Role of Hexadecapole Forces in Describing gamma -Band States in the Rare-Earth Region

摘要

Calculations are made for the isoscalar transition rates B(IS2, gr.->2/sup +/2 gamma ) and B(IS4, gr.->4/sup +/2 gamma ) in the random phase approximation with a common system of equations for hexadecupole interactions lambda/sub mu /=22 and 42, and for the inelastic form factors in the folding model. The analyzing powers and cross sections in the (p-bar, p/sup '/) reaction with E/sub p/65 MeV are calculated within the coupled-channel method by using the microscopic form factors for the levels 2/sup +/2 gamma and 4/sup +/2 gamma in /sup 168/Er. It is shown that extremely large values of B(IS4, gr.->4/sup +/2 gamma ) obtained in the (p-bar, p/sup '/) and ( alpha , alpha /sup '/) reactions are mostly due to the contribution of indirect excitation channels but not to a strong hexadecapole interaction lambda/sub mu /=42. A moderate value of the hexadecapole interaction constant kappa/sub 0//sup (42)/=0.012 fm/sup 2//MeV provides a satisfactory description of the available experimental data. 20 refs.; 3 figs. (Atomindex citation 19:098028)