Shape coexistence in¹¹⁹I at high spin

Abstract

Competition between single-particle and collective modes of excitation is observed in 119I at high spin. Whereas rotational states, associated with a prolate pi h11/2 orbital, are yrast for spins I<or=39/2, a noncollective oblate state is yrast at Ipi =43/2-. This state is interpreted as the fully-aligned pi (h11/2 (X) g7/22)23/2- (X) nu (h11/22)10+ configuration outside a 50114Sn64 core. Several other noncollective states are observed above this state. At the highest spins, the collective states again become yrast when a pair of h11/2 neutrons align. The rotational pi h11/2 (X)( nu h11/22) structure could be followed up to Ipi =63/2-.