27,397 research outputs found
Time-dependent analysis of the nuclear and Coulomb dissociation of 11Be
The breakup of 11Be on carbon and lead targets around 70 MeV/nucleon is
investigated within a semiclassical framework. The role of the 5/2+ resonance
is analyzed in both cases. It induces a narrow peak in the nuclear-induced
breakup cross section, while its effect on Coulomb breakup is small. The
nuclear interactions between the projectile and the target is responsible for
the transition toward this resonant state. The influence of the parametrization
of the 10Be-n potential that simulates 11Be is also addressed. The breakup
calculation is found to be dependent on the potential choice. This leads us to
question the reliability of this technique to extract spectroscopic factors.Comment: 9 pages, 6 figures, to be published in the Proceedings of the Second
Argonne/MSU/JINA/INT RIA Workshop on Reaction Mechanisms for rare Isotope
Beams (2005
A comprehensive model to determine the effects of temperature and species fluctuations on reaction rates in turbulent reacting flows
The use of probability theory to determine the effects of turbulent fluctuations on reaction rates in turbulent combustion systems is briefly reviewed. Results are presented for the effect of species fluctuations in particular. It is found that turbulent fluctuations of species act to reduce the reaction rates, in contrast with the temperature fluctuations previously determined to increase Arrhenius reaction rate constants. For the temperature fluctuations, a criterion is set forth for determining if, in a given region of a turbulent flow field, the temperature can be expected to exhibit ramp like fluctuations. Using the above results, along with results previously obtained, a model is described for testing the effects of turbulent fluctuations of temperature and species on reaction rates in computer programs dealing with turbulent reacting flows. An alternative model which employs three variable probability density functions (temperature and two species) and is currently being formulated is discussed as well
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Formation of the Wink Sink, A Salt Dissolution and Collapse Feature, Winkler County, Texas
UT Librarie
Thermodynamic entropy production fluctuation in a two dimensional shear flow model
We investigate fluctuations in the momentum flux across a surface
perpendicular to the velocity gradient in a stationary shear flow maintained by
either thermostated deterministic or by stochastic boundary conditions. In the
deterministic system the Gallavotti-Cohen (GC)relation for the probability of
large deviations, which holds for the phase space volume contraction giving the
Gibbs ensemble entropy production, never seems to hold for the flux which gives
the hydrodynamic entropy production. In the stochastic case the GC relation is
found to hold for the total flux, as predicted by extensions of the GC theorem
but not for the flux across part of the surface. The latter appear to satisfy a
modified GC relation. Similar results are obtained for the heat flux in a
steady state produced by stochastic boundaries at different temperatures.Comment: 9 postscript figure
Friedel oscillations in disordered quantum wires: Influence of e-e interactions on the localization length
The Friedel oscillations caused due to an impurity located at one edge of a
disordered interacting quantum wire are calculated numerically. The electron
density in the system's ground state is determined using the DMRG method, and
the Friedel oscillations data is extracted using the density difference between
the case in which the wire is coupled to an impurity and the case where the
impurity is uncoupled. We show that the power law decay of the oscillations
occurring for an interacting clean 1D samples described by Luttinger liquid
theory, is multiplied by an exponential decay term due to the disorder. Scaling
of the average Friedel oscillations by this exponential term collapses the
disordered samples data on the clean results. We show that the length scale
governing the exponential decay may be associated with the Anderson
localization length and thus be used as a convenient way to determine the
dependence of the localization length on disorder and interactions. The
localization length decreases as a function of the interaction strength, in
accordance with previous predictions.Comment: 7 pages, 7 figure
Bohmian Mechanics and Quantum Information
Many recent results suggest that quantum theory is about information, and
that quantum theory is best understood as arising from principles concerning
information and information processing. At the same time, by far the simplest
version of quantum mechanics, Bohmian mechanics, is concerned, not with
information but with the behavior of an objective microscopic reality given by
particles and their positions. What I would like to do here is to examine
whether, and to what extent, the importance of information, observation, and
the like in quantum theory can be understood from a Bohmian perspective. I
would like to explore the hypothesis that the idea that information plays a
special role in physics naturally emerges in a Bohmian universe.Comment: 25 pages, 2 figure
Are All Particles Identical?
We consider the possibility that all particles in the world are fundamentally
identical, i.e., belong to the same species. Different masses, charges, spins,
flavors, or colors then merely correspond to different quantum states of the
same particle, just as spin-up and spin-down do. The implications of this
viewpoint can be best appreciated within Bohmian mechanics, a precise
formulation of quantum mechanics with particle trajectories. The implementation
of this viewpoint in such a theory leads to trajectories different from those
of the usual formulation, and thus to a version of Bohmian mechanics that is
inequivalent to, though arguably empirically indistinguishable from, the usual
one. The mathematical core of this viewpoint is however rather independent of
the detailed dynamical scheme Bohmian mechanics provides, and it amounts to the
assertion that the configuration space for N particles, even N
``distinguishable particles,'' is the set of all N-point subsets of physical
3-space.Comment: 12 pages LaTeX, no figure
Quantum Mechanics of Extended Objects
We propose a quantum mechanics of extended objects that accounts for the
finite extent of a particle defined via its Compton wavelength. The Hilbert
space representation theory of such a quantum mechanics is presented and this
representation is used to demonstrate the quantization of spacetime. The
quantum mechanics of extended objects is then applied to two paradigm examples,
namely, the fuzzy (extended object) harmonic oscillator and the Yukawa
potential. In the second example, we theoretically predict the phenomenological
coupling constant of the meson, which mediates the short range and
repulsive nucleon force, as well as the repulsive core radius.Comment: RevTex, 24 pages, 1 eps and 5 ps figures, format change
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