MEASURED MAGNETIC-MOMENTS OF 2(1)(+) STATES IN PT-190-198 AND INTERACTING BOSON MODEL DESCRIPTION OF M1 SYSTEMATICS IN THE PLATINUM ISOTOPES

The g-factor of the 2(1)(+) state in Pt-190 has been measured for the first time using the thin-foil transient-field technique with a targe enriched (to 4.19%) in Pt-190. Precessions for the 2(1)(+) states of Pt-190,Pt-192,Pt-194,Pt-196,Pt-198 were measured simultaneously. The Coulomb excitation cross section to the 2(1)(+) state in Pt-190 was also measured relative to the 0(1)(+) --> 2(1)(+) excitations in Pt-194 and Pt-196. The near constancy of g(2(1)(+)) for the even Pt-190-198 isotopes is in marked contrast with the behaviour observed in neighbouring even W-182-186 and Os-186-192 nuclei and the predictions of the proton-neutron interacting boson model in the limit of F-spin symmetry, It is shown that the observed g-factor and M1 transition systematics in the Pt isotopes can be described by appropriate F-spin symmetry breaking, while maintaining satisfactory descriptions of the energy levels and E2 properties.