Nuclear binding energies: Global collective structure and local shell-model correlations

Abstract

Nuclear binding energies and two-neutron separation energies are analysed starting from the liquid-drop model and the nuclear shell model in order to describe the global trends of the above observables. We subsequently concentrate on the Interacting Boson Model (IBM) and discuss a new method in order to provide a consistent description of both, ground-state and excited-state properties. We address the artefacts that appear when crossing mid-shell using the IBM formulation and perform detailed numerical calculations for nuclei situated in the 50–82 shell. We also concentrate on local deviations from the above global trends in binding energy and two-neutron separation energies that appear in the neutron-deficient Pb region. We address possible effects on the binding energy, caused by mixing of low-lying 0 + intruder states into the ground state, using configuration mixing in the IBM framework. We also study ground-state properties using a macroscopic–microscopic model. Detailed comparisons with recent experimental data in the Pb region are amply discussed.