The world’s most powerful neutrino beam is one step closer to becoming a reality. The Proton Improvement Plan II, or PIP-II, project reached a milestone in October when it successfully performed a transportation test of a “dummy load” between the U.S. Department of Energy’s Fermi National Accelerator Laboratory outside of Chicago and Daresbury Laboratory in England, outside of Liverpool. The test validated the system researchers will use to ship the delicate cryomodules that will make up a large part of a new linear proton accelerator at Fermilab. The new machine will power the production of neutrinos for the Deep Underground Neutrino Experiment.
Members of the international PIP-II collaboration from the United Kingdom, France and India will develop, manufacture and assemble cryomodules needed for the project, scheduled for completion in 2028. To ensure that the completed cryomodules will safely reach Fermilab, the PIP-II team is conducting extensive transportation tests well in advance.
The frame boards the cargo plane at O’Hare. Photo: Brian Hartsell, Fermilab
For the first test earlier this year, PIP-II collaborators assembled a transportation frame that will be the blueprint for the eventual cryomodule transportation frame and test-drove it on a highway. The PIP-II team at the Science and Technology Facilities Council of UK Research and Innovation, or STFC UKRI, with input from Fermilab, led the frame’s design.
For testing purposes, the team loaded the frame with a cryomodule analog called a dummy load: concrete blocks with the dimensions, weight and mounting points of the actual cryomodule, which will be 10 meters long and weigh 27,500 pounds, or 12,500 kilograms.
First test flight
The latest test — the frame’s first transatlantic voyage — began on Sept. 23 at Fermilab’s Industrial Center Building in Batavia, Illinois. There, the team installed the dummy load and secured it inside the transportation frame, just as a cryomodule would be. They also outfitted the system with sensors to capture shocks observed during the test.
On Sept. 26, the frame left Fermilab in Batavia and traveled via trailer to Chicago’s O’Hare International Airport. Two days later, it was loaded onto a cargo plane and departed for Luxembourg; Luxembourg Airport is headquarters and hub for a cargo transportation airline, so all cargo flights must first pass through the small country. At Luxembourg Airport, several members of the Fermilab PIP-II team met the frame. Using a large crane, they off-loaded it from the plane and then lifted it onto a truck’s trailer, covering it in a tarp for its road trip to the United Kingdom, which departed on Sept. 30.
“The successful validation of the transportation frame using the dummy load is a testament to the dedicated international collaboration that comprises PIP-II.” – Saravan Chandrasekaran
After a lengthy road trip, including passage through the Channel Tunnel, the frame reached Daresbury Laboratory, a research lab located near Liverpool and operated by STFC UKRI, on Oct. 3. PIP-II partners removed the panels and dummy load from the frame and examined the sensors, bumpers, springs and other hardware. After checking all components, they reassembled the transport system, loaded it onto the truck and sent it on its way back to Fermilab on Oct. 5. The dummy load arrived back in Batavia, Illinois, on Oct. 11.
Signs of a successful collaboration
“I would call this an unqualified success,” said Jeremiah Holzbauer, the PIP-II transportation sub-project manager at Fermilab. “Everything went just about as well as we could hope for.”
Jon Lewis, project manager for the STFC contribution to PIP-II, agreed. “This is a significant de-risking exercise for us — and a real test of the frame designed by Mitchell Kane from our Projects and Mechanical Engineering group,” he said. “It’s also great to be able to host our Fermilab colleagues at Daresbury Laboratory once again. Working closely with Jeremiah Holzbauer, Adam Wixson and Ryan Thiede has reinforced our working relationship between the two labs.”
Saravan Chandrasekaran, technical manager for the PIP-II 650-MHz cryomodule at Fermilab, said, “The successful validation of the transportation frame using the dummy load is a testament to the dedicated international collaboration that comprises PIP-II.”
The truck backs into the facility at UKRI-STFC. Photo: Mitchell Kane, Fermilab
The team performed the test using procedures, techniques and oversight that were as realistic as possible. From the isolation system and vibration instrumentation to handling, logistics and customs, the test closely mimicked what the real cryomodules will go through during transportation. The good news: All aspects of the transportation system were deemed validated by this test.
PIP-II’s next step is to use the same frame to ship a complex prototype cryomodule, now in assembly at Fermilab, to the UK and back. Testing the prototype before shipment, while at STFC UKRI, and after its return will demonstrate that the transport process can protect these delicate systems during the long transport. This test is currently planned for early 2023.
In a few years, STFC will ship the production cryomodules in their own transportation frame to Fermilab for the construction of PIP-II.
“The strong collaborative program we have with Fermilab for STFC’s delivery of superconducting cryomodules for PIP-II relies massively on our ability to safely transport these highly complex and fragile systems over an extremely long distance,” said Peter McIntosh, STFC UKRI technical coordinator for PIP-II and deputy director of the Accelerator Scence and Technology Centre at STFC’s Daresbury Laboratory. “The transport frame that we have developed is critical for ensuring we can provide sufficient protection.
“This recent transportation test has not only provided important evidence for how shock loads have been effectively suppressed, but it has also allowed the Daresbury teams to verify many of the local logistics procedures,” McIntosh said. “This first assessment will prove incredibly important for when the next major validation is performed.”
Follow the journey
Fermilab group poses with the shipment at Fermilab’s ICB. Photo: Lynn Johnson, Fermilab
Fermi National Accelerator Laboratory is supported by the Office of Science of the U.S. Department of Energy. The Office of Science is the single largest supporter of basic research in the physical sciences in the United States and is working to address some of the most pressing challenges of our time. For more information, please visit science.energy.gov.
