^(90)Mo电磁跃迁几率的测量

Measurements of Electromagnetic Transition Probabilities in ^(90)Mo

利用束流能量为 116MeV的59Co(35Cl,2p2n) 90 Mo反应布居90 Mo的高自旋态 .用 10台反康普顿HPGe探测器组成的探测阵列进行γ γ符合测量 .通过多普勒展宽峰的形状分析测定90 Mo高自旋态的寿命 .在正宇称衰变系观察到增强的M1跃迁 ,推断I =13以上是扁椭形变 .负宇称高自旋态具有大的B(E2 )值 ,并随自旋增大而起伏变化 .正、负宇称态之间的跃迁显示增大的E1跃迁 ,似有八极关联的可能 .但是 ,90

High spin states of 90 Mo have been populated by the reaction 59 Co( 35 Cl,2p2n) 90 Mo at beam energy of 116 MeV. A detector array consisting of 10 anti Compton HPGe detectors was used for γ γ coincidence measurements. Lifetimes of high spin states in 90 Mo are determined by analysing the Doppler broadened line shapes. Enhanced M1 transitions are observed in the positive parity decay sequence and oblate deformation is suggested above 13 + state. A appreciable staggering of E2 transition rates associated with large B( E2) values is found in the high spin states with negative parity. Transitions between positive and negative parity states exhibit enhanced B (E1) values, looking like existence of octupole correlation. However, 90 Mo does not lie in the mass regions of nuclei possessing octupole deformation predicted by theories.