Particle Identification Performance of the ATLAS Transition Radiation Tracker

The Transition Radiation Tracker (TRT) is the outermost charged particle tracking device of the ATLAS Inner Detector. In addition to its tracking capabilities the TRT provides discrimination between electrons and pions over the energy range between 1 and 200 GeV by utilizing transition radiation. The electron identification is further improved using the measurement of the signal length. The same information can be used for kaon identification at low momenta as well as to search for new physics phenomena such as supersymmetric stable massive particles. In this note, we present the particle identification performance of the TRT detector during the first year of 7 TeV collision data-taking.