The Large Hadron Collider (LHC) collimation system, which protects the accelerator's components, must be upgraded to accommodate CERN's future accelerator performance.
A major upgrade of the Large Hadron Collider's (LHC) collimation system began during the first long-term shutdown of CERN's accelerator facility (LS1, 2013-2015) in preparation for the High-Luminosity LHC, and continued with LS2 (2019). ~2021). (HL-LHC). As its name suggests, HL-LHC exceeds the LHC in terms of luminosity, that is, the number of collisions that occur within an LHC experiment. Accelerator equipment therefore requires enhanced protection, and this is where collimation systems come into play.
What is a collimator?
A collimator is a moving block made of a material that can absorb particles. It is shaped like a jaw and closes tightly around the beam to remove particles that deviate from its trajectory. The materials used in these jaws and their various components can withstand extreme pressures and temperatures, as well as high levels of radiation.
Why do you need to clean your beams?
Particles that deviate from the beam path can strike sensitive accelerator components, such as superconducting magnets, disrupting their operation or even damaging them. To prevent this, collimators will be placed at strategic locations around her LHC ring, where they will absorb stray particles or deflect them towards the beam dump. Protection is especially important near experiments where beam sizes are reduced to increase the likelihood of collisions.
The LHC currently has 118 collimators of various types. The future HL-LHC will be equipped with 126 collimators, including a brand new model custom-made at CERN. Recently, the development and testing of two new prototypes (TCLPX and TCTPXH) was successfully completed under the supervision of François-Xavier Nuiry, the engineer responsible for the production of the HL-LHC collimator. These are double-beam collimators aimed at LHC interaction points 1 (ATLAS detector) and 5 (CMS detector). This optimized configuration allows the two beams (circulating in opposite directions) to pass through the same vacuum chamber, freeing up space for thicker and more powerful collimator jaws in this position.
“These two prototypes are innovative in several ways,” explains Dylan Baillard, mechanical engineer in CERN's Targets, Collimators and Dumps section. “They are equipped with remote adjustment and leveling systems, which help reduce the radiation dose received by the work team. Collimator flanges can be more easily connected and disconnected thanks to the integrated connection tool Finally, an ion pump is used to ensure good vacuum quality, as the collimator near the beam always operates in a vacuum and must not disturb the circulation of the beam.”
Final tests were successfully completed in December, and mass production of the two new types of collimators is expected to begin this year. During Long Term Outage 3 (LS3, 2026-2028), 12 double-beam collimators will be installed on the machine.
