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 the chains 144−154 60Nd, 146−160 62Sm, 148−162 64Gd, and 150−166 66Dy, energy levels, E2 transition rates, and two– neutron separation energies are described by using the most general (up to two–body terms) 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.