Phase transitions and critical points in the rare-earth region

A systematic study of isotope chains in the rare-earth region is presented. For chains 60 144 2 154Nd, 62 146 2 160Sm, 64 148 2 162Gd, and 66 150 2 166 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.