We report the precipitation and control of metal nanoparticles inside transparent glasses. An Ag ϩ -doped silicate glass sample was first irradiated by using an 800 nm femtosecond laser at room temperature and then annealed at 550°C. The area near the focal point of the laser beam became gray after laser irradiation and yellow after further annealing at 550°C for 10 min. Absorption and electron spin resonance spectra of the glass sample showed that a portion of silver ions near the focused part of the laser beam inside the glass were reduced to silver atoms after the laser irradiation. These silver atoms aggregated to form nanoparticles after further annealing at temperatures above 500°C. A mechanism is suggested that consists of multiphoton reduction, which is induced by the fundamental light of the laser beam and supercontinuum white light, and diffusion of silver atoms driven by heat energy to form nanoparticles. The observed phenomenon may have promising applications for the fabrication of three-dimensional multicolored images inside a transparent material and for integrative micro-optical switches.

Nanoparticles have a wide range of electrical and optical properties owing to the quantum-size effect, surface effect, and conjoint effect of nanostructures. [1] Materials doped with noble-metal nanoparticles exhibit large third-order nonlinear

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Nanoparticles have a wide range of electrical and optical properties owing to the quantum-size effect, surface effect, and conjoint effect of nanostructures. [1] Materials doped with noble-metal nanoparticles exhibit large third-order nonlinear

No abstract

An upgrade plan of the KEK B-Factory (KEKB), Super KEKB (SKEKB) has been discussed in KEK. The R&D of main vacuum components for the SKEKB, such as beam ducts, bellows chambers and connection flanges etc., are now undergoing. Trial models of a beam duct with an antechamber and a bellows chamber with a comb-type RF shield were installed in the KEKB positron ring and tested with beam.Coatings with a low secondary electron yield were also investigated with the positron beam. A special connection flange with small impedance was examined in a test bench.

The first (Phase-1) commissioning of SuperKEKB, an asymmetric-energy electron-positron collider at KEK, began in February 2016, after more than five years of upgradation work on KEKB and successfully ended in June 2016. A major task of the Phase-1 commissioning was the vacuum scrubbing of new beam pipes in anticipation of a sufficiently long beam lifetime and low background noise in the next commissioning, prior to which a new particle detector will be installed. The pressure rise per unit beam current decreased steadily with increasing beam dose, as expected. Another important task was to check the stabilities of various new vacuum components at high beam currents of approximately 1 A. The temperature increases of the bellows chambers, gate valves, connection flanges, and so on were less than several degrees at 1 A, and no serious problems were found. The effectiveness of the antechambers and TiN coating in suppressing the electron-cloud effect (ECE) in the positron ring was also confirmed. However, the ECE in the Al-alloy bellows chambers was observed where TiN had not been coated. The use of permanent magnets to create an axial magnetic field of approximately 100 G successfully suppressed this effect. Pressure bursts accompanying beam losses were also frequently observed in the positron ring. This phenomenon is still under investigation, but it is likely caused by collisions between the circulating beams and dust particles, especially in the dipole magnet beam pipes.

Development of planar x-ray source using gated carbon nanotube emitter J. Vac. Sci. Technol. B 31, 02B110 (2013) Tungstate formation in a model scandate thermionic cathode J. Vac. Sci. Technol. B 31, 011210 (2013) Influence of gun design on Coulomb interactions in a field emission gun J. Vac. Sci. Technol. B 29, 06F605 (2011) Model scandate cathodes investigated by thermionic-emission microscopyA two-ring electron-positron collider with asymmetric energies-called the SuperKEKB-has been designed by the High Energy Accelerator Research Organization (KEK) as an upgrade of the KEKB B-factory (KEKB), which completed 12 years of operation in 2010. It is anticipated that the SuperKEKB will reach a luminosity of 8 Â 10 35 cm À2 s À1 , which is approximately 40 times larger than that of the original KEKB. The upgrade of the vacuum system is a key factor that will allow the SuperKEKB to achieve unprecedented high performance. Most of the beam pipes, especially in the positron ring, are newly manufactured to manage the electron cloud effect, and to reduce beam impedance, which is essential to keep the low-emittance beam stable. Our design of the vacuum system implements recent technologies and draws on various experiences and studies during the operation of the original KEKB. The basic design is near completion, and manufacturing of beam pipes and the major vacuum components, such as bellows chambers, gate valves and supports, are in progress. The installation of these components will start in 2013 with the aim of commissioning the SuperKEKB in