DISTO: a large acceptance multiparticle spectrometer for 1-3 GeV proton beams

A magnetic spectrometer system has been constructed for the study of reactions with multiple charged particles in the final state, induced by polarized proton beams of few GeV energy. The system is based on a large-gap dipole magnet, with a liquid hydrogen target nd scintillating fiber tracking detectors embedded inside the magnet. Multiwire proportional chambers, plastic scintillator hodoscopes, and threshold Cherenkov detectors placed outside the magnet provide additional tracking,triggering and particle identification capabilities. The system has been applied to study exclusive hyperon as well as pseudoscalar and vector meson production reactions at bombarding energies below 3 GeV. Additionally, it has been used to monitor the proton beam polarization at Laboratoire National Saturne. The components and performance of the system are reported.