Posts Tagged ‘mining’
Sandia’s Gemini-Scout: A Rescue Robot Optimized for Mining Disasters
Unveiled at this week's giant drone conference
When mines collapse, the biggest hindrance to a speedy search and rescue operation is the lack of information. Mining accidents generally bring about a buffet of dangerous conditions: structural weaknesses within the shafts themselves, poisonous vapors, explosive gases, flooded tunnels, etc. Rescue crews can’t charge into such conditions without proper reconnaissance, lest they risk compounding the situation by creating a second disaster on top of the first.
Gemini-Scout is designed to cope with all of these things so it can get down into a mine quickly, searching for survivors and assessing threats so human searchers can get into place as quickly as possible. Its tracked propulsion and articulated suspension allow it to climb rubble piles and crawl over uneven terrain. In the ground demo area at AUVSI, Gemini rolled easily over stair-like obstacles and into the sand and gravel pits, turning tight circles and kicking up a mess before climbing out just as easily. It took 45-degree climbs with no serious problems, and at less than two feet tall it maneuvered through tight spaces with ease.
But more specifically to its purpose, Sandia engineers explained, Gemini-Scout can move through up to 18 inches of water while sampling the air for toxic fumes (technically it can operate through deeper water, but doing so would immerse the air sensors on its mast). Those air measurements are critical because the data they collect paves the way for manned rescue operations. They also let rescue personnel know if they are dealing with explosive methane gases or other flammable vapors.
To that end, Gemini-Scout’s electronics are packed in explosion-proof casings. A blast triggered by something else might disable the robot, but its own electronics won’t provide sparks that could trigger a second explosion and complicate a search and rescue operation.
A thermal camera helps Gemini-Scout search for survivors and two way radios allow handlers to communicate with any survivors the robot locates. The ‘bot can even be configured to carry food, air tanks, or other supplies to trapped miners, or to drag them to safety.
And because mine disasters can happen unexpectedly anywhere in the world, Sandia engineers wanted to make it operable by just about anyone. Gemini-Scout is controlled with a standard Xbox 360 remote, so virtually anyone comfortable with Call of Duty can answer the call of duty in a time of crisis.
Acid Art: An Artist Uses Mine Drainage, Dissolved Electronics, and Other Pollutants as Paint
Janesko isn’t some eco-artist trying to ram an enviro-agenda down viewers’ throats, but rather an observer who has spent a lot of time thinking about how humans and the planet interact. And, as mentioned above, his art isn’t passive; he creates it by getting actively involved with his media, plunging watercolor paper into polluted streams and manipulating the iron-reddened sediment to create the effect he wants, or dissolving discarded electronic components in a carefully prepared bath so that the evaporated toxic stew creates color on his canvas (below).
The is a recommended read, but you can also check out Janesko’s works via his . For a hundred bucks, a carefully curated collection of toxic, highly acidic mine drainage could be yours.
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Almost a Mile Below South Dakota, A Race to Find Dark Matter
One of the biggest mysteries of physics could end with what scientists find 4,850 feet below the Black Hills of South Dakota
Now a team of physicists and former miners has converted Homestake’s shipping warehouse into a new surface-level laboratory at the Sanford Underground Laboratory. They've painted the walls and baseboards white and added yellow floor lines to steer visitors around giant nitrogen tanks, locker-size computers and plastic-shrouded machine parts. Soon they will gather many of these components into the lab’s clean room and combine them into LUX, the Large Underground Xenon dark-matter detector, which they will then lower halfway down the mine, where—if all goes well—it will eventually detect the presence of a few particles of dark matter, the as-yet-undetected invisible substance that may well be what holds the universe together.
The LUX project is just one of at least 10 efforts worldwide to find direct evidence of dark matter, and with a Nobel Prize and longer-term federal investment in play, the 50 researchers of LUX and 2,848 citizens of Lead (pronounced “leed”) are pretty open about wanting to be first. But already there are problems.
For several hours now on this June afternoon, I’ve been watching through a window into the clean room as four physicists dressed in identical white Tyvek suits, latex gloves, blue booties, surgical masks and protective glasses prepare to connect two of the primary components of the detector. The inner cryostat is a hollow cylinder the size of a trash can that everyone refers to simply as “the can,” and at the moment it is down below floor- level in a grate-covered pit. Hanging from a frame above the pit is the dome, which is a kind of lid for the can, and hanging from the dome itself is a complex assemblage called the skeleton. The idea is to carefully raise the can up around the skeleton, nesting one inside the other like a matryoska doll, until it connects with the dome cap, making a perfect seal.
The entire assemblage will eventually contain 31 gallons of –154°F liquid. xenon—the medium that will actually detect the dark matter— so precision is essential. But the various parts were machined at different sites, and without that perfect seal, air and impurities could infiltrate the experiment, potentially compromising the results. As Tom Shutt, a physicist at Case Western Reserve University and the co-founder of the LUX project, explains, “We’ve been on pins and needles to know how tight this can will be.”
Before they lift the can, though, the team must complete the skeleton itself. Right now it consists of little more than six thin titanium straps hanging down from the inner rim of the dome. The next task is to insert the three thick disks that make up the bulk of the skeleton. One of the physicists, hand-operating a small forklift, raises one of the copper disks to waist-height, and the others adjust a temporary support that will hold it in place as they make final adjustments to bolt it to the titanium straps. This process continues for each of the three disks: Lift, tighten, adjust, confer, adjust.
The physicists work their way down the skeleton until finally they are on hands and knees, spinning bolts into the last copper slab, just about six inches from the floor. In slow succession, they sit back on their heels or stand up to observe their handiwork. Shutt, who was responsible for coordinating the fabrication of the can, is up next. He excuses himself and heads to the clean room’s antechamber to suit up. (Common dust, the type one might drag in from anywhere, can have high levels of radioactivity that could obscure the signal if the detector does find dark matter.)
