The GEM-based detector for tracking the Compton-scattered photons in the Laser Polarimeter facility at VEPP4-M collider

The Laser Polarimeter is being developed at VEPP-4M collider for beam energy calibration by Resonant Depolarization technique. The essential part of this facility is a photon-tracking detector measuring coordinates of backscattered gammas. The detector is based on triple-GEM cascade with pad readout. Its design and the first results of the measurements with radioactive source are described in the paper.