LUX-ZEPLIN: The world’s most sensitive dark matter detector tested for the first time

A short test has shown that the new LUX-ZEPLIN dark matter detector is the most sensitive ever. It might be our best bet to finally find dark matter particles


Physics


July 7, 2022

An image of the upper PMT array, part of the Lux-Zeplin Lab at the Sanford Underground Research Facility.

LUX-ZEPLIN dark matter detector at Sanford Underground Research Facility in South Dakota is most sensitive ever

Matthew Kapust/Sanford Underground Research Facility

The search for dark matter just got a new pair of eyes. A test run of the LUX-ZEPLIN (LZ) detector in South Dakota has shown it to be the most sensitive dark matter detector still being made, and researchers are getting ready to turn it on and do some serious hunting.

LZ consists of a huge titanium tank filled with 10 tons of extreme pure liquid xenon† When a particle from outside the tank hits a xenon atom, it creates a flash of light that is measured by a series of detectors that surround the tank. The properties of that light can then be analyzed to determine what type of particle caused it. To protect the xenon from particles and radiation that we know don’t come from dark matter, the tank is surrounded by an even larger tank of purified water and the whole thing is buried well over a kilometer underground in an old gold mine.

“The center of LZ is the purest place on Earth, perhaps in the solar system. There is no other volume of space on or in this planet that is so free of radiation and dust,” says LZ team member Chamkaur Ghago at University College London. “We can only handle about a gram of dust in the detector — 3 grams of dust and we won’t be able to find anything.”

Decades of chasing dark matter particles have not been successful so far, so researchers have started making increasingly sensitive detectors. A 3.5-month test run that ended in April showed that LZ is the most sensitive yet. “We collected a few months of data and when we looked at that data, we were like, ‘oh shit, we’re already the best in the world,’” Ghag says. “It’s like building a new car and driving it around, and in that fast drive around the block you broke the world land speed record.”

Regardless of the sensitivity, however, three months was not long enough to actually find dark matter. Even if some got through the detector during that time, we wouldn’t have enough data to say for sure what it was, Ghag says.

“For now it’s a bit weird, we say we’re the best in the world at finding nothing,” he says. “But the prospect of finding new physics in a few years is very possible.”

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