Treasure Hunters

Author: Kenneth Garcia ’08Ph.D.

The ores of divine providence

are everywhere infused, and

everywhere to be found.

— Saint Augustine


Centuries ago, alchemists attempted to transform base metals such as lead and tin into gold, and explored the secrets of matter in order to find the “philosopher’s stone” or “elixir of life” that, according to Carl Jung, was more a spiritual quest than a technique for transmuting one chemical substance into another.


Modern geologists search for microscopic flecks of gold diffused over a broad area but invisible to the naked eye, then extract them using cyanide and carbon solutions, for profit.


In an abandoned gold mining tunnel, 4,850 feet beneath the earth’s surface at the former Homestake gold mine in the Black Hills of South Dakota, contemporary astrophysicists search for a mysterious substance called “dark matter,” and for clues to the formation of both stars and of the fundamental elements in the early universe.


These quest-like ventures suggest the secrets and treasures hidden within nature are a lure for both the profit-seeking and those seeking knowledge for its own sake.


The research in the deep mine piques my interest, for several unconnected reasons. First, why would scientists explore the formation of stars and matter in far-away galaxies in an underground gold mine utterly devoid of sun and starlight? Second, I have an affinity for gold mining and am fascinated by the ingenious processes of extracting it. Moreover, I am fond of mining tunnels; I slept in and explored them as a young man working for a mining exploration company in Nevada. I developed an abiding enchantment with the search for invisible gold as a metaphor for unveiling hidden mysteries, which is what scientific inquiry does. So when I heard about the experiments in the Homestake Mine, I had to investigate. The general public is not allowed in the mine, for safety reasons, but I found a way in. Two Notre Dame astrophysicists, Michael Wiescher and Dan Robertson, run a lab there — the Compact Accelerator System for Performing Astrophysical Research (CASPAR) — and they arranged a tour for me. I immediately booked a flight and hotel room.


The Homestake Gold Mine operated from 1878 until 2001. The town of Lead (pronounced “Leed”) grew around and on top of the mining tunnels. The tunnels go deep underground in a multilayered, honeycomb pattern. The deepest go 8,000 feet down. The mine produced more than 40 million troy ounces of gold over its lifetime. Homestake had its own logging operation to cut timber for structural support in the mine; its own coal mines in Wyoming for power; and its own railroad to transport the timber and coal. It had its own sawmill and foundries. Later, its engineers re-routed Spearfish Creek through miles of mountain tunnels to build a hydroelectric plant for the mine’s energy needs. From beginning to end the mining operation was an engineering marvel.


Today scientists from the University of California, Berkeley, Johns Hopkins, Brown, Yale, Stanford and Notre Dame (among others) have built labs at the Sanford Underground Research Facility (SURF) in those tunnels, almost a mile below the surface. There they search for the mysteries of the universe. The site is propitious because the labs are shielded by a mile of hard rock from the noisy clamor of solar and cosmic radiation that bombards the earth’s surface constantly. This enables scientists to explore the properties of subatomic particles called neutrinos, to search for “dark matter” and to investigate the formation of elements in a cosmic quiet place.


Think of it like this: You stand at one end of a train station in a major city at rush hour. The station floor is the size of a football field and the walls rise a hundred feet into a vaulted arch. Hundreds of people hurry about. They talk and shout in numerous languages. Children squeal and babies cry. Frequent announcements come over a loud speaker. Vendors hawk wares. The sound of rumbling trains vibrates through the walls, as do the squeal of air brakes. At the opposite end of the station, a mother is leaning to whisper something in her daughter’s ear. You want to know what she’s saying but cannot distinguish the whisper from the general din of the station. To discern it, you must first eliminate all the random noise. Then you must have a detector sophisticated enough to capture and translate that soft whisper. SURF is the astrophysicists’ version of that, a place where scientists filter out cosmic din and listen in on far-distant murmurs.


Scientists believe dark matter makes up about 80 percent of the universe because of anomalies in galaxies and their movement. Galaxies are vast systems of stars rotating around a center. Only gravity keeps the stars from drifting away. Gravity, however, is a weak force. The galaxy’s outer stars move with such great rotational energy that the gravity from all the observable mass in the galaxy is not sufficient to keep them tethered. In theory, they should be spinning away. In fact, the galaxy’s visible mass provides only about 20 percent of the gravity needed to counter the centrifugal forces seeking to hurl stars out into space. Scientists, therefore, hypothesize dark matter to explain the missing gravitational force. Dark matter, however, can’t be seen because it omits no light. It’s invisible and interacts only feebly with other particles, except through gravity. It exists in theory but hasn’t yet been confirmed experimentally. Scientists around the world search for evidence to confirm — or disprove — its existence.


