Performance of the Electron and Photon Trigger in p-p Collisions at a centre of mass energy of 900 GeV

This note summarises the performance of the electron and photon triggers which were run online during the ATLAS data taking period at the end of 2009. Approximately 20 $mu$b of data have been collected at a centre of mass energy of 900 GeV with around half of the 900 GeV data taken under stable beam conditions. During this period the Level-1 calorimeter trigger was working reliably and a good agreement between the energy calculated at the trigger level compared to the offline has been found. At Level-2 and Event Filter the quantities used in the trigger selections have been compared to the corresponding offline quantities and also here a good agreement is found. Furthermore, it will be shown that the Monte-Carlo predictions model reasonably well the data.