Single Hadron Response Measurement in ATLAS

Single hadron response measurement in minimum bias proton-proton collisions at a center of mass energy of $sqrt{s}=7$~TeV are presented. Together with test-beam results, these measurement form the basis to evaluate the calorimeter energy response uncertainty of jets at high transverse momenta. A novel technique to evaluate the jet energy response from the single particle response will be presented. The single hadrons response is measured in the momentum range of 0.5 to about 20~GeV in-situ, by comparing the calorimeter response of all energy deposits in a cone around an isolated track with the more precisely measured track momenta. The agreement between data and Monte Carlo simulation is on the level of a few percent. Using kaon and $Lambda$ particles, the calorimeter response of identified pions, proton and anti-proton is studied. The MC simulation describes the energy response of pions and protons well, but differences are observed for anti-protons. It is discussed how the jet calorimeter response uncertainty and its correlation between transverse momentum bins is determined from these measurements.