110 research outputs found

    Nonlinear-optical processes at streamer discharge in semiconductors

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    The possibility of light auto-channelling (self-trapping) in conditions of streamer discharge in hexagonal and cubic semiconductors was shown. It is considered the mechanism of discharge in the wide-gap compounds on the basis of representation about the light auto-channelling at streamer excitation, providing their high propagation velocity down to ~5∙10⁹ cm/s, the crystallographic orientation (directionality), filamentary character at thickness of the channel about 1 μm and absence of the catastrophic destructions of a crystal

    Structures and properties of Ti alloys after double implantation

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    В работе представлены новые результаты по исследованию структуры и физико-механические свойства приповерхностных слоев титановых сплавов после (W+, Mo+) ионной имплантации и последующего отжига при 550 С в течение 2 ч. Использование обратного рассеяния (RBS) ионов гелия и протонов, сканирующей электронной микроскопии (SEM) с микроанализа (ЭЦП), (WDS), протонов (ионов), индуцированного рентгеновского излучения (PIXE), рентгенофазового анализа (РСА) с геометрии скользящего падения (0,5 град.), измерения нанотвердости и модуля упругости, трения износа (цилиндр-пластины), измерения коррозионная стойкость в солевом растворе, мы исследовали VT-6 образцов, и определяется их сопротивления усталости при циклических нагрузках. Было обнаружено двойное увеличение твердости, снижение износа и увеличение сопротивления усталости, что было связано с формированием малодисперсного нитрида, карбонитрида, и интерметаллидных фаз.The paper presents new results on investigation of structure and physical-mechanical properties of near surface layers of titanium alloys after (W+, Mo+) ion implantation and subsequent thermal annealing under 550 C for 2 h. Using back scattering (RBS) of helium ions and protons, scanning electron microscopy (SEM) with microanalysis (EDS), (WDS), proton (ion) induced X-ray emission (PIXE), X-ray phase analysis (XRD) with a grazing incidence geometry (0.5 angle), measurements of nanohardness and elastic modulus, friction wear (cylinder-plate), measurements of corrosion resistance in a salt solution, we investigated the VT-6 samples, and determined their fatigue resistance under cyclic loads. Double increase of hardness, decrease of wear and increased fatigue resistance were found, which was related to the formation of small dispersion (nanodimension) nitride, carbonitride, and intermetalloid phases

    Structures and properties of Ti alloys after double implantation

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    В работе представлены новые результаты по исследованию структуры и физико-механические свойства приповерхностных слоев титановых сплавов после (W+, Mo+) ионной имплантации и последующего отжига при 550 С в течение 2 ч. Использование обратного рассеяния (RBS) ионов гелия и протонов, сканирующей электронной микроскопии (SEM) с микроанализа (ЭЦП), (WDS), протонов (ионов), индуцированного рентгеновского излучения (PIXE), рентгенофазового анализа (РСА) с геометрии скользящего падения (0,5 град.), измерения нанотвердости и модуля упругости, трения износа (цилиндр-пластины), измерения коррозионная стойкость в солевом растворе, мы исследовали VT-6 образцов, и определяется их сопротивления усталости при циклических нагрузках. Было обнаружено двойное увеличение твердости, снижение износа и увеличение сопротивления усталости, что было связано с формированием малодисперсного нитрида, карбонитрида, и интерметаллидных фаз.The paper presents new results on investigation of structure and physical-mechanical properties of near surface layers of titanium alloys after (W+, Mo+) ion implantation and subsequent thermal annealing under 550 C for 2 h. Using back scattering (RBS) of helium ions and protons, scanning electron microscopy (SEM) with microanalysis (EDS), (WDS), proton (ion) induced X-ray emission (PIXE), X-ray phase analysis (XRD) with a grazing incidence geometry (0.5 angle), measurements of nanohardness and elastic modulus, friction wear (cylinder-plate), measurements of corrosion resistance in a salt solution, we investigated the VT-6 samples, and determined their fatigue resistance under cyclic loads. Double increase of hardness, decrease of wear and increased fatigue resistance were found, which was related to the formation of small dispersion (nanodimension) nitride, carbonitride, and intermetalloid phases

    Conformational transitions of a semiflexible polymer in nematic solvents

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    Conformations of a single semiflexible polymer chain dissolved in a low molecular weight liquid crystalline solvents (nematogens) are examined by using a mean field theory. We takes into account a stiffness and partial orientational ordering of the polymer. As a result of an anisotropic coupling between the polymer and nematogen, we predict a discontinuous (or continuous) phase transition from a condensed-rodlike conformation to a swollen-one of the polymer chain, depending on the stiffness of the polymer. We also discuss the effects of the nematic interaction between polymer segments.Comment: 4 pages, 4 figure

    Measurements of differential production cross sections for a Z boson in association with jets in pp collisions at root s=8 TeV

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    Measurement of the mass difference between top quark and antiquark in pp collisions at root s=8 TeV

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    Measurements of t(t)over-bar charge asymmetry using dilepton final states in pp collisions at root s=8 TeV

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    Search for lepton flavour violating decays of heavy resonances and quantum black holes to an eμ pair in proton–proton collisions at √s = 8 TeV

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    A search for narrow resonances decaying to an electron and a muon is presented. The eμ mass spectrum is also investigated for non-resonant contributions from the production of quantum black holes (QBHs). The analysis is performed using data corresponding to an integrated luminosity of 19.7 fb-1 collected in proton-proton collisions at a centre-of-mass energy of 8 TeV with the CMS detector at the LHC. With no evidence for physics beyond the standard model in the invariant mass spectrum of selected eμ pairs, upper limits are set at 95 % confidence level on the product of cross section and branching fraction for signals arising in theories with charged lepton flavour violation. In the search for narrow resonances, the resonant production of τ sneutrino in R-parity violating supersymmetry is considered. The τ sneutrino is excluded for masses below 1.28 TeV for couplings λ132= λ231= λ311′= 0.01 , and below 2.30 TeV for λ132= λ231= 0.07 and λ311′= 0.11. These are the most stringent limits to date from direct searches at high-energy colliders. In addition, the resonance searches are interpreted in terms of a model with heavy partners of the Z boson and the photon. In a framework of TeV-scale quantum gravity based on a renormalization of Newton’s constant, the search for non-resonant contributions to the eμ mass spectrum excludes QBH production below a threshold mass Mth of 1.99 TeV. In models that invoke extra dimensions, the bounds range from 2.36 TeV for one extra dimension to 3.63 TeV for six extra dimensions. This is the first search for QBHs decaying into the eμ final state

    Measurement of the differential cross section for top quark pair production in pp collisions at √s=8 TeV

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    The normalized differential cross section for top quark pair (tt¯) production is measured in pp collisions at a centre-of-mass energy of 8TeV at the CERN LHC using the CMS detector in data corresponding to an integrated luminosity of 19.7fb-1. The measurements are performed in the lepton+jets (e/μ++jets) and in the dilepton e+e-, μ+μ-, and e±μ∓) decay channels. The tt¯ cross section is measured as a function of the kinematic properties of the charged leptons, the jets associated to b quarks, the top quarks, and the tt¯ system. The data are compared with several predictions from perturbative quantum chromodynamic up to approximate next-to-next-to-leading-order precision. No significant deviations are observed relative to the standard model predictions. © 2015, CERN for the benefit of the CMS collaboration
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