Schwengner R, Frauendorf S, Brown B A
Helmholtz-Zentrum Dresden-Rossendorf, 01328 Dresden, Germany.
Department of Physics, University of Notre Dame, Notre Dame, Indiana 46556, USA.
Phys Rev Lett. 2017 Mar 3;118(9):092502. doi: 10.1103/PhysRevLett.118.092502.
Low-energy M1 strength functions of ^{60,64,68}Fe are determined on the basis of large-scale shell-model calculations with the goal to study their development from the bottom to the middle of the neutron shell. We find that the zero-energy spike, which characterizes nuclei near closed shells, develops toward the middle of the shell into a bimodal structure composed of a weaker zero-energy spike and a scissorslike resonance around 3 MeV, where the summed strengths of the two structures change within only 8% around a value of 9.8 μ_{N}^{2}. The summed strength of the scissors region exceeds the total γ absorption strength from the ground state by a factor of about three, which explains the discrepancy between total strengths of the scissors resonance derived from (γ, γ^{'}) experiments and from experiments using light-ion induced reactions.
基于大规模壳模型计算确定了(^{60,64,68}Fe)的低能(M1)强度函数，目的是研究它们从中子壳底部到中部的发展情况。我们发现，表征靠近闭壳层核的零能尖峰在向壳层中部发展时，会演变成一种双峰结构，该结构由一个较弱的零能尖峰和一个位于约(3)兆电子伏处的类似剪刀状的共振组成，其中这两种结构的总强度在约(9.8,\mu_N^2)的值附近仅在(8%)的范围内变化。剪刀状区域的总强度比基态的总(\gamma)吸收强度高出约三倍，这解释了从((\gamma,\gamma'))实验以及使用轻离子诱导反应的实验得出的剪刀状共振总强度之间的差异。
