Short-Range, High-Momentum Effects in the ReactionO16(γ, p0)forEγ=100−300MeV

The ${}_{}{}^{16}{}_{}{}^{}\mathrm{O}(\gamma , p_0)$ cross section has been measured for a series of photon energies between 100 and 300 MeV at proton angles of 45°, 90°, and 135°. Above 250 MeV, the results exceed simple shell-model predictions by several orders of magnitude. The data are compared with a calculation which involves $\Delta$ excitation in an intermediate state.