How can you investigate a particle that is nearly undetectable? Justin Evans of the University of Manchester has been pondering this subject for the past decade.
“Clearly, the neutrino is a strange particle,” Evans added. “We haven’t even measured its absolute mass because it’s so light.”
Neutrinos are among the most abundant particles in the cosmos, but little is known about them due to their inability to be detected using traditional methods. Evans spotted an opportunity when the United Kingdom joined the Deep Underground Neutrino Experiment in 2015.
He explained, “We were thinking about what the UK could do for DUNE.” “We wanted to have a major effect and be a fundamental component of the detector,” says the team.
A huge wooden box arrived at the CERN Neutrino Platform on October 15 from Daresbury Laboratory in the United Kingdom. Inside was the first mass-produced DUNE anode plane assembly, a vital component in the DUNE Far Detector.
“It’s the first of 130 APAs that the UK will provide, which will be put in the first of the DUNE modules in South Dakota,” DUNE spokesperson Stefan Söldner-Rembold stated. “As a result, it is the DUNE Far Detector’s first key component to be developed.”
The experiment involves over 1,400 scientists and engineers from over 30 nations. Their goal is to provide a more complete picture of the origin of matter and the evolution of the universe. DUNE will track neutrinos and antineutrinos as they travel 800 miles from the Fermi National Accelerator Laboratory near Chicago to the Sanford Underground Research Facility in Lead, South Dakota, as part of the US Department of Energy’s Fermi National Accelerator Laboratory. Because these particles and their antimatter counterparts rarely interact with matter, they will pass straight through the earth before arriving at massive subterranean particle detectors that will be filled with 70,000 tons of liquid argon and have a total volume equivalent to about 22 Olympic-size swimming pools. Scientists will be able to analyze the differences in behavior between neutrinos and antineutrinos using these massive detectors. The findings will offer light on the role of neutrinos in the universe’s evolution.
The APAs are based on a concept pioneered by Nobel Laureate Carlo Rubbia in the 1970s. Each APA has 15 miles of hair-thin wire wrapped around a support structure the size of a church door in four different directions. A strong electric field pulls electrons released by a neutrino interacting with an argon atom toward the wires. Based on when and where the liberated electrons contact with the wires, scientists may reconstruct what happened during the original neutrino-argon interaction.
Adapting this approach for detecting neutrinos for DUNE—which will be built one mile underground to shield the detectors from cosmic rays that touch Earth’s surface—was a problem, despite the fact that it has been available for decades.
Evans explained, “That’s the ship-in-the-bottle part of underground physics.” “Everything has to go down in smaller portions than the mine shaft,” says the narrator.
The final APA design follows a successful two-year run of ProtoDUNE, a prototype of the DUNE detector at the CERN Neutrino Platform. These final DUNE-production APAs have just minor differences from the prototypes.
“We realized that some of the tubes that hold the wires needed to be larger,” Evans explained. “There were also a few screws that were difficult to get to.” It was a lot of boring and banal things, which is excellent because you want it to be boring and mundane.”
Another factor to consider was developing an APA template that could be used to mass-produce 150 APAs on both sides of the Atlantic: 130 in the UK and 20 in the US.
Hannah Newton, the project manager supervising the APA production at Daresbury Laboratory, said, “We required a design that is strong enough that we can build 150 of these.” “There will be no more tinkering.”
Three more APAs will arrive at the CERN neutrino platform in the next months for final testing inside the ProtoDUNE-SP cryostat in early 2022, with mass manufacturing set to begin in the spring. All APAs will be delivered to South Dakota for installation once they are completed.
“Cold electronics testing within ProtoDUNE will be the last evidence that all of the systems work together,” Newton explained. “It’s the ultimate confirmation that we’re ready to go and can increase production.”