Development and Reliability Testing of a new Low-Voltage Power Supply for the ATLAS Hadronic Tile-Calorimeter Phase-II Upgrade

The Large Hadron Collider (LHC), located at the Conseil Européen pour la Recherche Nucléaire (CERN) also known as the European Laboratory of Particle Physics, is a two- ring-superconducting-hadron accelerator and collider located on the Franco-Swiss bor- der. The LHC was successfully commissioned in 2010 for proton–proton collisions and is expected to deliver 500 fb−1 before Long Shutdown three (LS3) that is schedule to commence in 2026. Its successor, the HL-LHC, will provide a levelled instantaneous luminosity of L = 5x 1034 cm−2 s−1 and is projected to deliver an integrated luminosity of more than 4000 fb−1 to its two general purpose detectors, known as A Toroidal LHC Apparatus (ATLAS) and Compact Muon Solenoid (CMS), over a span of 10 years. The main motivation to up- grade the LHC is to fully exploit its physics potential. Through a series of machine and detector upgrades, it is possible to increase the instantaneous luminosity. This could un- lock many of the physics processes that are today inaccessible to the LHC because of the lack of statistics. The primary impacts of the HL-LHC on the detector environment are a direct consequence of an increase in delivered instantaneous luminosity. The ATLAS experiment will undergo its Phase-II Upgrade during Long-Shutdown 3 to ensure peak performance during high-luminosity operations. ATLAS is composed of several specialized sub-detectors one of which is the hadronic Tile-Calorimeter (TileCal). The TileCal will undergo numerous upgrades on of which will be to the Low-Voltage (LV) power distribution system that services its on-detector electronics. The on-detector finger Low-Voltage Power supplies form the second stage of the LV system. Their primary functional device is a transformer-coupled buck converter, known as a Brick, which is responsible for converting bulk power to that required by the on-detector electronics. All legacy Bricks will be replaced with a new version that employs several design changes to enable their reliable operation within the HL-LHC detector environment. In this thesis, the development of the Phase-II Upgrade Brick is presented with an emphasis placed on its thermal performance and reliability. A thermal analysis of the proposed upgrade Brick versions is presented with design changes occurring as a result. Due to the design change incorporating a new active component an irradiation campaign is conducted to qualify it for use within the high-luminosity detector environment. A re- liability analysis of the Phase-II upgrade Brick is conducted necessitated by the change of many critical components. The quality assurance procedure of the Bricks that is un- dertaken post-production is presented with particular attention placed on their Burn-in testing.