Electron performance with J/$\psi$ with the ATLAS detector

This paper describes the performance of low energy electron reconstruc- tion and identification at ATLAS with proton-proton collisions at a centre of mass energy of 7 TeV produced by the Large Hadron Collider. This study was performed with a sample collected from April to June 2010, correspond- ing to an integrated luminosity of 78 nb−1 . We present the reconstruction of prompt J/psi mesons decaying into e+ e− pairs. These electrons can be used to study the detector performance at low energy, as a complement of higher energy electrons coming from W and Z decays. A sample of ∼ 220 J/psi events can be selected. Their mass values reconstructed with different inputs agree with the values expected from the initial calibration of the ATLAS detector. The kinematics and shower shape distributions (used for identification purpose) have been extracted from the J/psi data sample and show a good agreement with the simulation.