Beam studies of SAD-150 heavy crystal PWO calorimeter, small angle multiphoton detector of GAMS-4π spectrometer

Small Angle Detector (SAD-150) is a PbWO4 heavy crystal electromagnetic calorimeter with high energy and coordinate resolution for multiphoton events. It has been included in the GAMS-4π setup and calibrated in muon and electron beams. Test measurements of forward emitted π0 and η in the π− p charge exchange reactions with 32.5GeV/c π− at the IHEP proton synchrotron are reported. The measured mass resolution in the η region agrees with the design value. SAD-150 performance does not deteriorate with π− intensities up to 106 π−/s per cell.