Radiation Testing of Low Voltage Power Supply for the ATLAS Tile Hadronic Calorimeter Phase-II Upgrade

The ATLAS Tile Hadronic Calorimeter, a subsystem of the ATLAS Detector at the Large Hadron Collider, is composed of 256 wedge-shaped modules and measures the energy of hadronic particles. Each module is equipped with a Low Voltage Power Supply (LVPS) consisting of eight transformer-coupled buck converters, which step down 200 Volts DC to the 10 Volts DC required for the front-end electronics. In preparation for the High-Luminosity LHC era, the Phase-II Upgrade must be implemented to accommodate the significantly increased integrated luminosity and radiation levels. Accordingly, analysis of radiation testing is an important focus for evaluating the robust nature of the LVPS electronics.

Due to being located on-detector, the LVPS is subject to the highest radiation exposure among all electronics in the Tile Hadronic Calorimeter. Electronic components of the LVPS, which are manufactured using Complementary Metal–Oxide-Semiconductor (CMOS), bipolar, or bipolar CMOS technologies, are scrutinized when exposed to different radiation sources. Radiation tests performed include Total Ionizing Dose (TID), Single Event Effects, and Non-Ionizing Energy Loss (NIEL). CMOS components are typically the least resilient to TID, while bipolar components are generally prone to displacement damage due to NIEL. Individual and mixed radiation effects on components are explored, and mitigation strategies, including circuit redesign and alternative chip selection, are utilized for a robust final design of the LVPS.