Ja n 19 99 Shell Model Monte Carlo Investigation of Rare Earth Nuclei

We utilize the Shell Model Monte Carlo (SMMC) method to study the structure of rare earth nuclei. This work demonstrates the first systematic " full oscillator shell plus intruder " calculations in such heavy nuclei. Exact solutions of a pairing plus quadrupole hamiltonian are compared with mean field and SPA approximations in several Dysprosium isotopes from A = 152 − 162, including the odd mass A = 153. Basic properties of these nuclei at various temperatures and spin are explored. These include energy, deformation, moments of inertia, pairing channel strengths, band crossing, and evolution of shell model occupation numbers. Exact level densities are also calculated and, in the case of 162 Dy, compared with experimental data.