Response of single isolated hadrons in the ATLAS calorimeter

Data produced in proton-proton collisions at a center-of-mass energy of $\sqrt{s} = 900$ GeV collected by the ATLAS experiment at CERN are used to select isolated tracks and to probe the calorimeter response associated to them. The ratio E/P between the energy E deposited in the calorimeter around the track impact point, and the track momentum P is measured over a wide rapidity range for particles with momentum range from 0.5 to 10 GeV. The average measured E/P is compared to the predictions of the Monte Carlo simulation.