In the Sanford facility, the Large Underground Xenon experiment (LUX), first built in 2009, attempted to detect traces of dark matter, which physicists think is composed of “weakly interacting massive particles,” or WIMPs. That’s according to the Sanford website.


Scientists hope that on occasion a WIMP will interact with normal matter through the weak nuclear force. At Sanford, they constructed the LUX dark matter detector and filled it with a third-of-a-ton of cooled super-dense liquid xenon. The xenon is surrounded by powerful sensors designed to detect the tiny flash of light and electrical charge emitted if a WIMP collides with a xenon atom within the tank. The detector’s location beneath nearly a mile of rock, and inside a 72,000-gallon, high-purity water tank, helps shield it from cosmic rays and other radiation that would interfere with a dark matter signal.


Garcia Nerds And Wimps

The SURF Visitor Center sells hoodies emblazoned with the words “Nerds Searching for WIMPS.” Unfortunately, the LUX dark matter detector was unsuccessful. Nonetheless, the nerds won’t quit. Sanford researchers are developing the LUX-Zeplin, which will be one hundred times more sensitive than LUX number one. I don’t pretend to understand the science behind this. It’s enough to know that scientists have the curiosity, imagination and creativity to fashion and conduct these complex, sophisticated — and yes, really cool — experiments; that the human mind has discovered so many secrets of nature; and that the universe reveals itself as greater and more mysterious than ever imagined to those willing to explore it attentively. The search for dark matter is a holy grail for modern astrophysicists (that’s a term they use).


Trained Sanford facility guides must accompany all researchers and visitors. Administrators don’t want the curious wandering down abandoned tunnels and getting lost. Lots of places to get lost. Connie Walter, the communications director, and Dave Vardiman, a former Homestake mining engineer now employed by the Sanford facility, are my guides. An intern from nearby Black Hills State University joins us.


Before we descend into the mine, we receive a safety briefing and sign a batch of forms, including a liability waiver (if a mile of earth collapses on us it’s our, not SURF’s, fault). Fair enough. We don our underground gear: steel-toed boots; heavy blue overalls; a white hard hat; and a canvas belt onto which we clip a charged battery and small re-oxygenation tank, which allows you to breathe for up to an hour in case of emergency. A 3-foot wire extends from the battery to a light, which can be clipped into the hard hat or hand-carried. I carry a bottle of water, a pen and writing pad, and my iPhone to record conversations.


Lowering or raising a cage (aka elevator) full of people or materials a mile underground requires massive hoists. Two large shafts — the Yates and the Ross — are the main sites of entry and egress. Wire rope 2 inches thick and 6,000 feet long coils around a large, conical steel cylinder in the hoist buildings above ground. The hoists and ropes were built in Pittsburgh in 1939. This 80-year old equipment, operated by former mine workers, still functions well.


A shaft is the vertical tunnel. Horizontal tunnels cut off the main shafts are called drifts. Drifts branch out about every 100 to 150 feet as one descends the shaft, all the way down. At each of the approximately 55 levels, the drifts wander off in multiple directions, following wherever the vein of gold went. Once the miners depleted the gold in one level, they extended the shaft down and began excavating horizontally there. Tom Regan, a former Homestake miner and now a safety consultant for Sanford, says there were once more than 2,000 miles of drifts. Many of them have been backfilled with sand and rubble, but 370 miles of them remain open. The deepest shaft goes down more than 8,000 feet, where the temperature from the rock pressure gets to 133 degrees Fahrenheit. The deep shafts and tunnels are now flooded from snowmelt and rainwater seeping into the earth. SURF pumps over 400 million gallons a year to keep the water from rising near the labs.


The cages measure 4½ feet wide by 12 feet long. When Homestake still operated, 32 men crowded into the cage so the company could get as many people into the mine as quickly as possible. Men “got to know their neighbors well,” as the old miners say. The cage plummeted at 2,000 feet per minute, and new miners sometimes lost their breakfast, which surely endeared them to the other 31 men. One can imagine the smell of sweat and rank breath on the trip back up, at the end of a shift of hard labor. Fortunately, the cage descends only 500 feet per minute today, and only up to 15 people may ride in it at a time.


Rock and timber form the structural frame for the shaft and cages. Water trickles down the shaft’s timbers for lubrication. Some of it splatters on us as we enter. I wonder about rotting wood, and if they replace the timbers periodically, and how. The cage handler tells the hoist operator via intercom to lower the cage to 4850. We descend. The cage rattles and creaks. We speak louder to hear one another. After we step out of the cage into a space called the Big X (where major drifts cross), we see not rock and dirt but futuristic tunnels with shiny insulation along the walls, silver metal jacket HVAC tubes, and modern water pipes and electric wires. Two tunnels curve gracefully away from one another. Other tunnels are framed in long corrugated metal vaults.


