2006 Sanford Underground Research Facility
Astronomical observations demonstrate that as much as a quarter of the universe is made up of some material which is invisible to conventional measurements. The gravitational effects of this invisible matter can be seen, even though the material itself cannot currently be detected. Until someone figures out how to observe, measure, and categorize what is currently referred to as dark matter, many of today’s most pressing uncertainties in physics and cosmology will remain unexplained.
Given the importance of this quest, it is interesting to note that today’s best research on dark matter is being carried out only because of the intervention of a private donor. The Homestake gold mine in South Dakota, which extends nearly a mile underground, is a perfect location for a dark-matter detector, because the overlaying rock shelters any instruments placed in the mine from false signals created by the cosmic radiation that surrounds us on the surface of the Earth. After the mine closed in 2003, various government agencies hoped to create a permanent physics lab in the underground site, but failed to find funding. In swooped philanthropist Denny Sanford, a Dakotan who made his fortune in banking and has given away more than a billion dollars. He put up $70 million to secure the site, pump water out of the shafts, and create the Sanford Underground Research Facility. This sparked the state of South Dakota to commit additional funds, and the U.S. Department of Energy to underwrite the cost of science experiments on the premises.
The first such experiment, known as the Large Underground Xenon detector, went into operation in 2013 and soon excited physicists by ruling out one favored theory on the nature of dark matter. The sensitivity of the detector was then increased for additional runs. A second important experiment under way at Sanford, called the Majorana Demonstrator, is searching to explain differences between matter and anti-matter, which could rewrite today’s standard theory of physics. In 2014 Congress funded a third major particle-physics experiment to be conducted in the Sanford Lab. It will involve beaming a string of neutrinos right through the earth from Illinois to South Dakota to test the behavior of the particles and clear up some mysteries fundamental to the origins of the universe.
- About the Sanford Underground Research Facility, sanfordlab.org/about/deep-science-frontier-physics