Performances of the signal reconstruction in the ATLAS Hadronic Tile Calorimeter

Abstract

The Tile Calorimeter (TileCal) is the central section of the hadronic calorimeter of ATLAS. It is a key detector for the reconstruction of hadrons, jets, tau leptons and missing transverse energy. TileCal is a sampling calorimeter using steel as an absorber and plastic scintillators as an active medium. The scintillators are read-out by wavelength shifting fibers coupled to photomultiplier tubes (PMTs). The analogue signals from the PMTs are amplified, shaped and digitized by sampling the signal every 25ns. The read-out system is designed to reconstruct the data in real time fulfilling the tight time constraint imposed by the ATLAS first level trigger rate (100kHz). The signal amplitude and phases for each channel are measured using Optimal Filtering algorithms both at online and offline level. We present the performances of these techniques on the data collected in the proton–proton collisions at center-of-mass energy of 7TeV. We show in particular the measurements of low amplitudes, close to the pedestal value, using as probe high transverse momenta muons produced in the proton–proton collisions.