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> en-US <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/4.0/" 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> serhii.hirnyk@karazin.ua (Serhii Hirnyk) serhii.hirnyk@karazin.ua (Serhii Hirnyk) Wed, 02 Oct 2019 00:00:00 +0300 OJS http://blogs.law.harvard.edu/tech/rss 60 Long-Lived Banana Orbit Formation of Suprathermal Electrons During MHD Spikes in Runaway Tokamak Discharges https://periodicals.karazin.ua/eejp/article/view/14355 <p>The secondary runaway electrons generation is the process in which already existing high energy runaway electrons knock out thermal plasma electrons directly into the runaway region by close Coulomb collisions. Such knocked-on electrons are immediately accelerated to ultrarelativistic velocities, since in the runaway region the toroidal electric field force overcomes the collisional friction force with thermal plasma particles. The avalanche of runaway electrons with mega-electron-volt energy emerges, hit of which with the construction elements of large-scale tokamaks and future international tokamak ITER can lead to catastrophic consequences. Due to its importance, this phenomenon is being actively studied both theoretically and experimentally in leading thermonuclear fusion centers. It is known that during secondary generation, the value of the transversal component of knocked-on electrons momentum with respect to the confining magnetic field may be significantly higher than the longitudinal one: <em>p</em><sub>⊥</sub>&nbsp;&gt;&gt;&nbsp;<em>p</em><sub>∥</sub>. Thus, conditions for knocked-on electron trapping in a non-uniform tokamak magnetic field occur (banana orbits). Such electrons can no longer be accelerated by the inducted toroidal electric field to high energies, avalanche formation is partially suppressed. The question is how long this population of knocked-on and trapped electrons exists. In the presented paper, it is shown the additional possibility of formation and existence of such long-lived banana orbits of suprathermal electrons under conditions of plasma MHD activity when MHD instability spikes induced the strong burst of the toroidal electric field that results in the abrupt growth in these knocked-on and trapped electrons. This phenomenon is considered for the recent low-density EAST (Institute of Plasma Physics, Chinese Academy of Sciences, Hefei, China) tokamak quasistationary runaway discharges. Long-lived trapped electrons (<em>p</em><sub>⊥</sub>&nbsp;&gt;&gt;&nbsp;<em>p</em><sub>∥</sub>) also have an influence on the intensity of ECE emission. The considered phenomenon is important for correct interpretation of the runaway experiments on present-day tokamaks.</p> Igor Pankratov, Volodymyr Bochko ##submission.copyrightStatement## https://periodicals.karazin.ua/eejp/article/view/14355 Tue, 01 Oct 2019 00:00:00 +0300 Analysis of Isolated Photons in Photoproduction in PYTHIA https://periodicals.karazin.ua/eejp/article/view/14356 <p>Collision of particles at high energies at accelerators is the main source of data used to obtain deeper understanding of the fundamental interactions and the structure of the matter. Processes of isolated photon production have provided many tests of theoretical descriptions of the universe on scales smaller than the proton. This work is dedicated to the analysis of the large amount of collision data that has been accumulated at ZEUS in 2004-2007 period and new methods of processing isolated photons that have been proposed. The authors develop software algorithms that allow obtaining the signal of isolated photons from the data collected on the ZEUS detector at electron-proton collider HERA, calculating the differential cross sections, and comparing the measured data with PYTHIA Monte Carlo predictions. Taking into account the features of the ZEUS detector, the photon signal is separated from the background events and the number of isolated photons is calculated. Computational mathematical and numerical methods have been used to simulate the interaction of particles in the detector. Monte Carlo predictions for differential cross sections as functions of the pseudorapidity and transverse energy of the photon <em>η</em><em><sup>g</sup></em>, <em>E<sub>T</sub></em><em><sup>g</sup></em> and the jet <em>η<sup>jet</sup></em>, <em>E<sub>T</sub><sup>jet</sup></em>, and the fraction of the photon momentum <em>х</em><em><sub>g</sub></em><em><sup>meas</sup></em> carried by the interacting parton have been calculated and compared with the experimental data. The results of the study are compared with the previous studies and show for the first time that all isolated photon HERA measurements are consistent with each other. New results show improved uncertainties. The formation of isolated inclusive photons and photons with