Trigger – scintillation counters S1-S Trigger conditions: S1 – to choose a narrow (0.1 mm or less) beam fraction S2 – to scan channeled and reflected beam fractions S3 – to overlap a channeled beam fraction S1 S2 – to determine an experiment axis S1 S3 – to find a perfect alignment for channeling S1, S2 – finger scintillators 0.1*1*10 mm 3 S3 – finger scintillator 2*1*10 mm 3 S1 Detector S3 Channeled fraction S2 Reflected fraction Crystal BPM

Electronic scheme of a trigger with scintillation counters S1-S3 – thin scintillators PMT – photomultipliers Electronic blocks from CERN: D1-D3 – discriminators CC1,CC2 – coincidence units Ch1-Ch3 – counters HV – high voltage source

Scintillation counter construction – JINR Scintillator is glued onto thin film with a reflecting surface Laser is used to align the scintillator with the beam Windows for the beam have the diameters of 30 mm Windows are closed by Al foils with thickness of 15 μm Beam Laser