  Lifetimes of the positive-parity yrast band in 189Pt were measured using the
recoil distance Doppler-shift method. A HPGe detector array consisting of 13
detectors was used in conjunction with the plunger device in CIAE. Excited
states of 189Pt were populated by the 176Yb (18O, 5n) 189Pt fusion-evaporation
reaction at a beam energy 87 MeV. The lifetimes of two levels belonging to the
yrast band are measured. The results show that the 17/2+ state in the yrast
band has large Qt value, but it deceases quickly with spin increasing. It may
be contributed from the shape driving effect of the quasi-neutron from the
i13/2 oribital.

Nuclear Experiment