the accompanying jet was measured in photoproduction with ZEUS detector at HERA collider using the integrated luminosity of 374 ± 7 pb<sup>-1</sup>. For the first time, more complex Monte-Carlo simulation models of isolated photons for ZEUS detector were generated and applied, and the description of the photon signal was improved. It has been found that PYTHIA describes the shape of the cross section as a function of <em>η</em><em><sup>g</sup></em> well enough, but does not fully reproduce the shape of <em>E<sub>T</sub></em><em><sup>g</sup></em>,<em> E<sub>T</sub><sup>jet</sup></em>, and the middle region of <em>х</em><em><sub>g</sub></em><em><sup>meas</sup></em>, while <em>η<sup>jet</sup></em> is described not very well. The reason for this discrepancy can be the lack of corrections of higher orders in the predictions for cross sections of direct photons. Scaling of the cross sections obtained with PYTHIA improves the description of <em>E<sub>T</sub></em><em><sup>g</sup></em> and <em>η</em><em><sup>g</sup></em>. The unsatisfactory description of <em>η<sup>jet</sup></em> indicates that further studies are required.</p> Andrii Iudin, Sergey Voronov ##submission.copyrightStatement## https://periodicals.karazin.ua/eejp/article/view/14356 Tue, 01 Oct 2019 00:00:00 +0300 Fixed Points Features in N-Point Gravitational Lenses https://periodicals.karazin.ua/eejp/article/view/14357 <p>A set of fixed points in N-point gravitational lenses is studied in the paper. We use complex form of lens mapping to study fixed points. There are some merits of using a complex form over coordinate. In coordinate form gravitational lens is described by a system of two equations and in complex form is described by one equation. We transform complex equation of N-point gravitational lens into polynomial equation. It is convenient to study polynomial equation. Lens mapping presented as a linear combination of two mappings: complex analytical and identity. Analytical mapping is specified by deflection function. Fixed points are roots of deflection function. We show, that all fixed points of lens mapping appertain to the minimal convex polygon. Vertices of the polygon are points into which dimensionless point masses are. Method of construction of fixed points in N-point gravitational lens is shown. There are no fixed points in 1-point gravitational lens. We study properties of fixed points and their relation to the center of mass of the system. We obtained dependence of distribution of fixed points on center of mass. We analyzed different possibilities of distribution in N-point gravitational lens. Some cases, when fixed points merge with the center of mass are shown. We show a linear dependence of fixed point on center of mass in 2-point gravitational lens and we have built a model of this dependence. We obtained dependence of fixed point to center of mass in 3-point lens in case when masses form a triangle or line. In case of triangle, there are examples when fixed points merges. We study conditions, when there are no one-valued dependence of distribution of fixed points in case of 3-points gravitational lens and more complicated lens.</p> Volodymyr Shablenko ##submission.copyrightStatement## https://periodicals.karazin.ua/eejp/article/view/14357 Tue, 01 Oct 2019 00:00:00 +0300 Structural State Effect on Mechanical Properties and Acoustic Emission of High-Purity Titanium at Different Types of Deformation https://periodicals.karazin.ua/eejp/article/view/14358 <p>The results on investigations of mechanical properties of high-purity titanium with grains ranging from tens of nanometers up to a few micrometers subjected to uniaxial tension, compression and microindenting are presented. Different structural states in high-purity titanium were formed by severe plastic deformation according to the scheme «upsetting – extrusion – drawing» in combination with annealing at temperatures of 250–550° C and quasi-hydrostatic extrusion at room and liquid nitrogen temperatures. The values of yield strengths and microhardness for samples of high-purity titanium with grains of different sizes are determined. It was shown that the combination of severe plastic deformation with cryogenic quasi-hydrostatic extrusion allowed to create high-purity nanocrystalline titanium with high mechanical properties. The obtained experimental data were analyzed for the implementation of the Hall-Petch relation and discrepancy between the values of yield strengths in tension and compression (strength differential or S-D effect). Satisfactory fulfillment of the Hall-Petch relation for high-purity titanium in the whole range of the studied grain size values was shown and a noticeable difference in the yield values for compression and tension was found. The values of the coefficients in the Hall-Petch equation for deformation by tension, compression and microindenting were determined. These coefficients are noticeably lower than the corresponding values for the industrial grades of titanium, i.e. in high-purity titanium, the grain boundaries are weaker barriers for moving dislocations than in the industrial titanium, whose boundaries are enriched with impurities. The features of the acoustic waves emission during compression of samples in various structural states were studied. It was concluded that the deformation of titanium in all the investigated structural states was carried out by dislocation slip.