Electron efficiency measurement at low energies with J/psi in ATLAS

The understanding of the reconstruction of electrons in the ATLAS experiment at LHC is one of the key issues for the run at a center of mass energy of 7 TeV and is of particular importance in any analysis with isolated electrons in final state. We describe the measurements performed using tag-and-probe techniques to establish reference electron efficiencies at low transverse energies based on J/psi->ee events, over the full pseudorapidity range of |eta|<2.5 The bulk of the poster is devoted to the electron identification efficiencies but also describes the selection of the Jpsi->ee events. The results are presented as efficiencies and also as scale factors to be applied to correct the expected efficiencies from simulation.