152 research outputs found

    Computer simulation of the photoluminescence of nanostructured aluminum oxide excited with pulsed synchrotron radiation

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    An algorithm and a program are developed to calculate the photoluminescence (PL) parameters for bulk single-crystal and nanoscale dielectrics excited with pulsed synchrotron radiation. The luminescence spectra of F and F+centers and the PL decay kinetics in single-crystal and nanoscale aluminum-oxide samples containing oxygen anion vacancies are calculated for various nanoparticle sizes. It is shown that a noticeable broadening of the bands and a decrease in the afterglow time is observed for nanoparticle sizes that are less than 20 nm. Β© 2013 Pleiades Publishing, Ltd

    Dosimetric application of green luminescence in irradiated TLD-500 detectors

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    The spectral and kinetic characteristics of thermoluminescence (TL) for anion-defective Ξ±-Al2O3 single crystals in the 4.4-2.2 eV range at 300-600 K were studied. Three-dimensional (3D) plots of the luminescence under research for a sample before and after UV irradiation at 623 K for 30 min were analyzed. The increase in the emission response in the 2.4 and 3.7 eV bands for the sample after the photothermal treatment was observed. The dominant contribution of a thermally stimulated process with first-order kinetics in the regularities of the 2.4 eV luminescence was shown. The linearity of the dose dependences for the 2.4 eV TL response in different samples at 10-5-1 Gy was demonstrated. The advantage of using the green thermoluminescence in the TLD-500 for solid state dosimetry was discussed. Β© 2013 Elsevier B.V. All rights reserved

    X-ray fluoresced high-Z (up to Z = 82) K-x-rays produced by LiNbO3 and LiTaO3 pyroelectric crystal electron accelerators

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    High-energy bremsstrahlung and K X-rays were used to produce nearly background-free K X-ray spectra of up to 87 keV (Pb) via X-ray fluorescence. The fluorescing radiation was produced by electron accelerators, consisting of heated and cooled cylindrical LiTaO3 and LiNbO3 crystals at mTorr pressures. The newly discovered process of gas amplification whereby the ambient gas pressure is optimized to maximize the electron energy was used to produce energetic electrons which when incident on a W/Bi target gave rise to a radiation field consisting of high-energy bremsstrahlung as well as W and Bi K X-rays. These photons were used to fluoresce Ta and Pb K X-rays.Comment: 6 pages, 6 figures, PD

    Luminescent and dosimetric properties of nanostructured ceramics based on aluminum oxide

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    The main features of thermoluminescence (TL) of nanostructured ceramics based on anion-defective aluminum oxide have been investigated. The kinetic parameters of the TL dosimetric peak at 475 K have been determined. The possibility of using nanostructured ceramics for beta-radiation dosimetry of high doses (up to 1 kGy) with thermoluminescence of deep traps has been justified. It has been found that the light sum of the dosimetric peak decreases with an increase in the heating rate due to the temperature quenching of the luminescence. The obtained results have confirmed that the mechanism of TL quenching in anion-defective aluminum oxide is associated with the temperature dependence of the probability of the capture in deep traps, which can be caused by thermal ionization of excited states of F-centers. Β© 2013 Pleiades Publishing, Ltd

    Disintegration of microcrystalline Zn2SiO4:Mn phosphor powder

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    Zn2SiO4:Mn (willemite) nanoparticles ∼30 nm in size have been prepared by disintegrating microcrystalline willemite powder in a planetary ball mill. X-ray diffraction and scanning electron micros-copy characterization showed that ball milling of the Zn2SiO 4:Mn powder for 60 min or a longer time ensured complete disintegration of the microcrystalline material and that the crystal structure of the resultant nanoparticles was identical to that of the parent powder. © 2013 Pleiades Publishing, Ltd

    Cooperation Model of Interaction Between the University and Industrial Enterprises

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    Настоящая Ρ€Π°Π±ΠΎΡ‚Π° посвящСна Ρ€Π°Π·Ρ€Π°Π±ΠΎΡ‚ΠΊΠ΅ ΠΏΠΎΠ΄Ρ…ΠΎΠ΄ΠΎΠ² ΠΊ Ρ„ΠΎΡ€ΠΌΠΈΡ€ΠΎΠ²Π°Π½ΠΈΡŽ ΠΌΠ΅Ρ…Π°Π½ΠΈΠ·ΠΌΠΎΠ² взаимодСйствия унивСрситСтов с организациями Ρ€Π΅Π°Π»ΡŒΠ½ΠΎΠ³ΠΎ сСктора экономики Π² условиях нСобходимости достиТСния тСхнологичСского сувСрСнитСта Π Π€. ΠŸΡ€Π΅Π΄ΡΡ‚Π°Π²Π»Π΅Π½Π° классификация ΡƒΡ€ΠΎΠ²Π½Π΅ΠΉ ΠΈ Ρ‚ΠΈΠΏΠΎΠ² взаимодСйствия, Ρ€Π°ΡΡΠΌΠ°Ρ‚Ρ€ΠΈΠ²Π°ΡŽΡ‚ΡΡ ΠΌΠΎΠ΄Π΅Π»ΠΈ стратСгичСского партнСрства Π½Π° основС создания совмСстной ΠΈΠ½Π½ΠΎΠ²Π°Ρ†ΠΈΠΎΠ½Π½ΠΎΠΉ инфраструктуры ΠΏΠΎΠ»Π½ΠΎΠ³ΠΎ Ρ†ΠΈΠΊΠ»Π°. Π’ Ρ€Π°ΠΌΠΊΠ°Ρ… ΠΏΡ€Π΅Π΄Π»ΠΎΠΆΠ΅Π½Π½ΠΎΠΉ ΠΌΠΎΠ΄Π΅Π»ΠΈ ΠΎΠ±ΡΡƒΠΆΠ΄Π°ΡŽΡ‚ΡΡ особСнности ΠΌΠ΅Ρ…Π°Π½ΠΈΠ·ΠΌΠΎΠ² трансфСра Ρ‚Π΅Ρ…Π½ΠΎΠ»ΠΎΠ³ΠΈΠΉ.This work is devoted to the development of approaches to the formation of mechanisms for interaction between universities and organizations in the real sector of the economy in the context of the need to achieve technological sovereignty of the Russian Federation. A classification of levels and types of interaction is presented, and models of strategic partnership based on the creation of a full-cycle joint innovation infrastructure are considered. Within the framework of the proposed model, the features of technology transfer mechanisms are discussed

    ANISOTROPY OF EXOEMISSION PROPERTIES OF QUARTZ SINGLE-CRYSTALS

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    The symmetrical aspects of exoelectron emission in quantz are discussed. The dependence of the emission intensity and the energy spectra on the emitting direction show that the anisotropy of the emission properties of quartz is determined by the point-symmetry group of a crystal. It is also shown that the absence of a symmetry center in a quartz lattice changes the charge distribution of the emission-active layer upon heating. TSEE related to piezoelectric polarization along certain crystallographic directions was obtained. </jats:p
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