He is soon joined by an additional grad student, and the clean room is getting crowded. The six physicists wheel the skeleton-bearing frame to the side and open the pit’s grate. One of them climbs down inside, connects two cables to the can, and scrambles out of the way. The cables are threaded through two pulleys on the frame, which the team slides back into place. They attach stacks of weights to the other ends of the cables, creating a simple elevator, and begin to slowly raise the can up and around the skeleton. Shutt stands to the side, his hands held palms out, fingers wiggling in anticipation like a kid waiting to open a gift.
Other scientists from the LUX project are gathering for the big moment—the moment when they will see if the can actually fits to form a functional detector—and I get elbowed over to the side window where the grad students have congregated. As the can nears the top, the murmurs die down. The skeleton is sliding perfectly into place. But, less than an inch from the dome, where the can should finally lock into place, it jams. Shutt and his team try to ease it up, and they try shoving it, but it just won’t budge. The physicists suspect that the can’s dimensions or the shape of the skeleton are off. Despite this apparent setback, they gamely pose for a few photos. Then they methodically lower the can back into the pit. They’ll try again tomorrow.
No one knows what dark matter is, or if it even really exists. For now, it is just a placeholder, an x that must be plugged into various calculations in order to square astronomical observations with the rules of Newtonian physics. The name comes from Fritz Zwicky, a Swiss astronomer who in 1933 used two well-established methods to calculate the mass of the Coma cluster, a group of more than 1,000 galaxies. One calculation was extrapolated from the movement of eight galaxies in the cluster using Newton’s second law of motion, which says, in essence, that the bigger the galaxy, the faster it spins. The other estimated the cluster’s total mass by quantifying the amount of light given off by its stars.
The results should have been equal, but instead the movement-based number was an order of magnitude greater. The Coma galaxies were spinning much faster than would be predicted by the amount of overall light emitted. For the Newtonian equation to add up, there had to be more mass. Zwicky dubbed this missing bulk “dark matter.”
Zwicky’s work was largely ignored until 1970, when another astronomer, Vera Rubin, documented similar discrepancies in the Andromeda galaxy. Since then, researchers have found that the visible mass in hundreds of other galaxies is also too small to explain the rate of motion, at least within the context of our current understanding of physics. Astronomers have also discovered invisible “gravitational lenses” that cause light to bend around themselves—despite these lenses having no identifiable mass with which to distort the fabric of spacetime and bend light in the first place. All of this suggested that more than 80 percent of the matter in the universe was simply invisible to us.
Today, most (but by no means all) physicists agree that dark matter exists, and that it is probably made up of what they call WIMPs, or weakly interacting massive particles. “Massive” doesn’t mean that the particles are large, but that they have mass and therefore both respond to and cause gravitational pull. “Weakly interacting” means that the particles, despite having mass, nonetheless only rarely interact with matter. Scientists also assume that WIMPs are electromagnetically neutral, which is why we can’t see them. Indeed, as of yet all arguments for the existence of dark matter are made from inference. No one has ever directly observed the stuff.
Many scientists, including Rubin, are skeptical about the WIMP theory, and in some cases about the notion of dark matter itself; they think Newtonian physics simply might not describe how motion works on a galactic scale. When I asked Dan Akerib, Shutt’s partner at Case Western and a principal investigator on the LUX project, why WIMPs are the most popular candidate, he adopted the standard scientific position—WIMPs are simply the best current theory: “A glib way to say it is that WIMPs are the least crazy thing to look for.”
Which is where LUX and other competing programs, all of which are premised on the existence of WIMPs, come in. When astronomers find evidence of dark matter throughout the universe, it appears to be unevenly distributed. Gravitationally, it behaves like regular matter: It clumps together. Dark-matter theorists currently suspect that it concentrates in a spherical cloud encompassing most galaxies. As our own solar system rotates in the Milky Way, both it and the galaxy move within one of these clouds, and the particles in the cloud—the WIMPs—flow through the Earth and everything on it at a rate, physicists guess, of about 100,000 per square centimeter per second.
The physicists at LUX and the teams of physicists that run the 10 or so competing programs hope to catch a WIMP in the act. These other detectors (some using germanium as their detector material, others using liquid xenon, as LUX does) are buried underground, in old mines and sewers or under mountains, to shield them from other cosmic particles that could masquerade as a WIMP.
Most WIMPS will evade the detection medium, but Shutt and Akerib theorize that around three or four per year will bump into the nucleus of one of the 1.6 octillion (that’s a billion billion billion) xenon atoms in LUX’s tank, and that when one does, it will set off two minuscule flashes of light— the first direct evidence that dark matter exists.
The can still doesn’t fit, even after another full day of lifting, tightening and adjusting, so Shutt has recruited me to drive him and one of his students to the hardware store in nearby Deadwood, the town in which famed Wild West lawman Bill Hickok played his last fateful card. The plan now is to file down a near-invisible inner weld seam near the can’s bottom, which the scientists think is catching on the skeleton, and to do so Shutt needs a Dremel rotary tool and several diamond-tipped bits. He seems unfazed by the fact that his $3-million detector to determine the true nature of the universe is on hold for want of an $80 power tool.
Filing a seam would normally be a simple task. But the can is made of titanium, which is extremely hard. The lab is only six months old and doesn’t yet have an on-site machine shop or many tools. If Shutt entrusts an unfamiliar shop with the can, he risks exposing LUX to low-level radioactivity from metal filings, which, like dust, could mask WIMP signals down the road. Every last nut and bolt must be as close to radiation-free as possible, so each material it touches or location it visits must be carefully vetted. The team will grind the seam in the clean room first thing in the morning.
