Quasielastic reaction mechanism studied using the reactionC12(e,e’p)

We have measured missing-energy spectra for the reaction ${}_{}{}^{12}{}_{}{}^{}\mathrm{C}$(e,e’p) in the quasielastic region in parallel kinematics at momentum transfers q of 585, 775, and 827 MeV/c. We observed ${}_{}{}^1{}_{}{}^{}$p and ${}_{}{}^1{}_{}{}^{}$s single-proton knockout peaks and large broad strength attributed to multinucleon knockout. We saw no increase in strength at pion threshold. The ratio of single-particle knockout to a distorted-wave impulse-approximation calculation is approximately constant with q. Multinucleon knockout is 25%–40% of the total cross section; it increases with q. This quasielastic non-single-nucleon knockout is much stronger than previously observed.