Dark matter experiment leaving northern Minn. mine

Dr. Dan Bauer
Dr. Dan Bauer works on the Cryogenic Dark Matter Search experiment at the Soudan Underground Mine on April 9, 2009.
Jerry Meier/University of Minnesota

Minnesota may no longer lead the search for dark matter on Earth.

Physicists plan to relocate an internationally-renowned underground laboratory north of Duluth to a deeper site in Canada by 2013.

The Soudan Underground Laboratory's research into tiny particles called neutrinos would continue, said laboratory manager Bill Miller, but the project to find dark matter would move to SNOLAB, an underground laboratory in Sudbury, Canada.

The Canadian laboratory is about 7,200 feet below the earth's surface -- about three times as deep as the Soudan site.

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Miller said it's unclear whether any of the Iron Range laboratory's eight full-time employees would lose their jobs.

"The hope is that the facility here would remain open, and they would use this for testing the new detectors before they got placed in the [Canadian] laboratory," he said.

The Soudan Underground Laboratory's search for dark matter has attracted widespread attention. In December, researchers with the laboratory's Cryogenic Dark Matter Search II project came close to announcing the discovery of dark matter on Earth.

Scientists have described dark matter as the glue holding the universe together and believe that it makes up as much as 90 percent of the material in the universe. Scientists know that it exists because of the gravitational force it exerts, but have been unable to see it or identify it.

Miller said Soudan researchers are still examining data from this winter, and that it's "very possible" that dark matter could be discovered before the laboratory relocates.

But he said that even if the laboratory is the first to discover dark matter, physicists would still need to relocate the project deeper underground to reduce interference from cosmic ray particles.

The particles frequently collide in the upper atmosphere, producing particle showers that rain down on Earth. The showers can interfere with sensitive laboratory equipment.

"It's that noise that we're trying to get away from," he said.

At the Soudan Underground Laboratory, scientists have recorded one to two cosmic ray events per second, compared to about 33,000 every second on the earth's surface. At the new site, researchers hope to reduce those numbers even further, making it easier to search for dark matter.