AUSTIN, Texas — Scientists studying dark matter say they may have detected a particle consistent with the mysterious substance for the first time, although researchers caution that the finding still needs further confirmation.
The potential breakthrough came from the LUX-ZEPLIN (LZ) experiment, which uses a particle detector located about a mile underground at the Sanford Underground Research Facility in South Dakota.
Scott Kravitz, an assistant professor of physics at the University of Texas at Austin and a member of the LZ research team, said scientists detected an interaction that they could not explain through known background particle interactions.
“There are plenty of interactions that we saw that we could sift through, but they didn’t look like dark matter until just recently when we saw one interaction that we just cannot explain with any of the known background interactions we can think of,” Kravitz said.
The LZ detector uses liquid xenon to search for weakly interacting massive particles, or WIMPs, a leading candidate for dark matter. When a particle interacts with a xenon atom, the collision can produce flashes of light and electrons that researchers can measure.
Scientists must determine whether the detected signal came from dark matter or another known particle, such as a gamma ray or neutron.
Kravitz said the detected signal had a higher energy and a distinct pattern that did not match the expected signatures of other particle interactions.
“It’s basically a flash of light that’s at much higher energy and with a particular signature that doesn’t match what that interaction would look like for the other types of particle interactions that we would expect,” Kravitz said.
Researchers have searched for dark matter for decades because scientists cannot observe it directly. Instead, they infer its existence from its gravitational effects on galaxies, stars, gas and other matter.
Kravitz described dark matter as the “invisible stuff” that helps hold galaxies together through its gravitational pull.
Scientists estimate that dark matter accounts for about 85% of the universe’s mass, but efforts to directly detect a dark matter particle on Earth have yet to produce definitive evidence.
The LZ experiment began collecting data in 2021 and involves about 200 collaborators. Researchers operate the detector deep underground to reduce interference from other particles that could obscure potential dark matter signals.
Kravitz said researchers need more data before they can determine whether the latest observation represents a dark matter particle.
The team expects to spend at least several months collecting and analyzing additional data.
“But we could be on the precipice of this happening and really being the first to definitively discover dark matter in this particular way,” Kravitz said. “So that’s very exciting for all of us.”