Magnetic Moment of the Lowest 6+ State in 42Ca

Abstract

The g -factor of the 3190 keV 6 ⁺ state in ⁴² Ca was measured by the time-differential perturbed-angular-distribution method in the ⁴⁰ Ca(α,2 p ) ⁴² Ca reaction. The result is g =-(0.50 _-0.03 ^+0.02 ). Assuming the 0.99f _7/2 ² +0.13f _7/2 f _5/2 configuration for the 6 ⁺ state, the magnetic moment for the 0f _7/2 neutron is deduced to be -1.99µ _N , being very different from the known magnetic moment of the ⁴¹ Ca ground state. The strong violation of the additivity relation is interpreted by a larger mixing of the core-excited deformed states into the ⁴¹ Ca ground state. The above magnetic moment for the 0f _7/2 neutron supports recent proposal that the orbital g -factor is enhanced in nuclei by around 0.1 _{τ z} if the quenching due to the second-order core polarization is taken into account.