The complex-particle ($A\le 4$) emission in the particle induced reaction was analyzed in the pre-equilibrium reaction mechanism. A simple closed form pre-equilibrium exciton model is employed. The complex particle is assumed to form with a certain formation probability from the excited particles (protons and neutrons) which correlate to each other with the right combination of proton and neutron numbers and the momentum in order to form a cluster. The complex-particle formation probability extracted from the proton induced reactions on several nuclei from ${}_{}{}^{12}{}_{}{}^{}\mathrm{C}$ to ${}_{}{}^{209}{}_{}{}^{}\mathrm{Bi}$ shows strong $A$ dependence.

NUCLEAR REACTIONS ${}_{}{}^{12}{}_{}{}^{}\mathrm{C}$, ${}_{}{}^{16}{}_{}{}^{}\mathrm{O}$, ${}_{}{}^{27}{}_{}{}^{}\mathrm{Al}$, ${}_{}{}^{54}{}_{}{}^{}\mathrm{Fe}$, ${}_{}{}^{89}{}_{}{}^{}\mathrm{Y}$, ${}_{}{}^{120}{}_{}{}^{}\mathrm{Sn}$, ${}_{}{}^{197}{}_{}{}^{}\mathrm{Au}$, ${}_{}{}^{209}{}_{}{}^{}\mathrm{Bi}\mathrm{}(p,x)\mathrm{}$, $E_p=62\mathrm{}$ MeV; ${}_{}{}^{54}{}_{}{}^{}\mathrm{Fe}\mathrm{}(p,x)\mathrm{}$; $E_p=29\mathrm{} \mathrm{and} 39$ MeV, ${}_{}{}^{58}{}_{}{}^{}\mathrm{Ni}\mathrm{}(p,x)\mathrm{}$, $E_p=90\mathrm{}$ MeV; pre-equilibrium exciton model.

• Received 28 November 1977

DOI:https://doi.org/10.1103/PhysRevC.17.1540