Deformation effects in Ni-56 nuclei produced in Si-28+Si-28 at 112 MeV

Velocity and energy spectra of the light charged particles emitted in the Si-28(E-lab = 112 MeV) + Si-28 reaction have been measured at the Strasbourg VIVITRON Tandem facility, The ICARE charged particle multidetector array was used to obtain exclusive spectra of the protons and alpha particles in the angular range 15degrees-150degrees and to determine the angular correlations of these particles with respect to the emission angles of the evaporation residues. The experimental data are analyzed in the framework of the statistical model. The exclusive energy, spectra of a particles emitted from the Si-28+ Si-28 compound system are generally well reproduced by Monte Carlo calculations using spin-dependent level densities. This spin dependence approach suggests the onset of large nuclear deformation at high spin. A reanalysis of previous alpha-particle data front the Si-30+ Si-30 compound system, using the same spin-dependent parametrization, is also presented in the framework of a general discussion of deformation effects in the A(CN)approximate to60 mass region.