Collectivity in even54116Xeand54118Xeisotopes

Abstract

High-spin states in the even ${}^{116}\mathrm{Xe}$ and ${}^{118}\mathrm{Xe}$ isotopes have been studied with the ${}^{58}\mathrm{Ni}{(}^{64}\mathrm{Zn})$ reaction at 265 MeV using the GAMMASPHERE array. Several new rotational bands have been identified in these nuclei, and previously observed bands have been extended. In ${}^{116}\mathrm{Xe}$, a strongly coupled $(\ensuremath{\Delta}I=1)$ rotational band attributed to the $\ensuremath{\nu}[{h}_{11/2}{(g}_{7/2}{,d}_{5/2}{)}^{1}]$ configuration and a decoupled $(\ensuremath{\Delta}I=2)$ rotational band identified with the $\ensuremath{\pi}[{h}_{11/2}{g}_{7/2}]$ configuration have been found. Experimental observations also suggest that another rotational band may be understood within the framework of smooth band termination. In ${}^{118}\mathrm{Xe}$, two well-developed sidebands have been observed to decay by multiple paths to the yrast band at spins near $14\ensuremath{\Elzxh}$ and $28\ensuremath{\Elzxh}$. Identification of the higher-lying sideband has resulted in a substantial revision to the previously proposed spin extent of the yrast band, thereby resolving an earlier disgreement with theoretical calculations.