This grant supports a research team led by Amar Vutha, Professor of Physics at the University of Toronto, to search for evidence of new fundamental particles by making careful measurements of atomic nuclei. Professor Vutha will pursue a well-known particle discovery strategy -searching for so-called time symmetry violation in nuclei- but will pursue a new approach to performing the measurements. The new method is expected to improve nuclear time-symmetry-violation measurement precision by a factor of one hundred to one thousand. Time-reversal refers to negating time in the equations used to describe a physical system. Intuitively, it means that time flows backwards rather than forwards. Time-reversal symmetry means that particles follow the same equations irrespective of whether one runs the clock forward or backward (one can’t determine which way the clock runs by watching the particles). Many laws of microscopic physics are time-reversal invariant, but not all. More to the point for this project, the known sources of microscopic time-reversal asymmetry (T-violation) are inadequate to explain the observed matter/antimatter asymmetry of the universe and new particles that participate in T-violating interactions are needed to explain that asymmetry. The traditional approach to searching for new T-violating particles / interactions involves making measurements on a modest number of free neutrons or atoms. By contrast, Vutha will search for nuclear T-violation using an octupole deformed nucleus embedded within a solid-state crystal. There are three primary reasons this new approach could significantly improve nuclear T-violation measurement precision. First, atoms in a solid-state crystal are more highly compacted than free atoms (or neutrons) so many more atoms can be measured. This improves precision. Next, the atom proposed for these measurements has a spatially deformed (i.e. non-spherical) nucleus and this enhances sensitivity to nuclear T-violation by a factor of 100 to 1000. Finally, the solid-state crystal lattice has a large internal electric field, and this too enhances a T-violation signal. Grant funds will support three primary workflows: design and construction of the experimental apparatus, identification and mitigation of sources of statistical noise and systematic error, and the use of precision optical and radio-frequency spectroscopy to perform T-violation measurements on the system.