A high-resolution study of the 12C(γ,p) reaction with 49-78.5 MeV tagged photons

We present tabulated cross-section measurements for the reaction 12C(γ, p) leading to resolved, low-lying, excited states of 11B. The measurements were obtained using tagged photons of 49-78.5 MeV and for mean laboratory proton emission angles from 65deg to 115deg. The proton excitation energy spectra are dominated by the ground state (3/2-), 2.13 MeV (1/2-), 5.02 MeV (3/2-) and 6.8 MeV doublet (7/2-, 1/2+) states of 11B. No evidence is found for the population of the 4.45 MeV (5/2-) state. Our analysis demonstrates that both the ground-state and excited-state cross-section data scale with momentum mismatch. The data are qualitatively discussed within the context of the existing (e, e'p) data and direct knockout and quasideuteron models. A consistent and quantitative understanding of the data will require more sophisticated models than are currently available. (orig.)