Evolution of collectivity in a ground-γ-band mixing scheme for even-even transitional nuclei

We propose an extended band-mixing formalism capable of describing the structure of the ground- and gamma-bands in a wide range of collective spectra beyond the regions of well-deformed nuclei. We apply it to explain the odd-even staggering effect observed in the gamma-bands of Mo, Ru and Pd nuclei and to obtain on this basis a consistent interpretation of new experimental data in the neutron rich region. As a result the systematic behaviour of the staggering effect, together with the mutual ground-gamma-band disposition, interband mixing and intraband level spacing are explained as the manifestation of respective changes in nuclear collectivity.