PHOTONUCLEAR ANGULAR-DISTRIBUTION SYSTEMATICS IN THE QUASIDEUTERON REGIME

We describe an applications-oriented method for determining continuum photonuclear angular distributions for emission of light particles (n, p, d, t, He-3, and alpha) in the quasideuteron regime (40 less than o r equal to E(inc) less than or equal to 140 MeV). Based on theoretical considerations by Chadwick and Oblozinsky for the angular forward-pea king in preequilibrium reactions, Kalbach's 1988 angular distribution systematics for a neutron projectile can be straightforwardly modified for use in photon-induced reactions. This results in photonuclear ang ular distributions which are less forward-peaked than their nucleon-in duced counterparts, due to the small momentum carried by a photon. Our predictions are compar ed against double-differential monochromatic C -12 (gamma, xp) data at 60 and 80 MeV and are seen to describe the mea surements fairly well.