Physicists utilizing the LUX-ZEPLIN (LZ) dark matter detector have observed mysterious single-particle interactions deep underground in a former gold mine in South Dakota, but they are proceeding cautiously before claiming a discovery.
To search for dark matter, LZ uses photomultiplier tubes (shown here before being installed in the detector) to capture light from particle interactions. Image credit: Matthew Kapust/Sanford Underground Laboratory.
The LZ experiment is an international collaboration involving 250 scientists and engineers from 39 institutions.
The detector consists of 10 tons of ultra-pure liquid xenon located 1 mile underground at the Sanford Underground Research Facility in South Dakota.
Managed by Lawrence Berkeley National Laboratory, it is specifically designed to search for WIMPs (weakly interacting massive particles).
“Dark matter interactions are anticipated to be exceedingly rare, so a large number of instances is not necessary to demonstrate the initial detection of dark matter,” stated Dr. Carmen Carmona, leader of the Penn State LZ Experiment Group.
“This particular signal came from a dataset area that we had not explored previously, requiring extensive additional investigation by our team to understand potential background causes and eliminate conventional explanations.”
After analyzing 220 days of live data collected between March 2023 and April 2024, the LZ team delved into a broader range of potential WIMP interactions capable of depositing more energy in the detector compared to previous studies.
If attributed to dark matter, the particle responsible is likely to weigh at least 200 GeV/c2 (gigaelectronvolts), over 200 times the mass of a proton, indicating more exotic interactions than basic theoretical models suggest.
The current signal falls below the five-sigma threshold required by physicists to claim a discovery. The new analysis stands at 2.6 sigma, indicating a mere 0.5% probability that it is merely a statistical coincidence from a known background.
“We are particularly intrigued by the confirmation of this event in an area where dark matter is anticipated and the competing background is minimal,” remarked LZ spokesperson Rick Gaitskell, a professor at Brown University.
“We are cautious not to jump to conclusions based on a singular event. We are not asserting to have observed dark matter.”
“However, we have uncovered something noteworthy and aim to share it with the scientific community for feedback.”
The team’s findings will be submitted to the journal Physical Review Letters.
Source: www.sci.news
