The Beam Loss Monitoring System after LHC Long Shutdown 2 at CERN

Most of the LHC systems at CERN were updated during the Long Shutdown 2, from December 2018 to July 2022, to prepare the accelerator for High-Luminosity. The Beam Loss Monitoring system is a key part of the LHC’s instrumentation for machine protection and beam optimisation by producing continuous and reliable measurements of beam losses along the accelerator. The BLM system update during LS2 aims at providing better gateware portability to future evolutions, improving significantly the data rate in the back-end processing and the software efficiency, and adding remote command capability for the tunnel electronics. This paper first recalls the Run 1 and Run 2 BLM system achievements, then reviews the main changes brought during LS2, before focusing on the commissioning phase of Run 3 and future expectations.