Backbending in theN=96 isotones

Abstract

The backbending in the even-even, N =96 isotones can be quantitatively accounted for by the rotation-alignment of the spins of neutrons in i 13/2 orbits, as shown by comparing the aligned angular momentum and relative Routhian for the s-bands in these isotones and for the i13/2 bands in the corresponding isotopes with N=97. The influence of protons on this backbending situation is shown to be indirect, acting through a change of the nuclear deformation, which yields a change of the moment of inertia of the g.s. band and of the non-rigid character of the rotation. The experimental data on the N =96 and 97 isotones are in reasonable agreement with cranking model calculations. Possible reasons for the inhibition of backbending in the h 9/2 proton bands in the odd-Z, N = 96 isotones, all related to a change of deformation, are presented.