Bonn 2010 – wissenschaftliches Programm
HK 30.3: Vortrag
Dienstag, 16. März 2010, 17:15–17:30, HG VIII
Calibration of the ALICE Transition Radiation Detector — •Raphaelle Bailhache — Institut für Kernphysik, Frankfurt, Deutschland
The ALICE Experiment is one of the four experiments installed at the Large Hadron Collider (LHC). It is equipped with a Transition Radiation Detector (TRD), a gaseous detector for electron identification and charged particle tracking located at a radius of 2.9 m. When a charged particle crosses the TRD, it ionizes the gas along its path and electrons drift in a uniform field of 700 V/cm over 3 cm before being amplified. To optimize the detector performance, the drift velocity of the electrons, the time-offset of the signal and the amplification factor have to be corrected for variations of the temperature, pressure and gas composition. Therefore a first determination of the calibration constants is done continuously during data taking. On the ALICE data acquisition system (DAQ) simple algorithms are executed. On the High Level Trigger (HLT), the tracks of charged particles are reconstructed online and used for the calibration. Offline improvements are achieved after the first reconstruction pass of the data. In this talk, we will show the results obtained with the seven TRD supermodules presently installed in ALICE. The performances of the different calibration steps are compared and tested on data taken with first proton beams and cosmic rays in the ALICE setup.