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

A magnetic spectrometer system has been constructed for the study of reacti ons with multiple charged particles in the final state, induced by polarize d 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 dete ctors embedded inside the magnet. Multiwire proportional chambers, plastic scintillator hodoscopes, and threshold Cherenkov detectors placed outside t he magnet provide additional tracking,triggering and particle identificatio n capabilities. The system has been applied to study exclusive hyperon as w ell as pseudoscalar and vector meson production reactions at bombarding ene rgies below 3 GeV. Additionally, it has been used to monitor the proton bea m polarization at Laboratoire National Saturne. The components and performa nce of the system are reported. (C) 1999 Elsevier Science B.V. All rights r eserved.