Preequilibrium neutron emission in 109Ag(3He,xn) and 111Cd(P,xn) reactions

Excitation functions of the reactions 109Ag(3He, xn) and 111Cd(p, xn) have been measured with stacked foil techniques for projectile energies E<=45 MeV and multiplicities x<=4 populating ground and spin isomeric states in sup(112-x)In. Preequilibrium (PE) contributions are more pronounced for the p than for the 3He entrance channel and for low multiplicities x and can be reproduced with the (geometry dependent) hybrid model. The observed isomeric cross section ratios require a reduced population for the high spin state (as compared with the expectation for equilibrated systems) whenever PE emission contributes significantly. Calculations for a full statistical model with a PE decay mode and approximate angular momentum conservation indicate PE neutron emission to be stretched in angular momentum space. For the (p,xn) reactions a more detailed coupling scheme is imperative whereas the (3He,xn) data suggest the competitive PE emissison of complex particles. (orig.)