Study of double pion photoproduction on the deuteron

The π+π−π+π− photoproductions on the proton and deuteron have been studied in a photon energy range of 0.8–1.1 GeV at the Laboratory of Nuclear Science, Tohoku University. Charged pions and protons were detected using Neutral Kaon Spectrometer. We obtained the cross sections for the p(γ,pπ+π−)p(γ,pπ+π−) and d(γ,pπ+π−)nd(γ,pπ+π−)n. The quasi-free process with a neutron spectator was extracted by the neutron momentum cut of pn>0.3 GeV/cpn>0.3 GeV/c. The cross section for the Δ++Δ−Δ++Δ− production was deduced in the non-quasi-free process of the γd→pnπ+π−γd→pnπ+π−. It was 13.4±0.4 μb13.4±0.4 μb at Eγ=0.82 GeVEγ=0.82 GeV.