## Magnetooptical effects in undoped bismuth silicate crystals

Published in category «Condensed matter physics»

The Faraday and the polar magnetooptical Kerr effects in undoped Bi12SiO20 (BSO) crystals have been investigated. The dependence of a turn angle of polarization plane on magnetic induction for both effects was established to be nonlinear. The results were interpreted within the framework of combined electromagnetogyration model. Electrogyration part of the contribution was due to the formation of the longitudinal internal electric field induced by optical spin orientation. It was shown that magnetism of nonshared electronic pairs of Bi–O hepthaedra made the contribution in the total gyration of BSO crystal.

## The annealing effect on green X-ray luminescence of zinc oxide powders

Published in category «Condensed matter physics»

The annealing effects on X-ray luminescence of zinc oxide powders have been investigated. Annealing was performed in vacuum and atmosphere. Thereafter, the samples were annealed in Ar : H2 gas mixture. The luminescence bands located at 515 nm after vacuum annealing and at 525 nm after air annealing were detected in the samples. Annealing in hydrogenous ambience had no effect on samples annealed previously in the vacuum. Luminescence intensity of air-annealed powders decreased significantly after annealing in hydrogenous ambience. All samples had complex decay time curves with three exponential constants.

## Influence of aluminum content in blocking layer on properties of green InGaAlN LEDs

Published in category «Condensed matter physics»

The influence of AlGaN blocking layer on properties of green InGaAlN LEDs has been studied. The variation in aluminum content was found to change both LEDs efficiency and emission maximum position.

## The electronic structure of excited argon-xenon molecules in the spectral region near xenon excited states

Published in category «Atom physics and physics of clusters and nanostructures»

The photoionization spectra of ArXe dimer molecules near the excited states Xe* 7p, 6d in the high-energy area 87500 – 90000 cm-1 close to the energy of ionization of molecules were recorded by the method of three-photon excitation of molecules followed by one-photon ionization. There are 12 states of Xe* in this area, two of these states are allowed at three-photon excitation. The spectrum recorded by monitoring the molecular ions ArXe+ has the complicated image. The dissociation limits of two vibrational systems were measured: ArXe*→Ar1S0+Хе*7р[5/2]2 и Ar1S0+Хе*6d[7/2]03. For these excited states the molecular constants and the potential curves were calculated. These data were obtained for the first time.

## A final DF-CО2 amplifier of the multi-terawatt picosecond 10 micrometer laser system

Published in category «Experimental technique and devices»

The paper presents the results of measurements of the gain and the energy of the amplified spontaneous luminescence of pulsed chemical DF-CO2 amplifier at an active medium pressure up to 2.5 atm. The values obtained and the large amplifier aperture (100 mm) allow to use it as a final amplifier of the multiterawatt 10-µm picosecond laser system.

## Backscattering of polarized laser radiation by thermalcontrol coatings and constructional materials

Published in category «Experimental technique and devices»

The backscattering of spacecraft materials and coatings illuminated by linearly polarized radiation of He-Ne laser at a wavelength of 632.8 nm has been studied. Bistatic measurement scheme was used, i. e. the laser and a detector were placed stationary. Variation of the incidence angle was carried out by sample rotation. There was a good agreement between the results of measurements and calculations.

## Quality assurance of proton ophtalmology: selection of collimation and scattering systems

Published in category «Experimental technique and devices»

This study covers basic requirements for scattering and collimation systems while creating a nozzle for treatment of malignant ocular tumors. The results of treatment simulations in Geant4 are represented.

## Drawing of capillaries and optical fibersusing high-temperature furnace with nonuniform azimuthal profile of temperature field

Published in category «Experimental technique and devices»

The effect of the nonuniform azimuthal profile of the temperature field in a high-temperature furnace on the cross-section ellipticity of the capillaries and optical fibers has been investigated experimentally. The control possibility for this ellipticity was demonstrated.

## Applicability analysis of diffusion approach for calculation of radiativecharacteristics of the high pressure gas discharge

Published in category «Physical electronics»

An analysis of the diffusion approach applicability for the radiation transfer calculations in the high pressure gas discharge has been carried out. It was shown that the diffusion approximation led to asymptotically correct results for the cases of optically thin and optically thick plasma columns. In the case of intermediate values of optical thickness the distinction between exact and diffusion approaches did not exceed 20 %.

