Status and future of the ATLAS Pixel Detector at the LHC

The ATLAS Pixel Detector is the innermost detector of the ATLAS experiment at the Large Hadron Collider at CERN. The detector provides hermetic coverage with three cylindrical layers and three layers of forward and backward pixel detectors. It consists of approximately 80 millions pixels that are individually read out via chips bump-bonded to 1744 n-in-n silicon substrates. Intensive calibration, tuning, timing optimization and monitoring resulted in the successful five years operation with good detector performance. The record breaking instantaneous luminosities of 7.7 · 1033cm−2s−1 recently surpassed at the LHC generate a rapidly increasing particle fluence in the ATLAS Pixel Detector. As the radiation dose accumulates, the first effects of radiation damage are now observable in the silicon sensors as an increase in the silicon leakage current and the change of the voltage required to fully deplete the sensor. The fourth pixel layer at the radius of 3.3 cm will be added during the long shutdown 2013-2014 together with the replacement of pixel services. Letter of Intent was submitted for the completely new pixel detector after 2023, capable to take data with extremely high leveled luminosities of 5 · 1034cm−2s−1 at High Luminosity LHC.