935 research outputs found

    Calculation of The Lifetimes of Thin Stripper Targets Under Bombardment of Intense Pulsed Ions

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    The problems of stripper target behavior in the nonstationary intense particle beams are considered. The historical sketch of studying of radiation damage failure of carbon targets under ion bombardment is presented. The simple model of evaporation of a target by an intensive pulsing beam is supposed. Stripper foils lifetimes in the nonstationary intense particle can be described by two failure mechanisms: radiation damage accumulation and evaporation of target. At the maximal temperatures less than 2500K the radiation damage are dominated; at temperatures above 2500K the mechanism of evaporation of a foil prevails. The proposed approach has been applied to the discription of behaviour of stripper foils in the BNL linac and SNS conditions.Comment: 12 pages, 5 figure

    A Revised Checklist of Mongolian Mammal Species

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    A revised annotated checklist of Mongolian mammals is presented, supplemented with comments on modifications in species- and genus-level taxonomy introduced over the last 30 years. The checklist includes 140 species compared to 124 species recognized three decades ago by SOKOLOV & ORLOV (1980). Since then, four species were newly described; seven species were registered for the first time on Mongolian territory. Names for more than 20 taxa have changed, on most occasions this change occurred not for purely nomenclatural reasons but rather as a result of taxonomic revisions at the species level which have elevated the rank of many nominal taxa treated previously as subspecies. Recent molecular studies have shown that many widespread Central Asian species, in fact, consist of several highly divergent phylogenetic lineages the taxonomic status of which is yet unclear. Therefore, further updates to our knowledge of mammal biodiversity in Mongolia are expected

    N-particle scattering matrix for electrons interacting on a quantum dot

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    We present a non-perturbative expression for the scattering matrix of NN particles interacting inside a quantum dot. Characterizing the dot by its resonances, we find a compact form for the scattering matrix in a real-time representation. We study the transmission probabilities and interaction-induced orbital entanglement of two electrons incident on the dot in a spin-singlet state.Comment: 4 page

    Ученый - инженер - учитель

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    The article covers the general stages of science and life journey of academician Yashcharytsyn, formation and development of his theory of technological heritage. It shows the influence of application of technological heritage theory aspects on ensuring qualitative characteristics in the process of metal processing using abrasive and edge tools.Рассмотрены основные вехи научного и жизненного пути академика П. И. Ящерицына, становление и развитие им теории технологической наследственности. Показано влияние применения положений теории технологической наследственности в обеспечение качественных характеристик процессов обработки металлов абразивными и лезвийными инструментами

    Dynamo effects in magnetized ideal-plasma cosmologies

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    The excitation of cosmological perturbations in an anisotropic cosmological model and in the presence of a homogeneous magnetic field has been studied, using the ideal magnetohydrodynamic (MHD) equations. In this case, the system of partial differential equations which governs the evolution of the magnetized cosmological perturbations can be solved analytically. Our results verify that fast-magnetosonic modes propagating normal to the magnetic field, are excited. But, what's most important, is that, at late times, the magnetic-induction contrast grows, resulting in the enhancement of the ambient magnetic field. This process can be particularly favored by condensations, formed within the plasma fluid due to gravitational instabilities.Comment: 7 pages, RevTex, accepted for publication to IJMP

    Magnetic field correlations in a random flow with strong steady shear

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    We analyze magnetic kinematic dynamo in a conducting fluid where the stationary shear flow is accompanied by relatively weak random velocity fluctuations. The diffusionless and diffusion regimes are described. The growth rates of the magnetic field moments are related to the statistical characteristics of the flow describing divergence of the Lagrangian trajectories. The magnetic field correlation functions are examined, we establish their growth rates and scaling behavior. General assertions are illustrated by explicit solution of the model where the velocity field is short-correlated in time

    The Zel'dovich effect and evolution of atomic Rydberg spectra along the Periodic Table

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    In 1959 Ya. B. Zel'dovich predicted that the bound-state spectrum of the non-relativistic Coulomb problem distorted at small distances by a short-range potential undergoes a peculiar reconstruction whenever this potential alone supports a low-energy scattering resonance. However documented experimental evidence of this effect has been lacking. Previous theoretical studies of this phenomenon were confined to the regime where the range of the short-ranged potential is much smaller than Bohr's radius of the Coulomb field. We go beyond this limitation by restricting ourselves to highly-excited s states. This allows us to demonstrate that along the Periodic Table of elements the Zel'dovich effect manifests itself as systematic periodic variation of the Rydberg spectra with a period proportional to the cubic root of the atomic number. This dependence, which is supported by analysis of experimental and numerical data, has its origin in the binding properties of the ionic core of the atom.Comment: 17 pages, 12 figure

    Casimir stress on parallel plates in de Sitter space

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    The Casimir stress on two parallel plates in de Sitter background for massless scalar field satisfying Robin boundary conditions on the plates is calculated. The metric is written in conformally flat form to make maximum use of the Minkowski space calculations. Different cosmological constants are assumed for the space between and outside of the plates to have general results applicable to the case of domain wall formations in the early universe.Comment: 6 page
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