Radiation levels at the large hadron collider (LHC) : discussion of the 2015 and 2016 proton physics operations

The variety of radiation sources in the Large Hadron Collider create a mixed and complex radiation field, unique in terms of particles and energies in- volved, but also in terms of ranges and doses. In order to limit the number of failure caused by the Single Event Effects (SEEs) in the electronic controller and reduce the consequent downtime of the LHC, Beam Loss Monitors (BLMs) and Radiation Monitors (RadMons) have been used during 2015 and 2016 to monitor the integrated doses and High Energy Hadrons fluence in the tunnel and in the shielded areas. The annual radiation levels have been compared, highlighting common and different aspects in the losses production in the LHC, as well as the pro- portionality with the dominant radiation sources, especially in the Long Straight Sections (LSSs) and in the shielded areas close to the high lumi- nosity experiment (ATLAS and CMS). Regarding the ARC sectors, through the comparison with 2012 measure- ments, some consideration have been pointed out regarding the impact of the e-cloud effect and the increasing of the beam-gas interaction during the operation at 25 ns compared to 50 ns. Looking forward to the HL-LHC, the increasing of energy to 14 TeV and the aimed luminosity up to 300fb−1 per year, request the maximization of the operation to achieve the physical goal. Mitigation actions are currently studied for the electronic control equipment. This includes detailed analysis of radiation field, intensity and Monte Carlo calculation as well as a constant radiation monitoring and benchmarking, in order to define the baseline for prediction of the future radiation levels in the LHC.