East European Journal of Physics https://periodicals.karazin.ua/eejp <p>International peer-reviewed journal devoted to experimental and theoretical research on the nuclear physics, cosmic rays and particles, high-energy physics, solid state physics, plasma physics and controlled thermonuclear fusion, physics of charged particle beams, plasma electronics, radiation materials science, physics of thin films, condensed matter physics, functional materials and coatings, technical thermophysics and industrial power,&nbsp;medical physics and physical technologies in an interdisciplinary context.</p> <p><strong>East European Journal of Physics</strong> <strong>has been selected for coverage in Clarivate Analytics products and services.&nbsp;Beginning with 2017 it will be indexed and abstracted in: "Emerging Sources Citation Index"(ESCI).</strong></p> V.N. Karazin Kharkiv National University en-US East European Journal of Physics 2312-4334 <p>Authors who publish with this journal agree to the following terms:<br><br></p> <ol type="a"> <ul> <li class="show">Authors retain copyright and grant the journal right of first publication with the work simultaneously licensed under a&nbsp;<a href="http://creativecommons.org/licenses/by/3.0/" target="_new">Creative Commons Attribution License</a>&nbsp;that allows others to share the work with an acknowledgement of the work's authorship and initial publication in this journal.</li> </ul> </ol> <ol type="a"> <ul> <li class="show">Authors are able to enter into separate, additional contractual arrangements for the non-exclusive distribution of the journal's published version of the work (e.g., post it to an institutional repository or publish it in a book), with an acknowledgement of its initial publication in this journal.</li> </ul> </ol> <ol type="a"> <ul> <li class="show">Authors are permitted and encouraged to post their work online (e.g., in institutional repositories or on their website) prior to and during the submission process, as it can lead to productive exchanges, as well as earlier and greater citation of published work (See&nbsp;<a href="http://opcit.eprints.org/oacitation-biblio.html" target="_new">The Effect of Open Access</a>).</li> </ul> </ol> ON DESCRIPTION OF THERMODYNAMIC PROPERTIES OF CRYSTALS IN THE APPROXIMATION OF AN ISOTROPIC MEDIUM. THE TWO-PARAMETRIC DEBYE MODEL https://periodicals.karazin.ua/eejp/article/view/pdf <p>When analyzing thermodynamic and kinetic properties of crystals whose anisotropy is not large and the considered effects do not relate to the existence of singled-out directions in crystals, one may use a more simple model of an isotropic medium with a good accuracy, after having chosen its parameters in an optimal way. Based on the quantum mechanical description it is shown that the method of approximation of the moduli of elasticity of a crystal by the model of an isotropic medium, proposed earlier in [2], follows from the requirement of the minimal difference between the free energies of a crystal and an approximating isotropic medium. The two-parametric Debye model is formulated, which, in contrast to the standard model where the average speed of phonons is introduced, takes into account the existence in an isotropic medium of both longitudinal and transverse phonons. The proposed model contains, except the Debye energy, an additional dimensionless parameter and, consequently, the law of corresponding states for the heat capacity being characteristic of the standard model does not hold. With taking account of the two phonon branches the structure of the density of phonon states proves to be more complex as compared to the standard model and has a singularity that resembles Van Hove singularities in real crystals. As an example, an application of the two-parametric Debye theory to such crystals of the cubic system as tungsten, copper, lead is considered. It is shown that the calculation of the low-temperature heat capacity of these crystals by means of the approximated moduli of elasticity within the framework of the two-parametric model leads to a considerably better agreement with experiment than in the case of the standard Debye model.