论文标题
$ a = 72 $ shape-transitional Point的Octupole集体的调查
Investigation of octupole collectivity near the $A =72$ shape-transitional point
论文作者
论文摘要
在中子缺陷的GE，SE和KR的同位素中，预计将增强的Octupole集体性，中子数$ n \ 40 $，并且确实以$^{70,72} $ GE观察到。然而，对于试图可靠地预测该质量区域的八杆基团体的理论模型来说，形状的共存和构型混合是一个臭名昭著的挑战，该质量区域中的八杆位集体性具有快速形状的变化，随着系统的核子数和旋转的变化。为了进一步研究微观构型，导致$ a \ 72 $的泛卵圆形 - 三方形状过渡及其对八杆的影响的影响，稀有的同位素$^{72} $ se和$^{74,76} $ kr是通过弹性蛋白质散射在非弹性蛋白质散射中，以易于kinematics进行了研究。虽然观察到$^{72} $ se的$ \ sim 32 $ 32 $ 32 $ weisskopf单位（W.U.）的八杆强度显着增强，但仅$ \ sim 15 $ W.U.以$^{74,76} $ kr观察。结合现有数据，新数据清楚地质疑了增强的八杆强度的简单起源，左右$ n = 40 $。目前的工作建立了两个具有独特八极强度的区域，突然的强度在$ a = 72 $形状过渡点附近增加。
Enhanced octupole collectivity is expected in the neutron-deficient Ge, Se and Kr isotopes with neutron number $N \approx 40$ and has indeed been observed for $^{70,72}$Ge. Shape coexistence and configuration mixing are, however, a notorious challenge for theoretical models trying to reliably predict octupole collectivity in this mass region, which is known to feature rapid shape changes with changing nucleon number and spin of the system. To further investigate the microscopic configurations causing the prolate-oblate-triaxial shape transition at $A \approx 72$ and their influence on octupole collectivity, the rare isotopes $^{72}$Se and $^{74,76}$Kr were studied via inelastic proton scattering in inverse kinematics. While significantly enhanced octupole strength of $\sim 32$ Weisskopf units (W.u.) was observed for $^{72}$Se, only strengths of $\sim 15$ W.u. were observed for $^{74,76}$Kr. In combination with existing data, the new data clearly question a simple origin of enhanced octupole strengths around $N = 40$. The present work establishes two regions of distinct octupole strengths with a sudden strength increase around the $A=72$ shape transitional point.
