Lake Superior is becoming a laboratory for one of physics' hardest-to-catch particles. The research vessel Neil Armstrong departed Duluth on Friday, Nov. 13, on the first of several trips to install neutrino detectors on the lake bottom off Two Harbors, Minnesota.
The work is part of the Experimental Neutrino Detector, or END, project, led by the University of Minnesota Duluth. Physics professor Alec Habig is the principal investigator. The project is backed by the U.S. Department of Energy's Office of Science, Fermilab and Brookhaven National Laboratory, and is described as costing tens of millions of dollars.
Neutrinos have no electric charge and almost no mass, and trillions pass through people each second without interacting. Researchers want to distinguish neutrinos in a beam generated at Fermilab in Illinois from background cosmic particles. That beam travels under Wisconsin and emerges through Lake Superior near Two Harbors on its way to detectors in northern Minnesota, a route in use since 2005 toward the former Soudan Mine lab and the operating NOvA facility.
Crews will lower five metal frames, each about 33 feet tall and weighing about 8,000 pounds, roughly 689 feet to the lakebed several miles offshore. Each frame carries 18 spherical photosensors, about the size of a beach ball, using technology developed by the KM3NeT collaboration for work deep under the Mediterranean Sea. More than three miles of fiber-optic cable will connect the sensors back to shore near Two Harbors.
Habig said the first frame was to be installed this week and data collection would begin as soon as the cables are connected. The work faces a tight window, because the Fermilab neutrino beam is scheduled to shut off in February 2027.
When the experiment ends, the sensor frames are to be retrieved and sent to Italy for use in the Mediterranean, while the cables will stay on the lakebed and be reused with university sensors to study Lake Superior itself.
