INELASTIC PROTON-SCATTERING FROM PT ISOTOPES AND THE INTERACTING BOSON MODEL

Inelastic proton scattering has been used to measure the d-sigma/d-OMEGA and A(y) angular distributions for several low-lying collective states in Pt-194, Pt-196 using 647 MeV polarized protons with special emphasis on the excitation of the 4+ states below 2 MeV. The data have been analyzed in the framework of the coupled-channels scheme using the program ECIS. Large E4 transition strengths to the 4+ states in both nuclei are found in sharp contrast with the predictions of the interacting boson model with only s (L = 0) and d (L = 2) bosons. It is found that although the E2 properties of these nuclei are consistent with the interacting boson model (sd) predictions, higher degrees of freedom, e.g., g (L = 4) bosons, need to be invoked in order to get a reasonable agreement with the measured E4 properties.