Performance and Calibration of the ATLAS Tile Calorimeter

The Tile Calorimeter (TileCal) is the central section of the ATLAS hadronic calorimeter at the Large Hadron Collider. This detector is instrumental for the measurements of hadrons, jets, tau leptons and missing transverse energy. Scintillation light produced in the tiles is transmitted by wavelength shifting fibers to photomultiplier tubes (PMTs). The resulting electronic signals from approximately 10000 PMTs are measured and digitized before being transferred to off-detector data-acquisition systems. After an initial setting of the absolute energy scale in test beams with particles of well-defined momentum, the calibrated scale is transferred to the rest of the detector via the response to radioactive sources. The calibrated scale is validated in situ with muons and single hadrons whereas the timing performance is checked with muons and jets. A brief description of the individual calibration systems (Cs radioactive source, laser, charge injection, minimum bias) is provided. Their combination allows to calibrate each part of the data acquisition chain (optical part, photomultiplier, readout electronics) and to monitor its stability to better than 1%. The procedure for setting and preserving the electromagnetic energy scale during Run 1 data taking is discussed. The issues of linearity and stability of the response, as well as the timing adjustment are also shown. The data quality procedures used during the LHC data‐taking and the evolution of the detector status are presented. The energy and the time reconstruction performance of the digitized signals is summarized and the noise behavior and its improvement with the detector consolidation in maintenance periods are shown.