## Analytical connection of ideal space-time focusing ion system elements

Published in category «Physical electronics»

A new approach to ideal ion optical system synthesis using analytical connection of ion optical elements is described. The method discussed prevents loss of ideal focusing in a place of elements junction. The theory described is used to build electrostatic ion trap.

## Temperature effects upon coherence of semiconductor lasers emission

Published in category «Physical optics»

The paper presents the study of thermal effects upon a semiconductor laser emission coherence for red radiation range and a diode-pumped Nd laser operating on second harmonic of green radiation range for operating temperatures (20 – 40° C). The coherence of the radiation was estimated by morphological Euler numbers of the interference patterns. A strong dependence of the interference patterns contrast on the operating temperature of emitting lasers was detected. Recommendations were given.

## The measurement of the induced birefringence of electrooptic materials through the modulation of light reflection coefficient

Published in category «Physics of molecules, clusters and nanostructures»

The article analyzes the measurement results for electrooptic (EO) birefringence of materials by modulating the reflection coefficient of monochromatic light polarized linearly that incidents on the surface of the EO medium. The cases of the normal light incidence and those in the area of the Brewster angle were reviewed. The sensitivity of the method was evaluated.

## Formation of channel optical waveguides under the glass poling

Published in category «Physical optics»

The physical model and numerical simulation of channel optical waveguides formation under the glass poling have been performed. The conditions of single-mode waveguide formation were found.

## Dipole moments of N-methylpyrrolidone in liquid state and in dilute aqueous solution

Published in category «Physics of molecules»

The study of temperature dependences of N-Methylpyrrolidone dipole moments (NMP) has been carried out in its liquid state and in dilute aqueous solutions. The dipole moment and the Kirkwood factor temperature dependences suggested the NMP to be weakly associated liquid. The NMP dipole moment in aqueous solutions calculated by Buckingham statistical theory of the dielectric polarization was 4.12 D at 25 deg.cent. indicating the absence of the expected polarization influence of the polar water molecules.

## Background processes while monitoring coherentJ/ψ-mesons photoproduction events in ultraperipheral proton-proton collisions

Published in category «Nuclear physics»

The contribution of two main background effects to the cross-section value of coherent J/ψ-meson photoproduction in ultraperipheral proton-proton collisions at Large Hadron Collider has been evaluated.

## Nuclear modification factors for electrons from decays of particles containing heavy quarks

Published in category «Nuclear physics»

The nuclear modification factors for electrons from semi-leptonic decays of particles containing heavy quarks are presented. The results obtained in the PHENIX experiment at RHIC in p + p and Au + Au collisions at sNN = 200 GeV. The comparison of the results with the calculations of the known theoretical models is shown.

## Analysis of piecewise linear stochastic systems in half-spaces by means of the Pugachev-Sveshnikov equation

Published in category «Mathematics»

An analytic approach is presented to obtain a probability distribution function of the state-vector of piecewise linear systems which have two domains (half-spaces) of linearity. The approach is based on the use of the Pugachev – Sveshnikov equation for the characteristic function and its reduction to the parametric Riemann boundary value problem for half-planes. Crandall’s problem for anisotropic viscosity friction is solved as an example of application of the derived theory. The displacement of a body, placed on a randomly oscillating foundation, is explored. And the asymptotical behaviour of the mathematical expectation of this body’s displacement is obtained.

## Norm minimization operators for compact sets in Euclidean space

Published in category «Mathematics»

Operators formulated are projection operators generalized and minimize the Euclidean space norm functional into a non-empty intersection of a linear manifold and a ball. Equivalent canonical forms, invariants and analytic representations of minimization and acceptable solutions operators are determined. The application of operators is illustrated through an objective analysis of sufficient conditions for asymptotic stability of nonlinear differential operators of closed locally optimal automatic control systems.

## Hard X-rays in solar flaring loops from accelerated electron beams

Published in category «Astrophysics»

The energy, spatial and pitch angle distributions of the accelerated electrons in the solar magnetic loops are considered. Hard X-ray spectrum and polarization are calculated. It is shown that the hard X-ray source at the looptop can be formed even with the anisotropic injection away from the looptop. The polarization degree is –30% at the top of the magnetic loop. A comparative analysis of the results with different parameters of the source of accelerated electrons and magnetic field is also carried out.