Scientists Deploy First-Ever Neutrino Detector in Lake Superior

A 238-foot ocean research vessel from Massachusetts, the Neil Armstrong, docked in Duluth this week to begin a unique scientific mission: hunting for “ghost particles” beneath the surface of Lake Superior.

Neutrinos are subatomic particles so elusive they pass through most matter without leaving a trace, yet they are the most numerous particles in the universe. While they remain largely mysterious, an experimental project led by the University of Minnesota Duluth aims to change that, MPR News reported.

“There are a billion of them for every normal electron or proton that you’re used to. So, the most numerous particle in the universe, and we know the least about them,” said Alec Habig, a physics professor at the University of Minnesota Duluth and lead investigator on the project.”

The Experimental Neutrino Detector project is the latest in a long legacy of neutrino research in Minnesota. Previous efforts included a neutrino detector located deep in the Soudan Underground Mine near Ely and a current lab in Ash River near Voyageurs National Park. This new mission, however, marks the first time that neutrino detectors will be deployed in a freshwater lake.

Connecting the dots in the dark

The mission relies on a particle beam generated by the U.S. Department of Energy’s Fermi National Accelerator Laboratory, or Fermilab, located outside of Chicago. That beam is currently aimed underground toward northern Minnesota, passing beneath Wisconsin and Lake Superior on its way to the labs in the north.

Because the current beam is scheduled to shut off in February, scientists are racing to capture data as it passes through the lake. The team has constructed five giant frames, each weighing 8,000 pounds and standing three stories tall. These frames hold 18 spherical sensors, known as digital optical modules, which are designed to detect the faint flashes of blue light emitted when neutrinos collide with atoms in the water.

“We can connect the dots and see it went from here to here and tell that it’s coming from the direction of Fermilab and not other cosmic radiation coming down from above,” Habig told MPR News.”

The project is a collaborative effort between the University of Minnesota Duluth, the U.S. Department of Energy, and two national labs, with sponsorship from the Defense Advanced Research Projects Agency, or DARPA. While the project’s total cost is estimated in the tens of millions of dollars, the practical applications remain speculative.

The search for future utility

Some reports suggest the research could eventually be used to track nuclear submarines or find secret nuclear reactors by detecting the neutrinos emitted by those facilities. However, John Bruzzese, a program manager for DARPA, said that the agency does not have a specific application in mind for this project. He compared the current uncertainty to the early days of X-ray discovery.

“When we discovered those, we could not imagine what the applications would be. Now we see this is part of daily life. Here with neutrinos, we don’t know what the future is. It’s DARPA’s role to continue monitoring, funding research, so that when we understand, we can prepare our nation for that new world,” Bruzzese said.”

The logistical operation begins in earnest on Thursday, when the Neil Armstrong travels to a location approximately 3 miles offshore from Two Harbors. Using a crane, the crew will lower the sensors into place on the lakebed and connect them to a temporary facility on the shore via fiber optic cables.

Once the experiment concludes, the sensors will be retrieved and transported to Europe for use in neutrino research deep in the Mediterranean Sea.

Testing freshwater neutrino detection feasibility at the lakebed

The project may not make a great discovery, but Habig emphasizes that the primary goal is to establish the feasibility of freshwater neutrino detection. By testing the sensors in this environment, researchers are building the necessary infrastructure and knowledge for future neutrino detectors.

The broader scientific ambition is to help answer the question: Why do we live in a matter-dominated universe? The sensors in Lake Superior represent an attempt to probe these fundamental questions of physics.

“What we’re doing here at the bottom of Lake Superior is nothing less than the exploration of the cosmos, to help answer the question: Why do we live in a matter-dominated universe? Or put more simply, why are we here?” said Rob Munier, Vice President for Marine Facilities and Operations at the Woods Hole Oceanographic Institution.”

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