256 research outputs found
Method of functional integration in the problem of line width of parametric X-ray relativistic electron radiation in a crystal
The coherent and non-coherent scattering effects on "backward" parametric
X-ray radiation by relativistic electrons in a crystal on the basis of the
method of functional integration is investigated. A comparison of contributions
of these effects to parametric X-ray radiation line width has been considered.
It is shown that in a number of cases the major contribution to the line width
of parametric X-ray radiation is made by non-coherent multiple scattering.Comment: 7 pages, LaTeX2e forma
Resonant Diffusive Radiation in Random Multilayered Systems
We have theoretically shown that the yield of diffuse radiation generated by
relativistic electrons passing random multilayered systems can be increased
when a resonant condition is met. Resonant condition can be satisfied for the
wavelength region representing visible light as well as soft X-rays. The
intensity of diffusive soft X-rays for specific multilayered systems consisting
of two components is compared with the intensity of Cherenkov radiation. For
radiation at photon energy of , the intensity of Resonant Diffusive
Radiation (RDR) generated by electrons passing a multilayer
exceeds the intensity of Cherenkov radiation by a factor of for
electrons with the same energy passing a foil. For a photon energy of
and electrons passing multilayer generate RDR exceeding
Cherenkov radiation generated by electrons passing a foils by a factor
.Comment: Talk presented at the RC2005, Frascati, Ital
Relativistic Oscillator Model and Delbr\"uck scattering
Elastic scattering of photons in a Lorentz-scalar potential via virtual
spin-zero particle-antiparticle pairs (`` Delbr\"uck scattering") is
considered. An analytic expression for the Delbr\"uck amplitude is found
exactly in case of an oscillator potential. General properties of the amplitude
and its asymptotics are discussed.Comment: 8 pages, LATEX, BINP 94-6
The influence of the structure imperfectness of a crystalline undulator on the emission spectrum
We study the influence of an imperfect structure of a crystalline undulator
on the spectrum of the undulator radiation. The main attention is paid to the
undulators in which the periodic bending in the bulk appears as a result of a
regular (periodic) surface deformations. We demonstrate that this method of
preparation of a crystalline undulator inevitably leads to a variation of the
bending amplitude over the crystal thickness and to the presence of the
subharmonics with smaller bending period. Both of these features noticeably
influence the monochromatic pattern of the undulator radiation.Comment: 26 pages, 9 figures, IOP style, submitted to NIM
Self-amplified Cherenkov radiation from a relativistic electron in a waveguide partially filled with a laminated material
The radiation from a relativistic electron uniformly moving along the axis of
cylindrical waveguide filled with laminated material of finite length is
investigated. Expressions for the spectral distribution of radiation passing
throw the transverse section of waveguide at large distances from the laminated
material are derived with no limitations on the amplitude and variation profile
of the layered medium permittivity and permeability. Numerical results for
layered material consisting of dielectric plates alternated with vacuum gaps
are given. It is shown that at a special choice of problem parameters,
Cherenkov radiation generated by the relativistic electron inside the plates is
self-amplified. The visual explanation of this effect is given and a possible
application is discussed.Comment: 8 pages, 4 figures,1 table, the paper is accepted for publication in
the Journal of Physics: Conference Serie
Synchrotron radiation from a charge moving along a helical orbit inside a dielectric cylinder
The radiation emitted by a charged particle moving along a helical orbit
inside a dielectric cylinder immersed into a homogeneous medium is
investigated. Expressions are derived for the electromagnetic potentials,
electric and magnetic fields, and for the spectral-angular distribution of
radiation in the exterior medium. It is shown that under the Cherenkov
condition for dielectric permittivity of the cylinder and the velocity of the
particle image on the cylinder surface, strong narrow peaks are present in the
angular distribution for the number of radiated quanta. At these peaks the
radiated energy exceeds the corresponding quantity for a homogeneous medium by
some orders of magnitude. The results of numerical calculations for the angular
distribution of radiated quanta are presented and they are compared with the
corresponding quantities for radiation in a homogeneous medium. The special
case of relativistic charged particle motion along the direction of the
cylinder axis with non-relativistic transverse velocity (helical undulator) is
considered in detail. Various regimes for the undulator parameter are
discussed. It is shown that the presence of the cylinder can increase
essentially the radiation intensity.Comment: 18 pages, 8 EPS figure
Electron-based crystalline undulator
We discuss the features of a crystalline undulator of the novel type based on
the effect of a planar channeling of ultra-relativistic electrons in a
periodically bent crystals. It is demonstrated that an electron-based undulator
is feasible in the tens of GeV range of the beam energies, which is noticeably
higher than the energy interval allowed in a positron-based undulator.
Numerical analysis of the main parameters of the undulator as well as the
characteristics of the emitted undulator radiation is carried out for 20 and 50
GeV electrons channeling in diamond and silicon crystals along the (111)
crystallographic planes.Comment: 16 pages, 8 figures, Latex, IOP styl
Enhancement Effects of Transition and Vavilov-Cherenkov Radiation Mechanisms Under Grazing Interaction of Fast Electrons With a Thick Substrate Applied by Thin Layer
The paper presents the results of a theoretical study and a mathematical model of radiation processes occurred during the grazing interaction of fast electrons with semi-infinite targets applied on a thin amorphous layer. The developed model considers Vavilov-Cherenkov and transition radiation mechanisms and predicts the possibility to enhance the angular radiation density under grazing incidence of fast electrons on the layer. The characteristics of possible extreme vacuum ultraviolet and soft X-ray sources are estimated
One-dimensional Model of a Gamma Klystron
A new scheme for amplification of coherent gamma rays is proposed. The key
elements are crystalline undulators - single crystals with periodically bent
crystallographic planes exposed to a high energy beam of charged particles
undergoing channeling inside the crystals. The scheme consists of two such
crystals separated by a vacuum gap. The beam passes the crystals successively.
The particles perform undulator motion inside the crystals following the
periodic shape of the crystallographic planes. Gamma rays passing the crystals
parallel to the beam get amplified due to interaction with the particles inside
the crystals. The term `gamma klystron' is proposed for the scheme because its
operational principles are similar to those of the optical klystron. A more
simple one-crystal scheme is considered as well for the sake of comparison. It
is shown that the gamma ray amplification in the klystron scheme can be reached
at considerably lower particle densities than in the one-crystal scheme,
provided that the gap between the crystals is sufficiently large.Comment: RevTeX4, 22 pages, 4 figure
Electromagnetic field and radiation for a charge moving along a helical trajectory inside a waveguide with dielectric filling
We investigate the electromagnetic field generated by a point charge moving
along a helical trajectory inside a circular waveguide with conducting walls
filled by homogeneous dielectric. The parts corresponding to the radiation
field are separated and the formulae for the radiation intensity are derived
for both TE and TM waves. It is shown that the main part of the radiated quanta
is emitted in the form of the TE waves. Various limiting cases are considered.
The results of the numerical calculations show that the insertion of the
waveguide provides an additional mechanism for tuning the characteristics of
the emitted radiation by choosing the parameters of the waveguide and filling
medium.Comment: 17 pages, 9 figures, discussion, graphs, and references adde
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