</p> Kseniya Kutniy, Igor Kislyak, Alexander Kalchenko, Petr Stoev, Mikhail Tikhonovsky, Pavel Khaimovich ##submission.copyrightStatement## https://periodicals.karazin.ua/eejp/article/view/14358 Tue, 01 Oct 2019 00:00:00 +0300 On Structural Aspects of Texture Changes During Rolling of Zr-2.5%Nb Alloy https://periodicals.karazin.ua/eejp/article/view/14359 <p>Using X-ray structural analysis, features of changes in characteristics of crystallographic texture during cold working of Zr-2.5%Nb alloy plates by longitudinal and cross rolling has been investigated. To make original plates, longitudinal fragments and rings of Æ15.0´1.5&nbsp;mm² tube annealed at 580 °C were used. The plates were rolled at room temperature to the degrees in the range from 6 to 56% with 5…7% per pass and the rate of 5...10s<sup>-1</sup>. Using the method of inverse pole figures with measuring by the Bragg-Brentano optical scheme, densities of reflections along normal to plane of the plates (pole densities) was determined. Based on this, distributions of orientations of <em>c</em>-axes of hcp lattice of the material have been analyzed. Local features of the distributions, which were attributed to signs of twinning effects in texture changes in the alloy, are revealed. At subsequent analysis, an effect of strain non-uniformity associated with prehistory of the plates was taken into account. It is established that the second stage of (moderate) changes in Kearns textural coefficient of the plates with the deformation degrees differs from the initial stage of accelerated changes by activation of compression twins. By the method of tilt scanning (of rocking curves) around the Bragg-Brentano position at registration of (0004) reflection intensities, changes in orientation distributions of <em>c</em>-axes in longitudinal and cross section of the plates for both parties were investigated. It is noted that the main textural changes in process of deformation of the plates occur in the cross-sectional plane of the original tube and are most expressed on the cross-rolling plates. The doublet in the distributions of<em> c</em>‑axes, characteristic for rolling texture of hcp metals of titanium subgroup, was noted just at the second stage of the texture changes in the material. Its directionality is mainly associated with the plane of cross-section of the original tube. A connection is revealed between features of the pole density distributions and expression degree of the textural doublet on the rocking curves. According to the results obtained and analysis of other publications, twinning nature of the textural doublet was confirmed and a schematic sequence of its formation was proposed with participation of compression twins of{112<sup>-</sup>2}{1<sup>-</sup>1<sup>-</sup>23} system and tensile twins of {101<sup>-</sup>2}{1<sup>-</sup>011} and{112<sup>-</sup>1}{1<sup>-</sup>1<sup>-</sup>26} systems.</p> Victor Grytsyna, Dmitry Malykhin, Tetiana Yurkova, Kostiantyn Kovtun, Tetiana Chernyayeva, Gennadiy Kovtun, Iryna Tantsura, Victor Voyevodin ##submission.copyrightStatement## https://periodicals.karazin.ua/eejp/article/view/14359 Tue, 01 Oct 2019 00:00:00 +0300 Energy Exchange Between the Field and the Active Medium of the Waveguide https://periodicals.karazin.ua/eejp/article/view/14360 <p>The work based on a semiclassical description, presents the results of studying the processes of absorption and radiation of a field in the form of a standing wave in a waveguide filled with a two-level active medium. Under conditions of spatial inhomogeneity of the field intensity, interference of quasi-periodic oscillations of population inversion occurs in different local regions of the waveguide. A quasiperiodic change in population inversion is determined by the Rabi frequency, which is known to be associated with the probability of induced radiation with a positive population inversion, or induced absorption with its negative value. Since the population inversion change is accompanied by absorption or emission of field quanta, this leads to the exchange of energy between the field and the active medium located in the waveguide. It is shown that the attenuation of a large-amplitude field to a waveguide filled with an unexcited active medium is nonlinear. In the developed mode, this process has the character of energy exchange between the field and the active medium.