9,125 research outputs found
The effect of electron surface scattering on fine metal particle electromagnetic radiation absorption
The magnetic dipole absorption cross section of a spherically shaped metal
particle was calculated in terms of kinetic approach. The particle considered
was placed in the field of a plane electromagnetic wave. The model of boundary
conditions was investigated taking into account the dependence of the
reflectivity coefficient both on the surface roughness parameter and on the
electron incidence angle. The results obtained were compared with theoretical
computation results for a model of combined diffusion-specular boundary
conditions of Fuchs.Comment: 9 pages, 5 figure
On the Fourier transform of the characteristic functions of domains with -smooth boundary
We consider domains with -smooth boundary and
study the following question: when the Fourier transform of the
characteristic function belongs to ?Comment: added two references; added footnotes on pages 6 and 1
Transverse Instabilities of Coasting Beams with Space Charge
Transverse beam stability is strongly affected by the beam space charge.
Usually it is analyzed with the rigid-beam model. However this model is only
valid when a bare (not affected by the space charge) tune spread is small
compared to the space charge tune shift. This condition specifies a relatively
small area of parameters which, however, is the most interesting for practical
applications. The Landau damping rate and the beam Schottky spectra are
computed assuming that validity condition is satisfied. The results are applied
to a round Gaussian beam. The stability thresholds are described by simple fits
for the cases of chromatic and octupole tune spreads.Comment: 6 pages, 2 figures, accepted by Phys. Rev. ST - Accel. Beam
Simulation of Beam-Beam Effects and Tevatron Experience
Effects of electromagnetic interactions of colliding bunches in the Tevatron
had a variety of manifestations in beam dynamics presenting vast opportunities
for development of simulation models and tools. In this paper the computer code
for simulation of weak-strong beam-beam effects in hadron colliders is
described. We report the collider operational experience relevant to beam-beam
interactions, explain major effects limiting the collider performance and
compare results of observations and measurements with simulations.Comment: 23 pages, 17 figure
H-theorem in quantum physics
Remarkable progress of quantum information theory (QIT) allowed to formulate
mathematical theorems for conditions that data-transmitting or data-processing
occurs with a non-negative entropy gain. However, relation of these results
formulated in terms of entropy gain in quantum channels to temporal evolution
of real physical systems is not thoroughly understood. Here we build on the
mathematical formalism provided by QIT to formulate the quantum H-theorem in
terms of physical observables. We discuss the manifestation of the second law
of thermodynamics in quantum physics and uncover special situations where the
second law can be violated. We further demonstrate that the typical evolution
of energy-isolated quantum systems occurs with non-diminishing entropy.Comment: 8 pages, 4 figure
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