T-violation search using nuclei in a crystal

The nature of dark matter, and the origin of the matter-antimatter imbalance of the universe, are glaring gaps in our understanding of high-energy physics. The breakdown of time-reversal symmetry (T) at ultra-high energy scales -- far above the reach of particle colliders -- is believed to underlie one or both of these puzzles. Fortunately, T-symmetry violation at extreme energy scales can be probed through precision measurements. Our experiments use ¹⁵³Eu, which exhibits an enhanced response to beyond-Standard-Model T-violation. The nuclear response is further amplified by electron-nuclear interactions in polarized Eu³⁺ ions in a crystal. The resulting characteristic energy shifts between hyperfine states can be measured in experiments. I will present some results from our search for signatures of T-violation.