Determination of the Jet Energy Scale Uncertainty in the ATLAS Detector

About one year after the first proton proton collisions at a centre of mass energy of sqrt(s)= 7 TeV the ATLAS experiment has achieved an accuracy of the jet energy measurement between 2-4% for jet transverse momenta from 20 GeV to 2 TeV in the pseudo-rapidity region up to eta=4.5. The jet energy scale uncertainty is derived from in-situ single hadron response measurement a long with systematic variations in the Monte Carlo simulation. In addition, the transverse momentum balance between a central and a forward jet in events with only two jets at high transverse momentum is exploited. The obtained uncertainty is confirmed by direct in-situ measurements exploiting the transverse momentum balance between a jet and a well measured reference like the photon transverse in photon-jet events or the total transverse track momentum. Jets in the TeV-energy regime can be also tested using a system of well calibrated jets at low transverse momenta against a high-pt jet.