The HL-LHC Upgrade of the ATLAS hadronic Tile Calorimeter

The High-Luminosity phase of LHC, scheduled to begin in late 2027, will deliver five times the LHC nominal instantaneous luminosity to the experiments. To ensure sound performance under the higher pile-up and radiation conditions, the ATLAS hadronic Tile Calorimeter (TileCal) will replace both the on- and off- detector electronics systems during the LHC long shutdown 3 (2025-2027). The upgraded front-end system will continuously digitize and read out shaped photomultipler tube (PMT) signals from every TileCal cell at a rate of 40 MHz, transmitting them over high- speed fiber links to the new back- end electronics to be stored in latency pipelines and digitally summed to produce improved trigger tower data for the Level-1 trigger. The front-end electronics are based on radiation-qualified commercial components, and use extensive redundancy to minimize single point failures. The Tile upgrade program has undergone extensive R&D and beam tests, and a "demonstrator" module was installed on ATLAS in 2019 for integration and testing in the actual detector environment.