Differential cross section for theH2(γ,p)n reaction between 100 and 255 MeV

Differential cross sections for the ${}_{}{}^2{}_{}{}^{}\mathrm{H}$(γ,p)n reaction were measured at five laboratory angles from 32.5° to 130°, for photon energies between 100 and 255 MeV, in 10 MeV steps. A quasi-monochromatic photon beam, obtained by positron in-flight annihilation on a liquid hydrogen radiator, was used, and the photon spectrum was measured on-line by a pair spectrometer. The normalization uncertainty is within ±5%. Data agree, within the total errors, with recent results of a tagged-photon experiment and of a measurement of the inverse process. The measured angular distributions were fitted by a sum of Legendre polynomials, and the results compared with recent calculations. Significant departures from the calculated angular distribution asymmetry have been found.