Reactions of Nickel with Alpha-Particles

Excitation functions for the alpha-particle induced reactions on Ni 58 , Ni 60 , Ni 61 , Ni 62 and Ni 64 have been measured at incident energies up to 40 Mev. The sum of the measured cross sections for Ni 58 appears to agree with the total reaction cross section calculated from the continuum theory for r 0 =1.7×10 -13 cm. The sum almost agrees with the optical-model analysis of reaction cross section for alpha-particles by Igo, but his prediction seems to give a little higher value. In the excitation function for the (α, α n ) reaction on Ni 58 , there is a small "knee" immediately after the effective threshold (around 23 Mev). The alpha-particle reactions on Ni 60 have been compared with the proton reactions on Cu 63 , the compound nucleus Zn 64 being the same for two cases. The prediction from the compound nucleus theory seems to hold roughly, and it seems inadequate to discuss strictly whether the discrepancy in energy is significant. The same is observed in the comparison between the alpha-particle reactions on Ni 62 and the proton reactions on Cu 65 .