The hardware store’s well-lit aisles offer up house paint and car parts and, in a nod to the local propensity for motorcycle travel, a calamine-and-cornstarch saddle- sore remedy called Anti Monkey Butt. Shutt asks a woman in a smock where the Dremels are, and we head directly for a central aisle, where we locate a dozen Dremels on a shelf below a pegboard holding hundreds of small plastic boxes of bits. Shutt pulls down handfuls of packages, scanning the labels for diamond, which emits no radioactivity, and instructs his student to do the same. He says that over the past few years he has spent more than $60,000 buying parts on eBay, including precision-cleaned bits, turbo pumps and $10,000 worth of orbital weld fittings. Akerib estimates that the team has also made hundreds of McMaster Carr orders.
As we continue our search, a young, bespectacled clerk with a patchy red beard strolls up, ready to assist. I’ve been anticipating the moment when I could observe a physicist-local interaction firsthand. The stories the scientists have told me have a common theme: The people who live in the area love the massive physics project taking place around (and beneath) their town. They approach the physicists at bars, grocery stores, gas pumps and the YMCA sauna to voice their support. More than 100 people showed up to a dark-matter talk given by Shutt and project co- founder Rick Gaitskell of Brown University, and afterward audience members followed the pair to a local bar for more. The town’s visitor center sells T-shirts emblazoned with the lab’s logo and the words “Nerds Searching for WIMPs.”
“These Dremel packages have a bunch of different accessories,” the clerk notes, pulling a box off the shelf. “We don’t need accessories,” Shutt says as he rifles through the plastic boxes of individual bits. “We need the most powerful motor you have.” They go back and forth a bit more. How about something with a variety of bits? No, we need diamond. What about these diamond bits? Nope, not big enough. This one, maybe? Nope. Finally, the clerk turns to me and asks where we’re from. I tell him that Shutt works in the Sanford lab and we’re getting tools for the detector. The clerk nods his head and looks at the growing pile of bits. Then he asks, “So how’s it going?”
The Lux Team’s competitors, though in some cases further ahead in their projects, are also working through their own problems. One project, the Cryogenic Dark Matter Search II, is located in an old iron mine in Minnesota. The physicists there made headlines in December 2009 when they thought they had detected two WIMP signals. Both turned out to be false alarms, but they intend to try again with a bigger detector called SuperCDMS. Another frontrunner, Xenon100, hidden under the Gran Sasso mountain in central Italy, is already operational. As the name indicates, Xenon100 uses a technology similar to LUX. But Xenon100’s detector tank is much smaller than LUX’s and also less sensitive. Thus far, it has detected nothing.
Researchers are also using indirect methods of finding WIMPs. In some cases, they aren’t searching for dark matter directly, but using Earth and space-based telescopes to search for the odd particles that are expected to result when two WIMPs come into contact and annihilate each other (a phenomenon supported by particle theory). Physicists at the Large Hadron Collider in Switzerland, meanwhile, are attempting to create their own WIMPs from scratch, by smashing protons together. A synthetic WIMP could help physicists recalibrate their detectors to look for natural particles in the correct energy range, but so far scientists have been unable to make one.
All of these efforts are expensive, and so the search for dark matter has created something of a boom in the towns where it takes place. In Lead, for instance, the Sanford lab is causing a rare uptick in the local real-estate market, creating extra business for local stores and restaurants and employing hundreds of local people, from mine-shaft maintenance workers to geologists to human-resources managers. And the lab is just the first stage in the larger DUSEL project, which is expected to receive more than $875 million from the federal government and has already pulled in another $47.3 million from the state and $70 million from private donors. That will fund the transformation of Homestake’s 370 miles of tunnels and 186 surface acres into the DUSEL complex: physics labs that will include LUX’s already-planned successors, which will have much larger xenon tanks and thereby increase the chances of capturing WIMPs.
Like the Homestake Mining Company before it, DUSEL is set to make Lead a company town. Homestake was more than just an employer; it influenced nearly every other aspect of life in the community. “If Lead needed it, Homestake built it,” says mayor Tom Nelson, whose grandfather, father and brother all worked for the mine. “They did the water system, they brought the power in, the railroad, the hospital, the recreation center, the company store, the bank. Everything was the company.” The Sanford lab, and the pending DUSEL project, may not run Lead’s local health clinic or bank, but it will bring money and jobs. Philanthropist and lab namesake T. Denny Sanford set aside $20 million of his $70-million donation for a science education center, where DUSEL researchers will lecture and students will get hands-on underground physics experience. The project’s annual operating budget is $23 million, more than half of which is spent locally with local suppliers or contractors. And around 70 former mine employees now work for the South Dakota Science and Technology Authority, the entity created to convert the property from mine to lab.
Beyond Lead there is another, larger community—the entire particle physics and astrophysics communities— rooting for the success of the project. Without WIMPs, the Standard Model of physics—the theory that governs the interactions of all known subatomic particles—is weakened, and scientists will have to rethink their assumptions about subatomic physics. And without hard proof that dark matter exists, our basic understanding of the composition of the universe unravels. “If it ends up that dark matter is not made of WIMPs, it will be much more disappointing in a philosophical sense than in a personal sense, in that humankind won’t know what dark matter is,” Shutt says. “We’re fully prepared that we might not find it ourselves. But if we as a community don’t find it, that will be awfully disappointing.”
Yet another full day has passed, and the can still does not fit. This time, though, I’m on the other side of the window, dressed in borrowed clean-room regalia. Shutt and I are peering down into the pit, where the can is on its side, two Tyvek-clad legs poking out of one end, as though someone wearing an enormous metal party hat had fallen forward on his stomach. The new Dremel screeches, then the grinding stops. My ears ring. The legs shimmy outward, revealing that they are attached to James White, another LUX researcher from Texas A&M, who looks up at me: “You wanna come help?”
