CERN is pulling the LHC apart to fit magnets 40% stronger

Disconnection work on the Large Hadron Collider began on September 7, 2026, the first step in removing the machine’s inner triplets, the focusing magnets that squeeze the proton beams just before they collide. The replacements, built with niobium-tin coils, reach 11.3 tesla, which CERN describes as about 40 percent stronger than the fields of the magnets they displace.

That figure compares magnetic field strength, not collision energy. The beams keep their energy; the new triplets are meant to focus them harder.

The inner triplets coming out

CERN’s own article, “The disconnection of the LHC has begun,” published on September 17, 2026 and written by Anaïs Schaeffer, places the work inside Long Shutdown 3. HiLumi LHC project leader Markus Zerlauth is quoted in that CERN article: the current inner triplets date back to the LHC’s construction and went into the machine between 2005 and 2007, and after nearly twenty years of operation they will give way to a new generation of more powerful magnets.

The ring is not coming apart everywhere. The triplets sit on either side of the ATLAS and CMS detectors, the two interaction points where the beams are focused for collision, and CERN Courier describes four identical assemblies of about 60 meters each, positioned 20 meters either side of those points. Jean-Philippe Tock, head of the LS3 coordination team, said that 16 cryostats and 28 cryo-assemblies will be installed in total.

Eleven tesla, niobium-tin and what 40 percent compares

The baseline matters. In the ScienceDaily republication of CERN’s article, the new magnets generate fields reaching 11.3 tesla, about 40 percent stronger than those produced by the current magnets. The article names the reference only as the current niobium-titanium magnets, so the 40 percent is a like-for-like comparison of the triplet magnets old and new, and it is a ratio of tesla, not of beam energy in electronvolts. The current ones use niobium-titanium; the new ones use niobium-tin, a compound that holds a superconducting state at higher fields but is brittle, requires a high-temperature heat treatment and needs a more sophisticated quench protection system, as CERN Courier reports in its account of the test stand.

CERN’s other pages quote different numbers for the same upgrade, because they compare different things. The HL-LHC technologies page speaks of a 12-tesla field against 8 tesla for the magnets currently in the LHC, and CERN’s media kit says the fields reach up to 12 tesla, roughly 50 percent above existing magnets. CERN Courier quotes 11.5 tesla against 8.5 tesla. Those are nominal or design values set against different reference magnets. The September 2026 statement, 11.3 tesla and about 40 percent, is the figure CERN attaches to the inner triplets now being swapped.

Earlier CERN reporting shows where the spread in numbers comes from. A CERN feature on the magnets describes a 1.5-meter short model tested in the United States reaching a 13-tesla peak field, a CERN-tested short model reaching 12.2 tesla, and a full-length 4.5-meter coil tested at Brookhaven National Laboratory in January 2017 reaching its nominal 13.4 tesla. Peak field inside the coil and the field a magnet delivers on its design specification are different quantities, which may account for one project being described with 11.3, 11.5 and 12 tesla at different times. Ezio Todesco, who leads work on the HL-LHC insertion-region magnets, called the scaling from one to seven meters of length “absolutely not a trivial task.”

A separate class of magnet shares the name and is easy to confuse with the triplets. The technologies page also mentions 11-tesla dipole magnets, whose installation was deferred beyond Long Shutdown 2. Those dipoles are not the inner triplets in the 40 percent figure.

Luminosity and the collision count

A stronger quadrupole squeezes the beam to a smaller spot, and a smaller spot means more collisions per bunch crossing. CERN’s media kit says the High-Luminosity project aims to raise integrated luminosity by a factor of 10 beyond the LHC’s design value, and the technologies page says the upgraded machine will produce 140 collisions each time two bunches meet, against about 30 today. The media kit adds that the collider is expected to make at least 15 million Higgs bosons a year, compared with around three million from the LHC in 2017.

The triplets are part of a larger package. According to the media kit, about 100 magnets of 11 new types will replace over a kilometer of the machine, and 16 superconducting crab cavities will be installed near ATLAS and CMS to enlarge the overlap of the incoming proton bunches.

None of the new triplet hardware is in the tunnel yet. Tock said the first quadrupole of the new triplets should arrive at the start of 2029, and the installation he described, 16 cryostats and 28 cryo-assemblies, is the work that date opens.

This article was produced with the assistance of AI and reviewed by Morning Overview editors prior to publication.

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