$ rays were detected using the SATURN/X-Array decay station to determine the fission-yield ratio and $\ensuremath{\beta}$-decay half-lives. The $^{134m}\mathrm{Sb}$ to $^{134}\mathrm{Sb}$ fission yield was determined to be $2.03\ifmmode\pm\else\textpm\fi{}0.05$ and the half-lives of $^{134m}\mathrm{Sb}$ and $^{134}\mathrm{Sb}$ were found to be $9.87\ifmmode\pm\else\textpm\fi{}0.08$ s and $0.674\ifmmode\pm\else\textpm\fi{}0.004$ s, respectively. These results represent the first isomeric yield ratio measurement for this nucleus, and improved measurements of the $^{134}\mathrm{Sb}$ ground state and the $^{134m}\mathrm{Sb}$ isomer half-lives.