Quasielastic12C(e,e′p)reaction at high momentum transfer

Abstract

We measured the ${}^{12}\mathrm{C}{(e,e}^{\ensuremath{'}}p)$ cross section as a function of missing energy in parallel kinematics for $(q,\ensuremath{\omega})=(970 \mathrm{MeV}/c, 330 \mathrm{MeV})$ and $(990 \mathrm{MeV}/c, 475 \mathrm{MeV}).$ At $\ensuremath{\omega}=475 \mathrm{MeV},$ at the maximum of the quasielastic peak, there is a large continuum ${(E}_{m}>50 \mathrm{MeV})$ 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 $\ensuremath{\omega}=330 \mathrm{MeV},$ 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 $\ensuremath{\omega}$ transform some of the single-nucleon knockouts into a multinucleon knockout, decreasing the valence knockout cross section and increasing the continuum cross section.