A Deep Sense of Place

Soudan iron mine offers neutrino science some bedrock support

by Mike Perricone

SOUDAN, Minn.— If Gertrude Stein had ever visited this far northeastern corner of Minnesota, she probably would have written about the Soudan region in the same way she did about Oakland, California: “There is no there, there”

But that’s all right, because the people up here like it that way. And they’d know that Gertrude Stein never worked in a mine. Most people up here have, one time or another, often through more than one generation, and often through lean times.

The number of miners is seriously declining in this region, called the Iron Range since rich ore deposits were discovered in 1865. The underground mines have largely given way to surface mining, which requires less labor, is amenable to mechanization, and produces far more ore from less-concentrated deposits by processing more rock, faster and cheaper, crushing the rock and separating the ore magnetically. Quantity outstrips quality.

But the underground mines remain. The Soudan Underground Mine is one of them, a national historic landmark since 1966—and a physics laboratory since 1979. With commendable foresight, the state of Minnesota has sought alternatives for more than 60 years to an over-dependence on mining for the economy of the region. The Iron Range Resources and Rehabilitation Agency was created by the 1941 Minnesota Legislature to help ease northeastern Minnesota’s dependence on the natural ore and timber industries.

The cavern housing the detector for the Main Injector Neutrino Oscillation Search, where nearly half of the projected 486 detector planes have been assembled and installed. The mural is 59 feet wide and 25 feet high.

The Soudan Underground Mine was closed in 1963 and placed on the National Register of Historic Places in 1966. It is operated as a state park by the Minnesota Department of Natural Resources, with 14 tours a day taking the fast and clamorous elevator ride nearly a half-mile below the surface. After descending, hard hat-wearing tourists can view old mine caverns with some of the equipment still standing in place.

Since Memorial Day, tourists have also been able to view the cavern housing the detector array for the Main Injector Neutrino Oscillation Search— nearly 500 assemblies of steel, scintillating plastic and electronic readouts, shaped like 28-foot stop signs, hung like file folders, each weighing 12 tons. The completed array will weigh 6,000 tons, about equivalent to a naval battleship, aimed at halting a small portion of the neutrino beam sent through the earth from Fermilab.

The tourists can also catch a glimpse of real miners—although these miners are now working for the University of Minnesota, assembling and mounting the detector planes that will halt a handful of neutrinos a day when the experiment is up and running, around 2005. The working crews were drawn largely from some 1,400 people laid off when the LTV Steel Mining Company shut down its facility in nearby Hoyt Lakes in May, 2000. It was just about that time that MINOS detector construction began.

“You never like to have good fortune based on someone else’s bad fortune,” said Assistant Lab Manager Jerry Meier. “But with the LTV layoffs, we were able to bring in people with excellent skills and experience. We really have quality crews working here.”

The crews work 10-hour shifts, four days a week. They work quickly, quietly, efficiently and fastidiously —the cavern floor glints under the stark white lighting. They work so well, in fact, that the production schedule had to be changed—because the crews were running ahead of the predicted rate for assembling and mounting the detector components shipped from Fermilab.

The assembly work in the cavern is quietly impressive, but the process of getting the components down the narrow elevator shaft is stunning.

The materials are delivered three times a week at 5:30 p.m., after the day shift and public tours have ended. The work is highly dependent on the weather, especially the wind conditions. When it’s windy, the crews can’t unload the boxes of scintillating plastic, which are about 30 feet long.

“We won’t let them unload the scintillator if the winds are above 25 mph,” Meier said. “The detector plate sections are heavy enough to withstand the wind, but the boxes of scintillator are too light and too hard to handle in the wind.”

