Angular Distributions of the Reactions Co59(p, α)Fe56 at 7.7∼14.1 Mev and Mn55(p, α)Cr52 at 7.6∼12.9 Mev

Abstract

The angular distributions of the reactions Co 59 ( p , α)Fe 56 and Mn 55 ( p , α)Cr 52 resulting in the ground and first excited states of the residual nuclei have been measured at 7.7, 8.7, 9.8, 10.85, 11.9, 13.1 and 14.1 Mev and at 7.65, 8.85, 9.65, 10.7, 11.8 and 12.9 Mev of the incident proton energy, respectively, making use of proportional counters. Similar behaviour was obtained for these four reactions. For the reaction Co 59 ( p , α)Fe 56 the forward peak in the angular distribution is prominent at 14.1 and 13.1 Mev and disappears gradually with decreasing proton energy, and the angular distribution is approximately 90° symmetrical below about 11 Mev. For the reaction Mn 55 ( p , α)Cr 52 the angular distribution is considerably forward peaked at 12.9 and 11.8 Mev and it approximately 90° symmetrical below about 10 Mev. It was found that the total cross section integrated from the angular distributions for both reactions decrease smoothly with increasing proton energy. It is considered that the reactions Co 59 ( p , α)Fe 56 and Mn 55 ( p , α)Cr 52 resulting in the ground and first excited states of the residual nuclei occur through the similar reaction process, that is, in the lower energy region the compound nucleus process plays a predominant role, although some contribution from the direct interaction process cannot be neglected, and the contribution from the direct interaction process becomes gradually significant with increasing proton energy and is predominant above about 11 Mev.