Decay pathways and entry-state population in (α,xnγ) and (3He,xnγ) reactions on 150Nd

Exclusive neutron spectra and angular distributions have been measured by n-γ coincidence techniques for (α,chinγ) and (3He,chinγ) reactions on 150Nd in the 25-44 MeV range. The results show that pre-equilibrium processes dominate low-energy light-ion induced reactions at certain beam energies. Analysis of the yrast γ-ray cascades in the residual nuclei shows that a well-defined minimum entry-state spin exists in final nuclei populated by pre-equilibrium processes. This in turn implies the existence of a minimum classical impact parameter for these reaction. These results are discussed in terms of phenomenological models of the reaction mechanisms. (orig.)