Combined Studies of the EM Calorimeter and the Inner Detector in the 2004 ATLAS Combined Testbeam

In 2004 at the ATLAS combined test beam, one slice of the ATLAS barrel detector (including an Inner Detector set-up and the Liquid Argon (LAr) calorimeter) was exposed to particles from the H8 SPS beam line at CERN. It was the first occasion to test the combined electron performance of ATLAS. This presentation will show the results obtained for the electromagnetic performance of the LAr calorimeter (linearity, uniformity and resolution). Results obtained with a very low energy set-up (electron energies down to 1GeV) will be presented validating the LAr electromagnetic energy reconstruction down to very low energies. Results obtained for the E/p ratio and a way how to extract scale parameters will be shown. Studies on Bremstrahlungs-recovery algorithms relying on the LAr calorimeter will be discussed on the basis of results obtained in the testbeam.