Triple-shape coexistence and superdeformation in Pb isotopes

Abstract

Triple-shape coexistence and superdeformation in Pb isotopes with neu- tron numbers N = 96 –138 is studied. The constrained calculations are performed within the Relativistic Hartree–Bogoliubov (RHB) model using DD-ME2, DD-PC1, and NL3* force parameters, and pairing interaction separable in momentum space. Triple-shape coexistence (spherical, prolate and oblate) manifests themselves in a clear manner in 184 − 190 Pb nuclei with axial RHB calculations. Triaxial RHB calculations further confirm the find- ings. Superdeformed minimum is observed for 188 − 220 Pb isotopes, and the corresponding excitation energy, deformation and depth of well are compa- rable within different force parameters used. The behaviour with neutron number of the superdeformed excitation energy, two-neutron separation energy in the ground state and superdeformed minimum, and its differ- ential are fairly reproducing the trend of the available experimental data. The present numerical results are compared with Macro–microscopic Fi- nite Range Droplet Model (FRDM) and Hartree–Fock–Bogoliubov (HFB) model based on the interaction Gogny-D1S force. Overall, a fairly satis- factory agreement is found within the different force parameters and the calculated and experimental results