Studies of muon response in Tile Calorimeter of ATLAS detector

ATLAS is a general purpose experiment designed to explore the physics landscape in proton - proton collisions at the unprecedentedly high energy regime of the Large Hadron Collider at CERN. The Tile Calorimeter (TileCal) is a sampling plastic scintillator/iron detector and provide accurate energy and position measurements of electrons, photons, isolated hadrons, jets, and transverse missing energy, as well as helping in particle identification and in muon momentum reconstruction. TileCal is divided into three cylindrical sections, referred to as the long barrel (LB) and two extended barrels (EB). Each of the three TileCal barrels is composed of 64 azimuthal segments, referred to as modules. Each barrel consists of several layers. The hybrid prototype associated to one Tile Calorimeter module of ATLAS detector with new electronics system – the Demonstrator has been tested together with one long barrel module of Tile Calorimrter with beams of different particles. In order to calibrate A layer of LBC Module – Module 0, muon and electron data were analyzed. Each PMT response of A layer (of LBC) was equalized, and corresponding calibration coefficients were obtained using two methods: 1) by use of truncated mean value of the muon energy distribution; 2) by use of peak value of the muon energy distribution. Application of the calibration coefficients obtained using truncated mean improved the energy response of electrons, i.e. distribution of each cell’s response became more flat, as expected. In order to study muon energy loss per unit of length in A layer of LBC, data obtained by testing the Demonstrator with muons were analyzed. The dE/dX (energy loss per unit of length) distribution was evaluated for each cell of A layer using three approaches, with expectations that dE/dX value in each cell will be more or less equal, i.e. distribution of dE/dX will be flat. These approaches use different selection criteria of physics events. As a result of the third approach expected muon behavior was obtained, i.e. muon energy loss per unit of length in A layer’s cells of LBC barrel was more or less equal. Spread of cells’ dE/dX distribution was around 1.6%, much less compared to two other approaches.