Coherent and incoherent π0 photoproduction from the deuteron

Differential cross-sections for the reactions d (γ,π0)d and d (γ,π0)pn have been measured at MAMI with the TAPS detector setup in the energy range 140 MeV < Eγ < 306 MeV. By use of the Glasgow tagging spectrometer an 0.8 MeV energy resolution for photons incident on the target was achieved. The π0 missing energy resolution was sufficient for a reliable separation of coherent and incoherent channels. The data for the break-up channel exhibit very strong final state interaction effects, whereas the observed angular dependence of the inclusive process d (γ,π0)X is in quantitative agreement with predictions for a quasi-free process. The observed absolute d (γ,π0)X cross-sections, on the other hand, are significantly smaller than predicted by the quasi-free process for Eγ >∼ 250 MeV. Associating this failure with the π0 photoproduction on the neutron would suggest that its cross-section is up to 25% below the presently believed value.