Developments of in-situ SEOP polarized He neutron spin filter in Japan

Kira, Hiroshi; Sakaguchi, Yoshifumi; Oku, Takayuki   ; Suzuki, Junichi; Nakamura, Mitsutaka   ; Arai, Masatoshi; Endo, Yasuo; Chang, L.-J.; Kakurai, Kazuhisa; Arimoto, Yasushi*; Ino, Takashi*; Shimizu, Hirohiko*; Kamiyama, Takashi; Oyama, Kenji*; Hiraka, Haruhiro*; Tsutsumi, Kenji*; Yamada, Kazuyoshi

The pulsed neutron source of J-PARC has started to operate in 2008 in Japan. To study structure of magnetic material and soft matters, polarized neutron scattering techniques are very important and powerful tools. It is urgently necessary for us to develop neutron spin polarizers for pulsed neutron scattering experiments. So we began the development of the in-situ SEOP system aiming to use it as a NSF for incident beam polarization and polarization analysis. In previous test performed by Ino et al., the He polarization reached 50% and not saturated yet. After that experiment, we began improving the SEOP system by installing the high power laser diode, the prism beam splitter and optimizing the beam-transform optics. By using this improved system, we performed the polarization test at BL10 in J-PRC and achieved the He polarization of 73%. We keep improving this in-situ SEOP system aiming to use it s an incident neutron polarizer at J-PARC.