Residual Interactions and Tilted Rotation in Odd-Odd 164Tm

Abstract

High-spin spectroscopy on odd-odd 164Tm has produced new illustrations of departures from the predictions of principal-axis cranking. Among the nine strongly coupled rotational bands observed, four are assigned to the parallel and antiparallel couplings of two configurations iπh11/2vi13/2 and πg9/2vi13/2. This represents the first time that the high-spin properties of both couplings can be explored. We find that the measured B(M 1)/B(E2) values in the K= 1(↑↓) coupling of πh11/2vi 13/2 are 50% larger than those in the K=6 (↑↑) coupling, and represent the largest seen in this nucleus. Tilted-axis cranking calculations successfully explain the M1/E2 ratios in these two bands, while the particle-rotor calculations did not reproduce the full low-K enhancement. No inversion in the signatures of the K=6πh11/2vi13/2 band is observed, but there is a small inversion in the K= 1 coupling up to I= 17ℏ and a large inversion in the πh9/2vi13/2 band up to I=19ℏ. Remarkably, particle-rotor calculations with a p-n interaction included are able to reproduce these inversions. A stronger p-n interaction is needed to explain an inversion in the πd3/2vi13/2 band.