Lifetime measurements of the high spin yrast states in128Ce

Lifetime measurements of the high spin states in the yrast band of¹²⁸Ce were performed using the Doppler shift attenuation method in connection with the reaction¹⁰⁰Ru(³²S, 2p2n)¹²⁸Ce at incident energy of 141 MeV. In the vicinity of the band crossing, the previously reported anomalously highB(E2) value was not observed. The gross behavior of the normalized transition strength is approximate to symmetric rotor. It is confirmed that the trend of increase in collectivity with decreasing neutron number, which was indicated in the previous studies on^130,132,134Ce, continues in¹²⁸Ce. The value of quadrupole deformation parameterβ ₂ deduced from the measured lifetimes is in good agreement with the theoretical calculation using a cranking model based on a non-axially deformed Woods-Saxon potential.