The Large Hadron Collider (LHC) is entering a major phase of its next-generation upgrade, with CERN beginning to remove key superconducting magnets around its ATLAS and CMS experiments.
The work will clear the way for a new focusing system designed to increase the collider’s luminosity as part of the High-Luminosity LHC (HiLumi LHC) programme.
Teams have been dismantling sections of the 27-kilometre machine since 7 September, preparing to remove 28 superconducting magnets.
The first magnet interconnection was cut this week at LHC Point 1, where the ATLAS experiment is located, marking the start of this stage of work during the LHC’s third long shutdown, LS3.
At the centre of the operation are new inner triplets, which focus the particle beams immediately before they reach the experiments.
The replacement magnets use niobium-tin superconducting coils and can produce magnetic fields of 11.3 tesla, around 40% stronger than those generated by the existing magnets.
Speaking on the work, Markus Zerlauth, the HiLumi LHC Project Leader, said: “This event is a major milestone for CERN, especially for the HiLumi LHC project team.
“The current inner triplets date back to the LHC construction phase and were installed in the machine between 2005 and 2007.
“After nearly twenty years of operation, they will give way to a new generation of even more powerful magnets. It’s truly remarkable to witness such a handover from one generation of innovation to the next.”
Why the magnets are being replaced
The LHC relies on thousands of magnets to control and manipulate its particle beams.
The inner triplets are particularly important because they consist of three quadrupoles positioned on either side of the experiments and tightly focus the beams before collisions take place.
This focusing compresses the beams, increasing the likelihood of particles colliding. That directly contributes to the collider’s luminosity, which measures the number of collisions occurring over a given period. Higher luminosity lets experiments collect more data.
The new magnets are therefore a key component of the HiLumi LHC, which is being developed to increase the LHC’s collision rate and data output substantially.
New technology for ATLAS and CMS
The replacement inner triplets result from years of research and development and represent a significant technological change from the current niobium-titanium magnets.
The new niobium-tin technology will be installed around ATLAS and CMS, where the increased luminosity is required.
ALICE and LHCb have different physics programmes and operating requirements, so they will retain their existing inner triplets, although these will be improved to allow both experiments to benefit from the luminosity increase.
Jean-Philippe Tock, Head of the LS3 Coordination Team, added: “The replacement of these magnets with the new HiLumi LHC inner triplets is crucial for the coming high-luminosity years.
“The first quadrupole of the new triplets should arrive in the tunnel at the start of 2029. In total, 16 cryostats and 28 cryo-assemblies will be installed – a major undertaking.”
Dismantling the LHC
The magnet removal is taking place as part of LS3, during which major sections of the accelerator are being dismantled and upgraded.
Since 7 September, teams have been working on the sections surrounding ATLAS and CMS to prepare the 28 superconducting magnets for removal.
The first interconnection cut now marks the beginning of a significant stage in CERN’s transition towards the HiLumi LHC.
