Performance of the ATLAS electromagnetic calorimeter for $\pi^0\to\gamma\gamma$ and $\eta\to\gamma\gamma$ events

The first collision data at √s=900 GeV have been used to extract the $\pi^0$ and $\eta$ signals in the $\gamma\gamma$ final state. The dedicated reconstruction, calibration and identification of these low energy photons are presented. Using the $\pi^0\to\gamma\gamma$ sample, the response uniformity along the pseudo-rapidity has been found to be better than ±2% from the ratio of data toMonte Carlo