Phase transitions and critical points in the rare-earth region

Abstract

A systematic study of isotope chains in the rare-earth region is presented. For chains ${}_{60}^{144\ensuremath{-}154}\mathrm{Nd},$${}_{62}^{146\ensuremath{-}160}\mathrm{Sm},$${}_{64}^{148\ensuremath{-}162}\mathrm{Gd},$ and ${}_{66}^{150\ensuremath{-}166}\mathrm{Dy},$ energy levels, E2 transition rates, and two-neutron separation energies are described by using the most general (up to two-body terms) interacting boson model (IBM) Hamiltonian. For each isotope chain a general fit is performed in such a way that all parameters but one are kept fixed, to describe the whole chain. In this region, nuclei evolve from spherical to deformed shapes and a method based on catastrophe theory, in combination with a coherent-state analysis to generate the IBM energy surfaces, is used to identify critical phase transition points.