Development of a ³He Spin Filter and Its Application at J-PARC

Abstract

³He spin filter is a useful neutron polarization device as a neutron polarizer and an analyzer in neutron scattering experiments because of its capabilities to polarize neutrons in broad energy range and cover wide solid angle. We are developing a ³He spin filter, based on the Spin Exchange Optical Pumping (SEOP) for polarized neutron scattering experiments at Materials and Life Science Experimental Facility (MLF) of J-PARC. A ³He gas-filling station was constructed at J-PARC, and several ³He cells with long spin relaxation times have been fabricated. A compact pumping systems with laser powers of 110 W was developed, and a ³He polarization of 85 % was achieved under real experimental conditions. Several user experiments utilizing the ³He spin filter are now being conducted at several beamlines at MLF. The development and utilization of ³He spin filters at MLF of J-PARC are reported.