Fiber Bragg Grating Sensors as Beam-Induced Heating Monitor for the Central Beam Pipe of CMS

The passage of a high-intensity particle beam inside accelerator components generates heating, potentially leading to degradation of the accelerator performance or damage to the component itself. It is therefore essential to monitor such beam-induced heating in accelerators. This paper showcases the capabilities of iPipe, which is a set of Fiber Bragg Grating sensors stuck on the inner beam pipe of the Compact Muon Solenoid (CMS) experiment installed in the CERN Large Hadron Collider (LHC). In this study, the wavelength shift, linked directly to the temperature shift, is measured and is compared with the computed dissipated power for a set of LHC fills. Electromagnetic and thermal simulations were also coupled to predict the beam-induced temperature increase along the beam pipe. These results further validate the sensing system and the methods used to design accelerator components to mitigate beam-induced heating.