Vermessung der Wechselwirkungszone im ATLAS-Detektor am LHC

In 2010 the ATLAS detector at the LHC recorded proton-proton collison data with a center-of-mass energy of 7 TeV. In this thesis, the ATLAS beam spot of three runs of the end of the 2010 data-taking period are measured using the distributions of primary vertices. Position, dimension and shape of the beam spot are analyzed concerning the run in total as well as the temporal developments during the run. For the run 167776 data the width of the beam spot are determined as $\sigma_X = (41.02\pm0.02)\mu$m, $\sigma_Y = (31.95\pm0.02)\mu$m and $\sigma_Z = (61.16\pm0.03)$mm. A tilt of the beam spot with respect to the axis of symmetry of ATLAS is observed causing the apparent higher width in the horizontal direction compared to the vertical direction. Using the coordinate system of the beam spot itself, the transversal width difference disappears. An expected emmitance growth and a movement of the center of the distribution during the runs are visualized and compared between the analyzed runs.