High-spin states and the first signs of band termination in156Ho

Abstract

High-spin states have been populated in ${}^{156}\mathrm{Ho}$ with the ${}^{14}{\mathrm{N}+}^{148}\mathrm{Nd}$ reaction at 96 MeV. The known level scheme has been considerably extended using the Gammasphere spectrometer. Configuration assignments for these bands have been deduced from their aligned angular momenta, signature splittings and from a systematic survey of the neighboring nuclei and these are compared with theoretical $B(M1)/B(E2)$ predictions from a semiclassical model. Evidence is also presented for the onset of band termination, or the beginning of a prolate collective to oblate noncollective shape change near the yrast line, at the highest spin states in two of the observed strongly coupled bands.