Relative Luminosity Measurement of the LHC with ATLAS FCAL HV currents

The measurement of the luminosity is an important issue in every particle collider experiment. This thesis studies the possibility of a measurement of the relative luminosity of the new proton-proton collider, the LHC, for the ATLAS experiment. The measurementis based on the readout of the high voltage return current of the electromagnetic section of the forward calorimeter FCAL1 in ATLAS. To investigate the proportionality between the FCAL1 HV currents and the luminosity of the LHC, the participation at testbeams with a small prototype of the FCAL1 and the analysis of the testbeam data is described. These testbeams took place at the U-70 proton accelerator in Protvino, Russia. During the testbeams it was possible to vary the beam intensity and to use this for a simulation of variable luminosities. The result is that the FCAL1 HV current depends linearly on the beam intensity and that this relative luminosity measurement is feasible in the ATLAS experiment with non-linearities less than 0.5%, both from a systematic and a statistical point of view.