Grant: Subatomic Physics Envelope - Project

A new high-density ultracold neutron (UCN) source will be constructed and developed at TRIUMF over the coming years. The initial experiment using the facility is a new measurement of the neutron electric dipole moment (nEDM). A non-zero value of the nEDM would violate time-reversal symmetry. The standard model predicts a value of 10^{-32} e-cm for the nEDM. But new sources of CP-violation are predicted by modifications to the standard model which seek to explain the baryon asymmetry (matter-antimatter asymmetry) of the universe. These new sources generally increase the nEDM by five orders of magnitude, tantalizingly close to the current experimental upper limit of < 2.9*10^{-26} e-cm. We have had a great deal of success at RCNP recently in R&D tests for this future experiment for TRIUMF. UCN density of 19/cc is achieved for the experiment, which is already more than an order of magnitude greater than 0.7/cc at Institut Laue-Langevin (ILL, Grenoble, France), whose experiment holds current best limit on neutron EDM. The novel aspects of our setup would be smaller geometry to suppress systematic uncertainty and improved co-magnetometry using Xe, taking advantage of the higher density of UCN source using a breakthrough production method with superfluid helium. The UCN source has recently been funded by the Japan Society for the Promotion of Science, and by CFI in Canada. Partner contributions from TRIUMF, Acsion Industries (Pinawa, MB), the Government of Manitoba, and the University of Winnipeg, will also support the project. The total project cost is $10.9M. In addition, KEK and RCNP in Osaka pledged ~$1.7M contribution to the project. An international expert review of the UCN project was held on September 20, 2010, which is expected to be followed by the signing of MOU among Winnipeg (CFI), TRIUMF, KEK, and RCNP. In April 2010, a three-year NSERC operation grant was awarded for the design and construction of UCN source and R&D of the nEDM experiment. The Canadian UCN group is rapidly growing. The funds we request here are for the operation for the additional members who will double the member list of the Canadian UCN collaboration.