Evidence for coexisting prolate and near-oblate shapes at high spin in 125 Cs

Excited states in the odd-proton nucleus Cs-125 were investigated by means of in-beam gamma-ray spectroscopy. The pi g(7/2) band is observed to fork into a Delta I = 1 coupled band and a Delta I = 2 decoupled band at high spins. To assign the possible configurations of these two bands, experimental B(M1)/B(E2) ratios and signature splittings have been evaluated for the Delta I = 1 band, and calculations based on the geometrical model, cranked shell model and total Routhian surfaces model have been performed. They are suggested to be a near-oblate band built on the (pi g(7/2)/d(5/2))circle times(nu h11/2)(2) configuration and a prolate band built on the pi g(7/2) circle times (pi h(11/2))(2) configuration, respectively.