Operational Experience with the ATLAS Pixel Detector at the LHC

Abstract

TheATLASPixel Detectoristhe innermost detectoroftheATLASexperimentattheLarge Hadron CollideratCERN, providing high-resolution measurements of charged particle tracks in the high radiation environment close to the collision region. This capability is vital for the identification and measurement of proper decay times of long-lived particles such as b-hadrons, and thus vital for theATLASphysics program. 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 chipsbump-bonded to 1744 n-on-n silicon substrates. In this paper results from the successful operation of the Pixel Detector at the LHC will be presented, including calibration procedures, timing optimization and detector performance. The detector performance is excellent: approximately 97% of the pixels are operational, noise occupancyand hit efficiency exceed the design specification, and a good alignment allows high quality track resolution.