Preequilibrium neutron emission in109Ag(3He,xn) and111Cd(p,xn) reactions

Excitation functions of the reactions¹⁰⁹Ag(³He,xn) and¹¹¹Cd(p, xn) have been measured with stacked foil techniques for projectile energies E≦45 MeV and multiplicitiesx≦4 populating ground and spin isomeric states in^112?x In. Preequilibrium (PE) contributions are more pronounced for thep than for the³He entrance channel and for low multiplicitiesx 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 emission of complex particles.