</p> Yurii M. Poluektov ##submission.copyrightStatement## 2018-09-23 2018-09-23 5 3 4 12 10.26565/2312-4334-2018-3-01 LONGITUDINAL-FLEXURAL SELF-SUSTAINED VIBRATIONS OF NANOTUBE CONVEYING FLUID https://periodicals.karazin.ua/eejp/article/view/11379 <p>Beam model of geometrical nonlinear longitudinal-flexural self-sustained vibrations of nanotube conveying fluid is obtained with account of nonlocal elasticity. The Euler-Bernoulli hypotheses are the basis of this model. The geometrical nonlinear deformations are described by nonlinear relations between strains and displacements. It is assumed, that the amplitudes of the longitudinal and bending vibrations are commensurable. Using variational methods of mechanics, the system of two nonlinear partial differential equations is derived to describe the nanotube self-sustained vibrations. The Galerkin method is applied to obtain the system of nonlinear ordinary differential equations. The harmonic balanced method is used to analyze the monoharmonic vibrations. Then the analysis of the self-sustained vibrations is reduced to the system of the nonlinear algebraic equations with respect to the vibrations amplitudes. The Newton method is used to solve this system of nonlinear algebraic equations. As a result of the simulations, it is determined that the stable self-sustained vibrations originate in the Hopf bifurcation due to stability loss of the trivial equilibrium. These stable vibrations are analyzed, when the fluid velocity is changed. The results of the self- sustained vibrations analysis are shown on the bifurcation diagram. The infinite sequence of the period-doubling bifurcations of the monoharmonic vibrations is observed. The chaotic motions take place after these bifurcations. As a result of the numerical simulations it is determined, that the amplitudes of the longitudinal and flexural vibrations are commensurable.</p> Konstantin Avramov ##submission.copyrightStatement## 2018-09-24 2018-09-24 5 3 13 23 10.26565/2312-4334-2018-3-02 ABOUT THE INFORMATIVE PARAMETERS OF MICHELSON INTERFEROMETERS WITH THE DIVISION OF AMPLITUDE AND THE WAVE FRONT https://periodicals.karazin.ua/eejp/article/view/11380 <p>At consideration of the theory of the Michelson’s experiment and conducting experiments on its scheme of dividing the amplitude of the light flux as an informative parameter, the difference &nbsp;in the lengths of the paths of the transverse and longitudinal rays of the light flux is used by measuring the shift of the interference pattern of the transverse and longitudinal rays. The significance of the other circuit parameters in determining the influence of the Earth's speed with the help of Michelson interferometers was not considered. The analysis of the parameters of the schemes of Michelson interferometers with the division of both the wave front amplitude and its wave front in the reference system associated with the interferometer is carried out in order to determine the influence of the interferometer speed on them. As a result of the analysis of the scheme with the division of amplitude, a linear dependence of the changes in frequency, the width of the reflected rays on the ratio &nbsp; &nbsp;of the device speed to the speed of light in interferometers. In the Michelson interferometer scheme with wave front division, the difference &nbsp;of paths length and the ray deflection angles are linearly dependent on the ratio of the device speed to the speed of light .These additional dependences are determined by the collinearity of the reflected rays and the speed of the observer's movement, in contrast to their perpendicularity in the interferometer with the division of the wave front amplitude. As a result of the comparison of the parameters in the reference system associated with the interferometer, it is concluded from their significance that the use of frequency changes, the width of the reflected rays in the interferometer with amplitude division, and the wave front interferometer, the difference in the path lengths &nbsp;of the rays, frequency, angle of deflection and the width of the reflected rays is preferable.</p> Volodymyr M. Svishch ##submission.copyrightStatement## 2018-09-24 2018-09-24 5 3 24 31 10.26565/2312-4334-2018-3-03 STRUCTURE AND PHASE COMPOSITION OF W-Si MULTILAYER X-RAY MIRRORS https://periodicals.karazin.ua/eejp/article/view/11153 <p>X-ray diffractometry in a hard region (l~0.154 nm) was used to study the phase structure, composition and construction of W/Si multilayer X-ray mirrors (MXMs) with thicknesses of t<sub>W</sub>&lt;10 nm for tungsten layers obtained by direct-current magnetron sputtering. Two series of samples were fabricated with different tungsten deposition rates, which differ approximately by a factor of 4: ~0.60 nm/s and ~0.15 nm/s. It is shown that tungsten layers have a polycrystalline (BCC) structure at thicknesses t<sub>W</sub>&gt;2.7 nm, and at t<sub>W</sub>&lt;1.9 nm they are amorphous. Using the sin<sup>2</sup>Y-method, it was found that in thin crystalline layers of tungsten (t<sub>W</sub>&lt;10 nm), more than 3 at.