Development and test of SEOP neutron spin filter in Japan

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

Polarized neutron scattering techniques are very important and powerful tools to study the fundamental structures of magnetic materials and soft matters. He has a very large absorption cross section for only neutrons in opposite spin state to that of the He nucleus. The scattering cross section of He is small. These two features allow nuclear spin polarized He gas to work as a NSF. Compared with other spin filters such as Heusler alloys and magnetic supermirrors, the He gas NSF have following advantages: it can polarize various energy of neutron such as cold, thermal and hot neutrons, it can work for broadband neutrons and it can be used for wide area and large divergence neutron beams. These characteristics of polarized He are convenient in use with J-PARC as NSF. We began the development of the on beam SEOP system aiming to use it s a NSF for incident beam polarisation and polarisation analysis. In this paper, we report the current development of SEOP system in Japan.