Linear momentum in the exciton model: Consistent way to obtain angular distributions

We present an exciton model for preequilibrium emission in nucleon-induced reactions in which linear-momentum conservation is included. The particle emission contributions from the first two preequilibrium stages are calculated by determining exact particle-hole state densities with a specific energy and linear momentum in a Fermi-gas model of the nucleus. Angular distributions arise naturally from our treatment and do not have to be added in an ad hoc way. The angular distributions that we obtain from the first two preequilibrium stages are identical to those found using the Kikuchi-Kawai quasifree scattering kernel.