Garcia Bj 8Michael Wiescher (left) and Dan Robertson have gone deep into the earth to study the life of stars and the nature of the universe. Photograph by Barbara Johnston

We follow a drift to the Majorana lab. The Majorana project began in 2015 as an international effort to search for “neutrinoless double-beta (0νββ) decay in 76Ge.” Got that? We can’t enter the lab because it has to be ultra clean, and we’re not. But we can see the researchers through two sets of sealed windows. They wear white gowns from heel to head, and face masks to keep breath germs from contaminating the lab. My scribbled notes say “germanium,” “lead shield” and “grow ultra-pure copper.” Yes, grow. Tons of lead bricks surround a shiny copper monolith — the purest copper in the world, which they grow down here. The lead has lovely hues of light and dark brown, and charcoal gray. It is smooth and appears to have been laid by professional masons. Lead keeps out radiation that exudes from the surrounding rocks. The copper is a beautiful bright orange, like the flame of fire. A shining gold rectangle (or is it polished brass?) frames the copper. Inside the copper are chunks of germanium (Ge) crystals. The structure would make a beautiful fireplace, the pride of any architect, even without the 76Ge 0νββ.


In preparation for the trip, I searched the Majorana website and discovered that their goal “is to determine whether a future 1-tonne experiment can achieve a background goal of one count per tonne-year in a 4-keV region of interest around the 76Ge 0νββ Q-value at 2039 keV.” Translated, I think that means they want to find out why there’s more matter than antimatter in the universe, and therefore why anything exists at all (philosophers and theologians often pose that question, too, in different lingo). Majorana scientists think certain neutrinos are fermion particles (also called “angel particles”) that are their own antiparticles. Huh.


As I stand outside Majorana, gazing at the lead and copper monolith, I drift into a reverie, recalling alchemical treatises I read years earlier. I remember two things from alchemy: Lead is the bad guy and gold is king. At Majorana, lead is a good guy, keeping bad radiation away from ultra-pure copper and germanium in search of angel particles.


Connie Walter asks if I’m ready to move on to the LUX dark matter detector. Maybe she senses me drifting down a dark tunnel and wants to pull me back before I get lost. “Sure, let’s go,” I say, wondering if I should have been a science fiction and fantasy writer.


We spend little time at the LUX site because it’s inactive. We have a look at the large cavern it was housed in — blasted out by Homestake in the 1960s specifically for Dr. Ray Davis of the Brookhaven National Laboratory, a pioneering scientist who first discovered neutrinos at this very site (winning him the 2002 Nobel Prize in Physics). Since there’s nothing going on right now, we press on to the Compact Accelerator System for Performing Astrophysical Research facility, a mile away, where I’m scheduled to meet with Notre Dame’s Dan Robertson.


I want to walk to CASPAR to get my daily steps, but our schedule is tight so we hitch a ride on an old locomotive driven by a former mine worker. The locomotive, built in 1928, pulls a cart with facing wood benches. Compact steel rails run through the center of the drifts, mile after mile of them, level upon level. The mine once had numerous locomotives hauling people and ore throughout the mine. I sit in the cart facing guide Dave Vardiman, who is a walking encyclopedia of geological and mining history. We talk about gold mines and cyanide extraction methods — which Homestake used — as we rumble through a long, narrow, solid-rock archway.


In a typical cyanide heap-leach process, tons of ore are pulverized and placed in an enormous pile. Thousands of gallons of cyanide are sprayed over the pile. The cyanide attaches itself to microscopic gold flecks and separates them from the rest of the ore. They then flow into a collection basin where they’re refined further until nearly pure gold remains.


The cyanide and other toxins like arsenic were then dumped into nearby Whitewood Creek creating a dull gray stream where neither fish nor micro-organisms could live. Children played in the stream, though, unaware of its toxicity. The chemicals burned holes in their clothing. In the 1970s the EPA made Homestake clean up the creek, and the company discovered an ingenious method of doing so. Some micro-organisms live deep in the mine, with no exposure to light or organic foodstuffs. For meals they eat chemicals, including sodium cyanide, arsenic and iron. Homestake pumps cyanide-laced water into holding ponds, where the organisms gorge on the chemicals and clean the water of them. Chlorine is then used to kill the organisms before returning the water into the ecosystem. The water cascades down the hillside a long distance, causing the chlorine gas to dissipate. Today, the stream is healthy again, a first-class trout stream, says Vardiman, as clean downstream as it is upstream of the mining site.


