The Atlas Tile hadronic calorimeter response to pions and protons

The improvement of the calorimeter resolution with the increase of energy is the main motivation for the major role played by calorimeters in LHC experiments. The hadronic Atlas-Tilecal calorimeter will measure the energy of jets produced in the central region of Atlas detector, the region of high precision measurements. A comparative analysis of the Tilecal calorimeter response to pions and protons has been done using positron and positive pion beams obtained in the H8 beam line at SPS. The significant amount of protons into the pion beams as well as the amount of pions and protons into the positron beams gave us the possibility to carry out this comparative analysis based on the new data taken with final modules of Tilecal. The separation between pions, protons and positrons has been done using the H8 line Cerenkov Counter as well as the simulation results of Tilecal response with GEANT3 and GEANT4 packages. The previous results obtained with Tilecal prototypes are confirmed by the new data - a higher response for pions as well as a better resolution for protons. For the first time, we have included in our analysis the study of the differences between the longitudinal and lateral profiles of pions and protons. All the results obtained using the experimental data were compared with the predictions of GEANT3 and GEANT4 codes. The final goal of our analysis is to estimate the possibility to use the proton-pion differences in the Tilecal calorimeter response in the identification of Atlas events, taking into account the great complexity of these ones. (author)