In this paper, we present recent progress in the development of hydrophobic silica aerogel as a Cherenkov radiator. In addition to the conventional method, the recently developed pin-drying method for producing high-refractive-index aerogels with high transparency was studied in detail. Optical qualities and large tile handling for crack-free aerogels were investigated. Sufficient photons were detected from high-performance aerogels in a beam test. c 2011

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The preparation and characterization of conducting polycarbazole (PCz) hybrid films with a colorless transparency are described. They were prepared by the vacuum evaporation of tin, aluminum, or gallium onto anion-doped green-colored PCz films, or by applying gallium to the films, followed by their exposure to ambient air. The resultant hybrid films consisting of an undoped PCz backbone and metal compounds exhibited good transparencies (90-95% at a wavelength of 550 nm). The hybrid films have a specific cross-sectional structure in which the small regions of the metal compounds are dispersed in the PCz backbone. The hybridization reaction was mechanistically explained on the basis of the combination of a metal corrosion reaction and polymer dedoping reaction, which was successfully supported by the chemical analyses of the hybrid films. The electric conductivities of the hybrid films, measured by a four-point-probe method, ranged from 2.2 x 10(-4) to 6.0 x 10(-3) S cm(-1), which are considered to be the lowest limit because the use of the hybrid films as an electrochemical electrode reveals that a network of conductive paths is preferentially formed in the film thickness direction rather than in the in-plane direction.