Cross Section Measurement of pp->Z(ee)+X with First Data from the ATLAS Experiment

This presentation will cover the different ingredients of a cross section measurement of the process pp->Z(ee)+X with the first data from the ATLAS detector. An important part of this measurement is the knowledge of the efficiencies, such as trigger-, reconstruction- and identification-efficiencies. Currently, efforts are being made to test datadriven techniques to determine those efficiencies using Monte Carlo simulations and to ensure the functionality of these methods when data is available. Current results will be presented and their influence on the cross section measurement will be discussed.