% Si can be contained. Tensile stresses in the layers of crystalline tungsten do not exceed 1.1 GPa. The construction of the radial distribution functions of atoms made it possible to establish that amorphous layers of tungsten have an arrangement of atoms close to b-W. In all samples, formation of silicide interlayers is observed at the interfaces, as a result of which the actual thickness of the tungsten layers is less than the nominal one. Amorphous silicide layers, necessarily formed at the stage of MXM manufacturing, contain tungsten disilicide. Depending on the deposition rate, disilicide can have an arrangement of atoms close to either the tetragonal phase, t-WSi<sub>2</sub> (~0.6 nm/s), or to the hexagonal phase, h-WSi2 (~0.15 nm/s). An improved model for the construction of amorphous W/Si MXMs is presented. Mechanisms for the formation of silicide layers are proposed, according to which the bottom silicide interlayers (W-on-Si) are formed mainly by ballistic mixing of tungsten and silicon atoms, and the top ones due to diffusion inermixing. The interdiffusion coefficients were estimated, which made it possible to establish that the deposited surface of the layers can be heated at least 250° above the substrate temperature. The ways of reducing the interface interaction are suggested.</p> Yuriy P. Pershyn Irina G. Shipkova Oleksandr Yu. Devizenko Valentine V. Mamon Vitalii S. Chumak Valeriy V. Kondratenko ##submission.copyrightStatement## 2018-09-21 2018-09-21 5 3 32 44 10.26565/2312-4334-2018-3-04 SCINTILLATION MONOCRYSTALS OF KDP:Tl AND KDP:Ce DOPED BY THALLIUM AND CERIUM FOR SELECTIVE DETECTION OF FAST NEUTRONS https://periodicals.karazin.ua/eejp/article/view/11381 <p>This research is going to explain the fast neutrons and gamma radiation registration by the new inorganic single crystals of the KDP (Potassium Dihydrogen Phosphat) group that was grown from the water solutions and activated by the thallium Tl<sup>+</sup> or cerium Ce<sup>3+</sup>. The appearance of the luminescence upon KDP:Tl crystals irradiation with the fast neutrons is explained by secondary ionizing radiation (recoil protons and oxygen recoil nuclei) with excitation of the activator under ionization losses for inhibition. Also the recombination mechanism with the radiation defects of the hydrogen sublattice going to transmit electron excitations to the region of the Tl<sup>+</sup> luminescence center. In the KDP:Ce crystals the excitation mechanism of the activator has a similar character, but the luminescence itself is due to the 5d&nbsp;®&nbsp;4f transition in Ce<sup>3</sup><sup>+</sup> ions. The detection efficiency for activated KDP:Tl and KDP:Ce crystals to the fast neutrons in comparisons with organic (plastic) scintillators were calculated theoretically and experimentally. For the crystal volume about 10x10x10 mm3 with the optimal activator concentration the fast neutron detection efficiency under irradiation of <sup>239</sup>Pu-Be is 12% for KDP:Tl and 16% for KDP:Ce, which is in a consistent with the theoretical calculation and is not lower according to the parameters of typical organic scintillators. A high natural selectivity of the KDP scintillators to the fast neutrons due to their low sensitivity to gamma radiation was detected. Herewith the internal discrimination of n/γ signals (the ratio of detection efficiencies for the fast neutrons and gamma quants) for activated KDP crystals is 7-8 times higher than of regular plastic scintillators.