QUASI-PARTICLE SPECTRA NEAR THE YRAST LINE

The yrast spectra of the nuclides 68 ≦ Z ≦ 70, 89 ≦ N ≦ 99 are analysed in terms of quasiparticle configurations in a deformed field rotating with the frequency ω. The excitation energy, e', in the rotating frame (Routhian) and the aligned angular momentum, i, relative to the ground state band as functions of ω are extracted from the experimental rotational bands which are classified with respect to their signature, α, and parity, π. These experimental quantities are compared with the ones calculated from the quasiparticle level diagrams. Phenomena like backbending and the occurrence of aligned bands in both even-even and odd-mass nuclei and their mutual relationship are interpreted in terms of quasiparticle configurations that may cross each other with increasing frequency. © 1979.