Triaxial shape coexistence and new aligned band in Os178

Abstract

High spin states in Os178 were studied by means of Ho165(Ne20,p6n)Os178 fusion evaporation reaction at a beam energy of 150MeV, using a clover detector array. Several new transitions belonging to Os178 were placed in a level scheme and a new aligned rotational band was observed in addition to earlier known bands. Spin-parity assignments for most of the proposed levels were made using the deduced directional correlation orientation and polarization measurements for the de-exciting transitions. Experimental results are compared with the projected angular momentum deformed Hartree-Fock model calculations and cranked Woods-Saxon model calculations. This nucleus is predicted to be prolate deformed in the ground state but the γ-softness at higher excitation is revealed by the cranked Woods-Saxon model and the geometrical asymmetric model calculations. © 2009 The American Physical Society.