Electron- and photon-induced proton knockout from ²⁰⁹Bi

Cross sections have been measured for the ²⁰⁹Bi(e,e^′p)²⁰⁸Pb and ²⁰⁹Bi(γ,p)²⁰⁸Pb reactions using electrons at E_e=293 and 412 MeV, and tagged photons at mean E_γ∼43.7 and ∼52.0 MeV, respectively. The ²⁰⁹Bi(e,e^′p)²⁰⁸Pb results are compared to complete distorted wave impulse approximation calculations, from which it is deduced that a model of ²⁰⁹Bi based on a 1h_9/2 proton orbiting an inert ²⁰⁸Pb core has a high degree of validity. The interpretation of the ²⁰⁹Bi(γ,p)²⁰⁸Pb results makes use of the (e,e^′p) results to constrain the calculation of the direct knockout contribution. Using this approach, a comparison of the ²⁰⁹Bi(γ,p)²⁰⁸Pb data to various calculations with and without meson exchange contributions shows that the enhancement of the (γ,p) cross section due to meson exchange is small. This is in contrast to results obtained for light nuclei, but in agreement with results for heavier nuclei.