Lifetimes of High Spin Yrast States in Odd-Proton Nucleus 131 Pr

Lifetimes of the high spin yrast states in the odd-proton-nucleus 131Pr have been determined by analysing the Doppler broadened line shapes for the de-exciting ?-rays following the 116Sn (19F,4n) 131Pr reaction at a bombarding energy of 95?MeV. The transition quadrupole moments extracted from the measured lifetimes exhibit a considerable reduction near the rotational frequency of 0.42?MeV, at which the J(1) and J(2) moments of inertia indicate a band crossing. The experimental result demonstrates occurrence of the nuclear shape change induced by band crossing associated with the alignment of a pair of h11/2 protons.