Magnetic Shield Design of In-situ SEOP Polarized 3He Neutron Spin Filter System

A polarized 3He neutron spin filter requires a suitably homogeneous magnetic environment to avoid depolarization of 3He nuclear spin. In the present study, we discussed the required performance of the magnetic shield for an in-situ spin exchange optical pumping neutron spin filter system and designed a magnetic shield with T1mag > 100 h under a magnetic field of 3.5 mT perpendicular to the guide field. We then constructed the magnetic shield and confirmed its performance. Finally, we succeeded in developing a magnetic shield for a polarized 3He neutron spin filter system for J-PARC.