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 α particles with 141Pr have been measured in the energy range
≈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 γ -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 α-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.
