Bonn 2010 – wissenschaftliches Programm

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HK: Fachverband Physik der Hadronen und Kerne

HK 36: Postersitzung

HK 36.51: Poster

Mittwoch, 17. März 2010, 14:00–16:00, HG Aula

The gas system for the ALICE Transition Radiation Detector — •Nora Pitz¹ and Chilo Garabatos Cuadrado² — ¹Institut fuer Kernphysik (IKF), Universitaet Frankfurt, Germany — ²Gesellschaft fuer Schwerionenforschung mbH (GSI), Darmstadt, Germany

The Transition Radiation Detector (TRD) of the ALICE experiment at CERN is a gaseous detector designed for electron identification, charged particle tracking and it also provides a fast trigger (6 μs). It consists of 18 super-modules with 540 individual detector chambers filled with a Xe/CO2 (85%/15%) gas mixture. The total gas volume is 25.8 m3. The gas has to be mixed, stored, distributed and circulated through the TRD which is ensured by the TRD gas system. Due to the high cost of Xe the recirculation in a closed loop is mandatory as well as the minimization of gas leakage, the purification and recovery of the gas. To monitor and follow the amounts of the components in the gas mixture an appropriate CO2 analyzer is implemented. Another issue is the pressure and flow regulation. The light construction of the TRD chambers limits the absolute overpressure to 3 mbar. In addition, the pressure gradient over the total height due to the weight of Xe is 2.5 mbar. Therefore it is necessary to segment the detector into height sections and regulate each sector independently. To assure a smooth process a permanent monitoring, controlling and analysis concerning O2-, H2O- and N2-contamination is therefore required. The actual status of the TRD gas system including all the above mentioned parts and parameters is presented and discussed in this talk.