In fall 2017, the Japanese-Canadian TUCAN (TRIUMF Ultra Cold Advanced Neutron) collaboration succeeded for the first time in producing ultracold neutrons (UCN). This was a major milestone towards the search for the elusive neutron electric dipole moment (nEDM). UCN move so slowly, about 5 meters per second compared to about 500 meters per second for air molecules, and with such low energy that they can be contained and observed. Thus, UCN are ideal for determining the neutron electric dipole moment (nEDM), which TUCAN aims to measure with the highest-ever precision. The nEDM is predicted to be vanishingly small, but if it is measured to be larger than expected, the TUCAN results could aid in solving a key cosmic puzzle: why there is much more matter than antimatter in the universe.

TRIUMF’s UCN facility is aiming to be the world’s highest-density source of ultracold neutrons. High density is critical to the research because most ultracold neutron experiments are statistics limited—the experiments require enormous numbers of individual measurements to arrive at a statistically reliable result. To support this effort, Momose group is developing atomic magnetometers based on the optical pumping of ¹⁹⁹Hg and ¹²⁹Xe isotopes, which will cohabit with UCN inside the nEDM experimental chamber, and will measure fluctuations of the magnetic field on the ppb scale.  We have succeeded in producing laser-polarized ¹⁹⁹Hg with orders of magnitude greater polarization than that obtained in a commercial NMR machine.  We are now working to identify sources of systematic error, and push the measurement precision to its ultimate limit.

For an overview of TUCAN visit an overview of TUCAN and the project page.