quadpole
HQ02a is a superconducting quadrupole magnet made from high performance niobium tin that lies at the heart of a new beam focusing system in development for CERN’s Large Hadron Collider. Lawrence Berkeley National Laboratory

The world’s most powerful atom-smasher may soon get even more souped-up thanks to a powerful new magnet made in the U.S.

Last week, the U.S. LHC Accelerator Program (LARP) successfully tested a new kind of superconducting magnet designed for CERN’s Large Hadron Collider in Switzerland. The magnet, which goes by the moniker HQ02a, contains a higher-performing but more delicate material than the current magnet inside the LHC.

Scientists use the LHC, which runs in a 17-mile loop underneath Switzerland and France, to unlock some of the deepest secrets of physics. The LHC spotted a particle last November that is very likely to be the Higgs boson, which could help explain why some subatomic particles have mass. To peer into the quantum mysteries, scientists use the LHC to accelerate beams of protons – the subatomic particles that huddle together in an atom’s nucleus – up to blazingly fast speeds and smash them together. By examining the detritus of proton-proton collisions, researchers can look for clues to unanswered questions.

Given that the protons are so minuscule, scientists have to keep the proton beams drawn in as tightly as possible to ensure that the particles collide when the beams smash into each other. To keep the beam focused, the LHC uses a powerful magnet. Currently, the LHC’s magnets have cables made from a superconducting substance called niobium titanium wound around them, but researchers knew there are even more powerful superconductors available.

One such substance is the material used the new magnet HQ02a – a compound called niobium tin. If used in the particle accelerator, niobium tin could draw the proton beam in even tighter, ensuring more subatomic smashing. But there are complications.

“Niobium tin is an advanced superconducting material that can operate at a higher magnetic field and with a wider temperature margin than niobium titanium,” the Lawrence Berkeley Lab explained in a press release. “Unfortunately, niobium tin is brittle and sensitive to strain – critical factors where intense electrical currents and strong magnetic fields create enormous forces as the magnets are energized.”

To stabilize the niobium tin cables, researchers created a thick aluminum shell to minimize any movements once the niobium tin coils were subjected to the powerful forces generated by the magnet.

HQ02a, along with other scheduled upgrades to the LHC, could eventually allow the particle accelerator to produce 10 times more particle collisions than the original design. That leap forward in capability could provide the necessary power to better understand the properties of the Higgs boson and other fundamental particles.

“This marks the end of the R&D phase and the beginning of the focused development of the magnets that will be installed for the LHC luminosity upgrade”, LARP director and Fermilab researcher Eric Prebys said in a statement. “However, the implications go well beyond that, in that it establishes high performance niobium tin as a powerful superconductor for use in accelerator magnets. This success is a tribute to the skill, hard work, and collaborative spirit of all of the people involved.”