Detailed analysis of the evolution and distribution of the total ionising dose in the LHC arc sections during the accelerator operation

Continuous particle losses are an integral part of each accelerator operation. Even though they are only a very small fraction of the total intensity, they result in the occurrence of the mixed radiation fields that are hazardous for the reliability and lifespan of equipment including electronic devices. Especially at high energy and high intensity accelerators, like the accelerators at CERN, the mixed radiation fields can influence the operation. With focus on the Large Hadron Collider's (LHC) arc sections, where the magnets structure is a periodic FODO lattice, the total ionising dose distribution has been analysed. The LHC is equipped with a beam loss monitoring system that is used in order to ensure safety of the accelerator's apparatus, however it also provides high resolution dose measurements, both in space and time. The studies of the data presented in this work shows that among regular baseline radiation levels, spikes can be observed. They exceed the baseline levels by up to three orders of magnitude. The location, evolution and cause of these radiation spikes and general baseline behaviour are investigated in detail. For this analysis data from the beam loss monitoring system was used with the separation between the different beam modes of the LHC proton-proton operation from Run 2, that spans over the years 2015-2018.