Using $Z^0 \rightarrow e^+ e^-$ for Electromagnetic Calorimeter Calibration

A new fitting method, using pp to X+Z events, with Z to e+e-, has been developped to calibrate the ATLAS electromagnetic calorimeter. Validity tests were carried on Pythia events, and the method was tested on the DC1 simulation data. These results can be extrapolated to the ATLAS configuration. The forseen 0.3 % precision on the calibration coefficients of 448 Delta eta x Delta phi regions could be achieved within two to three days, and monitored on this basis, at low luminosity.