Quasielastic C-12(e,e ' p) reaction at high momentum transfer

We measured the C-12(e,e'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-m>50 MeV) cross section extending out to the deepest missing energy measured, amounting to almost 50% of the measured cross section. The ratio of data to distorted-wave impulse approximation (DWIA) calculation is 0.4 for both p and 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 p shell and 1.0 for the 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. [S0556-2813(99)00701-3]