EXCLUSIVE O-16(GAMMA,PI-P) REACTION IN THE DELTA RESONANCE REGION

We report the first exclusive (gamma,pi--p) measurements on a complex nucleus. The O-16(gamma,pi--p) reaction was measured at pion laboratory angles of 64-degrees and 120-degrees. Coincident protons were detected over the quasifree angular correlation range using a vertical array of seven plastic scintillator detectors spanning +/-33-degrees about the scattering plane. The cross sections are compared to factorized distorted-wave impulse approximation calculations; these provide a good description of the backward angle data, but are in serious disagreement with the forward angle data.