A home for a neutrino detector, By TOM LAVENTURE, Staff Writer

Ash River considered for neutrino detector

Northern Minnesota may soon play an important role in better understanding dark matter in the universe, and the relationship between matter and antimatter.
The Department of Energy is welcoming comments on a draft environmental assessment for proposed construction and operation of a neutrino detector laboratory at Ash River. The project, NOvA, is part of the new neutrino physics research program and would be the “far detector,” in addition to a “near detector” at the main neutrino injector facility at Fermi National Accelerator Laboratory in Batavia, Ill.
The DOE is offering public review and comments on the draft environmental assessment until April 30, 2008 online at www.fnal.gov/pub/neighbors/nova/NovA-draft-EA-summary.pdf.
There are three types of known neutrinos. With an atomic mass near zero, they are uncharged elementary particles that are relatively unknown because they rarely interact with ordinary matter.
Scientists want the physics experiment to provide a better understanding of neutrino mass, weak interaction, its role in dark matter, and the relationship between matter and antimatter in general. The project would study the oscillation of neutrinos from one type to another.
NOvA is a collaboration of approximately 200 scientists and engineers from nearly 30 international laboratories. The University of Minnesota is the lead university under professor Marvin Marshak, Institute of Technology, and William Miller, Soudan Underground Mine Laboratory. They work in conjunction with Pepin Carolan, DOE NOvA project director, and John Cooper, Fermilab NOvA project manager.
Once approved and funding secured, the project construction would take from 2008 to 2013. It would expect to remain in operation through at least 2019. The detector would be removed and it is possible that the facility could be refitted for other scientific use.
“The NOvA Project is moving forward, albeit in slow measure at the moment due to an FY 2008 Congressional funding cut to high-energy physics research that impacted the project budget,” stated Sally Arnold, a physical scientist at the DOE Fermi site. “We, the U.S. Department of Energy, Fermilab, and the University of Minnesota, are making all possible strides to keep the project on track.”
The Ash River project would require a 40 foot dig into granite to house a proposed 20,000-ton “far detector” to monitor neutrino beams from an accelerator complex 504 miles away at the Fermilab in Batavia.
The Ash River site is on 89.6 acres of undeveloped land about 25 miles southeast of International Falls. It is about one mile from the entrance to Voyageurs’ National Park in St. Louis County. It is approximately 1,000 feet from the Ash River, and 2.8 miles from Lake Kabetogama.
This site was acquired by the University of Minnesota. It is the preferred site among many as the furthest possible U.S. location that is still in the direct line of the neutrino beam from Fermilab.
The DOE says the location requires a sensitive approach to the protected environment and the facility design would minimize visual impact from Voyageurs National Park. The far detector building would rise approximately 37 feet and have muted exterior colors. There would be no windows facing north to reflect sunlight at the park, and an earthen berm would surround much of the facility.
The DOE says detector components would be free of radioactivity. It would require 4.2 million gallons of scintillation fluid. The solution requires a five percent blending of pseudocumene, a toxic organic liquid that would be transported by tanker truck to the Ash River site.
Pseudocumene as a liquid is hazardous to water based organisms and to humans as a vapor. It would require containment during the blending, transfer, storage and use at the facility.
The detector would require 156 metric tons of Devcon-60 and also a toxic adhesive that would be delivered to the Ash River site in just over 600 separate 7,000-gallon truckloads.
The DOE says chemicals would be removed with the detector apparatus when the site is decommissioned at the end of the NOvA project. The liquid scintillator is primarily mineral oil and could be recycled as an alternative fuel.
The environmental assessment says the site would require the improvement of an existing logging road. Four sites of possible historic significance, three former logging camps and a railroad trestle, were reported within one mile of the site. A Cultural Resources Assessment found no existing architectural history surveys or known sites for the project area.