THE LARGE-ACCEPTANCE SPECTROMETER TAGX FOR PHOTOREACTION STUDIES AT THE 1.3-GEV TOKYO ELECTRON SYNCHROTRON

The study of photoreactions on light nuclei with the TAGX spectrometer started in 1987 using the 20% duty-cycle tagged-photon beam at the 1. 3-GeV Tokyo electron synchrotron. TAGX is comprised of a pi-sr magneti c spectrometer for detection of charged pions, kaons, and protons and a 0.85-sr time-of-flight spectrometer for neutrons. It has served in t he past eight years as a unique medium-energy-resolution multi-particl e spectrometer for coincidence experiments to detect such final states as pn, pp, pi(+) pi(-), ppn, pp pi(-), and pn pi(+)pi(-): some of whi ch were kinematically-complete measurements of three-particle and four -particle final states. Details of the detector components, their perf ormance. data acquisition, event reconstruction analyses, and detector -acceptance calculations are described together with the results of ex perience acquired in those experiments. A TAGX improvement in the mome ntum resolution required for charged particle measurements in the 1-Ge V photon energy region is also reported.