Investigation of theKπ=8−isomer in132Ce

Abstract

The decay of the ${K}^{\ensuremath{\pi}}{=8}^{\ensuremath{-}}$ isomer in ${}^{132}\mathrm{Ce}$ with an excitation energy of 2340.2 keV has been investigated using the ${}^{120}\mathrm{Sn}{(}^{16}\mathrm{O}{,4n)}^{132}\mathrm{Ce}$ reaction. A half-life of 9.4\ifmmode\pm\else\textpm\fi{}0.3 ms was determined. Two new decay paths have been found in the deexcitation of this isomer. The hindrance factors for the $E1,$ $M2,$ and $E3$ transitions deexciting the isomer have been determined. The decay properties of the ${8}^{\ensuremath{-}}$ isomers in the $N=74$ isotones are discussed. A band mixing mechanism involving the ground state and $s$ band seems to be responsible for the behavior of the reduced hindrance factors of the $E1$ transitions deexciting the ${K}^{\ensuremath{\pi}}{=8}^{\ensuremath{-}}$ isomers in these isotones. A $K$ mixing, characteristic of the axially asymmetric nuclei, may account for the reduced hindrance factors of the $E3$ transitions to the ${5}_{\ensuremath{\gamma}}^{+}$ states in ${}^{130}\mathrm{Ba}$ and ${}^{132}\mathrm{Ce}.$