Münster 2002 – scientific programme
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HK: Physik der Hadronen und Kerne
HK 14: Poster Session: Instrumentation and Applications
HK 14.16: Poster
Tuesday, March 12, 2002, 10:30–12:45, Foyer Chemie
Tracking Capabilities of COMPASS GEM Detectors† — •Frank Simon1, Jan Friedrich2, Boris Grube2, Bernhard Ketzer3, Igor Konorov2, Stephan Paul2, and Fabio Sauli3 — 1Max–Plank–Institut für Physik, München, Germany — 2Physik–Department E18 TU München, Garching, Germany — 3CERN, Geneva, Switzerland
For the small angle tracking of the COMPASS Experiment at CERN’s SPS accelerator, a total of 20 triple–GEM detectors, each with an active area of 31×31 cm2, are used. Prior to their successful operation in the COMPASS physics run in 2001, the detectors were tested in various particle beams to determine their tracking capabilities. The spatial resolution was shown to be better than 50 µm and an efficiency of 99% was reached for minimum–ionizing particles. The GEM detectors are equipped with an orthogonal two–dimensional projective readout that leads to a correlation between the charge collected on both readout coordinates. The charge ratio has a mean value close to unity and a width σ < 0.1. This can be exploited to resolve ambiguities due to multiple hits by combining hits on projections into space points and thus improve the track reconstruction. † Supported by BMBF, Germany and by Maier–Leibnitz–Laboratorium, Garching, Germany