Münster 2002 – wissenschaftliches Programm
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HK: Physik der Hadronen und Kerne
HK 34: Instrumentation and Applications IV
HK 34.2: Gruppenbericht
Mittwoch, 13. März 2002, 14:30–15:00, F
Track Reconstruction with Prototypes for ALICE TRD — •Oliver Busch — GSI Darmstadt
Hard processes, and in particular studies of charm and beauty production, have become the center stage for the ALICE physics program. The Transition Radiation Detector (TRD), in conjunction with other ALICE detectors, will allow to explore various aspects of dielectron physics, among them the production of quarkonia like J/ψ, ψ′ and the members of the Υ family. The study of such rare probes requires good electron identification and dedicated triggers to make the relevant signatures accessible to ALICE with sufficient statistics. The TRD provides the necessary capabilities to trigger on high pt (>3 GeV) electrons by means of track reconstruction in a magnetic field.
We have tested prototypes of the TRD composed of a radiator and a drift chamber with pad readout, filled with a Xe,CO2(15%) mixture and operated in a magnetic field of up to 0.3 T. The tests have been performed using the secondary pion beam at GSI Darmstadt with a momentum of 1 GeV/c. We compare results for different shapes of pads as well as various chamber geometries, in terms of trajectory reconstruction and single point resolution. As an important application, the Lorentz angle of ionization electrons drifting in a Xe based mixture has been measured directly for the first time. This quantity is relevant for the trajectory reconstruction in the final detector. We present the experimental results and compare them to GARFIELD calculations.