Semiclassical and quantum mechanical analysis of α -particle-induced reactions on praseodymium: A study relevant to precompound emission

Abstract

Background: The study of precompound emission has attracted considerable attention for testing nuclear models in light-ion-induced reactions at relatively higher energies above 10 MeV/nucleon.Purpose: Aiming to study the precompound emission and to develop systematics at low energies below 10 MeV/nucleon, where the compound emission process is likely to dominate, the excitation functions of the reaction residues produced in the interaction of $\ensuremath{\alpha}$ particles with $^{141}\mathrm{Pr}$ have been measured in the energy range $\ensuremath{\approx}14$--40 MeV. Further, the measured data have been analyzed within the framework of both the semiclassical and quantum mechanical models.Methods: The off-line $\ensuremath{\gamma}$-ray spectroscopy based stacked foil activation technique has been used to measure the excitation functions.Results: The experimentally measured excitation functions have been compared with the theoretical predictions based on both the semiclassical model codes, viz., pace4, talys-1.9, act, and alice91, and the quantum mechanical model code exifon. The analysis of the data shows that the experimental excitation functions could be reproduced only when the contribution of precompound emission, simulated theoretically, is taken into account. Further, the precompound fraction, which gives the relative importance of precompound emission over compound nucleus emission, has been deduced and is found to be energy dependent.Conclusions: Analysis of data indicates that in $\ensuremath{\alpha}$-induced reactions, the precompound emission plays an important role, even at the low incident energies, where the pure compound nucleus process is likely to dominate. The precompound fraction is found to strongly depend on the mass of the target nucleus and the excitation energy per surface nucleon of the composite system.