Operation and performance of the ATLAS semiconductor tracker

The semiconductor tracker is a silicon microstrip detector forming part of the inner
\ntracking system of the ATLAS experiment at the LHC. The operation and performance of the
\nsemiconductor tracker during the first years of LHC running are described. More than 99% of
\nthe detector modules were operational during this period, with an average intrinsic hit efficiency
\nof (99.74 0.04)%. The evolution of the noise occupancy is discussed, and measurements of the
\nLorentz angle, d-ray production and energy loss presented. The alignment of the detector is found
\nto be stable at the few-micron level over long periods of time. Radiation damage measurements,
\nwhich include the evolution of detector leakage currents, are found to be consistent with predictions
\nand are used in the verification of radiation background simulations.