Safe world is the key to the safe future

Nowadays, one of the most important purposes of mankind is to make world safer. It is not surprising because our generation have faced with a lot of environmental, social, economic and health problems. Although most of these problems are caused by people activity only people can change their life for better. When you are citing the document, use the following link http://essuir.sumdu.edu.ua/handle/123456789/3485

One-dimensional electron lattice system with a long-range interelectron repulsion on a disordered host lattice

We study what happens to generalized Wigner crystal, GWC (a regular structure formed by narrow-band electrons on a one-dimensional periodic host lattice), when there is a host lattice random distortion that does not break the host-lattice long-range order. We show that an arbitrarily weak distortion of the kind gives rise to soliton-like GWC defects (discrete solitons, DS) in the ground state, and thereby converts the ordered GWC into a new disordered macroscopic state — lattice Wigner glass (LWG). The ground-state DS concentration is found to be proportional to λ⁴ (λ is the typical host-lattice strain). We show that the low-temperature LWG thermodynamics and kinetics are fully described in DS terms. A new phenomenon of a super-slow logarithmic relaxation in the LWG is revealed. Its time turns out to be tens orders of magnitude greater than the microscopic ones. Analytical dependences of LWG thermodynamic quantities on temperature and λ are obtained for an arbitrary relationship between the relevant Coulomb energies and the electron bandwidth

Wigner-like crystallization of Anderson-localized electron systems with low electron densities

We consider an electron system under conditions of strong Anderson localization, taking into account interelectron long-range Coulomb repulsion. We establish that at sufficiently low electron densities and sufficiently low temperatures the Coulomb electron interaction brings about ordering of the Anderson-localized electrons into a structure that is close to an ideal (Wigner) crystal lattice, provided the dimension of the system is > 1. This Anderson-Wigner glass (AWG) is a new macroscopic electron state that, on the one hand, is beyond the conventional Fermi glass concept, and on the other hand, qualitatively differs from the known "plain" Wigner glass (inherent in self-localized electron systems) in that the random slight electron displacements from the ideal crystal sites essentially depend on the electron density. With increasing electron density the AWG is found to turn into the plain Wigner glass or Fermi glass, depending on the width of the random spread of the electron levels. It is shown that the residual disorder of the AWG is characterized by a multi-valley ground-state degeneracy akin to that in a spin glass. Some general features of the AWG are discussed, and a new conduction mechanism of a creep type is predicted

Intense plastic deformation of high-purity cast beryllium

The effect of intense plastic deformation on the mechanical properties, structure, and texture of high-purity cast beryllium was studied. For the first time, angular pressing of high-purity cast beryllium was carried out at temperatures of 600 and 500 °C. It is shown that the degree of grain refinement during angular pressing into a strip reaches a significant value. In one deformation cycle, the grain is crushed from 3 mm to 10 μm. The temperature dependences of the mechanical properties of the material of extruded billets in the initial state and after recrystallization annealing at a temperature of 650 °C for one hour were studied. It has been established that the best mechanical properties have samples of material deformed at 600 °C and subsequent annealing at 650 °C for an hour.Вивчено вплив інтенсивної пластичної деформації на механічні властивості, структуру і текстуру високочистого литого берилію. Вперше проведено кутове пресування високочистого литого берилію при температурах 600 і 500 0С. Показано, що ступінь подрібнення зерна при кутовому пресуванні в смугу досягає значної величини. За один цикл деформації зерно подрібнюється з 3 мм до 10 мкм. Вивчено температурні залежності механічних властивостей матеріалу видавлених заготовок у початковому стані і після рекристалізаційного відпалу при температурі 650 0С протягом однієї години. Встановлено, що кращі механічні властивості мають зразки матеріалу, деформованого при 6000С та після наступного відпалу при 650 0С протягом години.Изучено влияние интенсивной пластической деформации на механические свойства, структуру и текстуру высокочистого литого бериллия. Впервые проведено угловое прессование высокочистого литого бериллия при температурах 600 и 500 0С. Показано, что степень измельчения зерна при угловом прессовании в полосу достигает значительной величины. За один цикл деформации зерно измельчается с 3 мм до 10 мкм. Изучены температурные зависимости механических свойств материала выдавленных заготовок в исходном состоянии и после рекристаллизационного отжига при температуре 650 0С в течение одного часа. Установлено, что лучшие механические свойства имеют образцы материала, деформированного при 600 0С и после последующего отжига при 650 0С в течение часа

