Pixel Detector Studies for the ATLAS ITk Upgrade for the HL-LHC

<!--HTML-->The integrated luminosity of the Large Hadron Collider (LHC), which is proportional to the number of particles colliding and thus data being collected, is planned to be increased by a factor of 5-7.5 compared to the design luminosity of the LHC by the end of the 2020s. This step is motivated by the potential to measure Standard Model physics processes especially in the top quark and Higgs sector with high precision and discover new physics.<br>However, this upgrade to the High Luminosity-LHC will result in an increased particle density in the experiments, causing a higher hit occupancy in the detectors and an increased radiation damage. In order to tackle this problem, the current tracking detectors of the LHC experiments atlas and CMS need to be replaced by radiation harder, faster detectors of higher granularity. The inner tracking detector of the atlas Experiment will be upgraded to an all silicon detector by the end of 2028. There will be a new strip detector with planar sensors and a hybrid pixel detector which features inner layers with 3D sensors and outer layers with planar sensors.<br>The following work is focused on the outer layers of the pixel Detector and the different steps towards the upgrade. First, suitable sensors need to be decided on based on laboratory and test beam measurements. A second step is the pixel Detector module building with a newly developed tool and electrical and mechanical testing of the modules themselves. Validation measurements of the tool in addition to a well-defined assembly process are crucial for a successful production. Eventually, the performance of several modules together needs to be investigated, which is done by integrating them in a larger prototype structure built at CERN.<br>Results from all these steps are presented within the scope of this thesis.