MECHANISMS IN THE C-12(GAMMA,PN) AND (GAMMA,PP) REACTIONS

C-12(gamma,pn) and (gamma,pp) cross sections have been measured in kin ematics which emphasize direct 2N knockout for E-gamma = 120-400 MeV a nd theta(p) = 23 degrees-152 degrees. The cross sections for both reac tions peak strongly in the Delta-resonance region. Theoretical calcula tions that account for the medium dependence of the Delta propagator p redict a similar photon energy dependence to the data and describe the general trends of the measured (gamma,pp)/(gamma,pn) ratio. Both cros s sections show strong angular dependence, and the large differences b etween the two channels indicate different microscopic reaction mechan isms.