A nuclear emulsion prepared at Nagoya University was verified to be usable for autoradiography in comparison with a commercial emulsion used for this purpose, as production of many silver-salt photographic materials is now discontinued. Photographic characteristics of two nu- clear emulsions were estimated in terms of the sensitivity for light and β-rays, and the shapes of silver halide grains and developed silver grains were observed with electron microscopes. Autoradiography with β-rays was conducted by applying the emulsions on a sample with a radioisotope and evaluating the images formed on the emulsions. This emulsion prepared at Nagoya University has properties similar to those of the commercial one and can be used for autoradiography.

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The formation of gold nanoparticles with the gold deposition development was investigated by altering the concentration of the gold(I) com- plex (AC) and ascorbic acid (AcA) solutions or their concentration ratio AC/AcA in the developer with three methods: absorption spectrum measurement, atomic absorption spectroscopy and transmission electron microscopy. Several phenomena, such as the variation in the devel- opment rates, existence of an induction period in the development rates, shift in the wavelength of maximum absorption, expansion of the band width, simultaneous formation of silver atoms, and change in the smoothness of the particle surface, were observed. These phenomena depended not only on the concentration of both solutions but significantly on their ratio. All these phenomena changed at a concentration ratio equal to unity, and it was suggested that the formation process varied at approximately this ratio. A novel process, whereby silver halide was reduced by excess AcA to form silver atoms and these atoms subsequently reduced gold ions to form gold atoms, was proposed to explain the acceleration of the development rates, the disappearance of the induction period, red-shift and expansion of the band, as well as the ap- pearance of a rough surface on the particles.

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Island-shaped Au nano-particles were immobilized on an ITO transparent conductive film by a pulse electrolysis method capable of con- trolling the nucleation and the nuclear growth. Using this as an electrode, a polypyrrole thin film was immobilized by electrochemical po- lymerization. It was confirmed that the electrochromic stability of the polypyrrole film was greatly improved on the ITO electrode modified with the Au nano-islands.

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The J-PARC E07 experiment aimed to systematically detect double-strangeness nuclei with emulsion technologies. Thirty-three events were detected within 2 years by following of Ξ - tracks. One event of D001 among them was examined to identify the production and decay pro- cesses by energy and momentum conservation obtained from the track lengths and emission angles of daughter particles. The event was de- termined to be Λ1 Λ0 Be (8Be and two Λ particles) as the most likely case assuming Ξ - capture in the atomic 3D state of 14N. The binding energy of the two Λ hyperons and the core nucleus of this double-Λ hypernucleus was 15.22 ± 2.78 MeV, and the Λ-Λ interaction strength was 1.80 ± 2.78 MeV.

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