Watching the preparations, the unloading, and the elevator descent is like witnessing a combination of ritual dance and close order drill. The crew begins by essentially dismantling the elevator car, or cage, removing the sides and top. A pulley from the mine headframe begins slowly drawing the component— either the long wooden crate or the six-ton package of half a detector section—off the delivery truck. It takes so much space to shift the material from the horizontal to the vertical that part of the headframe support had to be removed and reconfigured. While the load is hanging there, and changing its orientation, the crew guides it to rest in the cage. Then it is sent 2,341 feet down the shaft to level 27, and unloaded by a similar process onto a track that carries it to a staging area in the cavern. Not a word or motion is wasted.

The operation can extend well into the night, as late as 3 a.m. For some of the crew members, this is not their only job. But they’re accustomed to working two jobs if necessary, shifting jobs because of layoffs or mine closings, or just because times aren’t what they used to be. Physicist Earl Peterson of the University of Minnesota has been part of the underground laboratory operation since 1979, when the proton decay experiment (Soudan II) began. He’s watched this sort of work performed for more than 20 years.

“These people have always lived here, and this is where they want to be,” Peterson said. “They’ll do what it takes to stay here.”

Mines aren’t the only feature of the area, or the only resource. Minnesota calls itself “Land of 10,000 Lakes,” which is probably an underestimate given the innumerable inland basins in this heavilyforested region alone. The forest is a threedimensional curtain of towering but stick-thin evergreens. Any peek through the curtain is likely to reveal a lake with miles of densely wooded shoreline interrupted by just a handful of clearings for prized and longstanding lakefront hideaways. The prevailing sentiment seems to be the fewer of those, the better—though many of them are having DSL lines installed.

“The city populations are declining, and we are seeing more people move into the rural areas,” said Lab Manager Bill Miller, who built his own home and has been living on a quiet lakefront property for more than 25 years. “With the growth of the Internet, people are realizing they can live and work and be connected just about anywhere.”

A phone call brought Miller the news that another neighbor was, indeed, interested in signing up for DSL. Miller explained that it would take five subscribers to get a line run out to the lake. “Now we just need two more,” he said.

Direct communication is still a priority on the project, and Miller frequently drives to Fermilab and back for meetings—a trip that can take as much as 10 hours each way (the neutrinos, meanwhile, will cover the straight-line distance of 450 miles in 0.0025 seconds). But distance driving seems to be the norm in this region. Miller has been known to drive with his wife on a Saturday to attend a Fermilab Arts Series presentation that night.

“Oh, it’s not that bad a drive,” he said with a shrug and a smile.

The arts have also reached down to Level 27 and made quite an impact. The University of Minnesota Foundation commissioned a mural for the MINOS cavern—a mural painted onto the rock wall, 59 feet wide by 25 feet high. The artist, Joe Giannetti of Minneapolis (whose accent betrays his origins in Brooklyn, New York), did his painting while dangling from a sling suspended from a support beam near the roof of the cavern. His distinctive technique was featured in a recent National Geographic television documentary about the MINOS project.

Giannetti was challenged, not only to find the right paint to adhere to the rock, but also to overrule his instincts in placing the image on the undulating surface. He had to steel himself to be guided by the image projected onto the wall from a slide projector across the cavern. Distortion in the close view translated to a normal image viewed from the second-level visitors’ gallery across the cavern. The mural’s fiery central focus area contains images of scientists such as Enrico Fermi and Wolfgang Pauli, Wilson Hall at Fermilab, George Shultz, a key figure in the history of Minnesota mining, and a number of surprises.

“The easy way out would have been to fill the horizontal space with a horizontal time line,” Giannetti said. “But I wanted a focus that would be the same from any angle, and not be lost from one end to the other. I’ve included the word ‘change’ in as many languages as people could give me translations for it. Neutrinos are changing all the time—just as we are, just as the universe is. I’m fascinated by neutrino science, and I admire the imaginations of the scientists. A scientist had to imagine this experiment, this series of detectors. This place is a temple of the human imagination.”

Scientists, miners and an artist have combined to create a special sense of place on Level 27. All that’s required is looking beneath the surface.