2,342 research outputs found
Stationary Charge Imbalance Effect in System of Coupled Josephson Junction
We investigate stationary charge imbalance effect in the system of coupled
overdamped Josephson junctions. We show that coupling between junction and
nonzero stationary charge imbalance in the resistive state bring to a decrease
of the Josephson frequency in the Josephson junctions of the stack. The formed
difference in Josephson frequency leads to the nonuniform switch to the Shapiro
step regime in the presence of external electromagnetic radiation and
appearance of kinks of voltage on the IV-characteristics of the stack. We also
show that stationary charge imbalance brings to the slope of the Shapiro step
due to the difference of the charge imbalance potential on the edges of the
step. The theoretical and experimental results for voltage bias coupled
Josephson junctions have been compared with the current bias case
Cosmic Rays from Gamma Ray Bursts in the Galaxy
The rate of terrestrial irradiation events by galactic gamma-ray bursts
(GRBs) is estimated using recent standard-energy results. We assume that GRBs
accelerate high-energy cosmic rays, and present results of three-dimensional
simulations of cosmic rays moving in the Galactic magnetic field and diffusing
through pitch-angle scattering. An on-axis GRB extinction event begins with a
powerful prompt gamma-ray and neutron pulse, followed by a longer-lived phase
from cosmic-ray protons and neutron-decay protons that diffuse towards Earth.
Our results force a reinterpretation of reported ~ 10^{18} eV cosmic-ray
anisotropies and offer a rigorous test of the model where high-energy cosmic
rays originate from GRBs, which will soon be tested with the Auger Observatory.Comment: 9 pages, 4 figures, ApJ Letters, in press. Clarified limit of
test-particle approximation, prediction that Auger will not confirm SUGAR
source. (Data may not appear onscreen at low magnification.) Simulations at
http://heseweb.nrl.navy.mil/gamma/~dermer/invest/sim/index.ht
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