Dynamic nuclear polarization system for the SANS-J-II spectrometer at JAEA

Abstract

We have developed a dynamic nuclear polarization (DNP) system for the SANS-J-II spectrometer at the JRR-3 atomic research reactor of Japan Atomic Energy Agency (JAEA). The DNP system is composed of a split-type horizontal superconducting magnet (3.3 T), a Gunn oscillator as a microwave source (94 GHz), and a cryostat (1.2 K). In particular, a sample cell with ∅40 in inner diameter and the magnet with a field homogeneity of 5×10−5 in a volume of ∅25 mm×8 mm were employed to polarize samples with a diameter of ∅20 mm for the ultra small-angle scattering experiment using the magnetic lens installed at the SANS-J-II spectrometer [S. Koizumi, H. Iwase, J. Suzuki, T. Oku, R. Motokawa, H. Sasao, H. Tanaka, D. Yamaguchi, H.M. Shimizu, T. Hashimoto, J. Appl. Crystallogr. 40 (2007) s474]. We obtained the proton polarization |P|=32% in the polyethylene doped with 2,2,6,6-tetra-methyl-piperidine-1-oxyl (TEMPO).