Observation of radiative B-->phi K gamma decays

The radiative decay B-->phi K gamma is observed for the first time. The branching fraction for the charged B--->phi K- gamma decay mode is measured to be B(B--->phi K- gamma)=(3.4+/-0.9+/-0.4)x10(-6). The photon energy distribution for the B--->phi K- gamma decay is presented. The signal for the neutral B(0)-->phi K(0)gamma decay mode is not statistically significant and an upper limit, B(B(0)-->phi K(0)gamma)<8.3x10(-6) at 90% C.L., is set. The analysis is based on a data set of 90 fb(-1) collected by the Belle experiment at the e(+)e(-) asymmetric collider KEKB.     

Periodic change of viscosity and density in an oscillating chemical reaction

It was found that the periodic change of the solution viscosity and density was generated in the Belousov-Zhabotinsky (BZ) reaction. This rhythmic phenomenon was observed in both the iron catalyst [[Fe(Phen)(3)](2+)-[Fe(Phen)(3)](3+)] and the cerium catalyst [Ce(III)-Ce(IV)] system, where the solution viscosity and density were synchronized with the redox potential in the in-phase mode. However, the time delay existed between the redox potential and the solution viscosity and density. The behavior of the BZ reaction was also monitored in the presence of the nonionic surfactant. This experiment revealed that, beyond the critical micelle concentration, the phase between the redox potential and the solution viscosity and density was synchronized into the antiphase mode. We suggested that the variation of the catalyst drove the oscillation of the solution viscosity and density in the BZ reaction.     

The first samarium(II)-mediated aryl radical cyclisation onto an aromatic ring

Intramolecular arylation of aryl radicals was mediated by SmI(2)/HMPA in the presence of i-PrOH to give spirocycles and/or reduced cine-cyclised products, while the reaction in the absence of i-PrOH gave the rearomatised fused rings.     

Measurement of branching fractions for B-->eta(c)K(*) decays

We report measurements of branching fractions for charged and neutral B-->eta(c)K decays where the eta(c) meson is reconstructed in the K(0)(S)K+/-pi(-/+), K+K-pi(0), K(*0)K-pi(+), and pp; decay channels. The neutral B0 channel is a CP eigenstate and can be used to measure the CP violation parameter sin(2phi(1). We also report the first observation of the B0-->eta(c)K(*0) mode. The results are based on an analysis of 29.1 fb(-1) of data collected by the Belle detector at KEKB.     

Adsorption of thiolates to singly coordinated sites on Au111 evidenced by photoelectron diffraction

The adsorption structure of methylthiolate (CH3S) adsorbed on Au(111), a long-standing controversial issue, has been unambiguously determined by scanned-energy and scanned-angle S 2p photoelectron diffraction. The methylthiolate molecules are found to occupy atop sites with a S-Au distance of 2.42 +/- 0.03 A. The angular distribution of the S 2p photoelectrons due to forward scattering reveals that the S-C bond is inclined by approximately 50 degrees from the surface normal towards both the [211] and [121] (nearest-neighbor thiolate) directions.     

Elastic friction drive of surface acoustic wave motor

Importance of elastic deformation control to obtain large output force with a surface acoustic wave (SAW) motor is discussed in this paper. By adding pre-load to slider, stator and slider surfaces are deformed in a few tens nanometer. Appropriate deformation in normal direction against normal vibration displacement amplitude of SAW existed. By moderate deformation, the output force of the SAW motor was enlarged up to about 10 N and no-load speed was 0.7 m/s. To produce this performance, the transducer weight and slider size were only 4.2 g and 4 x 4 mm(2).By traveling wave propagation, surface particles of the SAW device move in elliptical motion. Due to the amplitude of the elliptical motion is 10 or 20 nm order, the contact condition of the slider is very critical. To control the contact condition, namely, the elastic deformation of the slider and stator surface in nanometer order, a lot of projections were fabricated on the slider surface. The projection diameter was 20 micro m. In static condition, the elastic deformation and stress were evaluated with the FEM analysis. From this calculation and the simulation result, it is consider that the wave crest is distorted, hence the elasticity has influence on the friction drive condition.Elastic deformation of the stator surface beneath the projection from the initial position were evaluated. In 4 x 4 mm(2) square area, the sliders had from 1089 to 23,409 projections. Depression was independent to the contact pressure. However, the output force depended on the depression although the projection density were different. From the view point of the output power of the motor, the proper depression was independent to the projection density. Around 25 nm depression, the output force and output power were maximized. This depression value was almost same as the vibration displacement amplitude of the stator transducer.     

Polarization-mode dispersion measurement by an optical time-domain reflectometer with polarimetry assuming backscattering by randomly oriented nonspherical particles

In previous work on polarization-mode dispersion (PMD) measurement with an optical time-domain reflectometer with polarimetry (p-OTDR), scatterers were assumed to be a cloud of small spherical particles in a fiber. We have found that the p-OTDR waveforms were fitted well by modified Mueller matrices, assuming scattering by a cloud of nonspherical particles. We realized a PMD measurement based on the p-OTDR Jones matrix eigenanalysis (JME) method. The measured PMD was consistent with that of JME standard measurement with transmission-type polarimetry.     

Efficient sum-frequency generation of continuous-wave single-frequency coherent light at 252 nm with dual wavelength enhancement

Highly efficient frequency conversions were conducted to obtain deep-ultraviolet single-mode coherent light by use of two-stage external cavities. A power of 154 mW at approximately 252 nm was obtained with a conversion efficiency of more than 8% by doubly resonant sum-frequency mixing of 373-nm light from the first-stage conversion and 780-nm light from a single-mode Ti:sapphire laser. The output performance of the deep-ultraviolet light source is sufficient for use in the laser cooling of neutral silicon atoms.     

Time-resolved Auger decay in CsBr using high harmonics

The temperature-dependent decay dynamics of innershell holes in CsBr was measured by using high harmonics. The measured lifetime was as short as 1.5 ps at 340 K due to increasing the Auger-allowed final state density in the Urbach exciton tail, whereas it is 1.1 ns at 10 K, determined by radiative recombination. The temperature-dependent Auger lifetime extrapolated to a high temperature corresponds to the fully energy-allowed Auger decay. In the model to be presented, this yields an interatomic Auger decay lifetime of 2.4+3.8/-1.5 fs, in line with a theoretical calculation for NaF.     

Improved direct measurement of the parity-violation parameter Ab using a mass tag and momentum-weighted track charge

We present an improved direct measurement of the parity-violation parameter A(b) in the Z boson-b-quark coupling using a self-calibrating track-charge technique applied to a sample enriched in Z-->bb events via the topological reconstruction of the B hadron mass. Manipulation of the Stanford Linear Collider electron-beam polarization permits the measurement of A(b) to be made independently of other Z-pole coupling parameters. From the 1996-1998 sample of 400,000 hadronic Z decays, produced with an average beam polarization of 73.4%, we find A(b)=0.906+/-0.022(stat)+/-0.023(syst).