Levels ofCo59Populated in Compound-Nuclear Reactions

Abstract

Highly excited levels of ${}_{}{}^{59}{}_{}{}^{}\mathrm{Co}$ have been populated by the ${}_{}{}^{59}{}_{}{}^{}\mathrm{Co}(p,p^{\prime })$ and ${}_{}{}^{62}{}_{}{}^{}\mathrm{Ni}(p,\alpha )$ reactions induced by 14.0-MeV protons and by the ${}_{}{}^{56}{}_{}{}^{}\mathrm{Fe}(\alpha ,p)$ and ${}_{}{}^{59}{}_{}{}^{}\mathrm{Co}(\alpha ,{\alpha }^{\prime })$ reactions induced by 16.5-MeV $\alpha$ particles. Energy spectra were measured over the 30-150° angular interval and the results compared with the spin- and isospin-dependent statistical theory. The ($p,\alpha$), ($\alpha ,{\alpha }^{\prime }$), and ($\alpha ,p$) reaction spectra could all be fitted with the same level-density parameter and pairing energy of ${}_{}{}^{59}{}_{}{}^{}\mathrm{Co}:a=7.5\mathrm{}$ ${\mathrm{MeV}}^{-1\mathrm{}}$ and $\delta =1.29\mathrm{}$ MeV. In order to obtain agreement with these same parameters for the ($p,p^{\prime }$) reaction spectrum it was necessary to invoke a 30-40% contribution from a pre-equilibrium emission process. The sensitivity of the results of the various parameters of the theory is explored.