7,352 research outputs found
Hydrodynamic fluctuations in relativistic superfluids
The Hamiltonian formulation of superfluids based on noncanonical Poisson
brackets is studied in detail. The assumption that the momentum density is
proportional to the flow of the conserved energy is shown to lead to the
covariant relativistic theory previously suggested by Khalatnikov, Lebedev and
Carter, and some potentials in this theory are given explicitly. We discuss
hydrodynamic fluctuations in the presence of dissipative effects and we derive
the corresponding set of hydrodynamic correlation functions. Kubo relations for
the transport coefficients are obtained.Comment: 13 pages, no figures, two references adde
Self-assembled Zeeman slower based on spherical permanent magnets
We present a novel type of longitudinal Zeeman slower. The magnetic field
profile is generated by a 3D array of permanent spherical magnets, which are
self-assembled into a stable structure. The simplicity and stability of the
design make it quick to assemble and inexpensive. In addition, as with other
permanent magnet slowers, no electrical current or water cooling is required.
We describe the theory, assembly, and testing of this new design
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
Current reversals in a rocking ratchet: dynamical vs symmetry-breaking mechanisms
Directed transport in ratchets is determined by symmetry-breaking in a system
out of equilibrium. A hallmark of rocking ratchets is current reversals: an
increase in the rocking force changes the direction of the current. In this
work for a bi-harmonically driven spatially symmetric rocking ratchet we show
that a class of current reversal is precisely determined by symmetry-breaking,
thus creating a link between dynamical and symmetry-breaking mechanisms
Triple galaxies and a hidden mass problem
The authors consider a homogeneous sample of 84 triple systems of galaxies with components brighter than m = 15.7, located in the northern sky and satisfying an isolation criterion with respect to neighboring galaxies in projection. The distributions of basic dynamical parameters for triplets have median values as follows: radial velocity dispersion 133 km/s, mean harmonic radius 63 kpc, absolute magnitude of galaxies M sub B equals -20.38, crossing time tau = 0.04 H(sup minus 1). For different ways of estimation the median mass-to-luminosity ratio is (20 - 30). A comparison of the last value with the ones for single and binary galaxies shows the presence of a virial mass excess for triplets by a factor 4. The mass-to-luminosity ratio is practically uncorrelated with linear size of triplets or with morphological types of their components. We note that a significant part of the virial excess may be explained by the presence of nonisolated triple configurations in the sample, which are produced by debris of more populous groups of galaxies
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
Classical and relativistic dynamics of supersolids: variational principle
We present a phenomenological Lagrangian and Poisson brackets for obtaining
nondissipative hydrodynamic theory of supersolids. A Lagrangian is constructed
on the basis of unification of the principles of non-equilibrium thermodynamics
and classical field theory. The Poisson brackets, governing the dynamics of
supersolids, are uniquely determined by the invariance requirement of the
kinematic part of the found Lagrangian. The generalization of Lagrangian is
discussed to include the dynamics of vortices. The obtained equations of motion
do not account for any dynamic symmetry associated with Galilean or Lorentz
invariance. They can be reduced to the original Andreev-Lifshitz equations if
to require Galilean invariance. We also present a relativistic-invariant
supersolid hydrodynamics, which might be useful in astrophysical applications.Comment: 22 pages, changed title and content, added reference
Controlling integrability in a quasi-1D atom-dimer mixture
We analytically study the atom-dimer scattering problem in the
near-integrable limit when the oscillator length l_0 of the transverse
confinement is smaller than the dimer size, ~l_0^2/|a|, where a<0 is the
interatomic scattering length. The leading contributions to the atom-diatom
reflection and break-up probabilities are proportional to a^6 in the bosonic
case and to a^8 for the up-(up-down) scattering in a two-component fermionic
mixture. We show that by tuning a and l_0 one can control the "degree of
integrability" in a quasi-1D atom-dimer mixture in an extremely wide range
leaving thermodynamic quantities unchanged. We find that the relaxation to
deeply bound states in the fermionic (bosonic) case is slower (faster) than
transitions between different Bethe ansatz states. We propose a realistic
experiment for detailed studies of the crossover from integrable to
nonintegrable dynamics.Comment: 12 pages, 1 figur
The gas phase cyclization of deprotonated N-aryl-2-cyano-2-diazoacetamides
The document attached has been archived with permission from the publisher.1-Aryl-4-cyano-5-hydroxy-1,2,3-triazoles can be obtained in solution by base-catalysed cyclization of N-aryl-2-cyano-2-diazoacetamides. A similar reaction was shown to take place under conditions of negative ion chemical ionization in the ion source of a mass spectrometer. High resolution mass spectrometry, tandem mass spectrometry, charge reversal spectra, synthesis of the ions with known structures and quantum chemical calculations were used to prove the latter statement. The fact of the observed cyclization demonstrates once again the ability of mass spectrometry to study the gas phase chemical reactions that take place in solution.Vladislav V. Lobodin, Yuriy Yu. Morzherin, Tom Blumenthal, Daniel Bilusich, Vladimir V. Ovcharenko, John H. Bowie, and Albert T. Lebede
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