Polarization analysis for small-angle neutron scattering with a He spin filter at a pulsed neutron source

Okudaira, Takuya; Ueda, Yuki   ; Hiroi, Kosuke  ; Motokawa, Ryuhei   ; Inamura, Yasuhiro  ; Takata, Shinichi  ; Oku, Takayuki   ; Suzuki, Junichi*; Takahashi, Shingo*; Endo, Hitoshi*; Iwase, Hiroki*

Neutron polarization analysis (NPA) for small-angle neutron scattering (SANS) experiments using a pulsed neutron source was successfully achieved by applying a He spin filter as a spin analyzer for the scattered neutrons. The He spin filter covers a sufficient solid angle for performing SANS experiments, and the relaxation time of the He polarization is sufficient for continuous use over a few days, thus reaching the typical duration required for a complete set of SANS experiments. Although accurate evaluation of the incoherent neutron scattering, which is predominantly attributable to hydrogen atoms in samples, is practically difficult using calculations based on the sample elemental composition, the developed NPA approach with consideration of the influence of multiple neutron scattering enabled reliable decomposition of the SANS intensity distribution into the coherent and incoherent scattering components. To date, NPA has not been well established as a standard technique for SANS experiments at pulsed neutron sources. This work is anticipated to greatly contribute to the accurate determination of the coherent neutron scattering component for scatterers in various types of organic sample systems in SANS experiments at J-PARC.