Decays ofBa126andCs126

Abstract

The neutron deficient $^{126}\mathrm{Ba}$ has been produced by the reactions $^{115}\mathrm{In}(^{16}\mathrm{O},5n)^{126}\mathrm{La}\stackrel{\ensuremath{\beta}+,\mathrm{E}\mathrm{C}}{\ensuremath{\rightarrow}}^{126}\mathrm{Ba}$, $^{121}\mathrm{Sb}(^{11}\mathrm{B},6n)^{126}\mathrm{Ba}$, and $^{133}\mathrm{Cs}(p,8n)^{126}\mathrm{Ba}$. Its decay properties have been studied in equilibrium with the daughter activity of $^{126}\mathrm{Cs}$. About 100 $\ensuremath{\gamma}$ rays have been observed to be associated with the decay of the $^{126}\mathrm{B}\mathrm{a}\ensuremath{-}$$^{126}\mathrm{Cs}$ mass chain. The assignment of $\ensuremath{\gamma}$ rays to $^{126}\mathrm{Ba}$ and $^{126}\mathrm{Cs}$ activities has been done by measuring $\ensuremath{\gamma}$-ray spectra gated by $K$ x rays of Cs and Xe, respectively. The $\ensuremath{\gamma}\ensuremath{-}\ensuremath{\gamma}$ and $\ensuremath{\beta}\ensuremath{-}\ensuremath{\gamma}$ coincidence studies have been performed by using large volume Ge(Li) and plastic detectors and a two parameter analyzer system. Conversion coefficients of intense $\ensuremath{\gamma}$ transitions have been measured by using a conversion electron spectrometer consisting of a Ge(Li) detector and a cooled Si(Li) detector. Decay schemes of $^{126}\mathrm{Cs}$ and $^{126}\mathrm{Ba}$ are proposed. The levels in $^{126}\mathrm{Xe}$ are compared with predictions of the collective model.RADIOACTIVITY $^{126}\mathrm{Ba}$, $^{126}\mathrm{Cs}$ [from $^{115}\mathrm{In}(^{16}\mathrm{O},5n)$, $^{121}\mathrm{Sb}(^{11}\mathrm{B},6n)$, and $^{133}\mathrm{Cs}(p,8n)$]; measured ${E}_{\ensuremath{\gamma}}$, ${I}_{\ensuremath{\gamma}}$, ${I}_{\mathrm{ce}}$, $\ensuremath{\beta}\ensuremath{-}\ensuremath{\gamma}$, $\mathrm{x}\ensuremath{-}\ensuremath{\gamma}$, $\ensuremath{\gamma}\ensuremath{-}\ensuremath{\gamma}$ coincidence; deduced levels, $J$, $\ensuremath{\pi}$, $log\mathrm{ft}$, CC, multipolarities; Ge(Li), Si(Li), plastic detectors; natural targets.