Investigations of electric monopole transitions in medium-mass to heavy nuclei: Beyond mean field calculations with the Gogny force
Résumé
The five dimensional collective Hamiltonian (5DCH) implemented with Gogny force has been employed in systematic calculations of electric monopole transitions in even-even nuclei with masses . Significant improvements in the comparison between experimental data and calculations are achieved using (i) stronger collective masses than those inferred from the Inglis-Beliaev approximation and (ii) the transition operator as defined by Church and Weneser [E. L. Church and J. Weneser, Phys. Rev. 103, 1035 (1956)]. Main emphasis has been placed on the square of the transition strength, , for transitions between the first excited state and ground state levels. The dimensionless parameter has also been considered in 5DCH calculations covering the rare earth and actinide regions where sparse data are available. Finally, the quasiparticle random-phase approximation (QRPA) implemented with Gogny force has been considered as a complementary model for the interpretation of , , data available for and . The 5DCH model provides a reasonable description of collective transitions, but fails otherwise. Specific shell effects are not considered in the present modeling. Global improvements in and predictions would be achieved by implementing the energy density functional with quasiparticle components.