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 ${}^{58}\mathrm{Ni}(\alpha ,p){}^{61}\mathrm{Cu},{}^{58}\mathrm{Ni}(\alpha ,\mathit{pn}){}^{60}\mathrm{Cu},{}^{60}\mathrm{Ni}(\alpha ,p2n){}^{61}\mathrm{Cu},{}^{60}\mathrm{Ni}(\alpha ,n){}^{63}\mathrm{Zn},{}^{60}\mathrm{Ni}(\alpha ,2n){}^{62}\mathrm{Zn},{}^{61}\mathrm{Ni}(\alpha ,3n){}^{62}\mathrm{Zn}$, and ${}^{61}\mathrm{Ni}(\alpha ,2n){}^{63}\mathrm{Zn}$ 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 $\approx 8\text{−}40$ 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).

• Received 5 April 2008

DOI:https://doi.org/10.1103/PhysRevC.78.044606