Control, commissioning, operation and performance of the Phase-I upgrade of the LAr calorimeter electronics of the ATLAS detector

Research in high-energy physics aims to reveal the fundamental constituents of matter and elucidate the principles governing their interactions. This quest relies on sophisticated particle accelerators. The most powerful and currently the largest is the Large Hadron Collider (LHC) located at CERN (the European Organization for Nuclear Research). The LHC hosts four experiments, including ATLAS, a versatile particle detector designed to probe rare phenomena within collision data such as the search for the Higgs boson. After 15 years of running and a harvest of scientific results including the discovery of the Higgs boson in proton-proton collisions, the LHC is preparing two upgrade phases to increase its luminosity and collision rate. Corresponding upgrades of the ATLAS detector are imperative to maintain optimal data acquisition and performance in physics. The first upgrade phase, known as Phase-I, installed before the start of "Run 3" in 2022, incorporates among other things a new data path in the liquid argon calorimeter trigger system. This digital system, detailed in this thesis, replaces the old analog electronic trigger. Controlled and configured by systems based on OPC-UA (Open Platform Communications Unified Architecture) servers, the installation of this upgraded system was completed in March 2022. Looking forward, the second upgrade phase, during the extended shutdown of the LHC starting in 2026, will revise the entire electronic chain of the calorimeter, promising new computing and signal processing capabilities. This thesis details the control, operation, testing, and performance evaluation of this new upgraded electronics during this Phase-I for the liquid argon calorimeters of the ATLAS detector. The arrival of the beam for the start of "Run 3" implies a seamless integration into ATLAS operations. A crucial point will be the assessment and certification of the performance of the new triggering system compared to the analog trigger of the calorimeter. This thesis describes the work done to improve the performance as well as the stability of the electronic boards installed on the detector during this Phase-I.