Study of Protons and Alpha Particles Emitted fromBr75Compound Nuclei with Differing Angular-Momentum Distributions

The energy spectra and angular distributions of protons and $\alpha$ particles emitted from the compound nucleus ${\mathrm{Br}}^{75}$ formed at the excitation energies of 49 and 88 MeV have been studied. The ${\mathrm{Br}}^{75}$ compound nuclei were formed in three different ways: ${\mathrm{B}}^{11}$+${\mathrm{Zn}}^{64}$, ${\mathrm{C}}^{12}$+${\mathrm{Cu}}^{63}$, and ${\mathrm{O}}^{16}$+${\mathrm{Co}}^{59}$. The differences in the angular-momentum distributions of the compound nuclei formed in each of the entrance channels permitted the study of the particles emitted from specific ranges of angular momentum of the compound nuclei. The yield of $\alpha$ particles from the high-angular-momentum states was found to be significantly enhanced relative to that from the low-angular-momentum states and the average energy of the $\alpha$ particles emitted increased with the angular momentum of the compound nucleus. The yield of protons and their average energy was not significantly affected by angular momentum. These results are consistent with results calculated using an angular-momentum-dependent statistical theory of nuclear reactions.