Corrosion stability of molybdenum and tungsten coatings in lead-bismuth eutectic

The paper presents results of corrosion tests of tungsten- and molybdenum-based protective coatings, deposited on nickel-molybdenum alloys (hastelloy) in heavy metal melts (Pb, Bi, Pb–Bi eutectic). Results of an investigation of hastelloy samples without protective coating are given for comparison. The investigations were carried out under static conditions at 550 °C. The mechanical properties of the samples under investigation have been shown that the corrosion stability of the uncoated alloys studied decreases in the order: lead – lead-bismuth eutectic – bismuth. The use of protective tungsten and molybdenum coatings ensures corrosion stability of hastalloy with retention of its mechanical properties.Наведено результати дослідження корозійної стійкості нікель-молібденових сплавів (хастелой) в розплавах важких металів (Pb, Bi, Pb-Bi). Корозію вивчено в статичних умовах при температурі 550 °С. Встановлено, що в ряді розплавів свинець – свинець-вісмутова евтектика – вісмут корозійна стійкість вивчених сплавів падає. Показано, що використання захисних покрить з вольфраму та молібдену підвищує корозійну стійкість хастелою.Представлены результаты исследования коррозионной стойкости никель-молибденовых сплавов (хастеллой) в расплавах тяжелых металлов (Pb, Bi, Pb-Bi). Коррозия изучена в статических условиях при температуре 550 °С. Установлено, что в ряду расплавов свинец – свинец-висмутовая эвтектика – висмут коррозионная стойкость изученных сплавов падает. Показано, что использование защитных покрытий из вольфрама и молибдена повышает коррозионную стойкость хастеллоя

Mineral insulators for kompton detectors of neutrons with a metal hafnium emitter

One of the priority tasks of nuclear power industry is to increase the reliability and safety of nuclear power plants. In this regard, traditional detectors for measuring the neutron flux in the reactor core are being improved and new ones are developed. This work is dedicated to one of the tasks of creating a compton self-powered neutron detector, namely, the formation of an insulator of magnesium oxide on an emitter of metallic hafnium. The effect of three types of magnesium oxide of different purity and structural state, as well as annealing temperature on the electrical resistance of the insulator between the collector and the emitter of the detector, is studied. The detector prototypes were manufactured by filling with magnesium oxidepowders or by applying liquid-phase mixturesthereof.Одним з пріоритетних завдань атомної енергетики є підвищення надійності та безпеки ядерноенергетичних блоків. З цією метою вдосконалюються та розробляються нові датчики для вимірювання потоку нейтронів в активній зоні реактора. Дана робота присвячена дослідженню магнію оксиду як ізолятора в комптоновських детекторах прямого заряду з емітером з металевого гафнію. Досліджено вплив трьох видів магнію оксиду різного за чистотою та структурою, а також температури відпалу на електроопір ізолятора між колектором та емітером детектора. Виготовлена ізоляція дослідженних зразків детектора щляхом насипу та нанесенням рідкофазної магнієвої суміші.Одна из наиболее приоритетных задач атомной энергетики – повышение надежности и безопасности ядерно-энергетических установок. В связи с этим совершенствуются и разрабатываются новые датчики измерения потока нейтронов в активной зоне реактора. Данная работа посвящена одному из этапов создания комптоновского детектора прямого заряда, а именно формированию изолятора из окиси магния на эмиттере из металлического гафния. Исследовано влияние трех видов оксида магния различной чистоты и структурного состояния, а также температуры отжига на электросопротивление изолятора между коллектором и эмиттером детектора. Изготовлены опытные образцы детекторов методами засыпки и нанесения жидкофазной смеси оксида магния

In search of the QCD-Gravity correspondence

Quantum Chromodynamics (QCD) is the fundamental theory of strong interactions. It describes the behavior of quarks and gluons which are the smallest known constituents of nuclear matter. The difficulties in solving the theory at low energies in the strongly interacting, non-perturbative regime have left unanswered many important questions in QCD, such as the nature of confinement or the mechanism of hadronization. In these lectures oriented towards the students we introduce two classes of dualities that attempt to reproduce many of the features of QCD, while making the treatment at strong coupling more tractable: (1) the AdS/CFT correspondence between a specific class of string theories and a conformal field theory and (2) an effective low-energy theory of QCD dual to classical QCD on a curved conformal gravitational background. The hope is that by applying these dualities to the evaluation of various properties of the strongly-interacting matter produced in heavy ion collisions one can understand how QCD behaves at strong coupling. We give an outline of the applications, with emphasis on two transport coefficients of QCD matter -- shear and bulk viscosities.Comment: 31 pages, 7 figures; Lectures delivered by D. Kharzeev at the International QGP Winter School, Jaipur, India, February 1-3, 200

