Current status and perspectives in the development of an in-situ spin-exchange optical pumping He neutron spin filter at J-PARC

Oku, Takayuki   ; Kira, Hiroshi*; Hayashida, Hirotoshi*; Sakai, Kenji ; Hiroi, Kosuke  ; Shinohara, Takenao   ; Sakaguchi, Yoshifumi*; Ino, Takashi*; Oyama, Kenji*; Nakamura, Mitsutaka   ; Suzuki, Junichi*; Aizawa, Kazuya  ; Arai, Masatoshi; Endo, Yasuo; Kakurai, Kazuhisa

We have been developing a He neutron spin filter (NSF) for the efficient utilization of pulsed neutrons, since it can polarize neutrons effectively in a wide energy range. The He NSF is effective even for neutrons with energy higher than several-tens-meV, so that it will be useful for the study of high-energy magnetic excitation. Since the He NSF can also cover a large solid angle and polarize neutrons without deflecting them from their original course, it is suitable for the analyzer for SANS instruments and reflectometers. In addition, the He NSF will be a key device in the application of recently developed magnetic field imaging technique by using polarized pulsed neutrons. In order to apply the He NSF to such experiments at a pulsed neutron experimental facility such as the J-PARC, we have developed compact laser optics with a volume holographic grating (VHG) element for a spin-exchange optical pumping (SEOP) system, and composed an in-situ SEOP He NSF. Current status in the development and application of the in-situ SEOP He NSF at J-PARC will be presented, and perspectives will be discussed.