Spallation UCN Production for nEDM

A new superthermal UCN production in He-II, which is placed in a spallation neutron source, is discussed. In the new UCN source, the production rate is expected to be 200 UCN/cm3/s at a proton beam power of 500 MeV×40 μA and the UCN maximum energy of Ec = 210 neV. The γ heating in the He-II can be removed by means of 3He pumping according to calculations. For an EDM measurement, UCN are extracted from a He-II bottle through an aluminum window by using a superconducting magnet. The possibility of a 129Xe magnetometer for the EDM measurement is also discussed.