Adam Minter [2]At 7:20 a.m., on a hilltop overlooking the wooded highlands in Minnesota’s Iron Range, a dozen men and women emerge from parked cars, some wide awake in flannel and Carhartt, some weary in khakis and button-down shirts. A few discuss the Wild and the politics in nearby Ely; others trouble over germanium crystals and liquid nitrogen. Nobody bothers to look to the left, at the random assortment of old mining buildings and the pastoral view over the town of Soudan just beyond. Nor do they look up at the twenty-five-foot tall elevator frame, whistling in the soft breeze, nor down the black mine shaft that it straddles. This is all just part of getting to work on an average Monday morning.

Bill Miller, the stout, bearded manager of the Soudan Underground Laboratory, steps out of an orange Toyota Sienna station wagon. He walks with authority, but in an easy loping manner that suggests he never flaunts it. He slides open the door to a four-by-six-foot, two-story iron elevator car suspended over the mine shaft. The assembled group crowds into the space, shoes and boots scraping across a grimy metal floor.

Conversation continues, even as the door is slammed shut and the light is reduced to a pale glow through a dirty window. Then, promptly at 7:30, the car lurches down into a quick, absolute blackness that smears before the eyes and stops conversations in mid-sentence. The car shakes aggressively, almost enough to require handholds, as on a subway car. There is a brief flash of light from a bulb passed in the dark descent, then more darkness, more vibrations. The grinding and speed seem to increase. Another flash of light, then more darkness.

The noise stops abruptly, yet the car continues in relative silence, as if cut loose. A new, rotten light oozes through the window, illuminating long strips of concrete. After three interminable minutes, during which nobody speaks a word, the car slows and bounces to a stop. The daily commute is complete. A dirty face topped by a hard hat appears in the glass and the door slides open into a musty rock cavern run through by railroad tracks. Interrupted conversations start up again. A steel sign greets the passengers as they exit:

“LEVEL NO. 27—2341 FEET BELOW THE SURFACE—889 FEET BELOW SEA LEVEL.”

Miller turns right, leading the way into a four-and-a-half-story cavern where a device known as the “Far Detector” looms. Its 486 octagonal steel plates hang like ghostly blue and green file folders from a one-hundred-foot-long steel infrastructure. Each plate is twenty-seven feet in diameter, one inch thick, and punctured by a tree-trunk-sized, flesh-colored coil of wires and cooling hoses, which drops like a horse’s tail onto the cavern floor. Three stories of walkways run the length of the detector, providing access to cables that run in rainbow arcs from each plate to racks of monitors. The device has no moving parts and emits no sound, yet the cavern is filled with a low, constant hum not unlike the sound of blood flow magnified by a stethoscope. “Ventilation system,” Miller says by way of explanation. “Bats sometimes get stuck in it.”

In early 2005, the Far Detector will become the target for a beam of subatomic particles called neutrinos, fired through the earth from Fermilab, a particle accelerator five hundred miles to the south, on the outskirts of metropolitan Chicago. After a while, and nobody can say exactly how long it will take, enough neutrinos will be captured in the far detector’s six thousand kilotons of steel to allow physicists to determine whether, in fact, they change—or oscillate—in transit. This entire process is known as the Main Injector Neutrino Oscillation Search (MINOS), a grand experiment whose startup costs—including the far detector in Soudan, a smaller “Near Detector” at Fermilab, and the neutrino beam—run to more than $170 million in federal funding, with ongoing costs of about $1.4 million per year. In truth, it’s a modest sum for big physics, a fraction of the cost of several other national projects. But outcome, however, is of an entirely different order of magnitude: If MINOS works as planned, the results could fundamentally change our understanding of the universe.
Neutrinos, they are very small,
They have no charge and have no mass
And do not interact at all.
The earth is just a silly ball
To them, through which they simply pass,
Like dustmaids down a drafty hall....

—John Updike, from “Cosmic Gall”

In a world that seems increasingly complicated, there is some solace in knowing that certain physical concepts don’t waver. Energy conservation—the idea that what goes in must come out—is one of them. For example, when a balloon explodes, it does so with the force of the breath that filled it, no more or less. Likewise, when a cue ball moves across a pool table, it accelerates at a speed proportional to the force that hit it.