I wasn’t expecting to be put to work. I climb down the ladder to the pit, and White hands me the Dremel. He demonstrates on a seam close to the top of the can; the section I need to tackle is farther in, close to the bottom, where there is room for only one. It’s a tight fit. I’m folded in on elbows and knees, a position I can’t hold for long. A grad student shines a bright light through a flange at the bottom of the can and occasionally snaps my picture. I trace the errant seam with a gloved finger. It feels impossible that such a small thing could cause so many problems. I hold the Dremel bit firmly against it. Sparks fly as I start to grind. The sound is deafening.
I’d like to tell you that my Dremeling saved the day, that we successfully lifted the can shortly thereafter. But we didn’t. After hours of grinding and a burned-out $80 Dremel motor, the can still did not fit. It turns out that the LUX team spent another two weeks finishing the can campaign. I later learned, when I spoke to the physicists in September, that the key to success was filing down a few of the copper pieces on the skeleton, copper being much easier to grind than titanium. Between my visit and then, the team had confronted at least five similarly minor yet mission-jeopardizing challenges, including a case of seized bolts (a result of intense cleaning that left the threads of a flange and the rod that screws into it so spotless that they bonded together on a molecular level) that required an emergency search for lubricant and hacksaws.
Now LUX is 95 percent complete. The team is preparing for the first of several test drives in which they will lower the xenon-filled detector into a 66,000-gallon tank two stories below their lab and see how it runs. Next they will begin the work of planting LUX 4,850 feet underground, sometime late this year. And then the wait begins, as physicists and the residents of Lead collectively hope that the giant hole in the ground that over the years yielded so much treasure will provide them with continued economic stability—and possibly the secret to understanding the universe.
Two Miles Below South Dakota, A Race to Find Dark Matter
One of the biggest mysteries of physics could end with what scientists find 4,850 feet below the Black Hills of South Dakota
Now a team of physicists and former miners has converted Homestake’s shipping warehouse into a new surface-level laboratory at the Sanford Underground Laboratory. They've painted the walls and baseboards white and added yellow floor lines to steer visitors around giant nitrogen tanks, locker-size computers and plastic-shrouded machine parts. Soon they will gather many of these components into the lab’s clean room and combine them into LUX, the Large Underground Xenon dark-matter detector, which they will then lower halfway down the mine, where—if all goes well—it will eventually detect the presence of a few particles of dark matter, the as-yet-undetected invisible substance that may well be what holds the universe together.
The LUX project is just one of at least 10 efforts worldwide to find direct evidence of dark matter, and with a Nobel Prize and longer-term federal investment in play, the 50 researchers of LUX and 2,848 citizens of Lead (pronounced “leed”) are pretty open about wanting to be first. But already there are problems.
For several hours now on this June afternoon, I’ve been watching through a window into the clean room as four physicists dressed in identical white Tyvek suits, latex gloves, blue booties, surgical masks and protective glasses prepare to connect two of the primary components of the detector. The inner cryostat is a hollow cylinder the size of a trash can that everyone refers to simply as “the can,” and at the moment it is down below floor- level in a grate-covered pit. Hanging from a frame above the pit is the dome, which is a kind of lid for the can, and hanging from the dome itself is a complex assemblage called the skeleton. The idea is to carefully raise the can up around the skeleton, nesting one inside the other like a matryoska doll, until it connects with the dome cap, making a perfect seal.
The entire assemblage will eventually contain 31 gallons of –154°F liquid. xenon—the medium that will actually detect the dark matter— so precision is essential. But the various parts were machined at different sites, and without that perfect seal, air and impurities could infiltrate the experiment, potentially compromising the results. As Tom Shutt, a physicist at Case Western Reserve University and the co-founder of the LUX project, explains, “We’ve been on pins and needles to know how tight this can will be.”
Before they lift the can, though, the team must complete the skeleton itself. Right now it consists of little more than six thin titanium straps hanging down from the inner rim of the dome. The next task is to insert the three thick disks that make up the bulk of the skeleton. One of the physicists, hand-operating a small forklift, raises one of the copper disks to waist-height, and the others adjust a temporary support that will hold it in place as they make final adjustments to bolt it to the titanium straps. This process continues for each of the three disks: Lift, tighten, adjust, confer, adjust.
The physicists work their way down the skeleton until finally they are on hands and knees, spinning bolts into the last copper slab, just about six inches from the floor. In slow succession, they sit back on their heels or stand up to observe their handiwork. Shutt, who was responsible for coordinating the fabrication of the can, is up next. He excuses himself and heads to the clean room’s antechamber to suit up. (Common dust, the type one might drag in from anywhere, can have high levels of radioactivity that could obscure the signal if the detector does find dark matter.)
He is soon joined by an additional grad student, and the clean room is getting crowded. The six physicists wheel the skeleton-bearing frame to the side and open the pit’s grate. One of them climbs down inside, connects two cables to the can, and scrambles out of the way. The cables are threaded through two pulleys on the frame, which the team slides back into place. They attach stacks of weights to the other ends of the cables, creating a simple elevator, and begin to slowly raise the can up and around the skeleton. Shutt stands to the side, his hands held palms out, fingers wiggling in anticipation like a kid waiting to open a gift.
Other scientists from the LUX project are gathering for the big moment—the moment when they will see if the can actually fits to form a functional detector—and I get elbowed over to the side window where the grad students have congregated. As the can nears the top, the murmurs die down. The skeleton is sliding perfectly into place. But, less than an inch from the dome, where the can should finally lock into place, it jams. Shutt and his team try to ease it up, and they try shoving it, but it just won’t budge. The physicists suspect that the can’s dimensions or the shape of the skeleton are off. Despite this apparent setback, they gamely pose for a few photos. Then they methodically lower the can back into the pit. They’ll try again tomorrow.
