Development of laser optics for a spin-exchange optical pumping He neutron spin filter at J-PARC

Oku, Takayuki; Kira, Hiroshi*; Hayashida, Hirotoshi*; Sakai, Kenji; Ino, Takashi*; Hiroi, Kosuke; Shinohara, Takenao; Kakurai, Kazuhisa*; Suzuki, Junichi*; Aizawa, Kazuya

no journal, , 

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, since it can polarize a neutron beam with a large cross section without deteriorating projection image of the transmitted neutrons. In order to apply the He NSF to experiments at a pulsed neutron experimental facility such as the J-PARC, it is important to make the system stable and easy to setup and operate, because the system is located inside a radiation shield for high energy gamma ray and neutrons. In this situation, we have been developing laser optics with a Volume Bragg Grating (VBG) element for a spin-exchange optical pumping (SEOP) system, and an in-situ SEOP He NSF. The recent status of the work and results will be presented.