The role of nucleon knockout in pre-equilibrium reactions

Nucleon-induced pre-equilibrium reactions are predominantly direct reactions. At low incident energies, excitation of all but the lowest energy collective states can be well described in terms of one-step reactions that produce particle-hole pairs. As the incident energy increases, the probability of exciting a nucleon to the continuum rather than to a bound particle state also increases. These knockout nucleons can escape the nucleus or induce secondary collisions that create still other continuum or bound particle-hole pairs. We discuss their role in pre-compound nuclear reactions here, first in a semiclassical Monte Carlo description of the reaction and then in a quantum one-step calculation.