Inner invariant means and conjugation operators

It is shown that Paschke's result cannot be generalized to the [IN]-group setting given by Lau and Paterson. This resolves negatively a problem raised by Lau and Paterson.

     

The maximum size of the planar sections of random spheres and its application to metallurgy

A theorem of this paper proves that if the size distribution of random spheres is generalized gamma, its Wicksell transform and other related distributions belong to the domain of attraction of the Gumbel distribution. The theorem also shows the attraction coefficients of the distributions. The fatigue strength of high-strength steel is closely related to the maximum size of nonmetallic inclusions in the region of maximum stress of the steel. Murakami and others developed a method, making use of the Gumbel QQ-plot, for predicting the maximum size from the size distribution of inclusion circles in microscopic view-fields. Based on the Gumbel approximation of the maximum of wicksell transforms, a modified and extended version of Murakami's method is justified, and its performance is evaluated by simulation.     

Imaging a tunneling ionization front by using a schlieren method

A schlieren method was used to generate time-resolved images of the tunneling ionization front produced when an ultrashort high-power laser pulse irradiates He gas. By superimposing sequential schlieren images, we obtained information about the laser propagation and found that the ionization front propagated farther with decreasing density of the target gas. Ray-tracing suggested that this density dependence is a result of the spatial distribution of the laser intensity. Received: 20 May 1999 / Revised version: 19 August 1999 / Published online: 27 January 2000     

A conceptual design of a high-efficiency rep-rated pulsed power system for KrF laser drivers of inertial fusion energy

A conceptual design of a high efficiency, high repetition-rated (rep-rated) pulsed power system for an electron-beam (e-beam) pumped KrF laser driver for inertial fusion energy (IFE) is presented. The proposed pulsed power circuit incorporates linear induction voltage adders to charge pulse forming lines for the generation of 900 kV, 260 ns e-beamsat several Hz. This rep-rated power system meets the pulsed power requirements of the future IFE drivers that necessitate high amplifier efficiency as well as high laser energy. Received: 3 March 2000 / Published online: 16 June 2000     

Development of variable‐magnification X‐ray Bragg optics

A novel X‐ray Bragg optics is proposed for variable‐magnification of an X‐ray beam. This X‐ray Bragg optics is composed of two magnifiers in a crossed arrangement, and the magnification factor, M, is controlled through the azimuth angle of each magnifier. The basic properties of the X‐ray optics such as the magnification factor, image transformation matrix and intrinsic acceptance angle are described based on the dynamical theory of X‐ray diffraction. The feasibility of the variable‐magnification X‐ray Bragg optics was verified at the vertical‐wiggler beamline BL‐14B of the Photon Factory. For X‐ray Bragg magnifiers, Si(220) crystals with an asymmetric angle of 14° were used. The magnification factor was calculated to be tunable between 0.1 and 10.0 at a wavelength of 0.112 nm. At various magnification factors (M≥ 1.0), X‐ray images of a nylon mesh were observed with an air‐cooled X‐ray CCD camera. Image deformation caused by the optics could be corrected by using a 2 × 2 transformation matrix and bilinear interpolation method. Not only absorption‐contrast but also edge‐contrast due to Fresnel diffraction was observed in the magnified images.     

Photoemission study of Ag nanofilm grown on pseudomorphic fcc Fe(1 0 0)

An angle-resolved photoemission study for Ag nanofilm grown on pseudomorphic metastable-fcc-phase Fe(1 0 0) has been done in order to investigate in detail the quantized electronic structures. From the low-energy electron-diffraction and angle-resolved photoemission spectra, it is found that the present Ag nanofilms were grown in the direction of [1 1 1] on pseudomorphic fcc Fe(1 0 0) substrates. The angle-resolved photoemission spectra of Ag nanofilms grown on pseudomorphic fcc Fe(1 0 0) exhibit the features derived from Shockley-type surface state and additional fine-structures derived from the quantized state of Ag sp valence electron. The experimental nanofilm-thickness dependence of binding energies of these quantized states is compared with the theoretical calculation based on the phase accumulation model, taking into account the phase shifts of electron reflection at both interfaces of the Ag nanofilm. From these results, we discuss the quantized electronic structure in Ag nanofilm grown on pseudomorphic fcc Fe(1 0 0).     

Difference-frequency terahertz-wave generation from 4-dimethylamino-N-methyl-4-stilbazolium-tosylate by use of an electronically tuned Ti:sapphire laser

Among nonlinear materials, the organic ionic salt crystal 4-dimethylamino- N -methyl-4-stilbazolium-tosylate (DAST) is known for its large nonlinearity. We generated a coherent terahertz (THz) wave, using DAST, from the difference frequency between two oscillating wavelengths of an electronically tuned Ti:sapphire laser. In LiNbO(3), LiTaO(3), KTiOPO(4), and GaP crystals, THz-wave generation was not observed under the same experimental conditions. This result proves the high efficiency of DAST crystals for generation of difference-frequency THz waves.     

Rate constant measurements for initial addition reactions of radicals at the propagation step of photo‐polymerization as studied by pulsed EPR spectroscopy

Pulsed EPR spectroscopy was employed to determine reaction rate constants at an early stage of addition reactions in radical polymerizations triggered by four initiator radicals, which were generated by photodissociation of four parent molecules. Two monomers (tert‐butylacrylate and tert‐butylmethacrylate) were examined as reactant. Stern–Volmer analysis on the measured decay time of electron spin echo intensity of reacting radicals provides rate constants for addition reactions. We focused on rate constants for the second step reaction between monomer and adduct radical that is produced by the first step addition reaction between initiator radical and monomer. The rate constant measured by pulsed EPR was evaluated by theoretical calculations in the light of (1) enthalpy difference between product radical and reactants and (2) charge transfer interaction between reacting radical and monomer. Copyright © 2016 John Wiley & Sons, Ltd.     

Bose-Einstein correlations for pions produced inp p collisions at 360 GeV/c

Zeitschrift für Physik C Particles and Fields - Correlations among identically charged pions were measured for pions produced inp p collisions at 360 GeV/c using the EHS spectrometer. The...