No one knows what dark matter is, or if it even really exists. For now, it is just a placeholder, an x that must be plugged into various calculations in order to square astronomical observations with the rules of Newtonian physics. The name comes from Fritz Zwicky, a Swiss astronomer who in 1933 used two well-established methods to calculate the mass of the Coma cluster, a group of more than 1,000 galaxies. One calculation was extrapolated from the movement of eight galaxies in the cluster using Newton’s second law of motion, which says, in essence, that the bigger the galaxy, the faster it spins. The other estimated the cluster’s total mass by quantifying the amount of light given off by its stars.
The results should have been equal, but instead the movement-based number was an order of magnitude greater. The Coma galaxies were spinning much faster than would be predicted by the amount of overall light emitted. For the Newtonian equation to add up, there had to be more mass. Zwicky dubbed this missing bulk “dark matter.”
Zwicky’s work was largely ignored until 1970, when another astronomer, Vera Rubin, documented similar discrepancies in the Andromeda galaxy. Since then, researchers have found that the visible mass in hundreds of other galaxies is also too small to explain the rate of motion, at least within the context of our current understanding of physics. Astronomers have also discovered invisible “gravitational lenses” that cause light to bend around themselves—despite these lenses having no identifiable mass with which to distort the fabric of spacetime and bend light in the first place. All of this suggested that more than 80 percent of the matter in the universe was simply invisible to us.
Today, most (but by no means all) physicists agree that dark matter exists, and that it is probably made up of what they call WIMPs, or weakly interacting massive particles. “Massive” doesn’t mean that the particles are large, but that they have mass and therefore both respond to and cause gravitational pull. “Weakly interacting” means that the particles, despite having mass, nonetheless only rarely interact with matter. Scientists also assume that WIMPs are electromagnetically neutral, which is why we can’t see them. Indeed, as of yet all arguments for the existence of dark matter are made from inference. No one has ever directly observed the stuff.
Many scientists, including Rubin, are skeptical about the WIMP theory, and in some cases about the notion of dark matter itself; they think Newtonian physics simply might not describe how motion works on a galactic scale. When I asked Dan Akerib, Shutt’s partner at Case Western and a principal investigator on the LUX project, why WIMPs are the most popular candidate, he adopted the standard scientific position—WIMPs are simply the best current theory: “A glib way to say it is that WIMPs are the least crazy thing to look for.”
Which is where LUX and other competing programs, all of which are premised on the existence of WIMPs, come in. When astronomers find evidence of dark matter throughout the universe, it appears to be unevenly distributed. Gravitationally, it behaves like regular matter: It clumps together. Dark-matter theorists currently suspect that it concentrates in a spherical cloud encompassing most galaxies. As our own solar system rotates in the Milky Way, both it and the galaxy move within one of these clouds, and the particles in the cloud—the WIMPs—flow through the Earth and everything on it at a rate, physicists guess, of about 100,000 per square centimeter per second.
The physicists at LUX and the teams of physicists that run the 10 or so competing programs hope to catch a WIMP in the act. These other detectors (some using germanium as their detector material, others using liquid xenon, as LUX does) are buried underground, in old mines and sewers or under mountains, to shield them from other cosmic particles that could masquerade as a WIMP.
Most WIMPS will evade the detection medium, but Shutt and Akerib theorize that around three or four per year will bump into the nucleus of one of the 1.6 octillion (that’s a billion billion billion) xenon atoms in LUX’s tank, and that when one does, it will set off two minuscule flashes of light— the first direct evidence that dark matter exists.
The can still doesn’t fit, even after another full day of lifting, tightening and adjusting, so Shutt has recruited me to drive him and one of his students to the hardware store in nearby Deadwood, the town in which famed Wild West lawman Bill Hickok played his last fateful card. The plan now is to file down a near-invisible inner weld seam near the can’s bottom, which the scientists think is catching on the skeleton, and to do so Shutt needs a Dremel rotary tool and several diamond-tipped bits. He seems unfazed by the fact that his $3-million detector to determine the true nature of the universe is on hold for want of an $80 power tool.
Filing a seam would normally be a simple task. But the can is made of titanium, which is extremely hard. The lab is only six months old and doesn’t yet have an on-site machine shop or many tools. If Shutt entrusts an unfamiliar shop with the can, he risks exposing LUX to low-level radioactivity from metal filings, which, like dust, could mask WIMP signals down the road. Every last nut and bolt must be as close to radiation-free as possible, so each material it touches or location it visits must be carefully vetted. The team will grind the seam in the clean room first thing in the morning.
The hardware store’s well-lit aisles offer up house paint and car parts and, in a nod to the local propensity for motorcycle travel, a calamine-and-cornstarch saddle- sore remedy called Anti Monkey Butt. Shutt asks a woman in a smock where the Dremels are, and we head directly for a central aisle, where we locate a dozen Dremels on a shelf below a pegboard holding hundreds of small plastic boxes of bits. Shutt pulls down handfuls of packages, scanning the labels for diamond, which emits no radioactivity, and instructs his student to do the same. He says that over the past few years he has spent more than $60,000 buying parts on eBay, including precision-cleaned bits, turbo pumps and $10,000 worth of orbital weld fittings. Akerib estimates that the team has also made hundreds of McMaster Carr orders.
As we continue our search, a young, bespectacled clerk with a patchy red beard strolls up, ready to assist. I’ve been anticipating the moment when I could observe a physicist-local interaction firsthand. The stories the scientists have told me have a common theme: The people who live in the area love the massive physics project taking place around (and beneath) their town. They approach the physicists at bars, grocery stores, gas pumps and the YMCA sauna to voice their support. More than 100 people showed up to a dark-matter talk given by Shutt and project co- founder Rick Gaitskell of Brown University, and afterward audience members followed the pair to a local bar for more. The town’s visitor center sells T-shirts emblazoned with the lab’s logo and the words “Nerds Searching for WIMPs.”
