South Dakota Governor's Office of Economic Development

Final Four of physics: Money, access, depth key for Lead DUSEL

By Bill Harlan, Journal staff

LEAD — The vast, ridge-top parking lot at the Yates Shaft in Lead — in decades past filled with the cars and pickups of hundreds of gold miners — nowadays rarely has more than a handful of vehicles.

The Homestake gold mine closed in 2001. In 2003, the underground pumps were turned off, and the Yates and Ross shafts were sealed. Ever since, the mine has been slowly filling with water.

The empty parking lot and the flooding Homestake symbolize a loss for the gold-mining district of the northern Black Hills, which used to bill itself as "the richest hundred square miles on Earth."

But Homestake isn't dead yet.

Today, the handful of Homestake Mining Co. employees finishing the mine closure share the big parking lot and a big, brick office building with half a dozen personnel of the South Dakota Science and Technology Authority.

Science authority director Dave Snyder and his staff have been working with a nationwide consortium of scientists to win a four-way competition to be the site of a proposed national Deep Underground Science and Engineering Laboratory, or DUSEL.

Rock above deep underground labs shields sensitive experiments from cosmic rays, and committees of scientists assembled by the National Science Foundation have proclaimed a DUSEL a national priority.

Homestake, which is 8,000 feet deep, could be the world’s deepest science lab. But supporters of sites in Colorado, Minnesota and Washington also have strong proposals, and a Homestake lab presents at least one unique challenge.

A question of water
Snyder won’t discuss the details of the Homestake presentation to the NSF — it’s still a competition — but a question the NSF panel had to ask was, what about the water flooding the mine? Remote sensors show it has risen from the “8,000 level” to above the 5,600.

Doesn’t that ruin Homestake for use as a lab?

“Not at all,” Snyder said during an interview at his office near the Yates. “What’s it going to damage?”

Homestake removed equipment before the closure.

There also is precedent for flooding and pumping out the gold mine. The pumps were shut off during World War II, when gold miners were switched to mining strategic metals.

Snyder agrees it’s expensive to pump water from 8,000 feet down, but he also points out that pumping is less expensive than drilling, blasting and removing rock.

In fact, the state science authority already is working on a re-entry into the mine from the Ross Shaft, which sits on a spur of the same ridge, less than a mile from the Yates.

Both shafts give access directly to a level 4,850 feet underground, where the first experiments at Homestake would begin.

But if the National Science Foundation picks Homestake as its DUSEL, the gold mine in Lead could become the deepest underground lab in the world.

A physicist’s vision

Underground labs are useful for geologists and biologists, but particle physics and astrophysics are the driving forces behind the quest for a DUSEL.

Astrophysicist Kevin Lesko is principal investigator of a group of dozens of scientists from throughout the country who call themselves the “Homestake collaboration.”
Lesko is a senior physicist at the Lawrence Berkley Laboratory and a research physicist at the University of California at Berkley.

His specialty, for nearly 20 years, has been the detection of neutrinos — subatomic particles produced in stars and, here on earth, in accelerators.

Neutrinos, which move at near the speed of light, have no charge and almost no mass, so their rare collisions with other particles are difficult to detect against the noisy background of cosmic radiation on the surface of the earth.

That’s why Lesko and his colleagues go deep. His research has taken him to the world’s deepest lab currently, the Sudbury Neutrino Observatory in Canada.

Other elusive subatomic phenomena, are well accepted in theory but so far remain undetected — “proton decay,” for example, and “weakly interacting massive particles, or “WIMPs,” which could shed light on the ultimately elusive substance, “dark matter.”

Still other physicists hope to go deep to discover why there isn’t as much antimatter as there should be. (Which is not necessarily a bad thing. The discrepancy allows us to exist.)
Lesko thinks experiments in all these fields could find a home at a Homestake DUSEL. He envisions it as multi-level campus — ranging from offices, classrooms, dorms, maintenance facilities and a visitors’ center on the surface to geological and biological experiments at the very bottom of the mine, 8,000 feet underground.
“It’s the full spectrum of underground science we’re talking about,” Lesko said during a recent telephone interview from his home in California.

Biologists, for example, would study forms of life that can survive extreme conditions at the bottom of the mine, where rock temperatures reach 130 degrees.
Geologists would study rock fractures and the movement of water throughout the mine.

At 7,400 feet underground, Homestake would offer physicists the deepest, best-shielded underground lab in the world.
It also would have:

-- An interim lab 4,850 feet underground, still the world’s second deepest, which would offer space to experiments that didn’t need extreme depth.
-- Drive-in access to an uppermost level 300 feet underground, which could include testing facilities and maybe a visitors center.
“That hasn’t quite been worked out yet,” Lesko said.

‘Safe and convenient’ access
One of the NSF’s main questions to each of the four competing sites was about access — how quickly scientists can get to the laboratory and, once there, how quickly they can get underground.

“We’ll have a dedicated facility, exclusively for science, and that really adds to the ease of doing work there,” Lesko said.

In fact, Barrick Gold Corp. of Toronto, which owns Homestake, has donated the mine and 500 acres on the surface to the South Dakota Science and Technology Authority.

Minnesota also owns its own site — the Soudan Underground Laboratory, where science has been under way for more than 25 years.

