Magnetic moments of N = 50 isotones and proton core polarization

Abstract

Pulsed heavy-ion beams of 4He, 6Li, 32S and 35C1 have been used to populate isomeric states in N = 50 nuclei having a closed neutron shell and a rather pure ( p n 1 2 g m 9 2 ) proton configuration. The g-factors of the 3.4 μs 17 2 − state in 91Nb, the 9.3 ns 11 − state in 92Mo, the 10.1 μs 17 2 in 93Tc, the 65.5 ns 6 + state and the 68 μs 8 + state in 94Ru were measured for the first time and those of 8 + states in 90Zr and in 92Mo were remeasured with improved accuracy. The g-factors increase by (4.2 ± 0.8)% as the p 1 2 proton subshell is filled and decrease by (3.5 ± 1.4)% as the number of protons in the g 9 2 shell increases from two to four. Calculations that take core polarization into account in first-order perturbation theory explain quantitatively the observed magnetic moments. One-pion exchange current contributions have also been calculated.