Collaborative Research: NSF-BSF:Continuation of the XENONnT Experiment at LNGS

About This Grant

Dark matter is a mysterious substance that makes up most of the matter in the Universe, but it has never been seen directly. To uncover this cosmic enigma, scientists are conducting the XENONnT experiment. This experiment uses a detector filled with nearly nine tons of ultra-pure liquid xenon to search for extremely rare interactions that could help us understand what dark matter is composed of. XENONnT is the last experiment in the international XENON Dark Matter project, which has received support from the National Science Foundation since it began. This project creates a rich environment for educating students and researchers in the U.S. and around the world, with more than twenty institutions collaborating globally. The scientists working on this project are trained in advanced science and technology that cover multiple disciplines. The specialized tools and techniques they use, along with advanced data analysis and statistical methods, are not only important for understanding dark matter but also have significant applications in fields like medicine, nuclear safety, and data science. Candidates for the dark matter which dominates the matter content of the Universe span decades in mass and interaction cross-section with normal matter. The class of Weakly Interacting Massive Particles (WIMPs) has been the most studied theoretically and experimentally with indirect and direct searches as well as at the Large Hadron Collider. The sensitivity for WIMPs direct detection has increased by many orders of magnitude in the past twenty years thanks to experiments using liquid xenon in dual-phase time projection chambers with increasing target mass and decreasing background. The phased XENON Dark Matter project has led the direct detection field with its XENON10, XENON100 and XENON1T experiments and has paved the way to the current generation of multi-tonne scale liquid xenon detectors, including the largest of the XENON detectors, XENONnT with 6 tonnes of active target. The unprecedented ultra-low background achieved by XENONnT, the lowest among all direct searches, has enabled a sensitive search not just for WIMPs but also other rare interactions, such as the recent first observation of coherent elastic neutrino-nucleus scattering from solar B-8 neutrinos. This award will enable the XENON US groups to continue to contribute to the operation of the experiment at the Italian Gran Sasso Underground Laboratory (LNGS) and to continue to lead several science analyses using the data acquired to-date with the XENONnT detector. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.