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He Neutron Spin Filter (NSF) in the MLF at J-PARCSakai, Kenji; Oku, Takayuki; Hayashida, Hirotoshi*; Kira, Hiroshi*; Hiroi, Kosuke; Ino, Takashi*; Oyama, Kenji*; Okawara, Manabu*; Kakurai, Kazuhisa; Shinohara, Takenao; et al.
JPS Conference Proceedings (Internet), 8, p.036015_1 - 036015_6, 2015/09
The polarized He filter, which polarizes neutrons due to a large neutron absorption cross section of He with strong spin selectivity, becomes a convenient neutron spin filter (NSF) because it is operated immediately after its installation in beam lines without any neutron beam adjustments. For realizing such the NSF, a nuclear magnetic resonance (NMR) system is indispensable for monitoring He nuclear spin polarization 
of the NSF. We have developed the flexible NMR system based on adiabatic fast passage (AFP) and pulse NMR methods by using their complementary features. In comparing with the values of obtained by neutron transmission measurement at the beam line 10 of the J-PARC, we measured the correlations between the AFP and pulse NMR signals as changing condition of temperature, amplitude and applying period of the radio frequency field for the pulse NMR, and so on. As the results, we confirmed that our system would function enough as the monitor.
Takeda, Masayasu; Torikai, Naoya*; Ino, Takashi*; Tasaki, Seiji*
KENS Report-XIV, p.205 - 206, 2003/00
no abstracts in English
He neutron spin filters at J-PARC MLFOku, Takayuki
no journal, ,
We have been developing a He neutron spin filter (NSF) for the efficient utilization of pulsed neutrons, since the He NSF is effective for neutrons in the wide energy range. The He NSF is effective especially for neutrons with energy higher than several-tens-meV. It also can cover a large solid angle and polarize neutrons without deflecting them from their original trajectory, it is suitable for the analyzer for SANS and reflectometer instruments. 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 thick neutron beam 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 thick and bulky radiation shields for high energy gamma ray and neutrons. In this talk, we will report the development and application status of the He NSF at J-PARC MLF.
