Angular Distribution of (α, p) Reactions in Some Light Nuclei

The angular distributions of the proton groups corresponding to the lower states of the residual nuclei from the reactions C 12 (α, p )N 15 gnd ; F 19 (α, p )Ne 22 gnd, 1.28 MeV ; Al 27 (α, p )Si 30 gnd, 2.24 MeV ; and Si 28 (α, p )P 31 gnd, 1.27, 2.23, 3.13∼3.51 MeV have been measured using 22.5±0.2 MeV alpha particles. The angular distributions of the C 12 (α, p )N 15 gnd reaction are energy dependent. At 20.6 MeV steep rise in the forward angles is observed, but at 22.2 MeV the steep rise in the backward angles appears instead of the forward rise. The angular distributions of the F 19 (α, p )Ne 22 reaction are both peaked in the backward angles. The angular distributions of the Al 27 (α, p )Si 30 and the Si 28 (α, p )P 31 reactions show the diffraction-like patterns and they are interpreted with Butler's direct interaction theory.