Neutron scattering is a powerful method to investigate hierarchical structure and dynamics of soft matter. In this article, several experimental results of surfactant systems, binary liquid mixtures with antagonistic salt, lipid membrane and hydration water by means of Small-Angle Neutron Scattering, Neutron Spin Echo and Quasi-Elastic Neutron Scattering were introduced.

In this study, we established a low-cost, high-precision process for fabricating all-metal substrates for supermirrors for neutron focusing. The key material for this substrate is amorphous plating, which can be polished to achieve the sub-nm surface roughness required to fabricate multilayer supermirrors, and is phosphorus-rich electroless Ni-P plating. This fabrication process was established through multiple prototypes of focusing mirrors for the SOFIA neutron reflectometer at J-PARC MLF BL16. This paper describes the technical difficulties overcome in this development.

³He spin filter is a useful neutron polarization device as a neutron polarizer and an analyzer in neutron scattering experiments because of its capabilities to polarize neutrons in broad energy range and cover wide solid angle. We are developing a ³He spin filter, based on the Spin Exchange Optical Pumping (SEOP) for polarized neutron scattering experiments at Materials and Life Science Experimental Facility (MLF) of J-PARC. A ³He gas-filling station was constructed at J-PARC, and several ³He cells with long spin relaxation times have been fabricated. A compact pumping systems with laser powers of 110 W was developed, and a ³He polarization of 85 % was achieved under real experimental conditions. Several user experiments utilizing the ³He spin filter are now being conducted at several beamlines at MLF. The development and utilization of ³He spin filters at MLF of J-PARC are reported.

Polyrotaxane, in which cyclic molecules slide along polymer axis, has been applied to various functional devices and materials because of the unique molecular structure and dynamics. We investigated the nano-strucutre and dynamics of polyrotaxane in solution by means of small-angle neutron scattering (SANS) and quasi-elastic neutron scattering (QENS) with contrast variation technique. The contrast variation SANS studies verified the topological connection between the cyclic molecules and axial polymer in polyrotaxane. We succeeded in quantifying the molecular dynamics of the cyclic molecules and polymer axis by QENS measurements.

Japanese sword is well known as a strong and sharp weapon and has a long history of more than 1000 years. The making process have not been well known especially for old swords (Koto) before Edo era since there were no written documents. Crystallographic or metallurgical characteristics are useful to understand the swords characteristics and consider the making process. However, studies to obtain such information have been not so easy since proper non-invasive methods were not popular. Neutron diffraction and imaging are powerful tool, and Bragg edge transmission imaging is a unique tool to obtain crystallographic information over a large area. Here, we introduce neutron methods and information obtained, and studies about Japanese swords.

A pale yellow liquid was found in the vacuum scattering vessel in which the neutron detector is installed on the BL02 spectrometer in J-PARC MLF. The substance was characterized as phthalic acids, which are known plasticizers for poly(vinyl chloride) cable sheathing. The leakage mechanism of the plasticizers needs to be urgently clarified, as they contaminate the vacuum vessel and could be the cause of the background increase in the experimental neutron data. We purchased commercially available LAN-cables and evaluated the damage mechanism of the cable sheaths based on the changes in the weight and mechanical strength of the cables after gamma irradiation, neutron irradiation, and vacuum treatment. The results show that alpha, beta, or gamma irradiation caused a local disruption of the polymer chains of the cable sheaths, and depending on the extent of disruption, plasticizers or other additives in the cable sheath leaked out. Polyimide-coated LAN-cables are not currently commercially available. However, polyimide sheaths were not damaged by neutron irradiation over a short period of time (about half a day), indicating that they are a suitable candidate for cable sheaths.