In 1930, however, the Austrian physicist Wolfgang Pauli discovered a problem: A small amount of energy seems to vanish—that is, it is not conserved—in the aftermath of a certain type of subatomic reaction. Pauli refused to believe that energy conservation was violated, and so he attributed the loss to an uncharged particle of nearly no mass that departs the reaction with the missing energy. It was a bit of a reach, and Pauli knew it. “I have done a terrible thing,” he wrote despairingly. “I have postulated a particle that cannot be detected.” On this count, he was wrong. In 1956, in an experiment that would later win a Nobel Prize, two American scientists were able to detect the existence of Pauli’s particle, named the neutrino by Enrico Fermi. Later experiments showed the neutrino to exist in three types, or “flavors”: electron, muon, and tau. Yet for each flavor, there remained a problem: Did the elusive neutrino have mass? If so, the mass is so small as to be undetectable by any conventional means.

That’s when things got interesting. Following Pauli’s work, theorists predicted how many electron neutrinos should reach the Earth as a result of the sun’s nuclear processes. But when that hypothesis was first tested in 1967, the results showed that only one-third of the expected electron neutrinos were arriving (more recent experiments have raised the observed total to more than half of the expected rate). Several explanations have been offered for this solar neutrino deficit, but the most compelling and likely one is that neutrinos oscillate. That is, they change flavor as they travel from the sun to the Earth (and elsewhere, for that matter). The MINOS experiment is designed to produce several results, of which the most important is a definitive and controlled demonstration of neutrino oscillation. But for something to oscillate, it must have mass. And so, if neutrinos oscillate, it follows that they also have mass.

Why does anybody need to know this? Currently, every cubic inch of the universe is filled with hundreds of neutrinos; they pass through all matter, animal, vegetable, mineral, in a constant, steady stream, and yet almost nothing is known about their properties. If neutrinos have mass—and most physicists believe that they probably do—then they could help cosmologists explain why the universe behaves as if there is a whole lot more mass to it than what is observable. For example, physicists are unable to explain the velocity and shape of galaxies based upon current physical knowledge. This is because the force of gravity is proportional to mass, and there is simply not enough detectable mass in a galaxy to exert the gravity necessary to hold it together. In fact, it is widely accepted that visible mass accounts for only ten percent of the total mass of the universe. Thus, over the past couple of decades, physicists have been searching for “dark matter” that would account for the other ninety percent. Neutrinos, if they have mass, might offer a partial solution to this problem.

Neutrino mass has other implications. For decades, scientists have relied upon a theoretical explanation of the elementary forces and particles called the Standard Model. It is a remarkably robust theory that has sustained numerous experimental attacks on its predictive powers. Yet for all of its successes, the Standard Model is widely acknowledged to be incomplete. Among its likely weaknesses is its suggestion that neutrinos lack mass (though it does not rule out the possibility). Proof that neutrinos have mass will shift science several steps toward a new physics. “Hey, it’s fundamental to our understanding of the universe,” exclaims Professor Earl Peterson, director of the Soudan lab. “And we should find that kind of stuff out.”

Peterson has been trying to find that stuff out for most of his career. His office, overlooking the mall on the University of Minnesota’s Minneapolis campus, is a repository of deep questions and occasional answers. A bulletin board displays data plots dating back to the early 1980s; the desk and tables are piled high with dust-coated journals and papers. The erased ghost of a drawing of the MINOS detector is barely discernible on the blackboard. Peterson is a wiry, graceful presence amid the chaos; he projects an orderly intelligence, the confident timbre of his voice suggesting an intellect accustomed to being consulted.

A native of Washington, he showed an early aptitude for science and math, which eventually led him to a Ph.D. in elementary particle theory from Stanford. In 1967, he began post-doc work at the University of Minnesota, but the topic did not hold him. “After two years I started looking for something else to do,” he says with a wry laugh, cigarette in hand. His search took him to renowned designers Charles and Ray Eames, to whom he offered himself as a “concept person.” “They were very nice to me,” Peterson remembers, even though they turned him down. In the end, he was drawn back to academic physics and, eventually, to Minnesota.

During an impromptu visit to Harvard in January 1979, Peterson got his initial ideas about proton decay from some friends there who were “developing the first of the grand unified theories.” He returned to Minnesota, hoping to conduct an experiment to observe the phenomenon. But there was a logistical problem: A proton-decay experiment could only be conducted in a place shielded from the rain of cosmic rays constantly hitting the Earth’s surface. That is, it had to be done underground.

