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We review the results of very early phase optical follow-up observations of recent gamma-ray bursts (GRBs) with the multi-color optical telescopes “MITSuME”. The MITSuME telescopes were designed to perform “real time” and “automatic” follow-up observations prompted by the GCN alerts via the Internet. The rapidly slewing equatorial mounts allow MITSuME to start photometric observations within 100 seconds after the trigger for several GRBs. In particular, we detected a brightening just after the trigger for two GRBs. These phenomena could be interpreted as the “on-set” of afterglow. In this paper we summarize these optical observations with a brief interpretation.
Hard X-ray polarization is believed to be one of the most promising methods to investigate the physical processes just around the central engines by constraining the magnetic environment. For this purpose we are now developing a compact and highly sensitive hard X-ray polarimeter aboard a university class micro-satellite “TSUBAME”. We are now developing the flight model of the satellite aiming for the launch in late 2012 from Russia.
A novel process to fabricate a thick silica gel film on an aluminum substrate, named the “gap filling method”, has been developed. The process is based on a sol-gel method accompanied by phase separation in a submillimeter thick space defined by two facing substrates. Dielectric thick film integrated on a metal ground plate is successfully formed by using a SiO2 coated aluminum substrate and a cap plate covered with an amorphous carbon thin film, which control the hydrophilicity and the hydrophobicity of the plates, respectively. A thin continuous layer of less than 0.5 μm thick is formed at the interface between the porous film and the cap plate, which gives the film a smooth surface preferable for patterning metal circuits of an antenna. The observed dielectric constants (εr) at 60 GHz measured by the Fabry-Perot resonator method are in the range between 1.4 and 1.6. Methyl groups homogeneously distributed in the siloxane network give a hydrophobic siloxane gel film, thus the obtained films have enough environmental stability. These results show that the gap filling method is applicable to the preparation of the porous thick film that is needed for antenna applications.
Polycrystalline diamond films, single crystal bulk diamonds, and diamond powder were treated in microwave plasma of hydrogen at 1.6 torr under a negative direct-current bias of −150 to −300 V without metal catalyst. It was found that fibrous structures, uniformly elongated along the direction normal to the specimen surface, were formed on the diamond surfaces. Similar experiments for glasslike carbon resulted in conical structures with frizzy fibers at the tops. Transmission electron microscopy measurements indicated that the fibers formed on diamond consisted of randomly oriented diamond nanocrystals with diameters of less than 10 nm, while the conical structures formed on glasslike carbon consisted of graphite nanocrystals. Field emission measurements of the fibrous specimens exhibited better emission efficiency than untreated ones. The field emission electron microscopy of the fibrous glasslike carbon showed a presence of discrete electron emission sites at a density of approximately 10,000 sites/cm2.
Supercritical fluid extraction (SFE) technique which enables to fabricate mesoporous film at low temperature has been developed. Meso-structure silica films are prepared by sol-gel process based on the self-organization of surfactant templates, and the organic templates are successfully extracted from the films by supercritical CO2 (sc-CO2) modified with hydrogen peroxide at 80 °C and 19.6 MPa. The extraction process is analyzed by X-ray photoelectron spectroscopy and Fourier transform infrared spectroscopy of the films. In order to discuss the feasibility of such films obtained at low temperature for electronics applications with low dielectric and low dielectric loss, the mechanical properties and the densities of the films are compared with various silica films prepared by different method.
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