The ATLAS Pixel Detector operation and performance

The ATLAS Pixel Detector is the innermost detector of the ATLAS experiment at the Large Hadron Collider at CERN. It consists of 1744 silicon sensors equipped with approximately 80× 106 electronic channels, providing typically three measurement points with high resolution for particles emerging fromthe beam-interaction region. The complete Pixel Detector has been taking part in cosmic-ray data-taking since 2008. Since November 2009 it has been operated with LHC colliding beams at √s = 900 GeV, 2.36 TeV and 7 TeV. The detector operated with an active fraction of 97.2% at a threshold of 3500 e, showing a noise occupancy rate better than 10−9 hit/pixel/BC and a track association efficiency of 99%. The Lorentz angle for electrons in silicon is measured to be qL = 12.11◦ ±0.09◦ and its temperature dependence has been verified. The pulse height information from the time-over-threshold technique allows an improvement of the point resolution using charge sharing and particle identification at low momentum using the specific energy loss.