Angular Distributions of Proton Groups from theAl27(n, p)Mg27Reaction at 14 Mev

Abstract

A study has been made of the high-energy proton groups from the ${\mathrm{Al}}^{27}(n, p){\mathrm{Mg}}^{27}$ reaction at 14 Mev with emulsion detectors, continuous survey being made in the interval 10°-70° (lab system). Proton groups corresponding to the residual ${\mathrm{Mg}}^{27}$ nucleus left in the ground state and at excitations of 1.0, 1.6, 2.1, 2.8, and 3.5 Mev are identified. Several of these groups are characterized by a pronounced peaking in forward directions characteristic of direct interaction processes. The protons leading to the ground-state form a peak in the vicinity of 30°, those to the 1.0-Mev level at 36°, and those to the 1.6-Mev level at about 50°. The 3.5-Mev group is not resolved from known close-lying levels and the cluster exhibits an isotropic distribution. The 2.1-Mev and 2.8-Mev groups, corresponding to no previously reported levels in ${\mathrm{Mg}}^{27}$, also display an isotropic distribution and probably represent several unresolved levels. The three lowestlying levels shown approximate fits to theoretical curves consistent with reactions proceeding either by direct collision or by excitation of collective modes.