Improved limit on the radium-225 electric dipole moment

Searches for permanent electric dipole moments (EDMs) are sensitive probes of physics beyond the Standard Model that could explain the dominance of matter over anti-matter in the universe. ²²⁵Ra (t_1/2 = 15d, I = 1/2) is a particularly attractive system to use for an EDM measurement because its large nuclear octupole deformation makes it uniquely sensitive to symmetry-violating interactions in the nuclear medium. We have developed an experiment to measure the EDM of ²²⁵Ra based on laser cooling and trapping techniques, demonstrated a first “proof-of-principle” measurement, and most recently have significantly improved the sensitivity of our instrument. Upcoming experimental upgrades have the potential to improve our EDM limit by additional orders of magnitude.