Recoil ranges of ${\mathrm{C}}^{11}$ from the reaction ${\mathrm{C}}^{12}(p, pn){\mathrm{C}}^{11}$ are presented for incident proton energies from 0.25 to 6.2 GeV. From these data it is concluded that a neutron evaporation mechanism is probably not the major mechanism. The results are consistent with a fast reaction consisting of a single proton-neutron collision. Assuming this mechanism, an average kinetic energy of approximately 19 MeV can be deduced for the struck neutron (before the collision) in the ${\mathrm{C}}^{12}$ nucleus.

• Received 4 June 1962

DOI:https://doi.org/10.1103/PhysRev.128.711