I contributed to the development of a cryogenic hydrogen system for the spallation neutron source in J-PARC. It was verified through cryogenic tests that the cryogenic hydrogen system satisfied performance requirements. In May 2008, the spallation neutron source successfully provided the first cold neutron beam, which was cooled by the cryogenic hydrogen system. Through the development of the system, it was found that liquid and supercritical hydrogen had excellent cooling properties. I wish to investigate a hydrogen cooling system for superconducting and hydrogen energy systems.
Neutron supermirrors are increasingly important devices for transporting, bending, and focusing neutron beams. Reflected neutrons from a supermirror are divided into specular and off-specular (diffuse) components. The suppression of the diffuse component is important since it causes a serious problem when a supermirror is used in a focusing system for such purposes as small angle scattering measurement. The diffuse intensity can be decreased by more than an order of magnitude by adopting NiC/Ti multilayers instead of conventional Ni/Ti multilayers. In order to obtain insight into the mechanism that controls the diffuse intensity from a supermirror, the crystal structure of Ni and NiC monolayers and the interface structure of Ni/Ti and NiC/Ti multilayers were investigated. Diffuse intensity calculation based on the distorted wave Born approximation revealed that these differences in the structures explain the difference between the diffuse intensity of the Ni/Ti and NiC/Ti supermirrors.
The DNA is a novel Si-analyzer backscattering spectrometer. Construction of the DNA has been started in the Materials and Life Science Facility (MLF) of the Japan Proton Accelerator Research Complex (J-PARC). It is a twist of fate that the author, who is one of the instrument scientists of the DNA, started his scientific career in the biochemical science field to research deoxyribonucleic acid (DNA). This manuscript has been written to introduce the author himself with his recent studies of the instrument DNA.
According to historic papers in lubrication engineering, lubrication modes between two solids are essentially classified into three groups – boundary lubrication, mixed lubrication and full-film lubrication. This paper proposed some novel approaches for elucidation of lubrication phenomena using neutron reflectometry. For the studies on boundary lubrication, the neutron reflectometry is helpful to in-situ observe the ‘absorbed layer’ near the solid surface, while for the studies on full-film lubrication, it can reveal the density of lubricants at the solid-liquid interface. Those information will help to clarify the friction mechanism under lubrication in the field of tribology.
Neutron scattering measurements have been performed in a new non-Cu based quantum spin dimer system, Ba3Cr2O8, where Cr5+ (s=1/2) ion with the unusual 5+ electronic valence forms quantum dimers along the c-axis and a frustrating triangular lattice in the ab-plane. We found that there exist three singlet-to-triplet excitation modes even without field. Our complete analysis shows that the three modes are due to spatially anisotropic interdimer interactions that are induced by local distortions of the tetrahedron of oxygen surrounding the Jahn-Teller active Cr5+(3d1).
Various types of technique have been proposed for enhancement of reliability of crystal structure information of synthetic polymers. In particular, the organized combination of high-energy synchrotron X-ray and wide-angle neutron diffraction methods has allowed us to extract the exact hydrogen atomic positions of polymer crystals. The so-called X-N method has been applied for the first time to obtain the bonded electron density distribution of electronically-conjugated polymer system.
How can we understand the formation mechanism of various morphologies of biomembrane? We are trying to understand the formation mechanism from the view point of soft matter physics, i.e., from physical properties of lipid assembly. We have especially studied the mechanism of giant vesicles formation from the lipid film by means of time-resolved Small-Angle X-ray Scattering, and the results suggest that the morphologies of lipid membrane strongly depend on the kinetics of the formation process. Thus, the observation of formation kinetics of various membrane morphologies should become more important to understand the biomembrane formation from soft matter physics. For observing the kinetics of membrane self-assembly, time-resolved measurements of Small-Angle Neutron Scattering and Neutron Spin Echo spectroscopy will make a significant contribution and will shed light on the various morphologies of biomembrane.
Basics of neutron reflectivity measurements are described from an instrumental viewpoint. Principles of off-specular scattering measurement and spin-echo resolved grazing incidence scattering method are also introduced.
We will have review articles for the principles of neutron spin echo (NSE) spectroscopy including Mezei, resonance, modulated intensity spin echo, history of NSE, and applications of the NSE technique to various fields of science. We hope you will find the series are useful to understanding this particular technique and realize new ideas of science using the technique.
The principle of neutron spin echo (NSE) spectroscopy is introduced. We focus our attention on the conventional Mezei type NSE spectroscopy. NSE achieves the highest energy resolution among other neutron scattering techniques, since energy resolutions of neutrons and energy transfer of a sample are decoupled with each other using neutron spin degrees of freedom as a measure of energy transfer of the sample. NSE naturally Fourier transforms the energy to time domain. NSE gives intermediate scattering functions, I(q,t), instead of dynamic structure factors, S(q,ω). Not only the quasi-elastic scattering but also elastic scattering can be encoded within the neutron spin.