Quick ReadScientists say neutrinos are the most numerous particles in the universe, and yet we know the least about them. An experimental project in Lake Superior aims to discover more about them. A 238-foot ocean research ship from Massachusetts sailed across the Great Lakes to Duluth this week to begin a unique scientific mission to detect neutrinos: tiny, subatomic particles that may hold the secret to the beginning of the universe. Neutrinos are sometimes called “ghost particles” because they are extremely difficult to detect. They rarely interact with matter and pass through most materials without leaving a trace. They are also literally almost everywhere. “There are a billion of them for every normal electron or proton that we are used to. Therefore, they are the most numerous particles in the universe, and we know the least about them,” explained Alec Habig, a physics professor at the University of Minnesota Duluth, who is the principal investigator of the project. that will happen about five miles off the Duluth shoreline. Derek Montgomery for MPR News The Experimental Neutrino Detector project, as it is called, is the latest in a long legacy of neutrino research in Minnesota. It is designed to detect neutrinos 200 meters below the surface of Lake Superior and will mark the first time neutrino detectors will be deployed in a freshwater lake. MPR News helps you cut through the noise and build shared understanding. Please increase your support for this public resource and keep trustworthy journalism accessible to all. Since 2005, the U.S. Department of Energy’s Fermi National Accelerator Laboratory outside Chicago, known as Fermilab, has generated the world’s most powerful neutrino beam with a particle accelerator. That beam points underground toward northern Minnesota. For years there was a neutrino director located deep in the Soudan underground mine near Ely. Now, a lab in Ash River, just outside Voyageurs National Park, detects neutrinos from Fermilab. But that beam is scheduled to shut down in February because scientists built a newer one. The Neil Armstrong on Tuesday while docked at the Clure Terminal expansion dock in Duluth. Derek Montgomery for MPR News “That beam passes just below Wisconsin and eclipses Lake Superior off Two Harbors on its way to the labs to the north,” Habig said. “The opportunity to see what happens in Lake Superior as lightning passes through it is the reason we are here.” For the experiment, the teams built five giant structures. Each is about three stories tall and weighs about 8,000 pounds, and each frame contains 18 spherical sensors that are about the size of a beach ball and filled with photographic tubes. A DOM, or digital optical module, awaits installation Tuesday at the Clure Terminal expansion dock in Duluth. DOMs are underwater sensors designed to detect weak flashes of light produced when neutrinos interact with matter. Derek Montgomery for MPR News When neutrinos travel through water, they emit faint flashes of blue light when they occasionally collide with atoms. At night, photographic tubes can detect these flashes. The system is designed to differentiate the neutrinos in the beam from neutrinos generated by the sun and other natural sources. “We can connect the dots and see how it went from here to here and say that it came from the direction of Fermilab and not from other cosmic radiation coming down from above,” Habig said. The University of Minnesota Duluth is leading the project, in cooperation with the U.S. Department of Energy and two national laboratories. It is sponsored by the Defense Advanced Research Projects Agency, or DARPA. Emily Foley of the Woods Hole Oceanographic Institution talks about the sensor suite aboard the Neil Armstrong Tuesday while in the lab with the ship docked at the Clure Terminal Expansion Dock in Duluth. Derek Montgomery for MPR News Project leaders did not know the total cost, but said it is in the tens of millions of dollars. Some reports suggest the research could eventually be used to track nuclear submarines or find secrets. nuclear reactors detecting the neutrinos emitted by those facilities. John Bruzzese, DARPA’s program director, says the agency doesn’t have a specific application in mind for this project. Neutrinos, he said, remind him of the discovery of X-rays, which also pass through matter. “When we discovered them, we couldn’t imagine what the applications would be,” Bruzzese said. “Now we see that this is part of everyday life. Here with neutrinos, we don’t know what the future is. DARPA’s role is to continue to monitor and fund research, so that when we understand, we can prepare our nation for that new world.” With Neil Armstrong in the background, a 30-foot platform awaits the installation of digital optical modules, or DOMs. DOMs will help detect neutrinos. Derek Montgomery for MPR News The research vessel is called Neil Armstrong and comes from the Woods Hole Oceanographic Institution. On Thursday, it will sail to a location about 3 miles into the lake from Two Harbors, where it will use a crane to begin moving the sensors into place on the lake bed. Crews will then lay fiber optic cables to connect to a temporary facility on the shore near Two Harbors. At the end of the experiment, the underwater sensors will be recovered and sent to Europe, where they will be used in neutrino research in the depths of the Mediterranean Sea. DOM, or digital optical modules, hang from a platform on the expansion dock at the Clure terminal in Duluth. DOMs are underwater sensors designed to detect weak flashes of light produced when neutrinos interact with matter. Derek Montgomery for MPR News Researchers still don’t really know what they will learn from neutrinos. UMD’s Habig says this project may not be a big discovery. But it will lay the foundation for future neutrino detectors. “How does it work? What challenges are there? Can we do it?” He said.And those discoveries can help answer much broader questions, said Rob Munier, vice president of Marine Facilities and Operations at Woods Hole Oceanographic Institution. “What we are doing here at the bottom of Lake Superior is nothing less than exploring the cosmos,” Munier said, “to help answer the question: Why do we live in a universe dominated by matter? Or put more simply, why are we here?”
