The angular distribution of the recoiling ${\mathrm{C}}^{11}$ atoms from the reaction ${\mathrm{C}}^{12}(p, pn){\mathrm{C}}^{11}$, induced by 450-MeV protons, was measured. The results were compared with the theoretical calculations of Benioff and Person. The distorted-wave impulse approximation gives better agreement than does the plane-wave approximation. However, the theoretical values from both calculations appear to be too large at the backward angles. This may indicate the existence of competing mechanisms. The results reported here are in general agreement with the thick-target thick-catcher recoil measurements of Singh and Alexander. A similar comparison for the reaction ${\mathrm{Cu}}^{65}(p, pn){\mathrm{Cu}}^{64}$ indicates no agreement between the two types of experiment.

• Received 27 December 1965

DOI:https://doi.org/10.1103/PhysRev.145.754