Status of the ATLAS Pixel Detector at the LHC and its performance after three years of operation

The ATLAS Pixel Detector is the innermost detector of the ATLAS experi- ment at the Large Hadron Collider at CERN, providing high-resolution mea- surements of charged particle tracks in the high radiation environment close to the collision region. The detector provides hermetic coverage with three cylindrical layers and three layers of forward and backward pixel detectors. It consists of approximately 80 million pixels that are individually read out via chips bump-bonded to 1744 n-in-n silicon substrates. After three years of operation the detector performance is excellent: 96% of the pixels are opera- tional, at 3500 e threshold noise occupancy and efficiency exceed the design specification. The effect of radiation on the silicon sensor is measured and compared with model of radiation damage.