Collective excitations in the superdeformed well

Collective excitations are commonplace features in nuclei at normal deforma tion. It has been suggested that both in the ii similar to 190 and 150 supe rdeformed (SD) nuclei, collective vibrational states might occur in the sam e excitation energy range as quasi-particle and single-particle excitations . In particular, tile large deformation associated with SD nuclei brings to gether orbitals from many spherical shells and leads to tile close proximit y of states with opposite parity, favouring octupole shape vibrations. Howe ver, to date, similar to 200 SD bands have been reported ill more than 50 n uclei and in most cases, the excited SD bands have been interpreted as sing le or quasi-particle excitations. Only in very few cases, has the collectiv e excitation scenario been suggested. Where are the collective states in SD nuclei? The question is particularly relevant in even-even A = 190 nuclei in which SD states are observed at lower rotational frequency and hence til e additional influence of tile pair gap makes the collective excitations mo re competitive with quasi-particle excitations.