2,325 research outputs found
Slow solitary waves in multi-layered magnetic structures
The propagation of slow sausage surface waves in a multi-layered magnetic configuration is considered. The magnetic configuration consists of a central magnetic slab sandwiched between two identical magnetic slabs (with equilibrium quantities different from those in the central slab) which in turn are embedded between two identical semi-infinite regions. The dispersion equation is obtained in the linear approximation. The nonlinear governing equation describing waves with a characteristic wavelength along the central slab much larger than the slab thickness is derived. Solitary wave solutions to this equation are obtained in the case where these solutions deviate only slightly from the algebraic soliton of the Benjamin-Ono equation
Simulation of UHE muons propagation for GEANT3
A simulation package for the transport of high energy muons has been
developed. It has been conceived to replace the muon propagation software
modules implemented in the detector simulation program GEANT3. Here we discuss
the results achieved with our package and we check the agreement with numerical
calculations up to 10**8 GeV.Comment: 21 pages, 6 figures, 1 Table. AMSTeX document, acknowledgments adde
Phase mixing of Alfvén waves propagating in non-reflective magnetic plasma configurations
The ability of phase mixing to provide efficient damping of Alfvén waves even in weakly dissipative plasmas made it a popular mechanism for explaining the solar coronal heating. Initially it was studied in the equilibrium configurations with the straight magnetic field lines and the Alfvén speed only varying in the direction perpendicular to the magnetic field. Later the analysis of the Alfvén wave phase mixing was extended in various directions. In particular it was studied in two-dimensional planar magnetic plasma equilibria. Analytical investigation was carried out under the assumption that the wavelength is much smaller than the characteristic scale of the background quantity variation. This assumption enabled using the Wentzel, Kramers, and Brillouin (WKB) method. When it is not satisfied the study was only carried out numerically. In general, even the wave propagation in a one-dimensional inhomogeneous equilibrium can be only studied numerically. However there is one important exception, so-called non-reflective equilibria. In these equilibria the wave equation with the variable phase speed reduces to the Klein-Gordon equation with constant coefficients. In this paper we apply the theory of non-reflective wave propagation to studying the Alfvén wave phase mixing in two-dimensional planar magnetic plasma equilibria. Using curvilinear coordinates we reduce the equation describing the Alfvén wave phase mixing to the equation that becomes a one-dimensional wave equation in the absence of dissipation. This equation is further reduced to the equation which is the one-dimensional Klein-Gordon equation in the absence of dissipation. Then we show that this equation has constant coefficients when a particular relation between the plasma density and magnetic field magnitude is satisfied. Using the derived Klein-Gordon-type equation we study the phase mixing in various non-reflective equilibria. We emphasise that our analysis is valid even when the wavelength is comparable with the characteristic scale of the background quantity variation. In particular, we study the Alfvén wave damping due to phase mixing in an equilibrium with constant plasma density and exponentially divergent magnetic field lines. We confirm the result previously obtained in the WKB approximation that there is enhanced Alfvén wave damping in this equilibrium with the damping length proportional to ln(Re), where Re is the Reynolds number. Our theoretical results are applied to heating of coronal plumes. We show that, in spite of enhanced damping, Alfvén waves with periods of the order of one minute can be efficiently damped in the lower corona, at the height about 200 Mm, only if the shear viscosity is increased by about 6 orders of magnitude in comparison with its value given by the classical plasma theory. We believe that such increase of the shear viscosity can be provided by the turbulence
Weak interactions of supersymmetric staus at high energies
Neutrino telescopes may have the potential to detect the quasi-stable staus
predicted by supersymmetric models. Detection depends on stau electromagnetic
energy loss and weak interactions. We present results for the weak interaction
contribution to the energy loss of high energy staus as they pass through rock.
We show that the neutral current weak interaction contribution to the energy
loss increases with energy, but it is much smaller than the photonuclear energy
loss, however, the charged current contribution may become the dominant process
above the energy of GeV, depending on the parameters of the model.
As a consequence, the stau range may be reduced above GeV as
compared to the range neglecting weak interactions. We contrast this with the
tau range which is barely changed with the inclusion of charged current
interactions.Comment: 7 pages, 8 figures, version to be publishe
Application of oxide-metallic catalysts on valve metals for ecological catalysis
Запропоновано спосіб одержання оксидно-металевих каталізаторів методом одностадійного плазмово-електролітичного оксидування вентильних металів для знешкодження токсидів природного та техногенного походження. Обґрунтовано застосування оксидів мангану та кобальту як легуючих компонентів. Встановлено, що одержані оксидні покриви характеризуються високою каталітичною активністю в модельних реакціях конверсії токсичних компонентів, зокрема відпрацьованих газів двигунів внутрішнього згоряння
High energy leptons from muons in transit
The differential energy distribution for electrons and taus produced from
lepton pair production from muons in transit through materials is numerically
evaluated. We use the differential cross section to calculate underground
lepton fluxes from an incident atmospheric muon flux, considering contributions
from both conventional and prompt fluxes. An approximate form for the charged
current differential neutrino cross section is provided and used to calculate
single lepton production from atmospheric neutrinos. We compare the fluxes of
underground leptons produced from incident muons with those produced from
incident neutrinos and photons from muon bremsstrahlung. We discuss their
relevance for underground detectors.Comment: 11 pages, 9 figures v2: Revised to include the calculation of muon
bremsstrahlung events in comparison to pair production events. 1 new figur
UHE and EHE neutrino induced taus inside the Earth
Tau neutrinos interacting inside the Earth produce leptons which
thereafter can decay inside the atmosphere. The propagation of extremely
energetic \nut's and 's through the Earth is studied by means of a
detailed Monte Carlo simulation, taking into account all major mechanisms of
\nut interactions and energy loss as well as decay modes. The rates of
's emerging from the Earth are determined as a function of 's
energy for several cosmic neutrino models.Comment: 21 pages, accepted for publication in Astroparticle Physic
Charged Current Neutrino Cross Section and Tau Energy Loss at Ultra-High Energies
We evaluate both the tau lepton energy loss produced by photonuclear
interactions and the neutrino charged current cross section at ultra-high
energies, relevant to neutrino bounds with Earth-skimming tau neutrinos, using
different theoretical and phenomenological models for nucleon and nucleus
structure functions. The theoretical uncertainty is estimated by taking
different extrapolations of the structure function F2 to very low values of x,
in the low and moderate Q2 range for the tau lepton interaction and at high Q2
for the neutrino-nucleus inelastic cross section. It is at these extremely low
values of x where nuclear shadowing and parton saturation effects are unknown
and could be stronger than usually considered. For tau and neutrino energies
E=10^9 GeV we find uncertainties of a factor 4 for the tau energy loss and of a
factor 2 for the charged current neutrino-nucleus cross section.Comment: 20 pages and 11 figure
Propagation of supersymmetric charged sleptons at high energies
The potential for neutrino telescopes to discover charged stau production in
neutrino-nucleon interactions in Earth depends in part on the stau lifetime and
range. In some supersymmetric scenarios, the next lightest supersymmetric
particle is a stau with a decay length on the scale of 10 km. We evaluate the
electromagnetic energy loss as a function of energy and stau mass. The energy
loss parameter scales as the inverse stau mass for the dominating
electromagnetic processes, photonuclear and pair production. The range
can be parameterized as a function of stau mass, initial energy and minimum
final energy. In comparison to earlier estimates of the stau range, our results
are as much as a factor of two larger, improving the potential for stau
discovery in neutrino telescopes.Comment: 7 pages, 8 figures, version accepted for publication in Astroparticle
Physic
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