Study on pions plus photoproduction on deuterium

Pion plus photoproduction on deuterium was studied in the γd → nnπ+ reaction in the photon energy range of 380-500 MeV. π+ meson energy spectra are analyzed for pion escape angles in the range of 19-127 deg h.p. Pion energies correspond to the Δ33 resonance excitation in the πN system in the final state. The main results are as follows: the measurements made with the approximately 3% accuracy show that calculations by the Chew-Lewis model and in the pulse approximation differ from experimental data by 10-20% depending on the kinematic conditions; the account of corrections for nn and πN interactions in the final state improves the agreement with experimental data; the effect of corrections on the interaction in the final state exhibits itself most vividly in experiments on monochromatic photon beams. While studying the γd → NNπ reaction on bremsstrahlung beam of γ quanta, the contribution of rescattering process in the final state may reach 10-15%; in the near-threshold region of Esub(γ)-Esub(thresh.) <= 7 MeV the cross section of the γd → nnπ+ process in determined mainly by the nucleon-nucleon interaction in the final state