Lifetime Measurement of the Low Lying Yrast States in 189Pt

High-spin states in Pt-189 are populated through the heavy-ion fusion-evaporation reaction(176)Yb (O-18, 5n)Pt-189 at 87MeV beam energy. An array consisting of 13 HPGe detectors is used in conjunction with the plunger device in CIAE. The lifetimes of two levels in the yrast band are determined by using the recoil distance Doppler shift method. The transition quadrupole moments Q(t) are extracted. The results show that the 17(+)/2 state has a much larger Q(t) value than that of the ground state, whereas the value deceases quickly with spin increasing. This may contribute to the shape driving effect of the quasi-neutron from the i(13/2) orbital.