Signiflcant Amount of Pre-Equilibrium Contribution in the α+ 93Nb System at Energies ≈ 18-40 MeV

F. K. Amanuel ； B. Zelalem ； A. K. Chaubey ； Avinash Agarwal ； I. A. Rizvi

《Chinese Journal of Physics》 49卷4期 (2011/08) Pp. 884-892

並列摘要

To study the role of a large pre-equilibrium emission of light nuclear particle (s) on the excitation functions of the reaction channels (α, n), (α, 2n), (α, 3n), (α, 4n), (α, 2p), (α, p3n), and (α, αn) in the α+ 93Nb system, an experiment has been performed using an α beam up to 40 MeV at the Variable Energy Cyclotron Center, Calcutta (India). In the present work, the experimental measurement is carried out using the stack foil activation technique followed by off-line high-purity Ge γ-ray spectroscopy methods. Results of the experimental measurements have been analyzed using the statistical model code of ALICE-91 and compared with the existing data for the same system [J. Phys. Soc. Jpn. 59, 3916 (1990)]. The present analysis indicated that at higher energy points the pure compound nucleus calculations failed to reproduce the present experimental data at beam energies ≈ 18-40 MeV and revealed large contributions from pre-equilibrium emission. Furthermore, analysis of the data suggests that a summation of both equilibrium and pre-equilibrium emissions is needed to reproduce the present experimental data in the energy range considered.We also calculate the pre-equilibrium fraction as a function of the normalized projectile energy, and a definite dependence has been observed on the projectile energy and on the number of emitted particle(s).