“So we started looking for mines,” Peterson explains. “And it just so happened that Marvin [Marshak, professor of physics and astronomy at the University of Minnesota] and his family had been to Soudan and taken the historic mine tour. That’s where it started.” Peterson, Marshak, and their collaborators soon arranged for a small experiment to take place on an abandoned level of the old Soudan Mine, and on March 20, 1981, a teletype printer spit out the first data from the Soudan Underground Laboratory.According to the Soudan Mine interpretive program, the region around northern Minnesota’s Lake Vermilion was settled by gold prospectors in 1865. Though gold was never found, the aspiring miners soon located some of the purest and most plentiful iron ore deposits on the planet. By 1954, the Soudan Mine had been sunk almost a half-mile below the Earth’s surface.

After ceasing operations in 1962, the US Steel Corporation donated the Soudan Mine to the state of Minnesota, which today operates it as the Soudan Underground Mine State Park. The elevator to the twenty-seventh and deepest level, down Shaft No. 8, now transports tourists instead of miners. And, at 7:30 a.m. and 4:30 p.m., it transports the people who have reclaimed and expanded the mine as a physics lab.

It is late midmorning in the long office pod that hovers beside the MINOS detector. David Lee Roth’s “Yankee Rose” blasts from the office manager’s PC, while an assortment of physicists drink their morning coffee and discuss the day’s work plan with the lab crew. It’s a collegial environment where associations often date back to grad school (in the case of the physicists) or high school (in the case of the locally hired lab crew). Hierarchies are mostly non existent, with all parties focused on the daunting task of making the detector and its software run correctly. Professor Louis Barrett of Western Washington University, the MINOS far detector’s grandfatherly data acquisition coordinator, offers that “Maury’s the guy who thought of shooting a neutrino beam at the mine.” He gestures toward Dr. Maury Goodman, a gentle-mannered physicist from the Argonne National Laboratory outside Chicago, who is quietly reading his email. Goodman shyly mumbles something about “other people,” but his wife (who describes herself as “just a wife”), busy at the computer behind him, proudly bursts in, “I called my brother and said, ‘You won’t believe what he’s thought of now.’”

Goodman smiles uncomfortably and steps outside the pod to an exhibit that explains MINOS to the small number of Soudan Underground Laboratory visitors who don’t understand particle physics. He likens the experiment to “trying to hit the moon with a flashlight—the trick is being able to see the flashlight from the moon. That’s why we have to build something big.” He gestures with his laser pointer at the enormous detector. “I mean, it takes that to stop a few thousand neutrinos per year.” It is estimated that only nine thousand neutrinos will be stopped out of the five trillion that make the .0025-second trip from Fermilab in Illinois to (and through) the far detector in a year’s worth of runs. “And the reason to come up here, five hundred miles away from Chicago, is that we thought that there might be something going on with oscillation at that scale,” Goodman says, spreading his hands. “You couldn’t do this experiment using only ten or twenty meters.”

Back in the fluorescent-lit office pod, Bill Miller settles into his squeaky chair, in a cubicle squeezed to prison-cell proportions by computers, collapsing bookshelves, boxes of MINOS T-shirts, and stacks of binders. As lab manager, the forty-eight-year-old Miller is responsible for lab logistics, and over the last decade, he has been largely responsible for the design and installation of the far detector. But construction management skills alone are not enough to get a multi-million-dollar experimental apparatus built. It’s also necessary to have a fundamental understanding of the science involved in using that apparatus, and so Miller holds the additional title of assistant scientist. “Usually you’d have a Ph.D. in my job,” he admits, acknowledging that “I took an unusual path.” That’s an understatement, perhaps, considering Miller doesn’t even have a B.A.

Born in Florida to a minister in charge of the Presbyterian Church’s missionary program, Miller spent his childhood summers traveling among missionary camps in a VW van. In 1959, the family visited the Iron Range, and soon after bought a cabin on Snowbank Lake. “Essentially, I’ve been coming to the Ely area my entire life,” he explains. Now he and his wife (he has two grown children from a prior marriage) live outside Ely, in a house Miller constructed himself in the mid-1970s. It’s a modest-looking place from the outside, but the interior walls are lined in fine woods and wainscoted with the swirling copper patterns of cathode boards salvaged from a proton decay experiment.

Though Miller obtained a perfect GPA in his first year as a math major at the University of Southern Connecticut, he found greater satisfaction working as a guide in the Boundary Waters during the summer of 1974. He stayed in northern Minnesota, and “my parents were incredibly bummed,” he recalls with a laugh. (Though it was little solace to his parents, Miller was a phenomenal guide: A 1974 article from All Outdoors magazine extols his skills and concludes by comparing him to French-Canadian voyageurs who “wore earrings and let their hair fall to their waists.”)

