High-resolution study of the C12(γ,pγ')B11 reaction using a HpGe detector to resolve excited states of B11 through the observation of their γ-ray decays

Relative populations of states in B-11 following the C-12(gamma,p)B-11 reaction have been measured with high resolution using a 70% HpGe gamma detector to observe decay gamma rays from the residual nucleus. The triplet of states near 7 MeV in B-11 are resolved and the measured populations compared to previous data. The analysis includes a consideration of gamma-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 Delta currents, under the assumption that the photons are mainly absorbed on exchanged pions.