Cryogenic Design for TUCAN's New UCN Source*

A precision measurement of the neutron electric dipole moment (nEDM) is a good probe to search for new sources of CP violation and to solve puzzles which cannot be explained by the standard model. TUCAN (TRIUMF Ultra-Cold Advanced Neutron source) is an international collaboration between Canada and Japan, aiming to measure the nEDM at a sensitivity of 10^-27 ecm, a factor 30 better than the current limit, using a high intensity ultra-cold neutron (UCN) source. The TUCAN collaboration recently succeeded in producing the first UCN in Canada using a prototype UCN source installed on a dedicated proton beam line at TRIUMF. Our UCN source is based on a unique combination of a spallation neutron target and a superfluid helium (He-II) UCN converter. Following the success of this UCN source, the TUCAN collaboration is designing a considerably higher intensity UCN source based on the same combination. The new cryostat design will allow for operation at larger proton beam currents on the spallation target in order to achieve the necessary statistical sensitivity.
This presentation will describe the design of the He-II cryogenic system and the UCN transport system of the next generation UCN source.