To makes ends meet, Miller worked construction in the off-season. But construction, too, could be erratic, and in the winter of 1985 Miller was unemployed. Fortunately, the new lab manager for the Soudan Underground Laboratory, a neighbor of Miller’s, offered him a temporary job in civil construction. At the time, the lab was expanding from its modest roots as “found space” for the proton decay experiments developed by Earl Peterson and his colleagues into a facility capable of hosting multi-million-dollar experimental apparatuses. Miller remembers it as “a really cool job” where he spent his first two months “hauling muck in pails,” and “spending a month on the twenty-fifth level alone with a headlamp.” “He was just really smart, and could do whatever needed to be done,” Peterson recalls. Eventually, Miller’s employment was extended to the construction of the much larger and more complicated Soudan Two proton decay detector in a newly excavated space on the twenty-seventh level. “By the third or fourth month I started working with physicists,” Miller recounts.

The first formal proposals for the MINOS experiment were drawn up in 1990, but it was another four years before formal research and development began. When it did, Miller (who had become lab manager in 1991) played a leading role, developing most of the procedures and protocols necessary to construct the far detector at the Soudan Underground Lab. In total, eight years of planning took place before the detector’s first plate was assembled in the freshly excavated cavern.

“When you’re half a mile underground, it really is like trying to shove the ship back into the bottle,” Miller explains. “Everything had to come down in that four-by-six-foot elevator car. Every last piece of equipment, all six thousand kilotons of detector.” For example, a front-end loader was totally disassembled on the surface, lowered to the twenty-seventh level in pieces (each tire required one elevator trip), and reassembled underground. Each of the detector’s 486 plates was assembled from eight pieces of half-inch thick steel measuring six by twenty-seven feet, which were cut precisely to fit inside the elevator in six-ton bundles. On the other end, approximately 657,000 cubic feet of excavated material from the new cavern was brought to the surface. In all, the cavern excavation and detector construction required 29,613 one-way elevator trips (at a cost of $30 per trip), over twenty-three months. These were not trivial operations. In fact, Miller tested them in an exact mockup of the elevator car and head-frame that was built, along with a detector prototype, at Fermilab in Illinois.“The whole reason that we were able to do the thing under budget was that we got the very best millwrights and welders on the Range,” Miller explains. Just as the Soudan Underground Lab project was beginning to hire, the LTV taconite plant in nearby Eveleth was closed, putting hundreds of skilled laborers out of work. Doug Wiermaa had spent nearly 10 years at LTV when he interviewed for a job with MINOS. “It took us a while to figure it out, but Doug is really, really smart,” says Peterson. Wiermaa, who has a shy smile and works in jeans, a T-shirt, and an untucked, unbuttoned flannel shirt, clearly enjoys working with physicists. “None of us on the crew is educated—well, so-called ‘educated,’” he says. “But everyone down here treats us with respect, and they know that we know a few things they don’t.” He laughs as he recalls a physicist who approached him with a screw-gun in one hand, a screw in the other, and bewilderment on his face. “I think it was Louis [Barrett] who said that a physicist can tell you everything about a bolt except how to use it.”

Having worked on its construction, Wiermaa is now learning how to run the detector. In fact, for extended periods he and the six other crew members are the only staff assigned to the Soudan portion of the multi-million-dollar MINOS experiment. “We’re physicist-less a lot of the time,” shrugs Miller. “But that’s OK. We did it with other projects, too.” Maury Goodman is similarly nonchalant about entrusting the detector to the crew: “Maybe their instincts won’t be right all of the time. But look, they built the thing.”

You haven’t seen the buffalo?” Sergei Avvakumov asks. “Then turn left here,” he urges. The car speeds another mile or so through the prairie of the Fermilab campus, 40 miles west of downtown Chicago. “There.” The thirty-two-year-old Avvakumov, a native of Novosibirsk, Siberia, opens the door and stands at the roadside, a lanky, ethereal figure of at least six and a half feet, his thinning blond hair tossed in the breeze. He is wearing a MINOS T-shirt. Downwind, a herd of buffalo grazes on the restored prairie beneath the distinctive silhouette of Wilson Hall, Fermilab’s towering headquarters. “The buffalo have been out here from the beginning,” he says, displaying his detailed knowledge of Fermilab’s history. “But everything else has changed. It used to be farm fields out here. Now the suburban sprawl is really taking over,” he gestures toward several distant subdivisions creeping over the Illinois plains.

