Performance and operation of the semiconductor tracker (SCT)

After more than 3 years of successful operation at the LHC, we report on the operation and performance of the ATLAS Semi-Conductor Tracker (SCT) functioning in a high luminosity, high radiation environment. The SCT is constructed of 4088 silicon detector modules, for a total of 6.3 million strips. Each module is designed, constructed and tested to operate as a stand-alone unit, mechanically, electrically, optically and thermally. The modules are mounted into two types of structures: one barrel (4 cylinders) and two end-cap systems (9 disks on each end of the barrel). The SCT silicon micro-strip sensors are processed in the planar p-in-n technology. The signals are processed in the front-end ABCD3TA ASICs, which use a binary readout architecture. Data is transferred to the off-detector readout electronics via optical fibres. We find 99.3% of the SCT modules are operational and the hit efficiency exceeds the design specifications. We will report on the operation and performance of the detector, including an overview of the issues encountered. We will report the expected observation of significant increases in leakage currents from bulk damage due to non-ionizing radiation and make comparisons with the predictions. We will also cover the time evolution of the key parameters of the strip tracker, including the evolution of noise and gain and the tracking efficiency in the harsh LHC environment. Valuable lessons for future silicon strip detector projects will be presented.