Absolute measurement of the differential cross section for the reactionHe4(γ,p)3H from 63 to 71 MeV

Results are presented from a ${}_{}{}^4{}_{}{}^{}\mathrm{He}$ photodisintegration experiment performed with quasimonochromatic photons using a large solid-angle detector. The tagged-bremsstrahlung technique gave a reliable absolute normalization. In addition, an unambiguous separation of the proton-triton channel from other photodisintegration channels was achieved. A total cross section of 218±8 μb was measured at a mean energy of 67±4 MeV and Legendre coefficients up to ${\mathit{a}}_5$ were extracted from the angular distributions.