Two-body disintegration of the deuteron with 0.8-1.8 GEV photons

The differential cross section for the reaction 2H(γ,p)n has been measured for photon energies between 0.8 and 1.8 GeV, at several center-of-mass angles in the range 900-1430; a broader angular range was covered at several of the lower photon energies. The experiment was performed at the SLAC-NPAS facility using the 1.6 GeV/c spectrometer to detect the high energy protons produced by a bremsstrahlung beam directed at a liquid deuterium target. Contributions from concurrent disintegration by the residual electron beam were determined by measuring the proton yield without the Cu photon radiator. Experimentally, two-body photodisintegration is an ideal reaction with which to probe the nuclear response to large energy and momentum transfer, since the final state can be determined by detecting a single proton. Furthermore, the two-body final state greatly constrains the flow of transferred momentum. Asymptotic scaling behavior predicted by QCD-based constituent counting rules is suggested by the measured cross section; it is surprising that such behavior should occur at these relatively low photon energies. The question of whether the reaction dynamics are better described with a quark-gluon picture or a nucleon-meson picture is discussed