Development of an On-beam SEOP Polarized ³He Neutron Spin Filter

Abstract

We have started a polarized ³He neutron spin filter project in order to increase utilization efficiency of polarized neutrons in Japan. We adopted the on-beam spin exchange optical pumping (SEOP) technique to polarize the nuclear spins of ³He atoms to keep stable polarization performance of the ³He neutron spin filter. We performed neutron beam tests of our compact in-situ SEOP neutron spin filter (NSF) system at the NOP beamline in the Japan Research Reactor No.3 (JRR-3) and the BL10 beamline in the Materials and Life Science Experimental Facility (MLF) of the Japan Proton Accelerator Research Complex (J-PARC). The ³He gas polarization of 73% was achieved. Now we are developing a new design in-situ SEOP NSF system as an incident beam polarizer for JRR-3. We also performed a polarized neutron scattering measurements of Ni at BL10. This paper gives the present status of the development of in-situ SEOP system in J-PARC.