Alpha-particle and proton probes of nuclear shapes in the rare earth and mass 80 regions

Low emission barriers and large subbarrier anisotropies in the alpha-particle decay with respect to the spin direction, of Sn and rare earth compound nuclei, are examined in the light of recent calculations incorporating deformation. To explore the possibility of a correlation between the proton emission barriers and nuclear deformation, we studied proton spectra from the 52Cr(34S,2p2n)82Sr reaction. The proton spectra were observed with the Dwarf-Ball 4π CsI(T1) array, in coincidence with 18 Compton suppressed Ge detectors operated in conjunction with the Spin Spectrometer, a 4π NaI(T1) array. We found significant changes and shifts in the proton energy spectra as we selected gating transitions from bands of different moments of inertia or transitions from states of different spin in the same band. Substantial differences were also seen as a function of the γ-ray multiplicity. These results are discussed in terms of statistical model calculations incorporating deformation and structure effects of the emitting system. (author)