The U.S. Department of Energy’s Lawrence Berkeley National Laboratory has announced new results from the LUX-ZEPLIN (LZ) experiment, the world's most sensitive dark matter detector. The findings narrow down possibilities for weakly interacting massive particles (WIMPs), a leading dark matter candidate.
Conducted nearly one mile underground at the Sanford Underground Research Facility in South Dakota, LZ's latest results explore weaker dark matter interactions than previously searched and limit what WIMPs could be. Chamkaur Ghag, spokesperson for LZ and a professor at University College London, stated, "These are new world-leading constraints by a sizable margin on dark matter and WIMPs."
The collaboration found no evidence of WIMPs above a mass of 9 gigaelectronvolts/c2 (GeV/c2). This sensitivity helps researchers reject potential WIMP models that don't fit the data. The results were presented at two physics conferences on August 26: TeV Particle Astrophysics 2024 in Chicago, Illinois, and LIDINE 2024 in São Paulo, Brazil.
Scott Kravitz, LZ’s deputy physics coordinator and a professor at the University of Texas at Austin, compared the search for dark matter to "looking for buried treasure," emphasizing that their approach involves innovative tools rather than sheer numbers.
LZ’s design minimizes background noise through multiple layers that block outside radiation or track particle interactions to rule out false signals. Additionally, "salting" techniques were applied to add fake WIMP signals during data collection to avoid unconscious bias.
Scott Haselschwardt, LZ physics coordinator and assistant professor at the University of Michigan, noted the importance of avoiding bias when entering new regimes of data analysis.
Dark matter is estimated to constitute 85% of the universe's mass but has never been directly detected. The LZ detector uses 10 tonnes of liquid xenon to capture potential WIMP signals by observing light and electrons emitted during interactions.
Amy Cottle from UCL highlighted future research opportunities with this detector beyond just searching for WIMPs. These include examining rare decays of xenon atoms and other beyond-the-Standard-Model physics processes.
LZ is supported by numerous international institutions and funding bodies including the U.S. Department of Energy’s Office of Science, Office of High Energy Physics; Science & Technology Facilities Council (UK); Portuguese Foundation for Science and Technology; Swiss National Science Foundation; Institute for Basic Science (Korea); among others.