Reactions of Protons withNi58andNi60

Excitation functions up to 19 Mev have been measured for the ${\mathrm{Ni}}^{58}(p, 2p)$, ${\mathrm{Ni}}^{58}(p, pn)$, and ${\mathrm{Ni}}^{58}(p, \alpha )$ reactions, and for the ${\mathrm{Ni}}^{60}(p, \alpha )$ reaction up to 13 Mev. The ratio of the ($p, 2p$) cross section to the ($p, \mathrm{pn}$) cross section is 3.5 at 19 Mev, and increases with decreasing energy. It is proposed that this excess of proton emission can be accounted for by nuclear evaporation theory, and a computer calculation of the excitation functions using this theory is described. The calculation reproduces the ($p, 2p$) and ($p, \mathrm{pn}$) curves quite well, and gives evidence that the compound nucleus mechanism probably applies to these reactions. The calculated ($p, \alpha$) curve does not agree with the experimental results as well.