Signal observation from minimum ionizing particles and time resolution estimation in the Triple GEM detector

99-009 Recently a Triple-GEM detector constructed at PNPI has been tested in a PSI hadronic beam (pions at 215 MeV/c and protons at 350 MeV/c). GEM-foils used in the detector have a pitch of 140 microns and hole size in Kapton of about 40 microns. The detector has a sensitive area of 100*100 mm^2 and a 2 mm drift gap. The anode plane contains strips with 300 microns pitch. The detector was operated with the mixture of 0.7Ar+0.3CO2 at a gas gain about 1*10**4. It has shown good operation reliability in high intensity hadron beams up to 3*10**6 Hz/cm^2. Signals from both sides of the induction gap, i.e. from the GEM and from the anode strips, have been recorded with the wide-band digital scope. The current pulses produced by MIPs in the detector have been reconstructed. The time resolution of the Triple-GEM detector has been estimated from the recorded data: rms=6ns.