Quasielastic thinsp{sup 12}C(e,e{sup {prime}}p) reaction at high momentum transfer

We measured the {sup 12}C(e,e{sup {prime}}p) cross section as a function of missing energy in parallel kinematics for (q,{omega})=(970 MeV/c, 330 MeV) and (990 MeV/c, 475 MeV). At {omega}=475 MeV, at the maximum of the quasielastic peak, there is a large continuum (E{sub m}{gt}50 MeV) cross section extending out to the deepest missing energy measured, amounting to almost 50{percent} of the measured cross section. The ratio of data to distorted-wave impulse approximation (DWIA) calculation is 0.4 for both {ital p} and {ital s} shells. At {omega}=330 MeV, well below the maximum of the quasielastic peak, the continuum cross section is much smaller and the ratio of data to DWIA calculation is 0.85 for the {ital p} shell and 1.0 for the {ital s} shell. We infer that one or more mechanisms that increase with {omega} transform some of the single-nucleon knockouts into a multinucleon knockout, decreasing the valence knockout cross section and increasing the continuum cross section. {copyright} {ital 1999} {ital The American Physical Society}