ACCOUNT OF NONLOCAL IONIZATION AND SLOW ELECTRON ENERGY BALANCE IN GLOW DISCHARGE MODELS

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Ultra-high energy cosmic ray investigations by means of EAS muon density measurements

A new approach to investigations of ultra-high energy cosmic rays based on the ground-level measurements of the spectra of local density of EAS muons at various zenith angles is considered. Basic features of the local muon density phenomenology are illustrated using a simple semi-analytical model. It is shown that muon density spectra are sensitive to the spectrum slope, primary composition, and to the features of hadronic interaction. New experimental data on muon bundles at zenith angles from 30 degrees to horizon obtained with the coordinate detector DECOR are compared with CORSIKA-based simulations. It is found that measurements of muon density spectra in inclined EAS give possibility to study characteristics of primary cosmic ray flux in a very wide energy range from 10^15 to 10^19 eV.Comment: 7 pages, 7 figures. Presented at CRIS-2006, Catania, Italy, May 29 - June 2, 2006. Accepted for publication in Nucl. Phys. B (Proc. Suppl.

Characteristics of ADS target irradiated by 200…400 MeV proton beam

The problems of target choice for compact ADS with reactor thermal power 200…400 MW and 200…400 MeV proton beam are considered. Simulation results of neutron yield from fissile and non-fissile targets are presented and the optimal target sizes are calculated. The principal target design characteristics and its thermal condition are also considered.Рассмотрены вопросы выбора мишени для компактной электроядерной установки с мощностью реактора 200…400 МВт и энергией протонов 200…400 МэВ. Представлены результаты моделирования выходов нейтронов из размножающих и неразмножающих мишеней и определены оптимальные размеры мишени. Рассмотрены особенности конструкции мишени и вопросы ее температурного состояния.Розглянуто питання вибору мішені для компактної електроядерної установки з потужністю реактора 200…400 МВт і енергією протонів 200…400 МеВ. Представлено результати моделювання виходів нейтронів із розмножуючих і нерозмножуючих мішеней та визначені оптимальні розміри мішені. Розглянуто особли-вості конструкції мішені і питання її температурного стану

Excitation of surface plasmon waves with a nanoantenna: simple analytical solution and its numerical verification

В работе предлагается простой аналитический метод решения задачи о возбуждении поверхностных плазмон-поляритонов металлической наноантенной, расположенной вблизи поверхности металла. Метод основан на теореме взаимности и аналогичен нахождению амплитуд мод диэлектрических волноводов, возбуждаемых источниками тока. Для большей наглядности предлагаемый подход демонстрируется на примере наиболее простой двухмерной геометрии. Справедливость аналитического решения подтверждается результатами численного моделирования методами конечных разностей и конечных элементов. In this work, we demonstrate a simple analytical approach to the problem of surface plasmon polaritons excitation with a metallic nanoantenna placed above a metal surface. The method uses the reciprocity theorem and is similar to the calculation of amplitudes of dielectric waveguide modes excited by a current distribution. To maximize clarity of the demonstration, we formulate the problem in a simple two-dimensional geometry. The analytical results are shown to agree well with the numerical solution obtained by finite elements in frequency domain and finite difference in time domain methods.Работа выполнена при поддержке Российского фонда фундаментальных исследований (грант №20-02-00556А)

From nonassociativity to solutions of the KP hierarchy

A recently observed relation between 'weakly nonassociative' algebras A (for which the associator (A,A^2,A) vanishes) and the KP hierarchy (with dependent variable in the middle nucleus A' of A) is recalled. For any such algebra there is a nonassociative hierarchy of ODEs, the solutions of which determine solutions of the KP hierarchy. In a special case, and with A' a matrix algebra, this becomes a matrix Riccati hierarchy which is easily solved. The matrix solution then leads to solutions of the scalar KP hierarchy. We discuss some classes of solutions obtained in this way.Comment: 7 pages, 4 figures, International Colloquium 'Integrable Systems and Quantum Symmetries', Prague, 15-17 June 200

Quasiparticle picture of high temperature superconductors in the frame of Fermi liquid with the fermion condensate

A model of a Fermi liquid with the fermion condensate (FC) is applied to the consideration of quasiparticle excitations in high temperature superconductors, in their superconducting and normal states. Within our model the appearance of the fermion condensate presents a quantum phase transition, that separates the regions of normal and strongly correlated electron liquids. Beyond the phase transition point the quasiparticle system is divided into two subsystems, one containing normal quasiparticles and the other --- fermion condensate localized at the Fermi surface and characterized by almost dispersionless single-particle excitations. In the superconducting state the quasiparticle dispersion in systems with FC can be presented by two straight lines, characterized by effective masses $M^*_{FC}$ and $M^*_L$, respectively, and intersecting near the binding energy which is of the order of the superconducting gap. This same quasiparticle picture persists in the normal state, thus manifesting itself over a wide range of temperatures as new energy scales. Arguments are presented that fermion systems with FC have features of a quantum protectorate.Comment: 12 pages, Late

Estimation of the Dihedral Angle Between Metal Nanoparticles During Their Coalescence

The process of coalescence of various metal nanoparticles has been studied by the Monte Carlo method. The interaction of nanoparticles is described by a multiparticle Gupta type potential. An algorithm of recognizing and estimating a dihedral angle at the neck is developed. The dihedral angle between metal nanoparticles during their sintering is estimated

Structure optimization effects on the electronic properties of Bi2_2Sr2_2CaCu2_2O8_8

We present detailed first-principles calculations for the normal state electronic properties of the high T$_C$ superconductor Bi$_2$Sr$_2$CaCu$_2$O$_8$, by means of the linearized augmented plane wave (LAPW) method within the framework of density functional theory (DFT). As a first step, the body centered tetragonal (BCT) cell has been adopted, and optimized regarding its volume, $c/a$ ratio and internal atomic positions by total energy and force minimizations. The full optimization of the BCT cell leads to small but visible changes in the topology of the Fermi surface, rounding the shape of CuO$_2$ barrels, and causing both the BiO bands, responsible for the pockets near the \textit{\=M} 2D symmetry point, to dip below the Fermi level. We have then studied the influence of the distortions in the BiO plane observed in nature by means of a $\sqrt{2}\times\sqrt{2}$ orthorhombic cell (AD-ORTH) with $Bbmb$ space group. Contrary to what has been observed for the Bi-2201 compound, we find that for Bi-2212 the distortion does not sensibly shift the BiO bands which retain their metallic character. As a severe test for the considered structures we present Raman-active phonon frequencies ($q = 0$) and eigenvectors calculated within the frozen-phonon approximation. Focussing on the totally symmetric A$_{g}$ modes, we observe that for a reliable attribution of the peaks observed in Raman experiments, both $c$- and a-axis vibrations must be taken into account, the latter being activated by the in-plane orthorhombic distortion.Comment: 22 pages, 4 figure