March 2001

From University of Washington

Physicists hope to strike scientific gold in the Black Hills of South Dakota

A committee of leading physicists today advocated the renovation of the 125-year-old Homestake Gold Mine in the Black Hills of South Dakota as a unique underground science laboratory.

The National Underground Science Laboratory Committee, appointed by the Institute for Nuclear Theory at the University of Washington, met last weekend in Berkeley, Calif., and determined that Homestake provides an unparalleled opportunity for the United States to explore frontiers in a wide range of sciences that require absolutely quiet environments.

John Bahcall of the Institute for Advanced Studies in Princeton, N.J., who chairs the committee, noted that leading American scientists currently must work in deep underground laboratories in other countries.

"For example, the technique for measuring the mass of elementary particles known as neutrinos by observing a large tank of water was developed by American scientists in a mine near Cleveland. But when the most significant experiment to date was finally done, American scientists needed to work with others in a mine in Japan," Bahcall said. Determining neutrino mass is key to understanding fundamental forces in the universe and the nature of the Big Bang.

"Homestake will become a gold mine for science discoveries about physics, astronomy, biology and geology," Bahcall said.

"There is a very wide range of science that absolutely requires a deep underground location," said Kevin Lesko of the University of California's Lawrence Berkeley National Laboratory, the committee's co-chairman. Lesko said other topics for a national underground laboratory include the nature of the sun's interior, better understanding of supernovae, searches for dark matter, behavior and evolution of life in exotic environments, characteristics and stability of geologic structures, evaluation of groundwater resources, monitoring of nuclear weapons tests, and vulnerability of microelectronics and other materials to cosmic rays.

"The lack of interference from cosmic rays, radio waves and other disturbances that can be achieved at a Homestake laboratory represents a new frontier of science," Lesko said. He pointed out that the large number of tourists who visit Mount Rushmore and other Black Hills attractions provides a unique opportunity to educate and interest millions of Americans in fundamental science.

Marvin Marshak, a University of Minnesota professor who led a team that visited four potential sites in the United States and existing underground laboratories in Japan and Italy, said much cutting-edge science is being performed deep underground.

"The United States has a chance to lead the scientific world with a laboratory at Homestake in making discoveries about the fundamental laws of physics, biology and geology," he said.

John F. Wilkerson, a University of Washington physics professor and a committee member, said recent advances in experimental techniques have enabled a new generation of more sensitive experiments aimed at a better understanding of the basic framework for particle physics, called the Standard Model.

"New experiments in the very quiet environments available very deep underground will likely reveal new information that will help us understand how to make the Standard Model a better description of the universe in which we live," he said. "This U.S. laboratory will be unique. I expect scientists from all over the world will come to this laboratory to collaborate on major experiments."

The committee's report noted that although the Homestake site has distinctive strengths, a second site studied, Mount San Jacinto near Palm Springs, Calif., also could be developed into a world-class laboratory. The committee preferred Homestake because of a lower initial cost to achieve breakthrough science, a shorter time until the first experiments could be performed, and fewer unknowns regarding laboratory development. The committee noted that the Homestake Mining Corp. plans to close the mine at the end of this year. The mine for decades was the largest gold mine in the Western Hemisphere.

"The value of Homestake as a world-class laboratory site will diminish as the closing process proceeds, so the committee is suggesting continued work on Mount San Jacinto, and possibly some other mountain sites in the California-Nevada region," Bahcall said. "The Homestake proponents need to address transfer of the site to the state of South Dakota and a few other issues rapidly, before the knowledgeable staff at Homestake leave the area."

The committee also visited and studied sites near Carlsbad, N.M., and Soudan, Minn. Bahcall said that existing laboratories at both of those sites are performing important underground science studies. However, he said, those sites are not as deep as Homestake and Mount San Jacinto. Carlsbad scientists said that they could not make deep excavations at their laboratory without compromising the primary mission of the facility.

Wick Haxton, a physics professor who heads the UW's Institute of Nuclear Theory, said the easy part of the committee's deliberations was deciding that the United States needs a world-leading underground laboratory now. He characterized the arguments for a laboratory as "absolutely compelling." The hard part of the deliberations, Haxton said, was choosing among sites.

"Both Homestake and San Jacinto are stupendous, right up there. Homestake has a time advantage. If they can line things up, that's great. Otherwise, the U.S. will be first in the world with Mount San Jacinto." The committee's work is supported by grants from the National Science Foundation and the Office of Science of the U.S. Department of Energy.

Other committee members are Barry Barish, California Institute of Technology; Frank Calaprice, Princeton University; Janet Conrad, Columbia University; Peter Doe, University of Washington; Thomas Gaisser, University of Delaware; Kem Robinson, Lawrence Berkeley National Laboratory; Bernard Sadoulet, University of California, Berkeley; Henry Sobel, University of California-Irvine; Michael Visscher, Notre Dame University; and Stanley Wojcicki, Stanford University.

Joe Wang of Lawrence Berkeley National Laboratory, a geophysics expert, and Charles Nelson and D. Lee Petersen, consulting engineers of CNA Engineers, Minneapolis, provided technical assistance during the committee's studies of potential sites for underground laboratories.

For further information, contact Bahcall at jnb@sns.ias.edu; or Marshak at (612) 624-1312 or marshak@umn.edu; or Wilkerson at (206) 616-2744 or jfw@u.washington.edu; or Linda Vilett, Institute for Nuclear Theory administrator, at (206) 685-3958 or vilett@dirac.phys.washington.edu.











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