Nuclear spins and moments of Ga isotopes reveal sudden structural changes between N=40 and N=50

Abstract

Collinear laser spectroscopy was performed on Ga (Z=31) isotopes at ISOLDE, CERN. A gas-filled linear Paul trap (ISCOOL) was used to extend measurements towards very neutron-rich isotopes (N=36-50). A ground state (g.s.) spin I=1/2 is measured for Ga73, being near degenerate with a 3/2- isomer (75eV Eex 1keV). The Ga79 g.s., with I=3/2, is dominated by protons in the πf5/2 orbital and in Ga81 the 5/2- level becomes the g.s. The data are compared to shell-model calculations in the f5/2pg9/2 model space, calling for further theoretical developments and new experiments. © 2010 The American Physical Society.