Systematics in the structure of low-lying, non-yrast band-head configurations of strongly deformed nuclei

Strongly deformed nuclei show interesting paterns in the energy spectrum above around 1 MeV. An empirical investigation of the trends in the properties of the non-yrast $K^\pi=2^+_\gamma$ and $K^\pi=0^+_2$ bandhead configurations in nuclei that are related to one another through the addition or removal of alpha-particle-like structures, reveals their complex and changing behavior in contrast to the smooth behavior of the yrast states. A systematic application of the pseudo-SU(3) model for such a sequence of deformed nuclei from the rare earth region leads to an accurate and unified description of not only yrast, but non-yrast collective bands. The onset of deformation as manifested through the position of the excited bandheads in the spectra is understood and interpreted by using a realistic model Hamiltonian in conjunction with a microscopic distribution of the eigenstates across allowed proton and neutron strong- coupled SU(3) configurations.