First Experiment of Spin Contrast Variation Small-Angle Neutron Scattering on the iMATERIA Instrument at J-PARC

• Main Authors: Yohei Noda, Tomoki Maeda, Takayuki Oku, Satoshi Koizumi, Tomomi Masui, Hiroyuki Kishimoto
• Format: Article
• Language: English
• Published: MDPI AG 2020-09-01
• Series: Quantum Beam Science
• Subjects: small-angle neutron scattering; contrast variation; dynamic nuclear polarization; J-PARC
• Online Access: https://www.mdpi.com/2412-382X/4/4/33

Recently, we have developed a novel dynamic nuclear polarization (DNP) apparatus with a magnetic field of 7 T and a sample temperature of 1 K. High proton spin polarizations from −84% to 76%, for TEMPO doped polystyrene samples, have been demonstrated. This DNP apparatus satisfies the simultaneous requirement for quick and easy sample exchange and high DNP performance. On the iMATERIA (BL20) instrument at J-PARC, the first beam experiment using this DNP apparatus has been performed. For this experiment, the beamline was equipped with a supermirror polarizer. The stray magnetic field due to the superconducting magnet for DNP was also evaluated. The stray magnetic field plays an important role for in maintaining the neutron polarization during the transportation from the polarizer to the sample. The small-angle neutron scattering (SANS) profiles of silica-filled rubber under dynamically polarized conditions are presented. By applying our new analytical approach for SANS coherent scattering intensity, neutron polarization (<i>P</i>_N) as a function of neutron wavelength was determined. Consequently, for the neutron wavelength, range from 4 Å to 10 Å, |<i>P</i>_N| was sufficient for DNP-SANS studies.