SD Mine Picked for Deep Lab

The National Science Foundation (NSF) has chosen Homestake, a former gold mine in the Black Hills, near Lead, S.D., to be developed as a proposed deep underground science and engineering laboratory.

Homestake, the deepest mine in the United States at 8000 feet, was the source of the single largest gold deposit ever found in the Western Hemisphere. Chosen from four contenders, the site was prepared by a collaboration of researchers and submitted to an NSF selection panel through the University of California (UC) at Berkeley.

The National Science Foundation has chosen the Homestake gold mine in Lead, South Dakota, as the site for a new deep underground science facility. Homestake, the deepest mine in the United States, was the site of the single largest gold deposit ever found in the Western Hemisphere.

In recognition of a $70 million gift for the Homestake effort from philanthropists T. Denny Sanford, owner of the First Premier Bank and Premier Bankcard Inc., the new deep underground research facility will be named the Sanford Underground Science and Engineering Laboratory (SUSEL).

A number of scientific investigations require an underground environment -- the deeper the better, UC Berkeley said in a statement. "For example, there are questions important to the fields of astrophysics and physics that cannot be answered unless experiments are shielded from cosmic rays and other background radiation by thousands of feet of rock," it said. In addition to its depth, the Homestake mine has more than 375 of existing tunnels, which the university said makes it ideal for conversion into a research facility.

“The Homestake mine is a vast site capable of hosting a comprehensive suite of experiments in all major fields of science, including low background physics experiments and particle and nuclear physics experiments that require very large detectors,” said Kevin Lesko, a researcher with Berkeley National Laboratory's Nuclear Science Div. “The site can simultaneously host multidisciplinary deep subsurface studies in geosciences, geoengineering and microbiology.”

Kevin Lesko, here displaying a photomultiplier tube (Hamamatsu Photonics model 1408) from the Sudbury Neutrino Observatory in Sudbury, Canada. An expert in neutrino science with Berkeley Lab's Nuclear Science Div., he is the principal investigator for the scientific consortium that proposed the Homestake gold mine to be the site for a new NSF deep underground laboratory.

Lesko is an expert in neutrino science and the principal investigator for the scientific consortium that proposed the Homestake gold mine to be the site for a new NSF deep underground laboratory. Prominent among the experiments that require the ultralow backgrounds realized at great depths are studies of the elusive, ghostlike subatomic particles known as neutrinos.

The Homestake proposal calls for two major deep underground facility levels. One level will serve research operating from the surface on down to 4850 feet. Construction of the “laboratory at 4850” will entail modification of an existing scientific site and preparation of new experimental chambers. The other facility is planned for the 7400-foot-depth level. A large network of existing caverns, drifts, ramps and boreholes will be the basis for the future construction of this second level over the next 30 years.

“Our plans also include a near-surface facility with drive-in access for experiments that require only modest shielding,” said Lesko. “In addition, potential users have requested access to depth levels at 2000, 4100 and 8000 feet. Our task is to tailor the Homestake site for science access and reduce its foot-print to only the areas of greatest scientific interest.”

Placer mining in the Black Hills (Homestake Visitor Center archives)

In recent years, experiments at other underground neutrino laboratories have confirmed that the neutrino, once thought to be a massless particle, does indeed have a small amount of mass, and that the three families of neutrinos transform, or oscillate, between families. "Like all great discoveries, this finding has raised new questions," UC Berkeley said. "A next generation of neutrino experiments at the much greater depths of Homestake should help provide answers."

For example, Lesko said, "Detection of neutrinoless double beta decay, which can be done at Homestake’s SUSEL, is the only way to determine whether neutrinos are their own anti-particle.

To fully understand the neutrino, Lesko said beams of neutrinos originating from Fermilab, outside of Chicago, can be sent through nearly a thousand miles of rock to large detectors in Homestake. These detectors will search for evidence of a rare physical process, leptonic CP violation, that may help explain why the universe is dominated by matter rather than antimatter.