Garcia Author In Tunnel AlteredThe author outfitted in underground gear, including a re-oxygenation tank that supports breathing for an hour in an emergency.

Soon the drift opens out into a wide cavern near Notre Dame’s CASPAR lab. Another lab — The Long Baseline Neutrino Facility — will be built nearby. When that’s completed, scientists at Fermilab in Illinois will beam neutrinos through the earth to detectors here in South Dakota. They want to find out how neutrinos change “flavors” (transmute themselves?) from electron to muon, from tau to electron, and from muon to tau (but not to gold) during the 800-mile journey from Fermilab to the Sanford facility. That’s years in the future, though. Mining crews must first blast out enormous chambers (about the size of that big city train station, but twice as long) in the rock to house the lab. They’ll use good old-fashioned dynamite. The experienced Homestake miners will know how and where to drill the blast holes.


Before entering ND’s compact accelerator system, we have to clean our boots. We set one foot in, pull a lever, and water squirts on our boots while metal bristles rotate, like a mini carwash. We release the lever and do the same with the other boot. That gets some of the mine grime off.


The facility has bright lights, white walls and ceiling, and looks sterile. If you didn’t know you were a mile below the earth’s surface in a dirty hard rock mine, you might think you were in a hospital surgical unit. The walls and ceiling are covered with welded wire mesh (not visible to us) and sprayed white shotcrete. The mesh and shotcrete keep small debris from falling from the rock formation above. Multiple layers of epoxy and latex paint are spread over the shotcrete to seal out radon from the host rock, so it doesn’t influence the experiments. Fans run continuously to keep radon moving out of the mine. Scrubbers and filters further remove it, and a detector monitors radon levels at all times (radon is like some of that noise in the busy train station).


On CASPAR’s flat concrete floor, a 50-foot long piece of shiny-steel equipment stretches along the center of the chamber. Really, the equipment is plural — an assemblage of parts, some commercially bought and others manufactured in Notre Dame’s machine shops specifically for this lab, then transported piece by piece from Notre Dame and assembled here. A one million-volt accelerator that looks like a supersized machine screw occupies one end. Vacuum tubes and cylinders extend from the accelerator in a gently curving track. Magnets and lenses inserted along the track help curve and focus the particles thrust from the accelerator. Hundreds of wires connect the assembled pieces to computers. Shiny new gadgets everywhere — an experimental astrophysicist’s dream toy. Dan Robertson’s dream toy.


Robertson loves talking about his research, and Connie Walter jokingly asks him to keep the conversation with me to 20 minutes. He chuckles amiably and agrees. I timed my visit to coincide with his and his research assistants’ trip to install the final pieces of equipment and fire them up. Robertson hopes to switch the compact accelerator system on today, in fact, and test the equipment. There’s a glitch, however: a single radiation monitor is not yet in place, and SURF administrators won’t let him turn on the switch until it is. Robertson is not happy, and he lets it be known, but Sanford’s executive director won’t budge. Federal and state regulations.


I don’t have to pry information out of the astrophysicist; I merely ask a question and Robertson is off and running. My task becomes to find a micron-sized silent space in which to ask for clarification of this or that. His eyes beam. I ask what kind of experiments they plan to do. Lots of things, he says, among them study the ratio of carbon to oxygen in the universe. I capture words and fragments of phrases. Hurling ion particles of known masses at target particles of known mass to see what happens when they smash together. Something about hydrogen and helium. Ions. Bending energies (is bending a verb or adjective?). Thank god I’m recording this. I have trouble getting a handle and ask for concrete examples. Well, we want to simulate nuclear fusion reactions in stars, to reproduce a star’s environment and the reactions within it. I’m not quite as lost as I was at Majorana, and anyway, what really matters is the excitement of unveiling hidden mysteries. Nonetheless, I listen to my recording later that night and capture more of what he says. The accelerating system can hurl, say, protons or helium nuclei at various materials at the other end of the track, to see how they interact. Detectors measure neutrons and gamma rays produced by those interactions, giving scientists insights into activities within stars, such as the nuclear fusion that creates elements necessary for life. Huh. As the Sanford website says, “CASPAR’s goal is to mimic the nuclear reactions that happen in stars that are a bit ‘older’ than our sun. If we can do that, it could help complete our picture about how the elements in our universe are built.” Cool.


While still at the lab, I ask Robertson, “So, is CASPAR a sort of mini-CERN?” I’m referring to the Large Hadron Collider in Switzerland where they searched for the God particle.


