Surface effects in multistep reaction calculations

Surface effects of neutron and proton emission in the frame of the Feshbach-Kerman-Koonin theory are described in terms of the mean effective Fermi energy taken into account for the first projectile-target interaction. This analysis is carried out in conjunction with a realistic particle-hole state density including advanced Pauli and pairing correction, as well as an energy-dependent single-particle state density. Different energy dependences and values at the Fermi level of the single-particle state densities for holes and excited particles are considered in this respect multistep direct and multistep compound contributions to both neutron and proton emission following fast neutron induced reactions on 56 Fe and 46,48 Ti are discussed and found in agreement with experimental data. (author) 8 figs., 54 refs