Electron and Photon Reconstruction and Identification with the ATLAS Detector

This article presents the electron and photon reconstruction performance in ATLAS with the first LHC collision data at $sqrt{s}$~=~7~TeV collected up to the beginning of June 2010. Calorimetric and tracker related electron identification variables are shown to be in a fair agreement with the Monte Carlo model. %Material estimations in the inner detector were checked with photon conversions vertex position, complementarily to the energy flow from minimum bias events for material at larger radii. The position of the reconstructed photon conversions vertices has been used to compare the inner detector model used in Monte Carlo to the real one from data. The energy flow measured in the electromagnetic calorimeter with minimum bias data has been used to provide the same comparison at larger radii. $pi^0 ightarrow gamma gamma$ and $J/Psi ightarrow ee$ peaks were observed with a reconstructed mass in good agreement with both Monte Carlo and PDG value. 17 $W ightarrow e u$ candidates and one $Z ightarrow ee$ candidate have been observed in 6.69~nb$^{-1}$ of data.