Directional distribution of γ-rays in¹⁵³Gd from the decay of¹⁵³Tb

Abstract

A description of the N=89 transitional nuclei represents a sensitive test of the particle-rotor model. The success of such a treatment relies strongly on a knowledge of the angular moment of the states involved. Using the nuclear orientation technique unique spin assignments have been made for a large number of levels in 153Gd populated from the decay of 153Tb. In addition, the multipole characters of the dominant transitions have been determined. The measurements were carried out with the use of a top-loading 3He-4He dilution refrigerator, operating at a temperature of 12 mK. The results for the low-lying negative parity states are compared with the predictions of the Nilsson model, using potential parameters which reproduce correctly the expected sequence of states in the spherical limit.