The transition radiation tracker of the ATLAS experiment

The Transition Radiation Tracker is a part of the Inner Detector of the ATLAS experiment. It combines electron identification capability with charged particle track reconstruction. A total of 420000 electronic channels provide continuous tracking with many projective measurements. This paper gives details of some features of the TRT, from performance requirements to the consequences of its operation in the LHC environment. Some technical choices and operating conditions have been recently changed, the operating gas among them. Presently a large fraction of barrel and end-cap modules have been assembled in the US and Russia respectively. A strict quality assessment has been implemented at the assembly sites and at CERN upon arrival of the modules. The acceptance tests include dimensional surveys, wire tension measurements, gas tightness tests, high voltage training, and gas gain uniformity along each individual straw. First estimates of module quality are given.