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Forum News Service, Published March 30 2013

Not yet complete, Minnesota physics lab reaches milestone

DULUTH, Minn. – A northern Minnesota physics laboratory yet to be completed already has reached a significant milestone.

The first finished section of the NuMI Off-Axis Electron Neutrino Appearance far detector near Ash River has recorded its first three-dimensional images of a subatomic particle producing a shower of energy as it passed through the detector.

“These initial images are a testament to the innovation and ingenuity of University of Minnesota faculty and collaborating researchers around the globe,” Marvin Marshak, laboratory director and professor in the university’s School of Physics and Astronomy, said. “We are thrilled to receive these first tangible results and are excited for the remarkable research the NOvA detector will allow in the near future.”

The 14,000-ton NOvA particle detector is being built to study neutrinos – subatomic particles that can help researchers discover how the universe was formed and how it will change.

“Neutrino research is a journey to discover how our universe began,” Marshak said. “To actually construct the device that will enable this discovery is a special opportunity for our students.”

Neutrinos are called the ghosts of the universe because they have little or no mass, no electrical charge and tend not to interact with other matter. But they are so numerous that even a small mass for each could have huge consequences for understanding the universe. Any observed change of a neutrino between the three forms of the particle – electron, muon and tau – will allow researchers to begin calculating how much mass they might have.

The detector will study changes in neutrinos shot 500 miles through the Earth from a half-mile-long “gun” at Fermi National Accelerator Laboratory near Chicago. Fermilab will start sending a beam of neutrinos toward NOvA later this year.

The data the partly built detector collected came from cosmic rays. When cosmic rays pass through the NOvA detector, they leave straight tracks and deposit well-known amounts of energy – a perfect tool for calibrating a new detector.

“It’s taken years of hard work and close collaboration among universities, national laboratories and private companies to get to this point,” Fermi laboratory director Pier Oddone said.

In 2005, Fermilab began shooting neutrinos toward a detector at the Soudan Underground Science Laboratory to observe muon neutrinos. To detect them, the Soudan detector uses 5,000 tons of steel plates separated by photosensitive plastic strips to detect the brief flashes of light created when neutrinos hit atoms.

The Ash River detector will look for electron neutrinos, using more than 14,000 tons of mineral oil and PVC plastic containers. The entire detector will measure more than 200 feet long, 50 feet wide and 50 feet tall. The completed section of the detector is about 12 feet long, 15 feet wide and 20 feet tall. Construction of the

$40 million building that will house the detector began in 2009. Construction of the detector began last year.

An international collaboration, the $283 million NOvA experiment involves 169 scientists and engineers from 34 global universities and laboratories.


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