Structure of multiphonon vibrational states in Pd108,110

Coulomb excitation of Pd108,110 has been carried out with Ar40 projectiles. Both three-and four-phonon vibrational states were populated by the multiple excitation process. The level energies of these states and the B(E 2) values deviate significantly from the pure vibrational model. The boson expansion model and the interacting boson model were reasonably successful in describing the gross features of these two nuclei, but failed in some details. NUCLEAR REACTIONS Pd108,110(Ar40, Ar40') E=120 and 129.1 MeV; measured -ray yields at 0° and 55°; coupled-channel Coulomb excitation calculations performed; compared results with model calculations.