&nbsp; In this case, the wave attenuation is replaced by its growth, just as it happens in the well-known case of Landau kinetic damping. Competition of the processes of radiation and absorption leads to the fact that the nature of the oscillations (nutations) of the population inversion at different points of the waveguide space is different. The interference of nonsynchronous spatially localized oscillations of the population inversion in the volume of the waveguide leads to changes in the field amplitude. The paper also discusses the process of field excitation in a waveguide with a pre-inverted two-level active medium, taking into account external mechanisms for the absorption of wave energy. Consideration of these problems is important for understanding the processes of generation of induced radiation, which, as noted by C. Towns, is to a large extent coherent radiation.</p> Volodymyr Kuklin, Eugen Poklonskiy ##submission.copyrightStatement## https://periodicals.karazin.ua/eejp/article/view/14360 Tue, 01 Oct 2019 00:00:00 +0300 The Investigation of Mechanisms of Fast Neutron Registration in Oxide Scintillators https://periodicals.karazin.ua/eejp/article/view/14361 <p>The contributions of gamma rays from the inelastic scattering reaction and the resonant reaction in the process&nbsp;of slowing down fast neutrons inside the oxide detector volume are investigated. For this the countable efficiency&nbsp;of the ZnWO<sub>4</sub>, CdWO<sub>4</sub>, Bi<sub>4</sub>Ge<sub>3</sub>O<sub>12</sub> oxide scintillators in terms of pulses/neutron during the registration of the&nbsp;fast neutrons from a <sup>239</sup>Pu-Be source was measured. It is assumed that the response of detectors during neutron&nbsp;moderation in oxide scintillators with an effective thickness of about 40—50 mm is formed by instantaneous gamma&nbsp;rays from inelastic, resonant inelastic scattering reactions, as well as delayed gamma rays from the capture reaction&nbsp;of resonance neutrons. The parameters of the nuclei, which determine the detector response — the density of the&nbsp;nuclear levels of the compound nuclei being formed, the widths of the resonance regions, the lifetimes of the excited&nbsp;nucleus state were considered. It was found that the registration of a cascade of gamma rays from the discharge&nbsp;of excited levels leads to a significant increase in the countable efficiency of the detector and, as a consequence,&nbsp;an increase in the sensitivity of the detector to fast neutrons. The measured response in terms of pulses/neutron&nbsp;for the ZWO detector — 64, for CWO — 36, for BGO — 2.5. The response of the detectors was recorded by the&nbsp;broadband tract with a time feedback of τ~```0.7 ns. The measured values of the efficiency are explained by the fact&nbsp;that, in our case, the reaction of inelastic scattering is the starting process, which starts the process of discharging&nbsp;nuclear long-lived (~``` 1–1000 ns) states excited in both inelastic scattering and in resonance capture reaction. The registration of the gamma-quanta from discharge leads to an increase the countable efficiency of the detector. The observed increase of the countable efficiency of the secondary gamma quanta is realized when neutrons&nbsp;are moderated inside the oxide detectors with a thickness of 40—50 mm or more. The measurement error of the&nbsp;registration efficiency was about 7%.</p> Gennadiy Onyshchenko, Volodymyr Ryzhikov, Ivan Yakymenko, Valery Khodusov, Sergei Naydenov, Alexandr Opolonin, Sergei Makhota ##submission.copyrightStatement## https://periodicals.karazin.ua/eejp/article/view/14361 Tue, 01 Oct 2019 00:00:00 +0300 Competitive Binding of Novel Cyanine Dye AK3-5 and Europium Coordination Complexes to DNA https://periodicals.karazin.ua/eejp/article/view/14362 <p>The present study was undertaken to assess the applicability of the novel trimethine cyanine dye AK3-5 as a competitive ligand for the antitumor agents, Eu(III) coordination complexes (EC), in the DNA-containing systems, using the displacement assay as an analytical instrument. The analysis of fluorescence spectra revealed a strong association of AK3-5 with nucleic acids, with the strength of interaction being higher for the double stranded DNA, compared to the single-stranded RNA. The binding parameters of the cyanine dye have been determined in terms of the McGhee &amp; von Hippel neighbouring site-exclusion model and a classical Langmuir model. The AK3-5 association constant in the presence of DNA was found to be equal to 5.1×10<sup>4</sup> M<sup>-1</sup>, which is consistent to those of the well-known DNA intercalators. In turn, the binding of the cyanine to the RNA was characterized