Photonuclear Angular Distribution Systematics in the Quasideuteron Regime

Abstract

We describe an applications-oriented method for determining continuum photonuclear angular distributions for emission of light particles (n, p, d, t, ³He, and α) in the quasideuteron regime (40≤E _inc≤140 MeV). Based on theoretical considerations by Chadwick and Oblozinsky for the angular forward-peaking 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 angular distributions which are less forward-peaked than their nucleon-induced counterparts, due to the small momentum carried by a photon. Our pre- dictions are compared against double-differential monochromatic ¹²C(γ, xp) data at 60 and 80 MeV and are seen to describe the measurements fairly well.

KEYWORDS:

• photonuclear reactions
• continuum angular distributions
• systematics
• light particles
• quasideuteron regime
• preequilibrium reactions