High-resolution study of the 12C(γ,pγ')11B reaction using a HpGe detector to resolve excited states of 11B through the observation of their γ-ray decays

Relative populations of states in 11B following the 12C(γ,p)11B reaction have been measured with high resolution using a 70% HpGe γ detector to observe decay γ rays from the residual nucleus. The triplet of states near 7 MeV in 11B are resolved and the measured populations compared to previous data. The analysis includes a consideration of γ-proton angular correlations, which was not made in the previous measurement. The new and previous results corrected for angular correlation effects agree reasonably well with calculations that include one- and two-body nuclear currents, pion exchange, and Δ currents, under the assumption that the photons are mainly absorbed on exchanged pions