Chiral Magnetic Effect in Hydrodynamic Approximation

We review derivations of the chiral magnetic effect (ChME) in hydrodynamic approximation. The reader is assumed to be familiar with the basics of the effect. The main challenge now is to account for the strong interactions between the constituents of the fluid. The main result is that the ChME is not renormalized: in the hydrodynamic approximation it remains the same as for non-interacting chiral fermions moving in an external magnetic field. The key ingredients in the proof are general laws of thermodynamics and the Adler-Bardeen theorem for the chiral anomaly in external electromagnetic fields. The chiral magnetic effect in hydrodynamics represents a macroscopic manifestation of a quantum phenomenon (chiral anomaly). Moreover, one can argue that the current induced by the magnetic field is dissipation free and talk about a kind of "chiral superconductivity". More precise description is a ballistic transport along magnetic field taking place in equilibrium and in absence of a driving force. The basic limitation is exact chiral limit while the temperature--excitingly enough- does not seemingly matter. What is still lacking, is a detailed quantum microscopic picture for the ChME in hydrodynamics. Probably, the chiral currents propagate through lower-dimensional defects, like vortices in superfluid. In case of superfluid, the prediction for the chiral magnetic effect remains unmodified although the emerging dynamical picture differs from the standard one.Comment: 35 pages, prepared for a volume of the Springer Lecture Notes in Physics "Strongly interacting matter in magnetic fields" edited by D. Kharzeev, K. Landsteiner, A. Schmitt, H.-U. Ye

Transport Properties of the Quark-Gluon Plasma -- A Lattice QCD Perspective

Transport properties of a thermal medium determine how its conserved charge densities (for instance the electric charge, energy or momentum) evolve as a function of time and eventually relax back to their equilibrium values. Here the transport properties of the quark-gluon plasma are reviewed from a theoretical perspective. The latter play a key role in the description of heavy-ion collisions, and are an important ingredient in constraining particle production processes in the early universe. We place particular emphasis on lattice QCD calculations of conserved current correlators. These Euclidean correlators are related by an integral transform to spectral functions, whose small-frequency form determines the transport properties via Kubo formulae. The universal hydrodynamic predictions for the small-frequency pole structure of spectral functions are summarized. The viability of a quasiparticle description implies the presence of additional characteristic features in the spectral functions. These features are in stark contrast with the functional form that is found in strongly coupled plasmas via the gauge/gravity duality. A central goal is therefore to determine which of these dynamical regimes the quark-gluon plasma is qualitatively closer to as a function of temperature. We review the analysis of lattice correlators in relation to transport properties, and tentatively estimate what computational effort is required to make decisive progress in this field.Comment: 54 pages, 37 figures, review written for EPJA and APPN; one parag. added end of section 3.4, and one at the end of section 3.2.2; some Refs. added, and some other minor change

Low background detector with enriched 116CdWO4 crystal scintillators to search for double beta decay of 116Cd

A cadmium tungstate crystal boule enriched in $^{116}$Cd to 82% with mass of 1868 g was grown by the low-thermal-gradient Czochralski technique. The isotopic composition of cadmium and the trace contamination of the crystal were estimated by High Resolution Inductively Coupled Plasma Mass-Spectrometry. The crystal scintillators produced from the boule were subjected to characterization that included measurements of transmittance and energy resolution. A low background scintillation detector with two $^{116}$CdWO$_4$ crystal scintillators (586 g and 589 g) was developed. The detector was running over 1727 h deep underground at the Gran Sasso National Laboratories of the INFN (Italy), which allowed to estimate the radioactive contamination of the enriched crystal scintillators. The radiopurity of a third $^{116}$CdWO$_4$ sample (326 g) was tested with the help of ultra-low background high purity germanium $\gamma$ detector. Monte Carlo simulations of double $\beta$ processes in $^{116}$Cd were used to estimate the sensitivity of an experiment to search for double $\beta$ decay of $^{116}$Cd.Comment: 24 pages, 13 figures, 3 tables, accepted for publication on Journal of Instrumentatio