ATLAS Detector status, operations and performance

ATLAS is a general–purpose detector located at one of the four interaction points of the Large Hadron Collider (LHC) at the CERN laboratory near Geneva, Switzerland. In 2010 and since March 2011 LHC is colliding proton beams at the unprecedented centre–of–mass energy of 7 TeV. The last month of 2010 operation was dedicated to Pb–ion collisions at a centre–of–mass energy of 2.76 TeV per nucleon pair. A challenging task of the previous months was to cope with the increasing event rates due to the increasing luminosity delivered by the LHC collider. A survey of the main ATLAS subdetector systems, their operating conditions and the performance with colliding beams will be presented in this talk. The operation and the results obtained from the data collected so far demonstrate that the detector is robust and functioning very well .