We have investigated suitable magnetic field distribution to polarize neutrons based only on the electromagnetic interaction between a neutron magnetic moment and magnetic field, and found out a quadrupole field was the most suitable among simple multipole fields. Then we constructed a quadrupole magnet with a Halbach magnetic circuit as the neutron polarizing device. A cold neutron polarizing experiment of the quadrupole magnet was performed at the beamline C3-1-2-1 (NOP) of JRR-3 at JAEA. By passing through the aperture of the quadrupole magnet, positive and negative polarity neutrons are accelerated in opposite directions and spatially separated. Therefore, we extracted the one-spin component and analyzed its polarization degree. As a result very high neutron polarization degree P=0.9993±0.0025 was obtained. Then the quadrupole magnet was installed into the polarized neutron focusing geometry SANS instrument SANS-J-II of JRR-3. The instrument performance was enhanced by about 10 times compared with the case with the magnetic supermirror as the neutron polarizing device. The details are shown and discussed.

Although numerous works on physical properties of ring polymers were made for three decades, most of ring polymer samples used so far were not pure enough. Recently new HPLC technique with high resolution has provided rigorous characterization of rings. In this article, recent developments in solution and bulk properties of well-characterized ring polymers with high purity are described.

We are developing a neutron beam monitor with a gas electron multiplier (GEM) for the high-intensity total diffractometer at J-PARC. We checked the validity of the wavelength-spectrum distribution and the two dimensional image. The GEM-based detector operated well in the neutron irradiation test carried out at J-PARC. Therefore we found that as a neutron beam monitor, the GEM-based detector has good two-dimensional imaging ability.

The introductory lecture was set up to deepen the understanding of the residual stress in engineering components to researchers of material science and engineers. The method of the stress measurement using neutron diffraction is explained in the beginning. The present situation of the instrument for stress measurement, some recent researches on the residual stress and the expansion into the material science are going to be expressed.

Residual stresses have been one of the key factors in developing new materials and structures. Neutrons can penetrate a thousand to ten thousands times deeper than the conventional X-rays, and can be utilized to measure the stress in the interior of the material. In this article, the fundamental concept of the stress states in the engineering component and the relationship between the stress and the strain were explained. Some recent developments of the stress measurement were reported.

Recent extensive studies have revealed that polymer thin films showed very interesting but unusual thermal properties and stabilities. In the article we show that X-ray reflectivity and neutron reflectivity are very powerful tools to study the anomalous properties of polymer thin films.

This article describes the swelling behavior of polyelectrolyte brushes in aqueous solutions with different salt concentrations analyzed by neutron reflectometry. Densely-grafted polyelectrolyte brushes such as poly(2-(methacryloyloxy)ethyl phosphorylcholine) (PMPC), poly(2-(methacryloyloxy)ethyltrimethylammonium chloride) (PMTAC), and poly(3-dimethyl(methacryloyloxyethyl)ammonium propane sulfonate) (PDMAPS) were prepared on quartz substrate by "grafting-from" method based on a surface-initiated polymerization technique. Neutron reflectivity at swollen brushes/D₂O interface afforded the neutron scattering length density profiles and the corresponding volume fraction profiles based on a parabolic function to estimate the swollen brush thickness. PMTAC brush was fairly extended from the substrate surface in D₂O, while it shrunk in NaCl/D₂O solution due to the screening of the repulsive interaction between polycations by hydrated salt ions. In contrast, PDMAPS brush in D₂O formed shrunk structure due to strong attractive interaction between sulfobetain groups, while the swollen thickness was drastically increased by addition of salt ions to D₂O. Non-dependency of swollen thickness on NaCl concentration was observed in PMPC brush because of weak electrostatic interaction between phosphorylcholine groups.