Transient-field G-factor Measurement of the 1st 2+ States In the N = 82 Nuclei Ce-140, Nd-142 and Sm-144

The g-factor of the first 2+ states in three stable N = 82 nuclei, Ce-140, Nd-142 and 144Sm, have been measured using the transient magnetic field technique. The levels under study were Coulomb excited with 110-116 MeV S-32 beams and spin precession after passing a thin polarized iron foil was measured. The field strength has been checked using the first 2+ state in Sm-148 as internal calibration. The obtained values were 0.97 (9), 0.84 (7), 0.76 (11) for Ce-140, Nd-142 and 144Sm, respectively. These remarkably lower values with respect to shell-model predictions in a proton subspace are explained in terms of neutron core excitation by quasiparticle random-phase-approximation calculations