A goldmine of scientific research
||The underground home of the LUX dark matter experiment has a rich scientific history. Photo: Sandbox Studio with Ana Kova|
There's more than gold in the Black Hills of South Dakota. For longer than five decades, the Homestake mine has hosted scientists searching for particles impossible to detect on Earth's surface.
It all began with the Davis Cavern.
In the early 1960s, Ray Davis, a nuclear chemist at Brookhaven National Laboratory, designed an experiment to detect particles produced in fusion reactions in the sun. The experiment would earn him a share of the Nobel Prize in physics in 2002.
Davis was searching for neutrinos, fundamental particles that had been discovered only a few years before. Neutrinos are very difficult to detect; they can pass through the entire Earth without bumping into another particle. But they are constantly streaming through us. So, with a big enough detector, Davis knew he could catch at least a few.
Davis' experiment had to be done deep underground; without the shielding of layers of rock and earth it would be flooded by the shower of cosmic rays also constantly raining from space.
Davis put his first small prototype detector in a limestone mine near Akron, Ohio. But it was only about half a mile underground, not deep enough.
"The only reason for mining deep into the earth was for something valuable like gold," says Kenneth Lande, professor of physics at the University of Pennsylvania, who worked on the experiment with Davis. "And so a gold mine became the obvious place to look."
But there was no precedent for hosting a particle physics experiment in such a place. "There was no case where a physics group would appear at a working mine and say, 'Can we move in please?'"
Davis approached the Homestake Mining Company anyway, and the company agreed to excavate a cavern for the experiment.
—Amelia Willamson Smith