Single and double πo-photoproduction from the deuteron

Abstract

Photoproduction of neutral pions from the deuteron has been studied for incident photon energies from 200 MeV to 792 MeV with the TAPS detector at the Mainz MAMI accelerator. Total and differential cross sections covering the full angular range have been obtained for coherent and incoherent single πo-photoproduction. Good agreement between model predictions and the data was found for the coherent process. The incoherent cross section in the energy region of the Δ(1232)-resonance is overestimated by existing models. A comparison to model predictions indicates that final state interaction effects are much more important than for the coherent reaction. However, the angular dependence of the data in the Δ-peak region follows the pattern expected from the dominant excitation of the M1+-multipole on the free nucleon. The energy and angular dependence of single πo-photoproduction in the second resonance region is remarkably different from the reaction on the free proton, indicating a strong nuclear effect. Finally the total cross section for double πo-photoproduction from the deuteron has been measured for the first time and was used to estimate the cross section for double πo-photoproduction from the neutron.