8,171 research outputs found
Decay Process for Three - Species Reaction - Diffusion System
We propose the deterministic rate equation of three-species in the reaction -
diffusion system. For this case, our purpose is to carry out the decay process
in our three-species reaction-diffusion model of the form . The
particle density and the global reaction rate are also shown analytically and
numerically on a two-dimensional square lattice with the periodic boundary
conditions. Especially, the crossover of the global reaction rate is discussed
in both early-time and long-time regimes.Comment: 6 pages, 3 figures, Late
Persistence in systems with conserved order parameter
We consider the low-temperature coarsening dynamics of a one-dimensional
Ising ferromagnet with conserved Kawasaki-like dynamics in the domain
representation. Domains diffuse with size-dependent diffusion constant, with . We generalize this model to arbitrary
, and derive an expression for the domain density, with , using a scaling argument. We also
investigate numerically the persistence exponent characterizing the
power-law decay of the number, , of persistent (unflipped) spins at
time , and find where depends on
. We show how the results for and are related to
similar calculations in diffusion-limited cluster-cluster aggregation (DLCA)
where clusters with size-dependent diffusion constant diffuse through an
immobile `empty' phase and aggregate irreversibly on impact. Simulations show
that, while is the same in both models, is different except for
. We also investigate models that interpolate between symmetric
domain diffusion and DLCA.Comment: 9 pages, minor revision
Position and energy-resolved particle detection using phonon-mediated microwave kinetic inductance detectors
We demonstrate position and energy-resolved phonon-mediated detection of particle interactions in a silicon substrate instrumented with an array of microwave kinetic inductance detectors (MKIDs). The relative magnitude and delay of the signal received in each sensor allow the location of the interaction to be determined with ≲ 1mm resolution at 30 keV. Using this position information, variations in the detector response with position can be removed, and an energy resolution of σ_E = 0.55 keV at 30 keV was measured. Since MKIDs can be fabricated from a single deposited film and are naturally multiplexed in the frequency domain, this technology can be extended to provide highly pixelized athermal phonon sensors for ∼1 kg scale detector elements. Such high-resolution, massive particle detectors would be applicable to rare-event searches such as the direct detection of dark matter, neutrinoless double-beta decay, or coherent neutrino-nucleus scattering
Normal-superfluid interaction dynamics in a spinor Bose gas
Coherent behavior of spinor Bose-Einstein condensates is studied in the
presence of a significant uncondensed (normal) component. Normal-superfluid
exchange scattering leads to a near-perfect local alignment between the spin
fields of the two components. Through this spin locking, spin-domain formation
in the condensate is vastly accelerated as the spin populations in the
condensate are entrained by large-amplitude spin waves in the normal component.
We present data evincing the normal-superfluid spin dynamics in this regime of
complicated interdependent behavior.Comment: 5 pages, 4 fig
A Nonlinear Ergodic Theorem for Discrete Systems
27 pages, 1 article*A Nonlinear Ergodic Theorem for Discrete Systems* (Crowe, K. M.) 27 page
Estimation of Survival Rates from a Jolly-Seber Model with Tag Loss
22 pages, 1 article*Estimation of Survival Rates from a Jolly-Seber Model with Tag Loss* (Kremers, Walter K.) 22 page
On the Modelling of Epidemics
18 pages, 1 article*On the Modelling of Epidemics* (Castillo-Chavez, C.; Cooke, K.; Levin, S. A.) 18 page
Tests for Mortality and Recruitment in a K-Sample Tag-Recapture Experiment
16 pages, 1 article*Tests for Mortality and Recruitment in a K-Sample Tag-Recapture Experiment* (Pollock, K. H.; Solomon, D. L.; Robson, D. S.) 16 page
Renormalization Group Study of the A+B->0 Diffusion-Limited Reaction
The diffusion-limited reaction, with equal initial densities
, is studied by means of a field-theoretic renormalization
group formulation of the problem. For dimension an effective theory is
derived, from which the density and correlation functions can be calculated. We
find the density decays in time as a,b \sim C\sqrt{\D}(Dt)^{-d/4} for , with \D = n_0-C^\prime n_0^{d/2} + \dots, where is a universal
constant, and is non-universal. The calculation is extended to the
case of unequal diffusion constants , resulting in a new
amplitude but the same exponent. For a controlled calculation is not
possible, but a heuristic argument is presented that the results above give at
least the leading term in an expansion. Finally, we address
reaction zones formed in the steady-state by opposing currents of and
particles, and derive scaling properties.Comment: 17 pages, REVTeX, 13 compressed figures, included with epsf. Eq.
(6.12) corrected, and a moderate rewriting of the introduction. Accepted for
publication in J. Stat. Phy
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