A US experiment is poised to resolve confusion over whether dark matter has already been detected. The Large Underground Xenon Experiment (LUX) at Sanford Underground Laboratory in Lead, South Dakota — announced on 15 October that it will release its first results on 30 October.

LUX began taking data earlier this year, promising to rival or even surpass limits on dark-matter detection set by a competitor, XENON-100, which is located at Gran Sasso National Laboratory near L’Aquila, Italy. In 2011, XENON-100 ruled out many heavier and more strongly interacting dark matter particles, but its result is in tension with tantalizing data hinting at the existence of light dark-matter particles from two other US experiments, the Cryogenic Dark Matter Search (CDMS), and the CoGeNT experiment, both at Soudan Underground Laboratory in Minnesota. With more than 350 kilograms of liquid xenon held underground to snare dark-matter particles as they pass through the Earth, LUX might become the deciding vote. “I’m cautiously optimistic this could be the final word on the situation,” says dark-matter theorist Dan Hooper of Fermi National Accelerator Laboratory in Batavia, Illinois.

Of course the final word on whether CDMS and CoGeNT’s dark-matter particles are real is far from the final word on whether dark matter is detectable on Earth; more weakly interacting particles could still be out there, and plans exist to scale up both XENON-100 and LUX to try to find them.

Corrected October 24 to reflect that the CDMS is co-located with CoGeNT at Soudan Underground Laboratory.