</p> Aleksei P. Voronov Sergei V. Naydenov Igor M. Pritula Gennadiy M. Onyshchenko Aleksandr F. Shchus’ Ivan I. Yakymenko ##submission.copyrightStatement## 2018-09-24 2018-09-24 5 3 45 52 10.26565/2312-4334-2018-3-05 INVESTIGATION OF MECHANICAL PROPERTIES OF POLYIMIDE FILMS UNDER THE INFLUENCE OF LABORATORY-SIMULATED SPACE FACTORS https://periodicals.karazin.ua/eejp/article/view/11382 <p>In work the mechanical properties of polyimide films analogue kapton-H (manufactures of the People's Republic of China) by thickness 75 microns are studied in conditions of uniaxial stretching at temperature 293&nbsp;K after influence of space factors - a separate and joint irradiation by protons and electrons with energy Е=160 keV and fluence (the total flow of particles with incident on the samples) F=10<sup>16</sup> cm<sup>-2</sup>. The limit of the forced elasticity, the ultimate strength, the total strain before fracture and the contributions to the total deformation related to the elastic deformation occurring in the linear stage, the total forced elastic and irreversible deformation that contribute to the overall deformation of the samples at the nonlinear stage are determined. The total forced elastic deformation consists of a highly elastic deformation, reversible at the test temperature, and delayed elastic deformation. After exposure to irradiation, an increase in the limit of the forced elasticity of the films by 5-11%, a decrease in the ultimate strength by 10-14%, and a reduction in the total deformation by 20-28% were found. The maximum change in all mechanical characteristics occurs under the influence of proton irradiation. It is established that the decrease in the total deformation of irradiated films is mainly due to a 80% reduction in the contribution of irreversible deformation. The contribution of the total forced elastic deformation of the polyimide film practically does not change after irradiation, which has important scientific and applied significance.</p> Victory A. Lototskaya Leonid F. Yakovenko Evgeniy N. Aleksenko V. A. Velichko Ivan P. Zaritskiy Vyacheslav V. Abraimov Wen Zhu Shao Liu Hai ##submission.copyrightStatement## 2018-09-25 2018-09-25 5 3 53 60 10.26565/2312-4334-2018-3-06 ELECTROLYTIC PLASMA POLISHING OF COPPER https://periodicals.karazin.ua/eejp/article/view/11383 <p>Modern industrial technological processes require special preparation of metal surfaces. Currently, there are different methods of surface treatment of metal. Among them, it is possible to distinguish the method of electrolytic-plasma polishing (PEP– plasma electrolytic polishing) is distinguished as an innovative, due to its ecological properties, low energy consumption per unit of surface to be processed, high speed of modification and the possibility of processing parts of complex geometric shape. The main advantage of this method of surface modification is its ecological purity, which makes it possible to apply this technology to the food and pharmaceutical industry.&nbsp; Despite the large number of journal publications, electrolytic plasma polishing remains an innovative surface modification method that needs to be thoroughly studied in order to improve understanding of physical processes and optimize the surface modification process.&nbsp; The process of obtaining electrolytic plasma polishing of copper products in a solution of ammonium sulfate with the addition of sulfuric acid is considered in the paper. The experiment was divided into two stages. At first, the samples were treated for 600 seconds each for the obtain of temperature characteristics, with a strong correlation between the load current and the electrolyte temperature was observed. Dependence of the current on the temperature of the electrolyte showed four different modes of treatment. One of the modes showed the best results. During the second series of experiments, the processing of objects from 30 to 600 seconds. As a result of the conducted studies, optimal regimes for polishing copper objects were obtained.</p> Oleksii V. Mihal Oleksandr V. Moroz Roman I. Starovoytov I. V. Buriak ##submission.copyrightStatement## 2018-09-25 2018-09-25 5 3 61 67 10.26565/2312-4334-2018-3-07 SM-CO BASED MAGNETIC SYSTEM FOR 10 MEV TECHNOLOGICAL ELECTRON ACCELERATOR LU-10M https://periodicals.karazin.ua/eejp/article/view/11385 <p>Rare-earth permanent magnets are widely used in the accelerators of charged particles. However, the magnetic performance under irradiation remains a key issue for the most high energy applications such as accelerators with the energy up to 10 MeV. The aim of the work was to assess radiation and magnetic stability of Sm-Co and Nd-Fe-B permanent magnets under the direct electron irradiation with the energy of 10 MeV and bremsstrahlung. Sm-Co and Nd-Fe-B permanent magnets were produced by powder metallurgy method including PLP for the latter. The absorbed dose imposed by electron beam was 16 Grad (the total flux of electron per 1 cm<sup>2</sup> was 1.4х10<sup>17</sup>) and 160 Grad. The radiation activity of both Nd-Fe-B and Sm-Co