Angular correlations have been measured between protons scattered inelastically on ${\mathrm{S}}^{32}$ and the 2.25-Mev $\gamma$ rays from the decay of the first excited state. Measurements were made at incident proton energies of 5.7, 6.02, 6.2, and 6.34 Mev, the position of the proton detector being at 60°, 90°, 120°, and only in one case at 150°. The experimental correlations functions are all of the form $A+B{sin}^2\left[2\right(\theta -{\theta }_0\left)\right]$, where ${\theta }_0$ defines the axis of symmetry. At 6.02-Mev incident proton energy, ${\theta }_0$ is only slightly different from the recoil angle ${\theta }_R$; it is thereby inferred that the reaction goes mainly through a direct interaction mechanism. At 6.34 Mev, ${\theta }_0$ remains close to 90° for any scattering angle, in agreement with the compound nucleus theory. This fact suggests the presence of a strong resonance in the ${\mathrm{Cl}}^{33}$ compound nucleus. The correlations curves measured at 5.7 and 6.2 Mev are consistent with a competition between both reaction mechanisms.

• Received 12 July 1961

DOI:https://doi.org/10.1103/PhysRev.126.2174