“These Dremel packages have a bunch of different accessories,” the clerk notes, pulling a box off the shelf. “We don’t need accessories,” Shutt says as he rifles through the plastic boxes of individual bits. “We need the most powerful motor you have.” They go back and forth a bit more. How about something with a variety of bits? No, we need diamond. What about these diamond bits? Nope, not big enough. This one, maybe? Nope. Finally, the clerk turns to me and asks where we’re from. I tell him that Shutt works in the Sanford lab and we’re getting tools for the detector. The clerk nods his head and looks at the growing pile of bits. Then he asks, “So how’s it going?”
The Lux Team’s competitors, though in some cases further ahead in their projects, are also working through their own problems. One project, the Cryogenic Dark Matter Search II, is located in an old iron mine in Minnesota. The physicists there made headlines in December 2009 when they thought they had detected two WIMP signals. Both turned out to be false alarms, but they intend to try again with a bigger detector called SuperCDMS. Another frontrunner, Xenon100, hidden under the Gran Sasso mountain in central Italy, is already operational. As the name indicates, Xenon100 uses a technology similar to LUX. But Xenon100’s detector tank is much smaller than LUX’s and also less sensitive. Thus far, it has detected nothing.
Researchers are also using indirect methods of finding WIMPs. In some cases, they aren’t searching for dark matter directly, but using Earth and space-based telescopes to search for the odd particles that are expected to result when two WIMPs come into contact and annihilate each other (a phenomenon supported by particle theory). Physicists at the Large Hadron Collider in Switzerland, meanwhile, are attempting to create their own WIMPs from scratch, by smashing protons together. A synthetic WIMP could help physicists recalibrate their detectors to look for natural particles in the correct energy range, but so far scientists have been unable to make one.
All of these efforts are expensive, and so the search for dark matter has created something of a boom in the towns where it takes place. In Lead, for instance, the Sanford lab is causing a rare uptick in the local real-estate market, creating extra business for local stores and restaurants and employing hundreds of local people, from mine-shaft maintenance workers to geologists to human-resources managers. And the lab is just the first stage in the larger DUSEL project, which is expected to receive more than $875 million from the federal government and has already pulled in another $47.3 million from the state and $70 million from private donors. That will fund the transformation of Homestake’s 370 miles of tunnels and 186 surface acres into the DUSEL complex: physics labs that will include LUX’s already-planned successors, which will have much larger xenon tanks and thereby increase the chances of capturing WIMPs.
Like the Homestake Mining Company before it, DUSEL is set to make Lead a company town. Homestake was more than just an employer; it influenced nearly every other aspect of life in the community. “If Lead needed it, Homestake built it,” says mayor Tom Nelson, whose grandfather, father and brother all worked for the mine. “They did the water system, they brought the power in, the railroad, the hospital, the recreation center, the company store, the bank. Everything was the company.” The Sanford lab, and the pending DUSEL project, may not run Lead’s local health clinic or bank, but it will bring money and jobs. Philanthropist and lab namesake T. Denny Sanford set aside $20 million of his $70-million donation for a science education center, where DUSEL researchers will lecture and students will get hands-on underground physics experience. The project’s annual operating budget is $23 million, more than half of which is spent locally with local suppliers or contractors. And around 70 former mine employees now work for the South Dakota Science and Technology Authority, the entity created to convert the property from mine to lab.
Beyond Lead there is another, larger community—the entire particle physics and astrophysics communities— rooting for the success of the project. Without WIMPs, the Standard Model of physics—the theory that governs the interactions of all known subatomic particles—is weakened, and scientists will have to rethink their assumptions about subatomic physics. And without hard proof that dark matter exists, our basic understanding of the composition of the universe unravels. “If it ends up that dark matter is not made of WIMPs, it will be much more disappointing in a philosophical sense than in a personal sense, in that humankind won’t know what dark matter is,” Shutt says. “We’re fully prepared that we might not find it ourselves. But if we as a community don’t find it, that will be awfully disappointing.”
Yet another full day has passed, and the can still does not fit. This time, though, I’m on the other side of the window, dressed in borrowed clean-room regalia. Shutt and I are peering down into the pit, where the can is on its side, two Tyvek-clad legs poking out of one end, as though someone wearing an enormous metal party hat had fallen forward on his stomach. The new Dremel screeches, then the grinding stops. My ears ring. The legs shimmy outward, revealing that they are attached to James White, another LUX researcher from Texas A&M, who looks up at me: “You wanna come help?”
I wasn’t expecting to be put to work. I climb down the ladder to the pit, and White hands me the Dremel. He demonstrates on a seam close to the top of the can; the section I need to tackle is farther in, close to the bottom, where there is room for only one. It’s a tight fit. I’m folded in on elbows and knees, a position I can’t hold for long. A grad student shines a bright light through a flange at the bottom of the can and occasionally snaps my picture. I trace the errant seam with a gloved finger. It feels impossible that such a small thing could cause so many problems. I hold the Dremel bit firmly against it. Sparks fly as I start to grind. The sound is deafening.
I’d like to tell you that my Dremeling saved the day, that we successfully lifted the can shortly thereafter. But we didn’t. After hours of grinding and a burned-out $80 Dremel motor, the can still did not fit. It turns out that the LUX team spent another two weeks finishing the can campaign. I later learned, when I spoke to the physicists in September, that the key to success was filing down a few of the copper pieces on the skeleton, copper being much easier to grind than titanium. Between my visit and then, the team had confronted at least five similarly minor yet mission-jeopardizing challenges, including a case of seized bolts (a result of intense cleaning that left the threads of a flange and the rod that screws into it so spotless that they bonded together on a molecular level) that required an emergency search for lubricant and hacksaws.
