Grant: Subatomic Physics Envelope - Project

Our experiment aims measure the neutron electric dipole moment (nEDM) more precisely than ever before. A new measurement of the nEDM will place even tighter constraints on theories involving new sources of Charge-Parity (CP) violation beyond the standard model. It is believed these are required in order to explain the predominance of matter over antimatter (baryon asymmetry) in the universe today. The experiment will constrain broad classes of new physics scenarios which do not conserve CP. A new measurement also could impact a long-standing mystery in the standard model, involving the apparent lack of CP violation arising from the strong force. A discovery of a non-zero nEDM would be a major discovery, because it would shed light on a broad range of theories. A key tool in this search is a new source of ultracold neutrons (UCN). UCN are slow moving neutrons that can be stored in material, magnetic, and gravitational bottles. Once they have been confined using such methods, their properties can be studied very carefully to search for deviations from expectations based on the standard model of particle physics. Our scientific collaboration is named the TUCAN (TRIUMF Ultracold Advanced Neutron) collaboration. In the past three years, we completed experiments using a prototype source of UCN in Canada (at TRIUMF, Vancouver, BC), and we are now completing an upgrade with the help of collaborators from Japan. Funds for the upgrades and for a new neutron EDM experiment have been secured from the Canada Foundation for Innovation and partners including a substantial contribution from Japan. Once the upgrades are complete, the source is projected to provide the highest density of UCN in the world. The source will be used to advance fundamental physics experiments to unprecedented levels of precision. Our activities over the next three years will involve the completion of the UCN source upgrade and the nEDM experiment construction. The upgraded UCN source cryostat has been built and tested cryogenically in Japan and is now at TRIUMF awaiting installation (planned for early 2023). After the source has been installed, cryogenic testing will commence, followed by operation of the UCN source which will prove world-class neutron production rates. The magnetically shielded room that will house the nEDM experiment will be constructed at TRIUMF from late 2022 until summer 2023. This will be followed by experiments to characterize and control magnetic fields in the room. By 2025, we plan to transport UCN into the nEDM experimental region for first measurements of neutron spin precession. This will allow us to demonstrate our ability to measure the nEDM with a precision about an order of magnitude better than the current world's best.