Photopion angular distribution from 9Be(e, π+)9Li(g.s.)

Abstract The energy distribution of pions in the reaction 9 Be ( e , π + ) 9 Li was measured at E e = 200 MeV and the angular distribution was deduced for the pions leading to the ground state of the residual nucleus. Comparisons are made with several theoretical estimates including the surface production model, and the plane- and distorted-wave impulse approximations using the nuclear shell model and also the generalized Helm model. These theories qualitatively explain the experimental results with varying degrees of success depending on the model.