The upgrade of the readout electronics of the CMS Electromagnetic Calorimeter for High-Luminosity LHC

Precision measurements at the energy frontier require detectors capable of maintaining excellent performance under increasingly demanding experimental conditions. The High-Luminosity Large Hadron Collider will deliver unprecedented luminosity, significantly increasing both radiation levels and event pile-up in the CMS experiment. To preserve the physics capabilities of the Electromagnetic Calorimeter Barrel, a complete replacement of its on-detector electronics is foreseen as part of the CMS Phase2 upgrade programme. This thesis describes the qualification and validation of key elements of the upgraded readout chain. The work covers the characterization of the LiTE-DTU front-end ASIC, responsible for signal digitization, processing, and transmission; the qualification of the Very Front-End detector boards, which integrate the complete front-end readout chain; and the development of software and data acquisition systems required for large-scale testing and detector integration. Particular emphasis is placed on automation strategies, production-quality assessment, and system-level validation. Dedicated laboratory measurements were performed to evaluate the performance of the electronics under realistic operating conditions. The developed procedures and tools were also employed during beam-test campaigns, where the upgraded readout system was operated with electron beams and laser calibration data. These measurements provided an opportunity to study detector stability, timing behaviour, linearity, and energy reconstruction performance in an environment representative of future detector operation. The results demonstrate that the upgraded electronics chain satisfies the requirements of the CMS ECAL Barrel upgrade. Stable operation was achieved throughout extended data-taking periods, timing performance was shown to be consistent with design expectations, and energy reconstruction studies yielded a constant term of approximately 0.32%, compatible with both the project specifications and the performance of the current detector. The work presented in this thesis contributes to the readiness of the ECAL Barrel Phase2 electronics and provides experimental validation of technologies that will be employed during HL-LHC operation, to enable and exploit its unprecedented physics potential.