Transition radiation on semi-infinite plate and Smith-Purcell effect

The Smith-Purcell radiation is usually measured when an electron passes over the grating of metallic stripes. However, for high frequencies (exceeding the plasma frequency of the grating material) none material could be treated as a conductor, but ought to be considered as a dielectric with plasma-like permittivity. So for describing Smith-Purcell radiation in the range of high frequencies new theoretical approaches are needed. In the present paper we apply the simple variant of eikonal approximation developed earlier to the case of radiation on the set of parallel semi-infinite dielectric plates. The formulae obtained describe the radiation generated by the particles both passing through the plates (traditionally referred as "transition radiation") and moving in vacuum over the grating formed by the edges of the plates (traditionally referred as "diffraction radiation", and, taking into account the periodicity of the plates arrangement, as Smith-Purcell radiation).Comment: Submitted to Journal of Physics: Conference Serie

On spectral method in the axial channeling theory

The quantization of the transverse motion energy in the continuous potentials of atomic strings and planes can take place under passage of fast charged particles through crystals. The energy levels for electron moving in axial channeling regime in a system of parallel atomic strings (for instance, [110] strings of a silicon crystal) are found in this work for the electron energy of order of several tens of MeV, when a total number of energy levels becomes large (up to several hundreds). High resolution of the spectral method used for energy level search has been demonstrated. Hence this method could be useful for investigation of quantum chaos problem.Comment: 11 pages, 4 figures, presented on the conference "Channeling-2012", 23-28 September 2012 Alghero, Sardegna, Italy; accepted for publication in Nuclear Instruments and Methods

Contribution of incoherent effects to the orientation dependence of bremsstrahlung from rapid electrons in crystal

The bremsstrahlung cross section for relativistic electrons in a crystal is split into the sum of coherent and incoherent parts (the last is due to a thermal motion of atoms in the crystal). Although the spectrum of incoherent radiation in crystal is similar to one in amorphous medium, the incoherent radiation intensity could demonstrate substantial dependence on the crystal orientation due to the electrons' flux redistribution in the crystal. In the present paper we apply our method of the incoherent bremsstrahlung simulation developed earlier to interpretation of some recent experimental results obtained at the Mainz Microtron MAMI.Comment: VIII International Symposium "Radiation from Relativistic Electrons in Periodic Structures" (RREPS-09) Zvenigorod, Russia, September 7-11, 200

Spectral method in axial channeling theory

The energy quantization of transverse particle motion in continuous potentials of atomic chains and planes can occur when fast charged particles travel in crystals. In the proposed paper, the energy levels of electrons moving in the mode of axial channeling in a system of parallel atomic chains have been found. The energy eigenvalues were determined numerically using the so-called spectral method, which shows itself to good advantage in the problem of the plane channeling of charged particles in crystal

Scattering of electromagnetic wave by dielectric cylinder in eikonal approximation

The scattering of the plane electromagnetic wave on a spatially extended, fiber lake target is considered. The formula for the scattering cross section is obtained using the approximation analogous to eikonal one in quantum mechanic

On transition radiation by relativistic electron

The problem of relativistic electron transition radiation on a thin ideally conducting plate is considered. The space-time evolution of the electromagnetic field, which arises before and after the electron’s traverse of the plate, is analyzed. It is shown that at the moment of time t after the electron’s traverse of the plate for distances r > ct the reflected field is different from zero and entirely coincides with the Coulomb field of oppositely charged particle which should move in the direction of reflection. For distances r < ct the total field equals zero. A similar picture of field evolution takes place in the opposite direction. The potential jump at r = ct entirely defines the characteristics of backward transition radiation. The analogy in the development of the space-time picture of the electromagneticfield evolution in the processes of transition radiation and bremsstrahlung at the momentary scattering of the relativistic electron to a large angle is discussed

On the effect of anomalous photoabsorption in parametric X radiation

The parametric X radiation of relativistic electrons passing through a monocrystal is considered. It is demonstrated that, contrary to widespread option, conditions for the effect of anomalous photoabsorption to show up can be realized in the Laue scattering geometryye