Magnetic moments of 2_1^+ states in 124,126,128Sn

The g factors of the first-excited states of stable 124Sn and radioactive 126,128Sn were measured by the recoil in vacuum method with relatively high precision (particularly for 124,126Sn). The experiments were performed at the Holifield Radioactive Ion Beam Facility by Coulomb exciting 3 MeV/u beams in inverse kinematics on carbon and titanium targets. The results for 124Sn and 126Sn are in excellent agreement with recent shell model calculations. For 128Sn the experiment suggests an increase in the magnitude of g(2+1 ), as predicted by some models. The present results provide a sensitive probe of the valence orbitals that contribute to the 2+1 wavefunctions as one approaches the radioactive 132Sn double-shell closure.