magnets was within the acceptable limits after the irradiation. This makes rare-earth magnetic materials suitable for such applications. In order to avoid overheating during electron irradiation, magnets were cooled with the water (T=38 °С). In order to estimate the changes in magnetic flux, the integral of the 3D interpolation normal component of magnetic flux was used. Calculated S parameter measured in arbitrary units was chosen as integrated z-component of magnetic flux. It was shown that magnetic flux of Nd-Fe-B magnets became 0.92 and 0.717 of initial values for 16 Grad and 160 Grad correspondingly, but the magnetic flux of Sm-Co magnets had no change to the same absorbed doses. Thus, Sm-Co magnets were chosen for simulating and designing magnetic system for electron beam analysis of a technological accelerator with energy up to 10 MeV. The distance between the poles of the magnet was 25.25 mm. The highest magnetic field inside the magnetic system was 0.3110&nbsp;T. The effective distance was 33.53 mm. The measured parameters of the magnetic system based on Sm-Co magnets agreed with the simulation experiment. Magnetic system can also be used to adjust the accelerator in the energy range up to 10 MeV.</p> Vira A. Bovda Aleksandr M. Bovda Ivan S. Guk S. G. Kononenko V. N. Lyashchenko A. O. Mytsykov L. V. Onischenko ##submission.copyrightStatement## 2018-09-27 2018-09-27 5 3 68 74 10.26565/2312-4334-2018-3-08 DETERMINATION OF THERMODYNAMIC QUANTITIES OF BINARY METAL SYSTEMS WITH LOW SOLUBILITY OF COMPONENTS IN THE SOLID α-PHASE https://periodicals.karazin.ua/eejp/article/view/11387 <p>The method for determining the thermodynamic quantities: the partial enthalpy of dissolution , the activity coefficients &nbsp;and activities &nbsp;of the second component B in binary metallic systems with low solubility in the solid α-phase has been proposed. The algorithm for determining the above values is a sequence of preliminary calculations of the limiting and equilibrium distribution coefficients and construction of saturated solid solution lines for such systems with low solubility of the second component. Preliminarily obtained data are necessary for determining the partial enthalpy of dissolution and other quantities in the systems under study. Such a sequence of calculations is the proposed method for determining the thermodynamic parameters of dissolution. &nbsp;The values and temperature dependences of the dissolution enthalpy of component having a low solubility for such systems as Cd-Na, Cd-Tl, Te-Ga, Te-As, Te-Cu, Zn-Sn, as well as the activity coefficients &nbsp;and the activities &nbsp;of the second component in the saturating α-phase in these systems were determined. An analysis of obtained results on the enthalpy of dissolution shows that a change in the partial enthalpy with a change in the dissolution temperature is observed. When the temperature decreases from the melting point of the pure main component to the eutectic temperature, an increase in the partial enthalpies of dissolution of the second component is observed for studied systems.&nbsp;The Te-Ga system is characterized by a negative value . A negative value&nbsp;indicates an exothermic process of gallium dissolution in tellurium, in contrast to other systems in which the dissolution of the second component occurs with heat absorption. Analyzing the enthalpy of dissolution in the systems under study, it should be noted that the low values of &nbsp;&lt; 2000 J/mol are characterized by the systems Cd-Na and Te-Ga. For systems Te-Cu, Te-As, Te-Tl, Zn-Sn &nbsp;&gt; 15000 J/mol. Systems with a value &nbsp;&gt; 15000 J/mol reveal a tendency to the occurrence of retrograde solubility in them. The difference in values &nbsp;is found to be more than two orders of magnitude for different systems.</p> Alexey P. Shcherban Olga A. Datsenko ##submission.copyrightStatement## 2018-09-27 2018-09-27 5 3 75 81 10.26565/2312-4334-2018-3-09 It's worth remembering: "This Never Was Not in the USSR". - Ukraine, Kharkov, UFTI (Continuation: Beginning at No. 1 (2018)) https://periodicals.karazin.ua/eejp/article/view/11388 <p>The 100th anniversary of the National Academy of Sciences of Ukraine and the 90th anniversary of the UFTI - NSC "KHPTI". Dedicated to the bright memory of Academician I. Obreimov, the Director-organizer of the UFI</p> Alla Tan'shyna ##submission.copyrightStatement## 2018-09-27 2018-09-27 5 3 82 88 10.26565/2312-4334-2018-3-10