Performance of the ATLAS Transition Radiation Tracker Readout with High Energy Collisions at the LHC

The ATLAS Transition Radiation Tracker is the outermost of the three subsystems of the ATLAS Inner Detector. It contributes significantly to the precision of the momentum measurement of charged particles and to the identification of electrons. On the TRT front end electronics this is realized by discriminating the straw signal against two separate thresholds: a low one for tracking and a high one for electron identification. The electronics can also be configured to provide a trigger signal, which has been utilized to build a cosmic ray trigger that became extremely useful for the TRT as well as other subdetectors during ATLAS commissioning. This note will describe the TRT readout electronics and data acquisition, with emphasis on the experience gained during the first years of operation.