While the refrigerator in your kitchen gets cold enough to prevent your leftovers from spoiling, dilution refrigerators used for quantum computing research cool devices near the coldest physical temperature possible. Now at the U.S. Department of Energy’s Fermi National Accelerator Laboratory, researchers are building Colossus: It will be the largest, most powerful refrigerator at millikelvin temperatures ever created.
Colossus will offer 5 cubic meters of space and cool components to around 0.01K. Photo: Ryan Postel, Fermilab
Fermilab is known for its massive experiments, and Colossus will fit right in. Researchers from the Fermilab-hosted Superconducting Quantum Materials and Systems Center need lots of room at cold temperatures to achieve their goal of building a state-of-the-art quantum computer.
Unlike a kitchen refrigerator, which compresses gases called refrigerants to cool food, a dilution refrigerator uses a mixture of helium isotopes to create temperatures close to absolute zero, or zero kelvin: the coldest temperature imaginable in physics, which is physically impossible to reach.
“With the cooling power and volume that Colossus will provide, SQMS researchers will have unprecedented space for our future quantum computer and many other quantum computing and physics experiments,” said Matt Hollister, the lead technical expert on this project. “Colossus is named after the first electronic programmable computer, which was constructed in the 1940s for codebreaking. It was a historic milestone in the history of computing and seemed like an appropriate name for the size of our new refrigerator.”
SQMS scientists and engineers are tackling a challenge called quantum decoherence. Decoherence is a phenomenon that occurs when quantum information is obscured by signal noise or lost through the materials that make up the physical qubits, the basic units of a quantum computer.
The metallic, niobium cavities used by SQMS to develop better physical qubits are rooted in Fermilab’s renowned particle accelerator program. The lab’s expertise in superconducting cavities and cryogenics, essential in building modern, powerful particle accelerators, made Fermilab a prime location for hosting one of DOE’s national quantum information science research centers.
“Once we accomplish our goal of building this massive machine, we look forward to seeing the incredible physics and quantum computing experiments our fellow researchers have planned with Colossus.” – Matt Hollister, project lead technical expert
To make a quantum computer, researchers don’t just need high-quality qubits connected to each other, they also need a large quantity of these devices, too.
Most dilution refrigerators that operate at millikelvin temperatures offer only a fraction of the space compared to Colossus, which makes scalability a big hurdle for constructing a useful quantum computer. Colossus will be so large that it will be able to house hundreds to thousands of highly coherent cavities and qubits.
The new dilution refrigerator will be constructed around a repurposed facility originally used to test components for Fermilab’s Mu2e experiment at temperatures around 4K. When Colossus is fully built, it will offer 5 cubic meters of space and cool components to around 0.01K. That is 10 times the cooling power and 15 times the volume at that temperature than standard commercial dilution refrigerators.
“At SQMS, we use metallic cavities made of superconducting materials to perform our research. Superconducting materials are great at storing electromagnetic energy with very low losses, but the big caveat is they must be very cold,” Hollister said. “Thankfully, we are constructing a space to store hundreds to thousands of cavities and qubits, depending on the geometry and sizes of course.”
The construction of Colossus faces many challenges related to its large diameter of around 2 meters. Like an upside-down wedding cake, around seven plates with smaller and smaller diameters and lower and lower temperatures will be suspended from each other and will form the cryogenic structure of Colossus.
From left to right: Chris James, Grzegorz Tatkowski and Matt Hollister stand on top of the re-purposed cooling tank for Colossus. Photo: Ryan Postel, Fermilab
“A dilution refrigerator of this size-scale has never been built before. This presents numerous technical challenges our team is working through,” said Grzegorz Tatkowski, an SQMS cryogenic engineer. “We are designing Colossus for a rather large payload in terms of mass, and ensuring each plate reaches the right temperature specifications needed for this project is a challenge.”
To build it, technicians will repurpose the cryogenic plant and a control room originally used for the famed Collider Detector at Fermilab experiment, which provided data for researchers to discover the top quark and also provided a recent measurement on the mass of the W-boson.
“This is a much different cryogenics challenge than what I faced when I worked in the Neutrino Division at Fermilab,” said Chris James, a cryogenic engineer. “There we were working with massive tanks that could hold several tons of ultra-pure liquid argon to detect tiny particles called neutrinos. Here I am working with liquid helium that is around 0.01K, which is around 10,000 times colder than liquid argon.”
To finalize the design and specifications of Colossus, the SQMS team conducted an in-depth review process on the components for the fridge. The team expects to start major procurements in summer 2023.
“Once we accomplish our goal of building this massive machine, we look forward to seeing the incredible physics and quantum computing experiments our fellow researchers have planned with Colossus,” said Hollister. “The Colossus team is excited to build a first-of-its-kind machine to enable our upcoming experiments and create computational devices that will advance knowledge and capabilities.”
The Superconducting Quantum Materials and Systems Center at Fermilab is supported by the DOE Office of Science.
The Superconducting Quantum Materials and Systems Center is one of the five U.S. Department of Energy National Quantum Information Science Research Centers. Led by Fermi National Accelerator Laboratory, SQMS is a collaboration of 23 partner institutions — national labs, academia and industry —working together to bring transformational advances in the field of quantum information science. The center leverages Fermilab’s expertise in building complex particle accelerators to engineer multiqubit quantum processor platforms based on state-of-the-art qubits and superconducting technologies. Working hand in hand with embedded industry partners, SQMS will build a quantum computer and new quantum sensors at Fermilab, which will open unprecedented computational opportunities. For more information, please visit sqms.fnal.gov.
Fermi National Accelerator Laboratory is supported by the Office of Science of the U.S. Department of Energy. The Office of Science is the single largest supporter of basic research in the physical sciences in the United States and is working to address some of the most pressing challenges of our time. For more information, please visit science.energy.gov.