“To a limited extent,” he says, “but CERN uses far more energy and seeks to find out what particles split into when they’re smashed together. At CASPAR we want to see what they fuse into when we smash them.”


I want to ask if he’ll smash, say, lead particles into tin ions and see if they fuse into gold. We’re interrupted by a loud grating noise from an air compressor, though, and I forget my question. Plus, our time is up: 21:48 according to my iPhone.


Garcia Aerial View Of Open Cut

Back in the cavern outside the CASPAR facility, Dave Vardiman shows us an exposed rock that’s 1.8 billion years old, all twisted and folded and gray, with whitish striations. I touch it with my fingertips. The rock was once flat sediment at the bottom of a primeval ocean. Vardiman names the geological periods when the layers were laid down. Thousands of layers of sediment settled on the ocean floor. The weight of the ocean and the layers above created intense pressure and heat. Later, volcanic activity and the movement of tectonic plates lifted the sediments above the ocean to form the Black Hills, folding, twisting and contorting the layers as they did so. Gold settled out from other materials in the liquid cauldron. Vardiman finds a sheet of 8½-by-11 paper and lays it out flat. This is what that rock looked like under the ocean. Then the land lifted and deformed. He folds the paper into two arches that resemble a sine wave, then squeezes it to create a contorted, malformed sine wave. “Then the layers looked like this. We call it a deformation.”


A group of female students rides up the cage with us at the end of the tour. I assume they’re students, anyway; at my age, I cannot distinguish between students and assistant professors. They haul two heavy Igloo coolers into the cage. I ask if they’ve brought us beer for the journey up the shaft. “No,” one says, “believe me, you don’t want to drink what’s in here.”


Hmmm, I think. So what is in there?


Biologists and astrobiologists study extreme forms of life at the Sanford Underground Research Facility. Deep down. No light. No photosynthesis. The organisms eat chemicals and sulfur for food. Is that what’s in there? Are they taking that stuff up and out? What if it’s released into the world? Pandora’s Igloos.


After the half-day tour, I drive down the steep hill from the Sanford facility’s headquarters into the town of Lead. Homestake created the town and was the glue that held it together. “Homestake is Lead and Lead is Homestake” the saying went. Generations of men — and later, women — worked in the mine. In its heyday in the 1920s and ’30s, says Tom Regan, the mine employed from 2,500 to 3,000 men. The town had a population of around 8,500, with hardware and grocery stores, a bowling alley, swimming pool, opera house, churches, saloons, a health clinic and schools. Twenty-six different ethnic groups lived and worked there, says Regan: Slovenians, Italians, Irish, Poles, Chinese, Mexicans. A multicultural town, though they lived in enclaves and spoke different languages. When Homestake closed in 2002, its workers dispersed far and near looking for other employment. Some were fortunate and found work at hard-rock mines elsewhere. Some took low-paying jobs in nearby Deadwood’s gambling casinos. Others lost everything. Home values plummeted, school enrollments declined precipitously, and the town’s tax base dwindled. The population today is around 3,100.


As I descend the hill, my eyes are drawn to the town’s most prominent feature: a large open cut in the mountain, half a mile wide and more than 1,000 feet deep. It provides a stunning, view: layers of purple, brown, creamy white, pink, rust orange and gray — once horizontal layers of sediment beneath the ocean but now nearly vertical from volcanic uplift. Above this cut is where the Homestake “glory hole” began in 1878. Miners followed the lead of gold into the ground, tunneling as they went. Over time, the mountain began to cave downward. The timbers could not hold. Later, Homestake dug out the mountain and extracted gold from the subsidence. Now a mountain is gone and a deep hole exposes the geological history of the Black Hills.


How ought I think about this? Should I refer to this open cut as an unsightly scar on the land, as many environmentalists do, or as a revelation of the earth’s beautiful interior and its rich, complex history? Both are true, but I’m inclined to the latter. At least in this case. The old miners like to say, “the mine’s rock is so old, it not only saw the face of God but also felt Him squeeze it tightly in His hands.” It deserves to be seen and known. We can learn something about the mind of God by studying His recipe for slow-cooking the earth over a vast expanse of time, mixing its elements, and improvising as He goes. And not only that: based on research 4,850 feet below, we might learn how He forms the stars and simmers the broth that envelops them.


Kenneth Garcia is the associate director of Notre Dame’s Institute for Scholarship in the Liberal Arts and the author of Academic Freedom and the Telos of the Catholic University. His memoir Pilgrim River is due out in January. He has written for Gettysburg Review, Southwest Review and other publications.