Study of Features of the Diffraction of X Rays in a Quartz Crystal Modulated by Longitudinal and Transverse Ultrasonic Vibrations

JETP Letters - Features of the simultaneous action of longitudinal and transverse ultrasonic vibrations in the quartz crystal on the parameters of reflected X-rays are studied. It is shown that...     

Enhanced Physical and Mechanical Properties of Nitrile-Butadiene Rubber Composites with N-Cetylpyridinium Bromide-Carbon Black

The physical and mechanical properties of nitrile–butadiene rubber (NBR) composites with N-cetylpyridinium bromide-carbon black (CPB-CB) were investigated. Addition of 5 parts per hundred rubber (phr) of CPB-CB into NBR improved the tensile strength by 124%, vulcanization rate by 41%, shore hardness by 15%, and decreased the volumetric wear by 7% compared to those of the base rubber-CB composite.     

Using a plane wave approximation in simulation of radiation distribution in an X-ray Talbot interferometer

This study is devoted to the analysis of the plane-wave approximation applicability to X-ray radiation incident on an object. Based on simple calculations, it is shown that an X-ray tube focal spot 0.4 × 0.8 mm in size at distances of ~1 m can be considered as a point source; however, the plane-wave approximation for such X-ray radiation with energy E = 22keV is valid for radiation source–object distances much longer than 10 m.     

Kinematic grouping of reflections of parametric X-ray radiation

A model of parametric X-ray radiation (PXR) of moderately relativistic particles is developed within the kinematic theory taking into account radiation absorption. The model allows calculation of the PXR reflection intensity in a given direction taking into account diffraction of virtual photons on a set of “incidental” low-index crystallographic planes. It is shown that when a charged particle moves along certain crystallographic directions, the effect of kinematic grouping of reflections, at which lines of parametric radiation from various planes practically coincide, is observed.     

Nonlinear Fokker-Planck-Kolmogorov Equation in the Semiclassical Coherent Trajectory Approximation

A semiclassical asymptotic of the Cauchy problem is constructed for the two-dimensional Fokker-Planck equation with nonlocal nonlinearity in the class of trajectory concentrated functions based on the complex WKB-Maslov method. The system of Einstein-Ehrenfest equations describing the dynamics of average values of the coordinate operator and centered moments is derived. The results obtained are illustrated by a number of examples. __________ Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 6, pp. 38–47, June, 2005.     

Detection of parametric X-ray radiation from moderately relativistic protons in crystals

The spectral maxima of parametric x-ray radiation that are emitted by moderately relativistic protons interacting with various crystals have been detected. The spectral positions of these maxima depend on the crystal orientation angle and they are consistent with the theoretical values. The measurements were carried out with silicon and graphite crystals on the 5-GeV proton beam extracted from the Nuclotron at the Laboratory of High Energies, JINR.     

Tunable source of parametric X-ray radiation

A new design of an X-ray source with a radiation energy controllably varying from 2 to 130 keV and a radiation intensity exceeding >10^?5 photon/e^?/sr is suggested. The source is based on parametric X-ray radiation (PXR) generated by moderately relativistic electrons in an original geometry. In this geometry, kinematic bunching of PXR reflections is used, which makes it possible to increase the intensity of the source. A model to calculate the PXR characteristics that takes into account absorption of radiation, beam parameters, multiple scattering, and energy loss is developed. The monochromaticity of the source lines is estimated.