Berlin 2005 – wissenschaftliches Programm

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HK: Physik der Hadronen und Kerne

HK 35: Instrumentation und Anwendungen

HK 35.3: Vortrag

Dienstag, 8. März 2005, 17:30–17:45, TU MA144

Transition Radiation Spectroscopy with Prototypes of the ALICE TRD — •Christian Lippmann — Gesellschaft für Schwerionenforschung mbH, Darmstadt, Germany

The ALICE Transition Radiation Detector (TRD) consists of 540 large-area drift chambers with charge sensitive cathode pad read out. The TRD trigger performs online tracking and electron identification and thus requires excellent position resolution and pion rejection. As signatures to discriminate electrons from pions the different ionization energy loss and the emission of X-ray transition radiation photons by electrons are used.

To optimize the electron identification the knowledge of the spectral distributions of ionization energy loss and of detected transition radiation (TR) in the momentum region of interest are crucial. We carried out extensive measurements of TR spectra produced in our irregular foam/fiber radiators, in regular foil radiators, in pure fiber and in pure foam radiators at 1 to 10 GeV/c. To estimate additional contributions we also replaced the radiators by a dummy with similar radiation length. In all measurements the TR was separated from the beam by a strong magnetic field. The measurements were carried out at a secondary beam at the CERN PS in autumn 2004. To complete the picture, the data are compared to simulations.