Contributions as the year prize winner of achievements were follows,①contributions as one of the initial stage of the thermal neutron scattering in Japan, ②contributions of the research reactor JRR-3M as the main purposes were for the neutron science, and ③contributions for the success of the Japan-US collaboration of researches for the neutron-scattering.

We have been developing compact neutron source systems that are useful in research, manufacturing, and infrastructure on-site in RIKEN. The accelerator-based RANS and RANS-II are in constant operation indoors, and the RANS-III for outdoor use is under development. The RANS-μ neutron salt meter, which aims to prevent accidents involving bridges falling due to salt damage, is small enough to be mounted on a bridge inspection vehicle and has high measurement accuracy, and has been successfully tested for salt measurement on national highway bridges in Iwate and Miyagi prefectures in FY2022. The RANS-II model is being installed at Mirrotron Co. in Hungary. The key technologies are the high brightness of the source and the high signal-to-noise ratio of the measurement. We are developing new needs for neutron applications while realizing a minimal-size, practically useful neutron system that can be used in the field.

Mechanical properties, as the principal properties of structural metallic materials, are governed by the microstructures. To track the structure-property relationship associated with various solid-solid reactions such as phase transformation and plastic deformation, is crucial for the development of structural metallic materials. These dynamic solid-solid reactions occur in various extreme environments, including thermomechanical controlled process, cryogenic deformation, fatigue, etc., and are nearly impossible to be directly observed by conventional techniques. Neutron diffraction can provide crystallographic information such as phase fraction, lattice strain (stress), texture, dislocation density. This information can provide unique insights into microstructure evolution and deformation mechanisms in bulky materials. TAKUMI, an engineering materials diffractometer at MLF, J-PARC, covering a large d-range with a good balance between high neutron flux and high resolution, possessing advanced sample environments, is reliable for tracking the structure-property relationship associated with various solid-solid reactions under extreme environments. In the present paper, several recent studies associated with microstructure evolution and deformation mechanisms in steels and magnesium alloys investigated by in-situ neutron diffraction with TAKUMI are introduced.

Accurate Neutron-Nucleus Reaction measurement Instrument (ANNRI) is installed at the one of the beamlines in MLF in J-PARC, and nuclear reaction measurements have been conducted using the three types of γ-ray detectors, Ge, NaI, and LaBr. Recently, a ³He spin filter to polarize neutrons has become available in ANNRI, and several experiments have been performed using the produced polarized neutrons. Significant differences in the measured cross section and γ-ray emission depending on the direction of the neutron polarization were observed in the ¹¹⁷Sn(n,γ)¹¹⁸Sn reaction. A γ-ray polarimeter was also developed, and the circular polarization of emitted γ-rays was successfully measured at ANNRI for the ³²S(n, γ)³³S reaction using the polarized neutrons.