Development of portable polarized He neutron spin filter and its application to magnetic field imaging at J-PARC

Sakai, Kenji ; Oku, Takayuki   ; Hayashida, Hirotoshi; Kira, Hiroshi*; Shinohara, Takenao   ; Oikawa, Kenichi   ; Harada, Masahide   ; Kakurai, Kazuhisa; Aizawa, Kazuya  ; Arai, Masatoshi; Sakaguchi, Yoshifumi*; Suzuki, Junichi*; Ino, Takashi*; Oyama, Kenji*

In polarized neutron experiments, it is interested in expanding measurable neutron energy region up to epithermal neutrons. For realizing this situation, a Polarized He Spin Flipper (PHSF) has a key role because it can polarize from cold to epithermal neutrons, and flip neutron spins by flipping the He nuclear spin direction. We have developed the portable PHSF consisting of a cylindrical glass cell filled with He gas which is installed a solenoid coil of 20 cm in diameter and 30 cm long. After polarizing the He gas by irradiating a laser light based on a SEOP technique, the PHSF is brought by hands to experimental areas with kept its polarization. We carried out the feasibility test on our portable PHSF in the MLF of J-PARC and demonstrated it worked well by evaluating flipping ratios of polarized neutrons and attempting to visualize magnetic fields generated by sample coils.