The System of Anticoincidence Detectors of Space-Based Gamma-Ray Telescope GAMMA-400: The Characteristics Obtained Using Positron Beam of Synchrotron S-25R “PAKHRA” of the Lebedev Physical Institute, Russian Academy of Sciences

The space-based gamma-ray telescope must effectively separate photons from charged particles of instrumental background and cosmic rays. It requires that the anticoincidence system of the telescope must have high detection efficiency, large dynamic range and good enough energy and time resolution for charged particles. The main results obtained using 246 MeV secondary positron beam of synchrotron S-25R “PAKHRA” of Lebedev Physical Institute with prototype of system of anticoincidence detectors of space-based gamma-ray telescope GAMMA-400 are presented. The amplitude resolution, time resolution and charged particles detection efficiency are adduced. All measurements were performed using “fast” output of silicon photomultipliers of prototype scintillation detectors sensors. Fractal dimensions of temporal profiles registered during measurements using positron beam and atmospheric muons are discussed.