A HIGH ANGULAR-RESOLUTION AND TIME-OF-FLIGHT DETECTOR SYSTEM FOR RECOIL PROTONS FROM THE REACTIONS P(GAMMA, GAMMA)P AND P(GAMMA, PI-DEGREES)P

Using the Mainz NaI(TI)-BaF2 photon spectrometer CATS (Compton And Two photon Spectrometer) together with the prototype of a universal spect rometer for recoil protons TRAJAN (TRAjectory ANalyser) we have studie d different methods to disentangle Compton scattering by the proton fr om the large pi(0) background through the energy range of the Delta re sonance. CATS is a modular 48 cm empty set x 64 cm NaI(Tl) detector wi th an energy resolution of 1.5% combined with a 2 pi array of 61 BaF2 detectors. TRAJAN consists of a hodoscope with two planes, a wire cham ber with horizontal and vertical wires and a grid of horizontal and ve rtical plastic scintillator strips, followed by a wall of nine NaI(Tl) detectors. By this arrangement the proton energy was obtained via a t ime-of-flight analysis and the recoil angle of the protons via a traje ctory reconstruction. Additionally, a Delta E-E analysis of the detect ed particles allows us to suppress the electromagnetic background. By reconstructing the proton trajectory the segment of the scattering tar get can be determined where the Compton scattering process or the pi(0 ) production process had taken place. In this way it is possible to co rrect the event distributions for the smearing-out caused by the finit e target length and thus to improve on the separation of the two types of events.