The team running the biggest, most sensitive dark matter detector yet announced its first round of results yesterday—specifically, the lack thereof. Scientists at the Homestake Gold Mine in South Dakota cooled a vat full of 368 kilograms of liquid xenon to minus 150 degrees Fahrenheit, watched it for three months, and caught nary a glimpse of the particle clouds that should have theoretically shown up, the New York Times reports. But despite what you might think, scientists are bragging about how little they saw. "In 25 years of searching, this is the cleanest signal I've seen," said physicist/spokesman Richard Gaitskell.
The non-find is significant because, if confirmed, it would rule out one theory about dark matter. While scientists tend to suspect dark matter is made up of high-mass subatomic particles called WIMPS (weakly interacting massive particles), one experiment suggested it might actually be a lower-mass version. But if those particles existed, the Homestake experiment should have spotted 1,550 of them. "If there are 1,550 of them, boy are we going to see them," Gaitskell said. Next, researchers will add another factor of sensitivity to the device, and run the experiment again.