Radiation Environment in the LHC Arc Sections During Run 2 and Future HL-LHC Operations

The Large Hadron Collider (LHC) at the European Organization for Nuclear Research (CERN) is the largest accelerator in the world, spanning a circumference of 26.7 km. During its operation, small fractions of the beams are being continuously lost. This leads to mixed-field radiation that might affect electronic equipment through both cumulative and single-event effects. This article considers the radiation environment during Run 2 (years 2015-2018) in the LHC arc sectors that constitute approximately 70% of the accelerator, housing a huge amount of electronics. There, the main magnets' configuration is periodic, and the main contributor to losses is the interaction of the beams with residual gas molecules, resulting in relatively low-radiation levels, as opposed to different parts of the LHC. However, as presented, there are locations where losses are no longer dominated by residual gas. In these locations, radiation levels are higher by up to more than two orders of magnitude and could, therefore, be problematic in terms of cumulative radiation effects on electronics. In this article, the dose measurements from beam loss monitors have been combined with the FLUKA simulation for the arc sectors in order to indirectly retrieve the residual gas densities and radiation profile under the magnet cryostats, at the equipment level, for the losses caused by residual gas. Estimations for the radiation levels in the arc sectors during the high-luminosity LHC era and potential implications for the electronics are discussed as well.