Large pre-equilibrium contribution in α+natNi interactions at ≈8-40 MeV

To investigate pre-equilibrium emission of light nuclear particle(s), an experiment has been performed using alpha beams at the Variable Energy Cyclotron Center (VECC), Kolkata, India. In the present work, excitation functions for Ni-58(alpha,p)Cu-61,Ni-58(alpha,pn)Cu-60,Ni-60(alpha,p2n)Cu-61,Ni-60(alpha,n)Zn-63,Ni-60(alpha,2n)Zn-62,Ni-61(alpha,3n)Zn-62, and Ni-61(alpha,2n)Zn-63 reactions have been measured by using the stacked foil activation technique followed by off-line gamma-ray spectroscopy. Experimentally measured excitation functions have been compared with the prediction of the theoretical model code ALICE-91 with and/or without the inclusion of pre-equilibrium emission. Analysis of the data suggests that an admixture of both equilibrium and pre-equilibrium emission is needed to reproduce experimental data at energies approximate to 8-40 MeV and reveals significant contribution from pre-equilibrium emission. An attempt has also been made to estimate the pre-equilibrium contribution, which has been found to depend on projectile energy and on number of emitted particle(s).