Theoretical Calculation of the IBM1 Parameters and Band Crossing in Even Cerium Isotopes

An extended microscopic version of the interacting-boson model is developed. The properties of yrast-band states in even cerium isotopes up to the spin-parity of I-pi = 18(+) are calculated on the basis of this model. These spin values include those at which band crossing occurs. The model parameters are calculated on the basis of employing an average spherical potential and residual multipole forces. An extension of the model is accomplished via taking into account high-spin quasiparticle pairs, whereby a satisfactory description of energies and B(E2) values was obtained without introducing effective charges. The present investigation is a continuation of a similar analysis of the properties of low-lying collective states in even xenon and barium isotopes.