High-Resolution Measurements Of C-12(Gamma,Eta) And The Implications For The (Gamma,N) Reaction-Mechanism At Intermediate-Energy

High resolution measurements of the reaction C-12(gamma, n) at E(gamma) approximately 58 MeV are presented. The distribution of strength to the resolved bound final states in C-11 is compared with that of B-11 obtained in previous analogous (gamma, p) measurements and the implications for the theoretical description of (gamma, N) reactions are discussed. These new results confirm the importance of two-nucleon effects in intermediate energy photon absorption and highlight inadequacies in -state-of-the-art microscopic calculations of (gamma, N) reactions.