2,471 research outputs found
Radiation and shielding study for the International Ultraviolet Explorer
Technical advisory services to ensure integrity of parts and material exposed to energetic particle radiation for the IUE scientific instruments, spacecraft, and subsystems are provided. A significant potential for interference, degradation, or failure for unprotected or sensitive items was found. Vulnerable items were identified, and appropriate tests, changes, and shields were defined
Perturbations in the Kerr-Newman Dilatonic Black Hole Background: Maxwell Waves, the Dilaton Background and Gravitational Lensing
In this paper we continue the analysis of our previous papers and study the
affect of the existence of a non-trivial dilaton background on the propagation
of electromagnetic waves in the Kerr-Newman dilatonic black hole space-time.
For this purpose we again employ the double expansion in both the background
electric charge and the wave parameters of the relevant quantities in the
Newman-Penrose formalism and then identify the first order at which the dilaton
background enters the Maxwell equations. We then assume that gravitational and
dilatonic waves are negligible (at that order in the charge parameter) with
respect to electromagnetic waves and argue that this condition is consistent
with the solutions already found in the previous paper. Explicit expressions
are given for the asymptotic behavior of scattered waves, and a simple physical
model is proposed in order to test the effects. An expression for the relative
intensity is obtained for Reissner-Nordstrom dilaton black holes using
geometrical optics. A comparison with the approximation of geometrical optics
for Kerr-Newman dilaton black holes shows that at the order to which the
calculations are carried out gravitational lensing of optical images cannot
probe the dilaton background.Comment: 9 pages, 1 figur
Non-Singular Charged Black Hole Solution for Non-Linear Source
A non-singular exact black hole solution in General Relativity is presented.
The source is a non-linear electromagnetic field, which reduces to the Maxwell
theory for weak field. The solution corresponds to a charged black hole with
|q| \leq 2s_c m \approx 0.6 m, having metric, curvature invariants, and
electric field bounded everywhere.Comment: 3 pages, RevTe
Quantum Holonomy in Three-dimensional General Covariant Field Theory and Link Invariant
We consider quantum holonomy of some three-dimensional general covariant
non-Abelian field theory in Landau gauge and confirm a previous result
partially proven. We show that quantum holonomy retains metric independence
after explicit gauge fixing and hence possesses the topological property of a
link invariant. We examine the generalized quantum holonomy defined on a
multi-component link and discuss its relation to a polynomial for the link.Comment: RevTex, 12 pages. The metric independence of path integral measure is
justified and the case of multi-component link is discussed in detail. To be
published in Physical Review
Entanglement and State Preparation
When a subset of particles in an entangled state is measured, the state of
the subset of unmeasured particles is determined by the outcome of the
measurement. This first measurement may be thought of as a state preparation
for the remaining particles. In this paper, we examine how the duration of the
first measurement effects the state of the unmeasured subsystem. The state of
the unmeasured subsytem will be a pure or mixed state depending on the nature
of the measurement.
In the case of quantum teleportation we show that there is an eigenvalue
equation which must be satisfied for accurate teleportation. This equation
provides a limitation to the states that can be accurately teleported.Comment: 24 pages, 3 figures, submitted to Phys. Rev.
Evaporation and Fate of Dilatonic Black Holes
We study both spherically symmetric and rotating black holes with dilaton
coupling and discuss the evaporation of these black holes via Hawking's quantum
radiation and their fates. We find that the dilaton coupling constant
drastically affects the emission rates, and therefore the fates of the black
holes. When the charge is conserved, the emission rate from the non-rotating
hole is drastically changed beyond (a superstring theory) and
diverges in the extreme limit. In the rotating cases, we analyze the slowly
rotating black hole solution with arbitrary as well as three exact
solutions, the Kerr--Newman (), and Kaluza--Klein (), and Sen black hole ( and with axion field). Beyond the
same critical value of , the emission rate becomes very large
near the maximally charged limit, while for it remains finite. The
black hole with may evolve into a naked singularity due to its
large emission rate. We also consider the effects of a discharge process by
investigating superradiance for the non-rotating dilatonic black hole.Comment: 33 pages, LaTex, 14 postscript figure files (appended as a uuencoded
compressed tar file
Semiclassical Extremal Blackholes
Extremal black holes are studied in a two dimensional model motivated by a
dimensional reduction from four dimensions. Their quantum corrected geometry is
calculated semiclassically and a mild singularity is shown to appear at the
horizon.
Extensions of the geometry past the horizon are not unique but there are
continuations free from malevolent singularities. A few comments are made about
the relevance of these results to four dimensions and to the study of black
hole entropy and information loss.Comment: 16 pages, 2 figures upon request, CALT-68-1833 - (new version
corrects omissions in previous list of references
Nonstorm time dynamics of electron radiation belts observed by the Van Allen Probes
Abstract Storm time electron radiation belt dynamics have been widely investigated for many years. Here we present a rarely reported nonstorm time event of electron radiation belt evolution observed by the Van Allen Probes during 21-24 February 2013. Within 2 days, a new belt centering around L=5.8 formed and gradually merged with the original outer belt, with the enhancement of relativistic electron fluxes by a factor of up to 50. Strong chorus waves (with power spectral density up to 10-4nT2/Hz) occurred in the region L\u3e5. Taking into account the local acceleration driven by these chorus waves, the two-dimensional STEERB can approximately reproduce the observed energy spectrums at the center of the new belt. These results clearly illustrate the complexity of electron radiation belt behaviors and the importance of chorus-driven local acceleration even during the nonstorm times
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