Another site, the Henderson molybdenum mine in Colorado, is still a working mine, though Henderson proponents also argue good access.

The University of Washington’s proposal for a lab in the closed Pioneer railroad tunnel offers horizontal access as a selling point.

Colorado and Washington both point out that they, unlike Homestake, are near airline hubs.

So is the University of Minnesota at Minneapolis, though Soudan is four hours north by car.

But Lesko points out that the drive from Rapid City Regional Airport to Homestake — just over an hour — rarely involves traffic.
From the Homestake surface campus, access would be easy, Lesko said.

Two big shafts, the Ross and the Yates, drop 5,000 feet into the mine, and the hoists, with some renovation, are still usable.

In addition to drive-in access from Kirk Gulch to the 300-foot level, the Homestake proposal also includes a small, automated personnel elevator in the Yates Shaft. It would be available 24 hours a day, seven days a week. “It’s safe and convenient,” Lesko said.

A chunk of money
One of the early criticisms of building a new national laboratory in a small town in the Black Hills was money. How could a small state like South Dakota compete with the likes of California, Washington, Minnesota or even Colorado?

That criticism has been put to rest by several events:
-- In 2002, Sen. Tim Johnson, D-S.D., pushed through Congress a $10 million Community Development Block Grant to help develop Homestake.

-- In 2004 and 2005, the South Dakota Legislature, at the request of Gov. Mike Rounds, approved a package of about $35 million to further develop a Homestake lab.

-- In 2006, Rounds signed a deal with Barrick to accept the gold mine as a donation.

-- Also last year, philanthropist T. Denny Sanford announced he would donate $70 million to the Homestake lab, which is why the lab is now called the Sanford Underground Laboratory at Homestake.

The NSF has estimated it will cost $300 million to open a deep underground lab, and the Homestake proposal has a $115 million head start.
An interim lab

That Sanford donation — contingent upon the NSF picking Homestake as the DUSEL site — is a key part of Rounds’ plan to get an early start at Homestake with an interim lab at the 4,850 level.

Construction on an NSF-supported DUSEL couldn’t begin before fiscal 2009, but experiments at an interim lab at the 4,850-foot level at Homestake could as early as next year, partly because the 4850 remains dry and partly because there is access from two shafts.

The 4,850 also is handy because it was a major infrastructure level for the gold mine. Drifts and caverns are already mined out and ready for use.
The Sanford grant would provide:

-- $15 million to upgrade electrical systems and the big hoists in the Yates and Ross shafts and to install a smaller personnel hoist in the Yates Shaft, to give quicker access to the 4,850 level.

-- $20 million to develop laboratory and “clean-room” space at the 4,850 level.

-- $15 million to prepare for the deeper DUSEL proper at 7,400 feet underground.

-- $20 million for the creation of the Sanford Center for Science Education for students in kindergarten and above.

A big chunk of rock
The surface campus at a Homestake lab already has sturdy mine buildings with enough floor space for immediate lab needs.

Homestake’s biggest selling point, however, is the underground real estate. It occupies 32 cubic kilometers of hard, stable rock honeycombed with 300 miles of tunnels, called drifts. The horizontal drifts are in 60 levels from 300 feet to 8,000 feet underground.

Underground ramps connect many levels. Also, there are two deeper shafts in the mine, one from the 4,850 level to the 7,400 level and another from the 4,850 to the 8,000.
Caverns already drilled and blasted for the mine could be used for experiments.

Lesko says the Homestake collaboration already has received 85 proposals for experiments at in the interim lab at the 4850 level, which already has a place in physics history.
The late Ray Davis of Brookhaven National Laboratory installed a pioneer neutrino detector at the 4850 at Homestake, just around a corner from the Yates Shaft.

Davis, who won a Nobel Prize for the experiment in 2002, confirmed a prediction about neutrinos by the late John Bahcall of the Institute for Advanced Studies at Princeton. (A photo of Davis and Bahcall at the “neutrino tank” in Homestake appears in physics textbooks.) Bahcall suggested neutrinos have mass, and the Davis experiment and others later

confirmed it.

Bahcall also was known for a pronouncement that suggests Homestake would be a good location for a DUSEL. The three most important factors in an underground lab, Bahcall said, are “depth, depth and depth.”

A Homestake DUSEL

Pros:
-- Depth: At 8,000 feet, it's the world's deepest available hole.
-- Money: The state has $115 million available.
-- Speedy start: An interim lab could start science next year.
-- Ownership: the state of South Dakota has the title.
-- Infrastructure: Hundreds of miles of tunnels, shafts and caverns.
Cons:
-- Water: Homestake has been flooding for nearly four years.
-- Closure: No one’s been in the mine for four years.
-- Location: Western South Dakota is far from a metro area.
-- Infrastructure: The tunnels are there, but now the mine is a fixer upper.
For a comparison of all four sites being considered, go to www.rapidcityjournal.com/features/snews/mines/.
For continuous updates and reports from reporter Bill Harlan about the selection process and his travels to the four sites, visit The Final Four of Physics blog at http://www.rapidcityjournal.com/blogs/mines/
Contact Bill Harlan at 394-8424 or bill.harlan@rapidcityjournal.com