Calibration of the CMS Pixel Detector at the Large Hadron Collider

The Compact Muon Solenoid (CMS) detector is one of two general-purpose detectors that reconstruct the products of high energy particle interactions at the Large Hadron Collider (LHC) at CERN. The silicon pixel detector is the innermost component of the CMS tracking system. It determines the trajectories of charged particles originating from the interaction region in three points with high resolution enabling precise momentum and impact parameter measurements in the tracker. The pixel detector is exposed to intense ionizing radiation generated by particle collisions in the LHC. This irradiation could result in temporary or permanent malfunctions of the sensors and could decrease the efficiency of the detector. We have developed procedures in order to correct for these effects. In this paper, we present the types of malfunctions and the offline calibration procedures. We will also show the efficiency and the resolution of the detector in 2012.