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Abstract

For the High Luminosity Large Hadron Collider (HL-LHC) upgrade, the current tracking system of the ATLAS experiment will be replaced by an all-silicon system, called Inner Tracker (ITk). The closest to the collision point will be the Pixel Detector sub-system, instrumented with modules employing two sensor technologies: single-chip modules with 3D sensors and four-chip (quad) modules with planar sensors. For the planar sensors, the thin n^+-in-p technology was chosen, which implements sensors of reduced thickness and higher readout granularity with respect to the original pixel detector of the ATLAS experiment. The next phase of the ITk pixel project is the production, assembly and testing of pixel modules. The main focus of this thesis is the performance evaluation of assembled quad modules, which can be divided into the laboratory and test-beam measurements. For the former, the experimental setup was adapted and optimized in the scope of this thesis and used for testing of first assembled prototype quad modules. Assembled modules with sensors from different manufacturers will be tested with particle beams before and after irradiation. To ensure fast and smooth test-beam data reconstruction and analysis, the transition to the new framework, called Corryvreckan, was performed as a part of this thesis. Before choosing this framework as the standard tool for the analysis of ATLAS ITk pixel test-beam data, the validation was performed to compare its performance to that of previously used software packages. Additional functionalities were implemented to accommodate the non-uniform pixel matrix of the quad sensors. The framework as such was used to evaluate the performance of quad modules with two readout chip versions, the prototype RD53A chip and the pre-production ITkPixV1.1 chip. Quantities such as cluster size and residual distributions, as well as hit efficiency, were studied for various pixel sizes implemented for the quad modules. As a part of the pre-production phase, the characterization of sensors from one 100 µm thick wafer was performed. This allows to determine the quality of manufactured sensors with respect to the ITk requirements.