A NEW MULTISTEP DIRECT REACTION-MECHANISM - COLLECTIVE EXCITATIONS INTHE CONTINUUM

We show that pre-equilibrium inelastic scattering reactions to the con tinuum contain substantial collective components in addition to the mu ltistep direct and multistep compound reactions. These collective cros s-sections are calculated using the experimental data for low-lying co llective excitations supplemented where necessary by the giant multipo le resonances evaluated using the energy-weighted sum rule. The MSC an d MSD cross-sections are evaluated by the Feshbach-Kerman-Koonin theor y using a consistent set of parameters determined by analyses of (p, n ) reactions, that have practically no collective components. The resul ts are compared with high-resolution neutron inelastic scattering data and prove able to account for the absolute magnitude of the cross-sec tions and also their detailed structure.