Properties of the rotational bands in the transitional nucleus Pt189

High-spin states in Pt189 have been studied experimentally using the Yb176(O18,5n) reaction at beam energies of 88 and 95 MeV. The level scheme of Pt189 has been revised significantly and extended to high-spin states. Rotational bands have been analyzed in the framework of triaxial particle-rotor model, and a γ ≈ -30° triaxial shape and a near-prolate shape have been proposed to the νi13/2-1 and νf5/2(p3/2) bands, respectively. Two ΔI=2 transition sequences with similar energies have been observed, and they have been proposed to be associated with the νi13/2-2νf5/2(p3/2) configuration. The structure built on the νi13/2-2νf5/2(p3/2) configuration could be interpreted as a pair of pseudospin partners. The level energies in the pseudospin partner bands are well reproduced by the theoretical calculations of the triaxial particle-rotor model if a near-oblate shape is assumed. © 2009 The American Physical Society.