Photoproduction of positive pions from 16O at medium energies

Abstract

The reaction 16O(γ,π+)16N has been studied in the distorted wave impulse approximation (DWIA) using the free-nucleon photopion amplitude. The nuclear distortion effects on the emitted pion and also the effect of nuclear structure are investigated in detail. The effect of nuclear distortion is found to be small at lower energies but is of great importance resulting in large absorption of pions around the (3,3) resonance. Using realistic nuclear wave functions, it is found that the DWIA yields cross sections in fair agreement with the experimental data at γ-ray energies above 230 MeV but higher values at lower energies.