Identification of levels in^162,164Gd and decrease in moment of inertia between<i>N</i>= 98–100

Abstract

From prompt γ-γ-γ coincidence studies with a 252Cf source, the yrast levels were identified from 2+ to 16+ and 14+ in neutron-rich 162,164Gd, respectively. Transition energies between the same spin states are higher and moments of inertia lower at every level in N = 100 164Gd than in N = 98 162Gd. These observations are in contrast to the continuous decrease in the 2+ energy to a minimum at neutron midshell (N = 104) in Er, Yb and Hf nuclei. Mean-field calculations of the deformations do not follow the data, but give a smooth increase in β2 deformation to N = 102 for Gd nuclei.