Quasiparticle band structures in transitional nuclei

Major advances in the experimental techniques have made it feasible to perform detailed measurements of atomic nuclei at the extremes of angular-momentum, isospin and stability. Detailed spectroscopic studies have provided new insights in our understanding of nuclear many-body problem. Band structures have been observed up to very high angular momentum and far from the valley of stability. For instance, in the deformed nucleus Dy, sixty bands have been reported. The classification and the interpretation of these rich band structures is a challenge to nuclear theory. The three modes of excitations of rotational, vibrational and quasi-particle constitute the primary origin of the observed bands in nuclei. In spherical nuclei, the energy spectrum is primarily built on the quasi-particle excitations. In well deformed nuclei, rotational bands are observed and are classified using the Nilsson scheme