N. N. Nasonov

Collective effects in the polarization bremsstrahlung of relativistic electrons in condensed media

Abstract The influence of a medium structure on the features of the polarization bremsstrahlung (PB) of relativistic electrons is investigated theoretically. The essential quantitative change of PB spectrum because of the density effect is shown for relativistic electrons moving in an amorphous medium as well as the qualitative change of the spectral-angular distribution of PB photons emitted in a polycrystal

POLARIZATION BREMSSTRAHLUNG OF RELATIVISTIC ELECTRONS IN ALUMINIUM

Abstract The spectral-angular distribution of the polarization bremsstrahlung of relativistic electrons crossing a thin aluminium foil is measured. The earlier predicted strong difference between polarization bremsstrahlung properties for amorphous and polycrystalline targets is observed for the first time.

On the parametric X-rays along an emitting particle velocity

Parametric X-rays along an emitting particle velocity is studied for the Bragg scattering geometry. The absence of discussed radiation yield in the case of thick enough target when an influence of a photoabsorption plays an important role is predicted. The correct boundary conditions for an emission field at the out-surface of absorbing semi-infinite crystalline target are discussed.

An investigation of the parametric X-rays along the velocity of emitting particle

Parametric X-rays (PXR) along the velocity of relativistic electrons crossing a crystalline target is studied in this work. The detailed theory of PXR for Laue scattering geometry is developed with account of contributions of both PXR and transition radiation (TR) to the total emission yield. An influence of photoabsorption and interference between PXR and TR on the forward PXR properties are studied. Most appropriate conditions for the real experiment devoted to forward PXR observation are elucidated on the basis of the developed theory. The advantage of the use of heavy crystals with this aim in mind is shown. The expected experimental results are discussed.

Anomalous peak in the spectrum of polarizational bremsstrahlung from relativistic electrons moving through a solid target

The spectral-angular distribution of polarizational bremsstrahlung from relativistic electrons crossing a polycrystalline target is studied theoretically. The effect of substantial growth in the emission spectral density is predicted for photons emitted in the backward direction relative to emitting electron velocity.

Borrmann effect in parametric X-ray radiation

Abstract The suppression of the photoabsorption in parametric X-ray radiation by relativistic particles in a crystal is predicted. This dynamical effect caused by the contribution of emitting particle transition radiation to parametric X-ray radiation yield is possible in a crystal with a finite thickness only.

Investigation of contactless electron transmission through dielectric channels

The effect of the contactless transmission (guiding) of 10 keV electrons through cylindrical dielectric channels and planar channels formed by glass plates is studied. The capture and propagation of an electron beam along the channel axis, usual in these cases, are observed in the experiments with two plates. The deviation of the reflection angle from the specular angle and its dependence on the plate length and beamcurrent value under beam reflection from a single plate are investigated.

Measurement of the polarization bremsstrahlung of relativistic electrons in polycrystalline targets

The spectra of the collimated polarization bremsstrahlung of 7-MeV electrons intersecting Al, Cu, and Ni polycrystalline films have been measured. Detailed quantitative comparison of the experimental data with theoretical predictions has been performed. It has been shown that the model of a polycrystal as an ensemble of randomly oriented single crystals adequately describes the experimental results. This makes it possible to expect the development of a new method of diagnostics of the atomic structure of partially ordered solids.

On the effect of anomalous photoabsorption in the parametric X-rays

Suppression of the photoabsorption in parametric X-rays from relativistic electrons in a crystal is predicted. Such effect can be realized on condition of dynamical scattering of a fast particle equilibrium electromagnetic field only. It is shown that the emission angular density increases essentially due to considered effect.

Dynamical diffraction effects in the transition radiation of a relativistic electron crossing a thin crystal

Abstract Transition radiation (TR) of a relativistic electron crossing the in surface of a crystal may be scattered by a system of atomic planes. This effect may change essentially the interference between TR waves emitted from in and out surfaces of a crystalline target. The influence of the mentioned effect on total emission properties is studied in this work within the frame of the dynamical diffraction approach.