129Ce高自旋态的形状变化

通过¹¹⁶Sn(¹⁶O,3n)¹²⁹Ce反应,利用多普勒移动衰减法测量了¹²⁹Ce高自旋态的寿命.得到的跃迁四极矩表明¹²⁹Ce的集体性相对于核芯¹²⁸Ce减弱.这个因增加一个h_11/2中子而引起集体性的降低可以解释为由于形状驱动效应产生三轴形变所造成的.正、负宇称带的跃迁四极矩与角动量的关系呈现相似的变化趋势,推测一对h_11/2准质子可能对核芯性质起主要作用.

Shape Change of ~(129)Ce at High Spin States

High spin states of 129 Ce were populated through the reaction 116Sn(16O, 3n)129 Ce at a beam energy of 73 MeV. Lifetimes of the excited states were measured using the Doppler shift atten- uation method. The transition quadrupole moments Qt were deduced from lifetime data. The results indicate that collectivity of 129 Ce is reduced with respect to the even-even core 128 Ce. This reduction in collectivity caused by the addition of a h11/2 neutron can be interpreted as due to triaxial deforma- tion induced by shape driving effect. Although the Qt values of the negaive-parity band are some- what smaller than the ones of the positive-parity band, they exhibit a considerably sindlar behavior with increasing angular momentum. It would appear that the two h11/2 quasiprotons possibly have a dominant innuence on property of the core.