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T: Teilchenphysik
T 108: Spurkammern I
T 108.5: Vortrag
Montag, 18. März 2002, 15:00–15:15, SR 1039/40
Commissioning of Triple GEM detectors in the COMPASS tracker — •Jan Ehlers1, Cem Altunbas2, Klaus Dehmelt3, Jan Friedrich4, Boris Grube4, Steffen Kappler5,6, Bernhard Ketzer4, Igor Konorov4, Stephan Paul4, Alfredo Placci6, Leszek Ropelewski6, Fabio Sauli6, and Frank Simon7 — 1Ruprecht-Karls-Universitaet Heidelberg, Germany — 2State University of New York, Buffalo, U.S.A. — 3Florida Institute of Technology, Melbourne, U.S.A. — 4Technische Universitaet Muenchen, Germany — 5Universitaet Karlsruhe, Germany — 6CERN, EP division, CH-1211 Geneva 23, Switzerland — 7Max-Planck-Institut fuer Physik, Munich, Germany
For the small area tracking of particles within COMPASS, a fixed target experiment at CERN/SPS, up to now 14 out of 20 large-size (31 x 31 cm2) detectors based on the Gaseous Electron Multiplier (GEM) have been built, installed and commissioned. These new devices, consisting of three GEM amplification stages with a two-dimensional readout, combine good spatial resolution of better than 50 um with high rate capability, which is required by the large particle flux. At the same time the material exposed to the beam is minimized in order not to spoil the mass resolution of the spectrometer. The detectors were subject to extensive tests in the beam. They were showing, that full (i.e. > 98 % detection efficiency for minimum ionizing particles can be achieved at normal run conditions (total effective gain of 8000), while the occurence of discharges was successfully suppressed. First results of the operational characteristics of these detectors in the COMPASS beam 2001 are presented.