by a significantly lower association constant ( ~ 3.4×10<sup>3</sup> M<sup>-1</sup>) indicating either the external or “partially intercalated” binding mode. The addition of the europium complexes to the AK3-5-DNA system was followed by the fluorescence intensity decrease, with a magnitude of this effect being dependent on the EC structure. The observed fluorescence decrease of AK3-5 in the presence of europium complexes V7 and V9 points to the competition between the cyanine dye and antitumor drugs for the DNA binding sites. The dependencies of the AK3-5-DNA fluorescence intensity decrease <em>vs</em>. europium complex concentration were analyzed in terms of the Langmuir adsorption model, giving the values of the drug association constant equal to 5.4×10<sup>4</sup> M<sup>-1</sup>and 3.9×10<sup>5</sup> M<sup>-1 </sup>for the europium complexes V7 and V9, respectively. A more pronounced decrease of the AK3-5 fluorescence in the presence of V5 and V10 was interpreted in terms of the drug-induced quenching of the dye fluorescence, accompanying the competition between AK3-5 and Eu(III) complexes for the DNA binding sites. Cumulatively, the results presented here strongly suggest that AK3-5 can be effectively used in the nucleic acid studies and in the dye-drug displacement assays.</p> Olga Zhytniakivska, Anna Zabrudska, Uliana Tarabara, Kateryna Vus, Valeriya Trusova, Galyna Gorbenko, Atanas Kurutos, Todor Deligeorgiev ##submission.copyrightStatement## https://periodicals.karazin.ua/eejp/article/view/14362 Tue, 01 Oct 2019 00:00:00 +0300 Electric Double Layer Field Effect Transistor Using SnS Thin Film as Semiconductor Channel Layer and Honey Gate Dieletric https://periodicals.karazin.ua/eejp/article/view/14363 <p>The study aimed at the investigation and application of SnS thin film semiconductor as a channel layer semiconductor in the assembly of an electric double layer field effect transistor which is important for the achievement and development of novel device concepts, applications and tuning of physical properties of materials since the reported EDLFET and the modulation of electronic states have so far been realised on oxides, nitrides, carbon nanotubes and organic semiconductor but has been rarely reported for the chalcogenides. Honey was used as a gel like electrolytic gate dielectric to generate an enhanced electric field response over SnS semiconductor channel layer and due to its ability to produces high on-current and low voltage operation while forming an ionic gel-like solution similar to ionic gels which consist of ionic liguids. SnS gated honey Electric double layer field effect transistor was assembled using tin sulphide (SnS) thin film as semiconductor channel layer and honey as gate dielectric. The measured gate capacitance of honey using LCR meter was measured as 2.15 μF/ cm<sup>2</sup> while the dielectric constant is 20.50. The semiconductor layer was deposited using Aerosol assisted chemical vapour deposition and annealed in open air at 250 &nbsp;on an etched region about the middle of a 4×4 mm FTO glass substrate with the source and drain electrode region defined by the etching and masking at the two ends of the substrate. Iridium was used as the gate electrode while a copper wire was masked to the source and drain region to create electrode contact. The Profilometry, X-ray diffraction, Scanning electron microscope, Energy dispersive X-ray spectroscopy, Hall Effect measurement and digital multimeters were used to characterise the device. The SnS thin film was found to be polycrystalline consisting of Sn and S elements with define grains, an optical band of 1.42 eV and of 0.4 μm thickness. The transistor operated with a p type channel conductivity in a depletion mode with a field effect mobility of 16.67 cm<sup>2</sup>/Vs, cut-off voltage of 1.6 V, Drain saturation current of1.35μA, a transconductance of -809.61 nA/V and a sub threshold slope of -1.6 Vdec<sup>-1</sup> which is comparable to standard specifications in Electronics Data sheets. Positive gate bias results in a shift in the cut off voltage due to charge trapping in the channel/dielectric interface.</p> Thomas Daniel, Uno Uno, Kasim Isah, Umaru Ahmadu ##submission.copyrightStatement## https://periodicals.karazin.ua/eejp/article/view/14363 Wed, 02 Oct 2019 00:00:00 +0300 Supergravity Was Discovered by D.V. Volkov and V.A. Soroka in 1973, Wasn’t it? https://periodicals.karazin.ua/eejp/article/view/14364 <p>Supergravity is a remarkable theory combining supersymmetry and general relativity. While the theory has many developers from across the globe, we wish to address the question who were the real originators of this fantastic idea.</p> Steven Duplij ##submission.copyrightStatement## https://periodicals.karazin.ua/eejp/article/view/14364 Wed, 02 Oct 2019 00:00:00 +0300