--- title: "Large Hadron Collider upgrade gets niobium-tin magnets; 11.3-tesla coils will squeeze proton beams" url: https://badiyaa.com/cern-lhc-niobium-tin-magnets-hl-lhc/ published: 2026-11-11T06:58:00+00:00 modified: 2026-11-11T06:58:00+00:00 section: Science publisher: Badiyaa --- # Large Hadron Collider upgrade gets niobium-tin magnets; 11.3-tesla coils will squeeze proton beams CERN's High-Luminosity LHC upgrade installs niobium-tin focusing magnets rated at 11.3 tesla, up from 8.6 tesla in the current collider. The Large Hadron Collider is getting focusing magnets made from a material that physicists describe as brittle as glass. The [High-Luminosity LHC](https://en.wikipedia.org/wiki/High_Luminosity_Large_Hadron_Collider) upgrade at CERN, near Geneva, replaces the quadrupoles beside the ATLAS and CMS detectors with niobium-tin coils rated at **11.3 tesla**, up from 8.6 tesla in the magnets they replace. It is the first time this superconductor has been used in a large accelerator, according to a [US Department of Energy laboratory release](https://www.bnl.gov/newsroom/news.php?a=221617) on the first US-built unit. ## Why niobium-tin The existing LHC magnets use niobium-titanium, a ductile alloy that winds easily into cable. Its weakness is a ceiling: it stops superconducting at roughly 15 tesla. [Niobium-tin](https://en.wikipedia.org/wiki/Niobium%E2%80%93tin), the compound Nb3Sn, keeps carrying current without resistance up to about 30 tesla and has a critical temperature of 18.3 kelvin. The catch is mechanical. The finished compound cannot be drawn into wire. Makers instead pull composite strands that hold niobium and tin separately, wind them into a coil, and only then bake the coil so the two metals react. After that the coil cannot flex. A strain of around 1 percent can crack the conductor and permanently damage its ability to carry current. “It’s brittle like glass,” Giorgio Apollinari, head of the US accelerator upgrade project at Fermilab, said in the 2023 release. “When properly handled, glass can last for centuries, like in a cathedral window, but then one day you knock it, and it breaks.” ## What the magnets will do Quadrupoles focus beams the way a lens focuses light. The new ones sit on either side of the two biggest collision points and squeeze the opposing proton beams just before they meet. A tighter squeeze means more collisions. The US labs say their magnets will help raise the collision rate by a factor of five over the LHC’s original design value. A quick comparison shows the jump. At 11.3 tesla versus 8.6, the new quadrupoles are about 31 percent stronger by their rated field. The US-built units reach a peak of 12 tesla, which the labs put at roughly 50 percent above the current focusing magnets. And the number of collisions each time bunches cross is planned to climb from about 60 to 140, a little more than double. ## A 20-year build - **1986:** niobium-tin was suggested for the LHC but not pursued. - **2003:** the US Department of Energy set up the LHC Accelerator Research Program to learn how to build Nb3Sn accelerator magnets. - **2016:** the CERN Council approved the HL-LHC as a full project. - **2022-2023:** the first US cryo-assembly, 13 meters long and holding two magnets with 4.2-meter coils, was finished, passed tests at Fermilab and reached CERN. - **2025:** series production of the inner triplet quadrupoles was under way. - **2026-2030:** new magnets, crab cavities and other hardware go into the tunnel. Shipping was its own experiment. Before moving a real 25-ton assembly, the team sent a sensor-laden dummy of concrete and iron across the US and by sea to Switzerland. “The sensors were so good that we could tell when the truck was going over railroad tracks,” Apollinari said. The magnets run cold, at minus 271.25 degrees Celsius, a reminder that much of modern physics lives near absolute zero, as in the [record-cold atoms chilled aboard the Tiangong space station](https://badiyaa.com/tiangong-space-station-coldest-atoms-9-7-picokelvin/). The materials story echoes another recent one, where engineers found a way to [recrystallize molybdenum at room temperature](https://badiyaa.com/molybdenum-room-temperature-recrystallization/); molybdenum is also among the fibers used to stiffen niobium-tin wire. ## Limits The schedule has slipped before. The 2023 release targeted upgraded collisions in 2029; the current plan puts the start of physics with Run 4 in mid-2030, running to the end of 2033. Separate 11-tesla niobium-tin dipoles remain uncertain, with a final decision on installing them still pending. Plans call for eight US-built and eight CERN-built focusing assemblies to sit 100 meters underground around ATLAS and CMS, and the HL-LHC is scheduled to keep taking data through 2041. ## Further reading - [Wikipedia: High Luminosity Large Hadron Collider](https://en.wikipedia.org/wiki/High_Luminosity_Large_Hadron_Collider) - [Wikipedia: Niobium-tin](https://en.wikipedia.org/wiki/Niobium%E2%80%93tin) - [Brookhaven National Laboratory: First US-built focusing magnet arrives at CERN](https://www.bnl.gov/newsroom/news.php?a=221617) *Image: CERN, CC BY-SA 4.0 via Wikimedia Commons* *This article was produced with AI assistance and reviewed by our Editorial Desk. [How we work](https://badiyaa.com/editorial-policy/).*