Comparative Study of Pre-Equilibrium Models and Mechanism of Alpha Particle Induced Reactions

Excitation functions of (α, xn yp z α) reactions on 93 Nb and 169 Tm have been measured upto 50 MeV by stacked-foil activation technique with a view to improve the quality of data in the case of 169 Tm, which was earlier measured with a poor resolution scintillation detector. Comparisons are presented with the predictions of three pre-equilibrium models (i.e. Exciton, Hybrid and Index Models). While for (α, xn ) type of reactions reasonably explainable pre-compound contributions are found, there seem to be indications of direct inelastic scattering effects in (α, α x n ) type of reactions in medium and heavy nuclei.