Abstract
The response of pions and protons in the energy range of 20–180 GeV, produced at CERN's SPS H8 test-beam line in the ATLAS iron–scintillator Tile hadron calorimeter, has been measured. The test-beam configuration allowed the measurement of the longitudinal shower development for pions and protons up to 20 nuclear interaction lengths. It was found that pions penetrate deeper in the calorimeter than protons. However, protons induce showers that are wider laterally to the direction of the impinging particle. Including the measured total energy response, the pion-to-proton energy ratio and the resolution, all observations are consistent with a higher electromagnetic energy fraction in pion-induced showers. The data are compared with GEANT4 simulations using several hadronic physics lists. The measured longitudinal shower profiles are described by an analytical shower parametrization within an accuracy of 5–10%. The amount of energy leaking out behind the calorimeter is determined and parametrized as a function of the beam energy and the calorimeter depth. This allows for a leakage correction of test-beam results in the standard projective geometry.
Highlights
The Large Hadron Collider (LHC) at CERN collides protons with an energy of 7 TeV
The electron and muon contamination are below 0.5% for all beam energies
Unlike LHEP, in case of the QGSP list the underestimation of the longitudinal shower profiles is consistent in the energy range 20 to 180 GeV
Summary
The Large Hadron Collider (LHC) at CERN collides protons with an energy of 7 TeV. The resulting high center of mass energy will open a new chapter for particle physics exploring the high energy frontier. We study the response of the Tile Calorimeter (TileCal), located in the barrel part of the ATLAS detector, to pions and protons in the energy range of 20 to 180 GeV produced at the CERN SPS H8 test beam line. For the runs analyzed here a special nonprojective configuration of the test beam set-up has been used where the beam direction is perpendicular to the scintillating tiles (“90 degree configuration”) This configuration allows almost full shower containment and makes it possible to measure shower profiles up to 20 nuclear interaction lengths (λ). The energy resolution as a function of the calorimeter depth is presented
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