Now LUX is 95 percent complete. The team is preparing for the first of several test drives in which they will lower the xenon-filled detector into a 66,000-gallon tank two stories below their lab and see how it runs. Next they will begin the work of planting LUX 4,850 feet underground, sometime late this year. And then the wait begins, as physicists and the residents of Lead collectively hope that the giant hole in the ground that over the years yielded so much treasure will provide them with continued economic stability—and possibly the secret to understanding the universe.
Deep Below South Dakota, a Mine Becomes a Physics Lab, and Miners Return to Work
For traditional mining culture as well as particle physics, it's a real scientific gold mine
Homestake, with 370 miles of tunnels that plunge up to 8,000 feet underground, was once the largest and deepest gold mine in the western hemisphere. During its 126-year operation in Lead, South Dakota, a tiny Black Hills mountain town, the mine provided thousands with jobs and produced around $3.5 billion worth of gold. But in the late 1990s, gold prices dropped dramatically, and the mine started losing money -- tens of millions of dollars a year. The mine was closed in 2003, by which time most of its employees had been laid off.
Several years of uncertainty about the future of the site followed, but in 2007, the National Science Foundation chose Homestake as the location for a proposed $875 million underground laboratory, the U.S.’s first national lab in over two decades. While the federal project is still pending final approval -- and recent call its future into question -- an effort by the state to use the site for science has already reemployed dozens of former miners and revitalized the local mining community.
Underground lab space is required for both astrophysics and particle physics because the thick layers of rock above help shield sensitive experiments from cosmic radiation and other background noise. Building such a lab from scratch is prohibitively expensive. Existing infrastructure—like a mine—is needed to make such a project feasible. Thus, within two weeks of the announcement that Homestake would close, a team of physicists started campaigning to convert the mine into an underground lab: the Deep Underground Science and Engineering Laboratory ().
“Underground space is in short supply worldwide,” points out Kevin Lesko, DUSEL principle investigator. In 2000, Lesko helped organize a meeting on the need for a new underground lab. “Fortuitously, the announcement of the closure of Homestake happened around that time, and there was good agreement to make a lab out of it.”
Mining for Science
Other notable North American underground labs that started out as mines include the , located in a former iron mine in northern Minnesota, and , which sits in the Creighton nickel mine outside of Sudbury, Canada. While both have impacted their surrounding economies and communities, neither share Homestake’s unique transition from mine to lab: the Soudan mine shut down 20 years prior to its conversion, and Creighton is still operational.
During its tenure in Lead, Homestake Mining Company not only employed generations of local residents, it essentially built the community, including the local health clinic, recreation center, bank and railway. Lead’s 2,800 residents were understandably supportive of the prospect of extending the mine’s life as a science lab, as were local and state politicians. Even before the NSF decision, the state had drummed up $157 million in funding to create the first stage of the larger complex (this state-funded lab, named the Sanford Laboratory after philanthropist T. Denny Sanford, who donated $70 million to the project, already has two tenants preparing to run experiments, a neutrinoless double-beta decay project and a dark matter detector. Both will reside in the famous Davis Cavern, which once housed the first to measure solar neutrinos.
Even with all of this support, the transition from mine to lab hasn’t been a simple matter of handing over the keys to the mine, and numerous hold-ups plagued the project in the years between closure and NSF selection. Because of the delays, many former miners who hoped to be a part of the science center had to look elsewhere for employment, from the local timber and construction industries to mining operations across state lines. “The longer the closure went, people started losing faith that something would happen,” explains Greg King, one of the lucky few whom were able to stay on throughout the closure by helping with the final ore processing and environmental clean-up. “But a lot of people had in their mind: someday we’ll be back here.”
Those people were eventually proved right. Finally, in 2006, the project was ready to start hiring. To date, the South Dakota Science and Technology Authority (SDSTA) has received over 3,400 applications to work at the lab – 2,000 of them before the hiring was announced -- and today, 74 of the 122 employees are former Homestakers.
The group’s collective knowledge and experience at the mine have been instrumental in getting the site ready for science. King is a good example of this. A 30-year Homestake veteran, the 53-year-old started as a day laborer hauling rock in 1976 and worked his way to the top of multiple departments. He refers to the mine’s tunnels, shafts and winzes as easily as one might describe their own backyard. That knowledge paid off: today, King is the director of operations for the SDSTA/Sanford Lab and notes “everything that happens in the mine passes my desk.”
It’s a Family Affair
It’s not unusual for Homestake miners to span three, four or even five generations in Lead. King’s family, for example, has deep roots both the community and its mining culture. His sisters worked at Homestake’s tourist center, which includes the mine’s museum, and an uncle and two cousins were miners (one cousin died there in a mining accident). His parents owned one of Lead’s grocery stores from 1958 until 2000, and have operated the pastie shop, another local culinary institute, since 1975. Pasties are a miner’s meal, heavy meat-and-potato-filled pastries that resemble Italian calzones, brought to the U.S. by tin miners from Cornwall, England when they immigrated here the 1930s in search of work. The Kings’ pasties are popular throughout Lead, and the family even occasionally caters meetings at the Sanford Lab and SDSTA.
Other Homestake familial ties are less typical. Jim Hanhardt, 58, spent 15 years at Homestake before its closure, even helping maintain and eventually dismantle the famed Davis neutrino detector. He wanted to stay at Homestake as it became a lab. “I had watched this project and was interested in coming back for the science, but they weren’t ready yet when I needed a job.” So, after the mine closed, he traveled to southern California to help drill tunnel for a “treasure hunt”, a search for a lost underground river of gold (no joke) then spent five years at the Stillwater platinum and palladium mine near Nye, Montana, before returning to Lead.
