Abstract
A modified 4 pi-system PHASE is described, which is intended for studying multiple fragmentation reactions in a target bombarded by relativistic light nuclei on the synchrophasotron of the Joint Institute for Nuclear Research (JINR, Dubna). The setup contains five telescope spectrometers with a resolution of Delta Z/Z < 7% and an array of 64 scintillation detectors with large-area CsI(TI) film scintillator (20-25 mg/cm(2); approximate to 150 cm(2)), which allow the multiplicity of intermediate-mass fragments and their distributions with respect to escape angles to be determined. The use of a new construction of optical guides increased the optical resolution of scintillation detectors by a factor of 1.4, decreased scatter of the resolution of various counters relative to the average value, and significantly suppressed the background caused by the beam halo.