935 research outputs found
Calculation of The Lifetimes of Thin Stripper Targets Under Bombardment of Intense Pulsed Ions
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
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
We present a non-perturbative expression for the scattering matrix of
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
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
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
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
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
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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