Measurements of Deuteron Photodisintegration up to 4.0 GeV

The first measurements of the differential cross section for the $d(\ensuremath{\gamma},p)n$ reaction up to 4.0 GeV were performed at the Continuous Electron Beam Accelerator Facility (CEBAF) at Thomas Jefferson Laboratory. We report the cross sections at the proton center-of-mass angles of 36\ifmmode^\circ\else\textdegree\fi{}, 52\ifmmode^\circ\else\textdegree\fi{}, 69\ifmmode^\circ\else\textdegree\fi{}, and 89\ifmmode^\circ\else\textdegree\fi{}. These results are in reasonable agreement with previous measurements at lower energy. The 89\ifmmode^\circ\else\textdegree\fi{} and 69\ifmmode^\circ\else\textdegree\fi{} data show constituent-counting-rule behavior up to 4.0 GeV photon energy. The 52\ifmmode^\circ\else\textdegree\fi{} and 36\ifmmode^\circ\else\textdegree\fi{} data disagree with the counting-rule behavior. The quantum chromodynamics (QCD) model of nuclear reactions involving reduced amplitudes disagrees with the present data.