Had Russian funding for science not collapsed in the mid-1990s, Avvakumov might very well have remained in Russia. But after completing his M.A. at the Moscow Institute of Physics and Technology, he found himself unemployed. “So I decided to study some more.” He entered the University of Rochester in 1994 to pursue his Ph.D. “It took me one year to complete the classes,” he says with a modest shrug. The remainder of his graduate education was spent at Fermilab, working on a neutrino experiment for his thesis.

Fermilab was established in the early 1960s to provide American physicists with the most powerful tool ever built for probing the fundamental constituents of matter. At its most basic, the facility consists of massive, billion-dollar magnets arranged in a four-mile circle around a tube the diameter of a drinking straw. Within that tube, subatomic particles are accelerated to phenomenal speeds and energies, thanks to the magnets, and then collided. Scientists are able to observe or deduce the nature of the subatomic world from the patterns left behind. Some particles can be diverted into a second accelerator—the Main Injector—which pushes them to even greater speeds and energies; they’re then fired through a high-tech gauntlet that transforms the particles into a nearly pure beam of neutrinos streaming north, toward Soudan.

Now working full-time on the MINOS experiment, Avvakumov is participating in the design of software that will reconstruct the paths of those few neutrinos that get captured by the far detector in Minnesota. He knows the Soudan Underground Lab well, having spent fourteen months there working on electronics. It is a period he remembers with fondness, since northern Minnesota reminds him of Siberia. Currently he spends most of his time in the twelfth-floor MINOS Control Room in Wilson Hall, which, despite its grand name, is a barren office equipped with a blackboard, conference table, worn sofa, ragged carpet, and three computers connected to the Soudan Underground Lab.

From the control room, Avvakumov points outside to a series of observation buildings, one of which temporarily houses the MINOS Near Detector, which is essentially identical to Soudan’s far detector, except for its smaller size. Oriented immediately downwind from the neutrino beam as it emerges from the Main Injector, it will allow physicists to measure the beam at its origination point, and compare it with measurements taken downstream at Soudan. With any luck, the differences should be significant enough to prove neutrino oscillation.

Unfortunately, contractor snafus, flooding, and a number of serious safety lapses have delayed construction of the Near Detector and the neutrino beam by two years and several million dollars. As a result, the Far Detector in the Soudan mine has been pressed into temporary service as a very expensive cosmic ray detector, reading the highest-energy particles that penetrate through 2,700 feet of earth and rock, until the MINOS experiment finally goes online in 2005. “Frankly,” sighs Bill Miller, “if things hadn’t gone so well with construction in Soudan, the funding for the project probably would’ve been pulled completely.”

Though sunlight is only a memory underground, there is an undeniable sense of approaching darkness as the day comes to an end at the Soudan Underground Lab. Lights are extinguished, computers idled. Yawns emanate from physicists and crew alike. Sitting in his office as the day winds down, Miller downloads “homework” onto a flash memory card and considers the future of the Soudan Underground Lab, which is not promising at the moment. “They could pull the plug on us in 2012,” he notes. The follow-up experiment to MINOS—named Off-Axis—will likely occur in northern Wisconsin. Soudan has long been a candidate as a site for the National Underground Laboratory (NUL), but funding is unlikely in the current environment. More seriously, the proposed NUL lacks a clear rationale, especially given the lack of detailed knowledge about the kinds of experiments it will house, according to one physicist associated with Soudan. Many believe that in the long and short term, building for specific experiments saves money. Either way, the Homestake Mine in South Dakota’s Black Hills is the leading candidate for an NUL, if one is ever built.

“Boat leaves in three minutes,” a carefree voice announces over the Soudan intercom system. “Boat leaves in three minutes.”
Miller finishes packing his bag. “Anyway, there just aren’t many places in the world like this.” He leads the way out of the office, stopping to shut off the lights. “And I hope people keep finding reasons to come up—and down—here,” he says as he clangs down the office pod’s metal steps.
“Boat leaves in two minutes,” the voice says gleefully. “Boat leaves in two minutes.”

Miller stands by the door to the MINOS cavern and watches as the crew makes its way to the elevator. Certain that everyone is out, he extinguishes the lights and walks to the waiting boat, without a glance back at the total darkness he’s leaving behind.