ENERGY DEPOSITION IN (ALPHA,ALPHA') REACTIONS AT 60 MEV U(-1)

The reaction Bi-209(alpha,alpha') has been studied E-Beam = 240 MeV, e xploring the possibility of producing hot nuclei with low-angular mome ntum, in the mass region A similar to 200, suitable for studies of the level-density parameter. The possibility of using the energy of the i nelastically scattered alpha particles to determine the excitation ene rgy deposited in the target nucleus has been checked by measuring evap orated charged particles, neutrons, fission fragments and gamma-rays. Comparison of the (alpha, alpha') data with results from the fusion re action B-11 + Pt-198 --> Bi-209 and statistical model calculations see ms to indicate that, in the case of inelastic cr scattering, not all t he energy dissipated in the collision is normally deposited as thermal excitation in the target nucleus. From evaporated proton spectra ther e is evidence for a strong pre-equilibrium component even at the most backward angles.