95 ton cryogenic device will help Fermilab explore universe’s biggest mysteries

As the massive 95-metric ton coldbox completed its cross-ocean journey, the crowd at Fermilab braving frigid winter temperatures could imagine what the particle accelerator being chilled to minus 456 F by the device must feel like.

The coldbox is part of Fermilab’s Proton Improvement Plan II (PIP-II) project, a new 215-meter linear accelerator. When completed in 2029, it will fire a high-energy beam 800-miles to a repurposed mineshaft one-mile beneath Lead, South Dakota. The accelerator will be the most powerful continuous-wave proton accelerator in the world. The beam will contain neutrinos, the most mysterious known fundamental particles in the universe.

Embarking from France, the 55-by-14-foot coldbox was shipped across the Atlantic Ocean, barged up the Mississippi and Illinois Rivers, and hauled into Fermi National Accelerator Laboratory in Batavia all in the name of explaining the universe’s mysteries. Scientists will try to solve puzzles like why post-Big Bang matter conquered anti-matter, and what undiscovered secrets unify all the fundamental forces of nature.

“When you’re dealing with a vessel of this size, we can’t transport it by road for long distances,” Alex Martinez, a cryogenic engineer at Fermilab, said. “That’s why we had to get it on a barge up the Mississippi River. There was no other logical way of doing it. Winter weather was a concern. But navigating the river’s locks turned out very straight-forward. A large-capacity crane then took it off the trailer as we skated it through Fermilab.”

The ground-breaking project, known as the Deep Underground Neutrino Experiment (DUNE), will be the most innovative neutrino experiment in the world, making Fermilab distinct from other global particle accelerators, like CERN in Europe.

By the time you finish reading this sentence, trillions of neutrinos forged in nuclear reactions within our sun will pass through your body. You won’t feel the sub-atomic particles, a million times less massive than electrons, because they seldom interact with ordinary matter. What physicists find spooky about the particles containing no electric charge, is that as they travel through space, they seem to undergo an identity crisis.

Neutrinos come in three different “flavors” – electron, muon, and tau – yet while traveling at nearly the speed of light, they alter their properties, switching back-and-forth between the different types. Physicists believe studying these transitions could illuminate everything from dark energy, the evolution of the universe, and perhaps even lead to a “theory of everything,” unifying our knowledge of all the fundamental forces.

“Neutrinos could explain why we have this matter and anti-matter asymmetry,” Pantaleo Raimondi, director of the PIP-II project, said. “In the sun, where nuclear fusion produces trillions of neutrinos, they somehow produce matter when they interact with matter. Because they have energy, the energy can be reconverted into matter. However, if neutrinos are to change flavors while traveling, they create an exotic matter that is not stable, so it decays in fractions of a second. This means the overall balance of matter in the universe is related to neutrinos’ tricky behavior.”

The coldbox is the heart of the PIP-II cryogenic system, cooling helium gas to below the average temperature of outer space. This allows the particle beam to fire at full power without losing energy from radiated heat. The superconductive materials within the accelerator, made from the element niobium, are chilled to minus 452 F to further prevent energy loss. As electric fields bounce back and forth, Fermilab’s physicists can precisely time their waves to accelerate the particle beams.

Physicists at Fermilab and in South Dakota will try to capture and detect neutrinos as they oscillate during their rapid journey through the Earth’s mantle.

Christian Boffo, PIP-II’s project manager, said the advances of the project go far beyond the world of physics.

“The advances in superconducting materials have an impact on medical technologies, like MRI systems, which use the same materials,” he said. “We are also working on projects where it can be used for water purification using an electron beam that we developed in our accelerators.”

The U.S. Department of Energy approved the PIP-II project in 2020 for a total cost of $978 million. The new particle accelerator will be the first on American soil built with significant international contributions, more than $310 million, from France, India, Italy, Poland and the U.K. The successful collaboration should set the blueprint for future global physics projects.

The coldbox was contributed by India’s Department of Atomic Energy. It was assembled at a technologies workshop in France, before departing on Oct. 14, 2024. A week later, it was loaded onto a transport ship, before a 25-day voyage across the Atlantic to the Port of New Orleans.

From Louisiana, the coldbox took a two-week journey up the Mississippi River and the Illinois River to Romeoville, Illinois. Once on dry land again, the coldbox cruised at a maximum 10 mph to Fermilab’s welcoming arms on Jan. 15.