The former Homestake Gold Mine in Lead, S.D., has a hallowed place in the history of physics as a spot where nothing happens.
It was here, in the 1970s, that Raymond Davis Jr. tried to catch neutrinos, spooky subatomic particles emitted by the sun, in a vat of cleaning fluid a mile underground and for a long time came up empty. For revolutionizing the study of those particles, he shared the Nobel Prize in physics in 2002.
On Wednesday, an international team of physicists based in the same cavern of the mine announced a new milestone of futility, this time in the search for dark matter, the mysterious, invisible ingredient that astronomers say makes up a quarter of the cosmos.
In 110 days of running, they said, the biggest, most sensitive dark matter detector yet, a vat of 368 kilograms of liquid xenon, they have not seen a trace of the clouds of dark matter particles that theorists say should be wafting through space, the galaxy, the Earth and, of course, us.
At least not yet. The experiment has just begun.
As has been typical of the dark matter industry, the scientists took pride and hope in how clearly they did not see anything. This means, they said, that their detector is working so well that they will easily see a dark matter particle when and if it decides to drop in.
“In 25 years of searching, this is the cleanest signal I’ve ever seen,” said Richard Gaitskell, a professor of physics at Brown University and the spokesman for an international collaboration that operates the experiment known as LUX, for Large Underground Xenon.
The announcement capped a morning of ceremony, which included the governor of South Dakota, to celebrate the first results from the experiment - the first occupant of the Sanford Underground Research Facility, a lab being developed in the old mine with a mixture of state and private money.
LUX is the latest in a long series of ever larger experiments that have teased and taunted the world’s physicists over the last few years. They are all in abandoned mines or other underground places to shield them from cosmic rays, which could cause false alarms. Gaitskell said in an interview that the biggest source of noise in the LUX device was trace radioactive elements in the metal of its own circuits.
