The pulsed neutron source, JSNS, in J-PARC will be one of the most intensive neutron source in the world. After 7-year construction since 2001, it has started commissioning since May 2008 to be a user facility from December 2008. The first neutrons were created in 30 May this year, and more than 10 instruments are under construction or in commissioning. 1 MW in the acceleration power will provide very bright neutron flux, which is about 1,000 times in intensity from the previous neutron source in Japan. We expect an occurrence of a large stepwise development in neutron sciences not only on high pressure science but other large number of sciences in the near future.

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User operation of J-PARC started in December of 2008. It is expected that high pressure material science and the investigation of the Earth’s interior will greatly improve using the high flux pulse neutrons of J-PARC. In this article, current status of neutron powder diffraction beamlines and our strategy of high pressure experiments will be introduced.

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It is great exciting news for our high pressure science community in Japan that the first pulsed neutron beams were delivered to J-PARC Materials & Life Science Experimental Facility (MLF) on May 30th, 2008. We believe that the newly dedicated pulsed neutron beams will open a new window in the high-pressure science world. Over the past 7 years, we have prepared some projects to build a high pressure and high temperature material science beamline in the MLF. In this article, we will give a brief overview of the progress of those projects and also introduce a newly designed high-pressure cell and a neutron focusing mirror for in-situ neutron diffraction experiments at high pressure and high temperature.

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Advanced Fundamental Research on Hydrogen Storage Materials (HYDRO☆STAR), was launched in 2007 to investigate the fundamental properties of hydrogen storage materials. The interest is focused on basic understanding of the hydrogen-metal interactions in metal hydride systems. Neutron scattering technique, which is capable of determining hydrogen positions and bonding states, is a key tool to investigate the interactions, and becomes significantly powerful when combined with high pressure technique, which realizes high hydrogen density states by compression of metal lattices. In this article, we present high-pressure neutron scattering techniques using Paris-Edinburgh cell and hydrogen-gas cell under development at J-PARC and JRR-3.

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In the history of high pressure neutron science, the most crucial technical progresses would be the developments of Paris-Edinburgh cell in ISIS, pulsed neutron spallation source in UK. They now permit in situ high pressure and high/low temperature neutron scattering studies for both crystals and amorphous materials. In this article, from the practical point of view, a short introduction for the principle of time-of-flight neutron scattering method, data calibration methods for structure analysis with some previous studies are shown. Also, the required improvements and future prospects to the technique are proposed.

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Temperature, pressure, and ethanol concentration dependence of the structure and dynamics of dipalmitoyl phosphatidylcholine (DPPC) aqueous solution were investigated by small-angle neutron scattering and neutron spin echo experiments. A swollen phase, in which the mean repeat distance of lipid bilayers is larger than these of the other phases, is found between the liquid-crystalline phase and the interdigitated gel phase. The nature of the swollen phase is similar to the anomalous swelling state observed above the main transition temperature.

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Small-angle neutron scattering (SANS) and neutron spin echo (NSE) spectroscopy have been used to elucidate static and dynamic structures of a microemulsion system composed of a nonionic surfactant, water, and oil. Using the contrast variation neutron scattering technique, static structure parameters are evaluated, and the molecular volume change with pressure is calculated. The bending elastic modulus increases with increasing pressure. This tendency is similar to the microemulsion system composed of anionic surfactant, water, and oil. Therefore, a universal feature of the surfactant membrane as a response to pressure is clarified, that is, the surfactant membrane becomes rigid at high pressure due to the increase of density of the hydrophobic tail of surfactant molecules and their aggregates.

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Aspects of development of experimental techniques at Geodynamics Research Center (GRC), Ehime University, using Kawai-type multianvil apparatus (KMA) for various studies in deep Earth mineralogy, have been reviewed in conjunction with the author’s scientific achievements in this field. Precise measurements of some physical properties of minerals at the pressure and temperature conditions corresponding to certain depths of the lower mantle are now possible, by combinations of synchrotron radiation, advanced anvil materials, new cell designs, and ultrasonic and other techniques using KMA. KMA has also been used to synthesize ultrahard nano-polycrystalline diamond (NPD) by direct conversion from graphite. NPD has potential as new hard material for generation of higher pressures, and challenges in producing large (∼1 cm) NPD and its application to various apparatus have just started at GRC and other related laboratories.

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