Magnetic moments of 2 1 + states in 124,126,128 Sn

The g factors of the first-excited states of stable Sn-124 and radioactive Sn-126,Sn-128 were measured by the recoil-in-vacuum method with comparatively high precision. The experiments were performed at the Holifield Radioactive Ion Beam Facility by Coulomb exciting similar to 3 MeV/u beams in inverse kinematics on carbon and titanium targets. The results for Sn-124 and Sn-126 are in excellent agreement with recent shell-model calculations. For Sn-128 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)(+) wave functions as the double-shell closure at Sn-132 is approached.