Development Of A Helium-3 Cryostat For A Ultra-Cold Neutron Source

Ultra-cold neutrons (UCNs) have a very small kinetic energy as a level of a few hundred neV and can be confined in a material bottle. The TUCAN (TRIUMF Ultra-Cold Advanced Neutron) collaboration established for aiming to build a high-intensity UCN source on a dedicated proton beamline at TRIUMF. The source is composed of a combination of a spallation neutron target and a superfluid helium UCN converter. Estimated heat deposit from spallation reaction on the superfluid helium is approximately 10 W. In order to achieve the requirement of superfluid helium temperature, a high-power helium-3 cryostat has been developed. Heat transport property in superfluid helium at 1.0 K is also a key element of the UCN source cryogenics.