The ATLAS Semiconductor Tracker: operations and performance

After more than 3 years of successful operation at 2 the LHC, we report on the operation and performance of the Semi-Conductor Tracker (SCT) functioning in a high luminosity, 4 high radiation environment. The SCT is part of the inner tracking system of the ATLAS 6 experiment at CERN and is constructed of 4088 silicon detector modules for a total of 6.3 million strips. We find 99.3% of the 8 SCT modules are operational, noise occupancy and hit efficiency exceed the design specifications; the alignment is very close to 10 the ideal to allow on-line track reconstruction and invariant mass determination. We will report on the operation and performance 12 of the detector including an overview of the issues encountered. The observables employed to monitor online and offline the 14 quality and the performance of the data acquired by the SCT will be described and discussed.