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[en] Several new thermosetting resins with a three dimensional network structure similar to that of CR-39 were polymerized to study their characteristics as nuclear track detectors. The comparison of the molecular structures of these resins gives us an important clue to develop highly sensitive polymeric track detectors. For example, butanediol bis allylcarbonate (BuAC) shows the sensitivity about ten times higher than diallyl and adipate (DAA). This suggests the carbonate groups in the BuAC molecule provide a much higher sensitivity than the ester groups in the DAA. During the course of this study, thermosetting resins with good etching properties and various sensitivities have been developed. Though the sensitivity of DAA is low, it will be useful for observations of ultra heavy cosmic rays and heavily ionizing particles at low energies. (author)

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[en] In order to develop new polymeric track detectors of high sensitivity, we have introduced sulphonate groups to thermosetting resins with three dimensional network structure. The test sample of the copolymer of CR-39 with diethylene glycol bis (allyl sulphonate), DEAS, shows about three times higher sensitivity than that of CR-39 for 6 MeV alpha particles and 1.7 GeV/n iron nuclei. (author)

[en] In order to develop new polymeric track detectors of high sensitivity, we have introduced sulphonate groups to thermosetting resins with a three-dimensional network structure. The test sample of the co-polymer of CR-39 with diethylene glycol bis(allyl sulphonate), DEAS, shows about three times higher sensitivity than that of CR-39 for 6 MeV alpha particles and 1.7 GeV n^-1 iron nuclei. The sensitivity for protons, however, has not yet been increased. The further improvement of this sample, SR-86, will open new fields of application for track detectors. (author)

[en] The relationship between the detection sensitivity for charged particles and the molecular structure of polymers like CR-39 was studied while changing the average chain length of the carbonate linkages cross-linking the polyallyl chains. It has been found that the polymer shows the highest sensitivity when the length of the carbonate linkages is about 1.6 times longer than that of CR-39. Just after polymerization this polymeric track detector named SR-90 has about 3 times higher sensitivity than CR-39 but ageing effects on its sensitivity are very strong. In this connection a model of the latent track formation and the mechanism of the track fading are discussed on the basis of the recombination of free radicals produced by charged particles. (author)

[en] SR-86 is a new polymeric track detector made by co-polymerizing CR-39 monomer with diethylene glycol bis(allyl sulphonate), DEAS. This detector is about three times more sensitive than CR-39 to alpha particles and high energy heavy ions. However, its sensitivity to protons is slightly lower than that of CR-39. In an attempt to improve the sensitivity of SR-86 to protons, we studied extensively the effects of co-polymerization and etching conditions. These studies provided some useful information about the mechanism of track formation in polymers. (author)

[en] The mechanism of CO oxidation reaction on oxygen-precovered Pt(111) surfaces has been studied by using time-resolved near-edge x-ray absorption fine structure spectroscopy. The whole reaction process is composed of two distinct paths: (1) a reaction of isolated oxygen atoms with adsorbed CO, and (2) a reaction of island-periphery oxygen atoms after the CO saturation. CO coadsorption plays a role to induce the dynamic change in spatial distribution of O atoms, which switches over the two reaction paths. These mechanisms were confirmed by kinetic Monte Carlo simulations. The effect of coadsorbed water in the reaction mechanism was also examined