Identification and Analysis of Prompt Dose Maxima in the Insertion Regions IR1 and IR5 of the Large Hadron Collider

During the operation of the LHC the continuous particle losses create a radiation field in the LHC tunnel and the adjacent caverns. Exposed electronics and accelerator components show dose dependent accelerated aging effects and stochastic Single Event Effects which can lead to faults and downtime of the LHC. In order to achieve an optimal life duration, the position of the equipment is chosen in dependency of the amplitude of the radiation fields. Therefore, it is crucial to monitor the prompt dose distributions along the whole LHC. By using the LHC beam loss monitor and RadMon systems, the prompt dose during the accelerator operation is continuously monitored. Measurements in the long straight sections and the dispersion suppressors in IR1 (ATLAS) and in IR5 (CMS) have shown that the radiation levels have localised maxima which exceed the base line by 1 to 2 orders of magnitude. The analysis of these radiation peaks will be presented and the underlying loss mechanisms will be discussed. The results will help to identify areas not suitable for radiation sensitive electronics. Implications on the expected radiation levels for High-Luminosity LHC are also discussed.