Radiation impact of collimation beam losses in the LHC and HL-LHC

Abstract

Beam dynamics and Monte Carlo beam-matter interaction simulations play a vital role in the design and performance assessment of high-energy proton and ion colliders. The collimation system of the Large Hadron Collider (LHC) is leading by example with its proven ability to protect and assure an unobstructed operation during the past years. This thesis aims to further develop the complex simulation chain involved in the study of the collimation related beam losses as well as to accurately estimate its predictive capabilities. An unprecedented benchmark against Beam Loss Monitor (BLM) measurements is presented with extensive analysis of particle showers and their origins. Furthermore, the proton losses during the Run 2 operational period (2015-2018) in the betatron cleaning insertion region are estimated. Predictions for upcoming High Luminosity-LHC (HL-LHC) are made utilising a new scaling method based on the integrated proton intensity. The new scaling method and the proton loss estimates for Run 2 are benchmarked against passive dosimeter measurements during the same years. In addition, the tools are then applied in order to quantify the radiation impact that beam losses have in the collimation system itself as well as in the normal and Super-Conducting (SC) magnets. The short term radiation effects concerning the collimator material robustness and the power deposited in the SC coils are examined. Lastly, the long-term degradation of organic (dose) and crystalline materials (DPA), found in the magnets and collimator absorber blocks, respectively, are presented for the HL-LHC lifetime.