Polarized-proton scattering by even-mass germanium and selenium isotopes at 22 MeV incident energy

Elastic and inelastic scattering of 22.3 MeV polarized protons from even-mass nuclides 70-76Ge and 76-80Se has been studied. The elastic data have been analysed by optical-model techniques; also the elastic and inelastic data together have been investigated using a coupled-channels formalism. In the latter case the original optical-model parameters had to be modified in order to obtain an adequate description of the elastic scattering process. The 21+ and 31- states are described satisfactorily by the coupled channels formalism in a vibrational model. This model represents the 02+ states better than expected, and the 22+ and 41+ states only if the 2+ and 4+ levels are treated as mixtures of one-phonon and two-phonon components. Alternatively, a rotational description of the 21+, 22+ and 41+ states was moderately successful. Some features may be understood qualitatively from the interacting-boson approximation (IBA-2)