Deep inside a mountain in central Italy, scientists are laying a trap for dark matter. The bait? A big metal tank full of 3.5 tons (3,200 kilograms) of pure liquid xenon. This noble gas is one of the cleanest, most radiation-proof substances on Earth, making it an ideal target for capturing some of the rarest particle interactions in the universe.
It all sounds vaguely sinister; said Christian Wittweg, a doctoral candidate at the University of Münster in Germany, who has worked with the so-called Xenon collaboration for half a decade, going to work every day feels like “paying a Bond villain a visit.” So far, the mountain-dwelling researchers haven’t captured any dark matter. But they recently succeeded in detecting one of the rarest particle interactions in the universe. [11 Biggest Unanswered Questions About Dark Matter]
According to a new study published today (April 24) in the journal Nature, the team of more than 100 researchers measured, for the first time ever, the decay of a xenon-124 atom into a tellurium 124 atom through an extremely rare process called two-neutrino double electron capture. This type of radioactive decay occurs when an atom’s nucleus absorbs two electrons from its outer electron shell simultaneously, thereby releasing a double dose of the ghostly particles called neutrinos.