Tübingen 2003 – scientific programme

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HK: Physik der Hadronen und Kerne

HK 4: Instrumentation und Anwendungen I

HK 4.6: Talk

Monday, March 17, 2003, 17:15–17:30, C

Measurements of electron attachment in Xe, CO₂ (15%) gas of ALICE TRD — •Georgios Tsiledakis — GSI Darmstadt

The ALICE Transition Radiation Detector (TRD) will be used for electron identification and particle tracking in high multiplicity environment in heavy-ion collisions at LHC. This requires accurate pulse height measurements in drift chambers filled with Xe, CO₂ (15%) gas mixture over the drift time of the order of 2 µs. Therefore, it is of main importance to avoid any possible charge loss by electron attachment. We present measurements of pulse height distributions in drift chambers operated with Xe, CO₂ mixtures performed during prototype tests for the ALICE TRD. After studying the general behavior of these distributions under clean conditions, we investigate the attachment of primary electrons on oxygen and SF₆ contaminants in the detection gas. We compare our results with simulations of charge transport for various gas mixtures. We also present gas quality checks via gas chromatography analysis and ⁵⁵Fe measurements using especially-built monitoring detectors.