Recoil ranges of C11 from the reaction C12(p,pn)C11 are presented for incident proton energies from 0.25 to 6.2 Gev. From these data it is concluded that a neutron evaporation mechanism cannot be the major mechanism. The result for incident energies of 3 and 6.2 Gev are consistent with a fast reaction consisting of a single inelastic nucleon-nucleon collision. Assuming this mechanism, an average kinetic energy of 19 Mev can be deduced for the struck neutron (before the collision) in the C12 nucleus.