Research and Development of the Detector Control & Data Acquisition Systems for the New Small Wheel Upgrade of the ATLAS experiment at CERN and Performance Evaluation of the Micromegas detector

This dissertation presents the research and development of the Detector Control and Data Acquisition Systems for the New Small Wheel (NSW) upgrade within the ATLAS experiment at CERN, alongside a comprehensive performance evaluation of the Micromegas detector. The NSW upgrade is pivotal for adapting the ATLAS detector to the challenges created by the increased luminosity of the future Large Hadron Collider (LHC) runs. This work navigates the complexities of integrating complex technologies into a high-radiation environment, demonstrating a critical contribution to the successful deployment and operation of the NSW project. The upgrade involves the replacement of the existing ATLAS Small Wheel Muon detector with a new, advanced system capable of operating in high background radiation levels-up to 22 kHz/cm2, while maintaining high precision in muon track reconstruction and Level-1 trigger information. The NSW consists of two innovative gaseous detector technologies: small-strip Thin Gap Chambers (sTGCs) for rapid trigger response and high- precision tracking, and Micromegas (MM) detectors, which are micro-pattern gas detectors offering excellent spatial resolution due to their small conversion region and fine strip pitch. This thesis highlights the design, the operational principles and the integration of these technologies across 16 detection layers, detailing the challenges and solutions in configuring such a complex system. A significant focus is placed on the ATLAS Data Acquisition (DAQ) system, particularly the FELIX system- an FPGA based interface facilitating communication between the detector's front-end electronics and back-end software components. The intricacies of the GBT protocol, the GBT-SCA ASIC's role in signal processing, and the development of a robust control and monitoring network through the SCA ecosystem are discussed in detail. This includes the creation of novel tools and mechanisms for enhancing data integrity and system reliability. Moreover, the thesis delves into the Detector Control System (DCS), emphasizing its critical role in ensuring the detector's consistent and safe operation. The development and implementation of control systems for various operational aspects, such as high voltage and gas leak validation for Micromegas detectors, are examined. This segment high- lights the bespoke architecture of the NSW DCS and its integration to the broader ATLAS DCS framework, showcasing the advanced electronics monitoring capabilities developed for overseeing more than 100 000 parameters. The experimental section presents a thorough analysis of the Micromegas detector's performance, including the operational gaseous detector principles, signal generation and the impact of various operational parameters. Results from extensive testbeam campaigns at H8 and GIF++ facilities offer insights into the detector's response under high interaction rates, illustrating the successful adaptation of the technology for high-luminosity environments. This research not only contributes to the ATLAS experiment's readiness for future LHC runs, but also advances the field of particle physics instrumentation. By addressing the challenges of high-luminosity data acquisition and control in one of the most demanding experimental environments, this work sets a precedent for future detector technologies and their implementation in large-scale scientific research. Through meticulous design, testing and validation, the thesis underscores the pivotal role of innovative detector and control technologies in pushing the boundaries of particle physics research, offering valuable lessons for the development of future experiments in high energy physics and beyond.