Calibration of electrons and photons with the ATLAS detector, and its impact on ATLAS precision measurements

A precise energy calibration of electrons and photons is a key ingredient to many measurements performed with the ATLAS detector, such as the measurement of the Higgs boson mass. An improved calibration scheme is based on corrections derived from collision data, multivariant algorithms for the energy reconstruction and finally electrons from Z boson decays to set the absolute energy scale. Studies of the longitudinal shape of electromagnetic showers also lead to an improved detector material simulation. The calibration is checked with electrons from J/psi decays and photons from radiative photon decays. This contribution will describe the calibration scheme and the cross checks and the impact on ATLAS measurements.