“These same detectors could also be used to search for nucleon decay, a long-sought signal of grand unified theories,” Lesko said.

Other astrophysical research planned for SUSEL include studies of nuclear astrophysics, future generation gravity wave detectors, geoneutrino and solar neutrino experiments. Scientists at SUSEL will also get a closer than ever look at the earth’s crust and new opportunities for monitoring the movement of groundwater. They will also be able to examine the unique biochemistry of organisms that thrive under heat and pressure conditions which would be deadly to surface dwellers. Carbon sequestration efforts -- the idea of safely burying global warming gases like carbon dioxide underground -- should also receive a significant boost, the university said.

Joseph Wang, a scientist with Berkeley Lab’s Earth Sciences Div. and a senior Homestake proposal investigator, said, “A flagship earth science experiment at SUSEL could involve geomicrobiology searches for the limits of, extent of and details of life in the underground. These investigations would probe fundamental questions at the crossroads of biology and geology, including whether there are new or very old forms of life underground.”

Lesko added, “Experiments at SUSEL will also open entire new avenues for basic engineering studies that could extend our understanding of rock properties, create and stabilize future excavations, and develop new technologies and techniques to create safer underground environments.”

An aerial view of the Homestake mine site, which is located in the Black Hills of South Dakota. Already the site of one Nobel Prize-winning experiment, the new facility, to be known as the Sanford Underground Science and Engineering Laboratory (SUSEL), is expected yield more scientific “gold” across a wide number of research fields.

Mining operations at Homestake, which began in 1876 and continued until 2001, yielded 40 million ounces of gold. In 1965, nuclear physicist Raymond Davis, of Brookhaven National Laboratory set up the world’s first solar neutrino detector at a depth of 4850 feet deep conducted the research that won him a share of the 2002 Nobel Prize in physics.

Two years after mining operations ceased, South Dakota Gov. Mike Rounds established a project to oversee transfer of the Homestake property from Barrick Gold Corp., which had earlier merged with the Homestake Mining Co., with the ultimate goal of converting the mine into a deep underground science and engineering laboratory.

In 2004, at the urging of the governor, the South Dakota legislature created the South Dakota Science and Technology Authority to oversee the Homestake conversion project and subsequently allocated $35 million for the effort. In addition, a $10 million federal Housing and Urban Development grant was secured for rehabilitating the mine’s infrastructure. This HUD grant is now being used to reopen the shafts and instal pumping equipment to remove water from the lower levels (Homestake has been slowly filling with water since it was closed in 2003.) A new elevator compartment -- or "cage," in mine parlance -- has already been certified for re-entry into the Ross Shaft, one of two that descend 4850 feet into the mine.

Berkeley Lab and UC Berkeley organized the Homestake collaboration that year with Lesko at the helm. Bill Roggenthen, professor of geology and geological engineering at the South Dakota School of Mines and Technology, became the Homestake collaboration’s co-principal investigator.

The University of California at Berkeley, on behalf of the Homestake collaboration, submitted the Homestake conceptual design proposal to the National Science Foundation in January. Three other sites were also considered: the Soudan Mine in Minnesota, the Henderson Mine in Colorado and the Pioneer Tunnel in Washington.

NSF will provide $5 million for the next three years to design the facility. The total cost of the program is expected to be $500 million; construction is expected to start in 2010.

The NSF has indicated its intention to provide $5 million a year for the next three years to develop a more specific technical design for the laboratory. The NSF Science Board, Congress and the president must approve the project. Half of the total cost would be used to develop scientific instrumentation for the laboratory.

An NSF decision on the lab first was expected in April but was delayed. A committee of scientists reviewed 250-page proposals from all four sites, plus materials from visits to the sites. NSF staff and attorneys also worked on the decision, Berkeley Lab said.

For more information, visit: www.lbl.gov