Structure changes inEr160from low to ultrahigh spin

Abstract

A spectroscopic investigation of the $\ensuremath{\gamma}$ decays from excited states in $^{160}\mathrm{Er}$ has been performed in order to study the changing structural properties exhibited from low spin up toward ultrahigh spin ($I~60\ensuremath{\hbar}$). The nucleus $^{160}\mathrm{Er}$ was populated by the reaction $^{116}\mathrm{Cd}$($^{48}\mathrm{Ca}$,4$n$$\ensuremath{\gamma}$) at a beam energy of 215 MeV, and resulting $\ensuremath{\gamma}$ decays were studied using the Gammasphere spectrometer. New rotational structures and extensions to existing bands were observed, revealing a diverse range of quasiparticle configurations, which are discussed in terms of the cranked shell model. At spins around 50$\ensuremath{\hbar}$ there is evidence for oblate states close to the yrast line. Three rotational bands that have the characteristics of strongly deformed triaxial structures are observed, marking a return to collectivity at even higher spin. The high-spin data are interpreted within the framework of cranked Nilsson-Strutinsky calculations.