The ATLAS Inner Detector commissioning and calibration

Abstract

The ATLAS Inner Detector is a composite tracking system consisting of silicon\npixels, silicon strips and straw tubes in a 2 T magnetic field. Its\ninstallation was completed in August 2008 and the detector took part in data-\ntaking with single LHC beams and cosmic rays. The initial detector operation,\nhardware commissioning and in-situ calibrations are described. Tracking\nperformance has been measured with 7.6 million cosmic-ray events, collected\nusing a tracking trigger and reconstructed with modular pattern-recognition and\nfitting software. The intrinsic hit efficiency and tracking trigger\nefficiencies are close to 100%. Lorentz angle measurements for both electrons\nand holes, specific energy-loss calibration and transition radiation turn-on\nmeasurements have been performed. Different alignment techniques have been used\nto reconstruct the detector geometry. After the initial alignment, a transverse\nimpact parameter resolution of 22.1+/-0.9 {\\mu}m and a relative momentum\nresolution {\\sigma}p/p = (4.83+/-0.16) \\times 10-4 GeV-1 \\times pT have been\nmeasured for high momentum tracks.\n