Early days of Japanese neutron scattering science were lectured by one of fathers of Japanese neutron scattering science. The special focus was placed on the low dimensional magnetism which led the Solid State Physics in the world in 1960s-70s.

Application of neutrons to biophysics was one of my long dreams from my student age. In order to understand the design principle of protein, I believed that neutron is an effective tool. Neutron inelastic scattering studies of protein dynamics are the proof of my conviction. The inelastic scattering spectrum I obtained is the most precise spectrum of a protein, and makes possible to compare with the theoretical spectrum. Both the conformation dependence and hydration dependence of protein dynamics are clarified by quasielastic scattering and dynamical transition behavior. Neutron can see hydrogen atom. By high resolution neutron crystallography, we revealed that the special type of hydrogen bond, low barrier hydrogen bond, is formed in the active center of photoactive yellow protein. We should extend neutron biophysics to the problems in life science.

In this article, a new high-pressure apparatus for single-crystal magnetic neutron diffraction under 10 GPa is described. First, new hybrid-anvil, which is composed of an opposed pair of a supported SiC anvil and a tungsten carbide (WC) anvil with a center-dimpled culet, is introduced. Next, results of an investigation of pressure-transmitting media are shown. The hydrostaticity of the media is essential for the single-crystal diffraction experiments. Finally, a thermal neutron focusing device with a lot of curved supermirrors is shown. The device can compensate weak magnetic signals from tiny samples in high-pressure cells. As examples of the studies using the apparatus, the high-pressure single-crystal magnetic neutron diffraction experiments on 4f-electron systems PrFe₄P₁₂ and HoB₂C₂ are taken up.

A new inelastic scattering measurement method utilizing multiple incident energies simultaneously (Multi-E_i measurement) greatly enhances the measurement efficiency. This method takes advantage of the fact that the monochromating chopper of a chopper spectrometer at a pulsed source can in principle transmit monochromatic beam several times in one repletion cycle of the pulsed source. In this article, we will describe the principle of the Multi-E_i measurement, and how we developed it on the chopper spectrometer 4SEASONS at J-PARC.

Recently it is well known that the physical properties of polymer thin film are quite different from those of bulk state. Among them glass transition temperature (T_g) of polymer thin film is most extensively studied because T_g is directly related to the thermal stability of polymer thin film in itself, however the detailed mechanism of T_g in thin film is still lacking. In order to overcome such a situation we tried to study the dynamics of polymer thin film by neutron scattering. We found that the low mobility interfacial layer was related to the decrease of mobility with decreasing film thickness by the inelastic neutron scattering studies. From the neutron reflectivity measurements we observed the distribution of T_g in thin film. The dynamic heterogeneity is the essential idea to understand the singular physical properties of polymer thin film.

Bragg edge transmission imaging using pulsed neutrons is expected as a new evaluation tool for engineering materials because it can non-destructively examine crystalline structural information inside the bulk with high spatial resolution over wide area simultaneously. Methodology of quantitative imaging of crystal lattice strain was developed at ISIS. However, crystallographic texture and microstructure could not be quantitatively visualized although these are important factors for controlling strength, workability and electromagnetic properties of a material. Therefore, we developed the Rietveld-based comprehensive analysis code, RITS, for neutron transmission data. Furthermore, we successfully evaluated not only strain but also texture and crystallite size owing to the RITS code, and also carried out the verification experiment with a neutron powder diffractometer. In this article, the quantitative visualization of texture and crystallite size by the RITS code is mainly presented.

Hydrogen in mineral plays an important role in the deep earth because it has a significant effect on physical properties. An ability of neutron diffraction that can detect the hydrogen is thus a useful tool in mineral physics. Here I present results of neutron diffraction studies that investigate (1) pressure-induced hydrogen bond symmetrization in δ-AlOOH(D), and (2) hydrogen position in nominally anhydrous minerals of wadsleyite.

Double-network hydrogels (DN-gels) are a new class of cross-linked polymer networks having high mechanical properties while containing ~90 wt.% water. To investigate the origin of the toughness, small-angle neutron scattering (SANS) and neutron spin echo (NSE) were applied. The SANS results in both deformed and undeformed conditions for a tough DN-gel made of poly- (2-acrylamido-2-methyl-1-propane sulfonic acid) (PAMPS) and polyacrylamide (PAAm), are presented. The SANS measurements indicate that the deformation of DN-gels results in periodic and mesoscale (~1.5 μm) compositional fluctuations in both PAMPS and PAAm. In addition, SANS measurements also indicate that the DN-gel constituents favorably associate with each other in water. This favorable association between PAMPS and PAAm is consistent with the rheological and NSE results on solution blends of these two polymers. The implications of the above observations to toughening mechanisms are discussed.

Peptide amphiphile (PA) micelles are unique materials, whose morphologies are controlled by the peptide secondary structure as well as the length of the peptide and alkyl chains. The dynamics of the thermally-induced structural transition of our designed PA micelles was investigated by in situ small-angle neutron scattering (SANS) and Circular Dichroism (CD). The results revealed the time-evolution of the peptide secondary structure and the micellar morphology after temperature-jump. We propose the mechanism of these cooperative transitions: the change of the peptide secondary structure from α-helix and random coil to β-sheet induces the micellar structural transition from the spherical to the worm-like.

The DAQ group of KENS has developing a data acquisition (DAQ) system for neutron scattering experiments in the MLF/J-PARC. The DAQ system has adopting the event-mode data taking instead of a conventional histogram-mode data taking to expand flexibility of measurements. The KENS-DAQ group, therefore, has developed the new DAQ system so called a NeuNET system for ³He PSD. The NeuNET system is realized scalable and distributed DAQ system by using electronics modules with a high speed network data transfer technique and software which based on component middleware.