Jim’s son, Mark Hanhardt, 29, was drawn to Homestake for another reason: astrophysics. Mark, a second-year graduate student in physics at the South Dakota School of Mines and Technology, turned down several other grad school offers because the draw of DUSEL was far too strong. Today, he is helping build photomultipliers for the Large Underground Xenon Experiment, a dark matter detector to be built in the Davis cavern. He hopes to eventually return to his “true love”, neutrinoless beta decay, experiments for which are also planned for DUSEL.
Whatever the draw, the promise of DUSEL is keeping local miners and mining traditions alive.
“I was really sad that the mine had to close,” says Bonnie King, the pastie baker, “But I know things have to change. I’m really happy that there is something going on here—it is good for the community to have this to look forward to and it gives the whole town hope that it will build the economy in the area.”
Chilean Miners May Ride ‘Phoenix’ Capsule to Safety As Early as Tomorrow Night
Here’s how it’s going to .
, rescuers on the surface were able to get fresh water, food, and other supplies to the trapped men via tiny boreholes, but to drill a shaft big enough for the men to escape was another story altogether. The rescue shaft is only about the size of a bicycle tire, stretching all the way from the surface to the 500-square-foot chamber where the men have been living since August. Moving 33 men through a narrow, somewhat unstable shaft is going to take some technological trickery.
The biggest trick by far is the custom-built rescue capsule, designed in part by NASA engineers who have been the Chilean Navy devise a means to ferry the men to the surface. At just 21.5 inches in diameter, “Phoenix” – as the capsule is known – weighs nearly 1,000 pounds and stands about 14 feet tall. The men packed tighlty inside will be hooked to an oxygen supply good for 90 minutes (the trip to the surface will hopefully take no more than half an hour for each miner). The capsule is fitted with exterior wheels that will help it slide down the borehole as it is lowered by a massive crane.
As of about around noon Monday, engineers had finished reinforcing what they thought to be weak parts of the shaft and conducted a of the Phoenix capsule, taking it down 2,000 feet into the ground (just 46 feet shy of where the miners are awaiting rescue). The next step is a manned test of the rig. After enough dry runs have convinced rescue officials that the rescue vehicle is safe the rescue will begin, an event that has been termed “D-Day.”
Barring any setbacks, D-Day could begin late Tuesday night, with the first miner surfacing in the early hours of Wednesday morning. First, a Chilean Special Forces medic will descend to assess the state of the miners. Miners in decent condition will be sent up first, followed by the weakest and least healthy of the group. The strongest and most healthy miners will be the last out of the mine. Each miner will be in constant communication with rescuers while in the capsule, and each will wear special glasses to shield his sensitive eyes – now more than two months without natural daylight – from the sun. The operation will likely go on until Thursday morning.
And what happens if the capsule gets stuck? We don’t want to jinx the operation by even mentioning the possibility, but the capsule is equipped with an escape hatch in the bottom that would allow a miner to descend back down into the shelter. Here’s hoping no one has to use it, as there’s a planned for them up here on the surface.
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Radio-Style System of Communication Via Magnetic Waves Demonstrated in Deep Mines
New technology to improve mine safety
A new system developed by Lockheed Martin aims to change that, by using magnetic waves to carry voice and text messages.
The works like a radio, but at extremely low frequencies. Unlike radio waves, magnetic energy can penetrate coal and rock, says Dave LeVan, the research engineer at Lockheed who developed the system.
It can connect to the short-wave radios miners use to communicate within mine shafts, but it has a much longer range and can reach the surface.
Each MagneLink system consists of two units, one on the surface and one inside the mine. The in-mine unit is encased in an explosion-proof box and uses very little power, so if it were to short out, there wouldn’t be enough energy to produce a spark that could ignite methane inside the mine.
It would be placed near the mine’s refuge chambers, which are now required in underground mines and are designed to shelter miners in case of an explosion.
The Sago disaster was the impetus for the work, along with some inspiration from a former Lockheed engineer whose uncle worked in West Virginia coal mines, LeVan says. He learned that mine telephones may only be placed near elevators, and that in any case, the wires would melt in a fire or an explosion. He wanted to develop a wireless system instead.
Initially, he considered sonar, familiar to Lockheed’s engineers who work on submarine communications. But LeVan found that sonar takes a lot of power, and any mine device needs to be low-powered enough to prevent a spark.
“Sparks were just not going to work,” he said. “In my research, I ran across many discussions about how magnetic fields are easily able to penetrate rock and coal, so I thought of a wireless system that uses magnetic fields to go through the rocks.”
The MagneLink system modulates text and voice much like a radio would. Each unit includes a keyboard for text messages and a device to capture voice, but the audio input takes longer to reach the surface. Its battery lasts 24 hours and it would most likely be turned on only in an emergency, LeVan says.
Lockheed tested the system last month and found it works inside the mine to a distance of 2,800 feet. It can penetrate about 1,550 feet from the surface.
Warren Gross, Lockheed's project manager for MagneLink, says he expects the system to be certified by the federal government in the next couple of months. Lockheed has worked with the National Institute of Occupational Safety and Health to develop the system, he said.
In other mining news, mine safety inspectors said Monday that methane sensors at Massey Energy Co.'s Upper Big Branch mine had not been tampered with. An explosion at the mine this spring killed 29 miners and injured two.
Although the MagneLink system would not have helped those men, it represents a new step in mine safety, which has been in the government's spotlight since the Sago disaster.
Gross said several mining firms are interested in the technology, and some have allowed Lockheed engineers to interrupt their work to test the system.
“The coal companies are after this communication device as well,” he said.