Atomic analogue of photonuclear configurational splitting

It is shown that the polarized bremsstrahlung (PB) emitted upon the scattering of a relativistic charged particle’s Coulomb field by atomic electrons yields direct information on the electronic structure of a medium. Indeed, in the X-ray photon energy range 1–10 keV, PB exhibits collective features and the PB intensity sharply increases. At higher photon energies, the coherence of shell electrons rapidly collapses, which is accompanied by a drastic decrease in the PB intensity; hence, the position of the PB spectrum kink allows estimation of the atomic size.     

Generation of circularly polarized photons by relativistic electrons moving in a crystal

The relativistic-electron (relativistic-positron) acceleration arising in its scattering on the potential of a crystal atomic string is highly anisotropic, which causes polarization of accompanying radiation. The possibility of developing an efficient source of circularly polarized photons by using electrons or positrons of energies attainable at many operating accelerators is demonstrated and analyzed.     

Electromagnetic interactions in liquid helium

The Hamiltonian of interaction of liquid helium with the quantized electromagnetic field plays an important role in such phenomena as Raman scattering, excitons, and possible cooperative effects of exchange of virtual photons. This interaction has been derived from first principles by application of an appropriate unitary transformation to the second-quantized Hamiltonian of nuclei and electrons interacting with the quantized radiation field. The transformation is chosen so that the atomic bound states appear explicitly in the relevant scattering and reaction terms of the transformed Hamiltonian.     

Polarization bremsstrahlung in α decay

A mechanism of formation of electromagnetic radiation that accompanies α decay and is associated with the emission of photons by electrons of atomic shells due to the scattering of α particles by these atoms (polarization bremsstrahlung) is proposed. It is shown that, when the photon energy is no higher than the energy of K electrons of an atom, polarization bremsstrahlung makes a significant contribution to the bremsstrahlung in α decay.     

X-ray radiation toward relativistic electrons incident on a flat target

Features of X-ray radiation emitted toward the velocity vector of relativistic electrons incident on a flat target are discussed. The contribution of polarization bremsstrahlung (PB) considered as scattering of the intrinsic field of a fast charge by electrons of the medium is estimated taking into account its dispersion properties. Spectral-angular characteristics of coherent and incoherent PB are analyzed for unstructured and structured targets. Such PB feature not only different intensities, but also different angular dependences reaching a maximum near the velocity direction of a fast charge. It is shown that coherent PB emitted from the target surface layer is characterized by an extraordinary, i.e., inversely proportional to the squared frequency, intensity dependence.     

Influence of substance characteristics on the interaction parameters of high-energy photons with free electrons

Various types of interaction of high-energy photons with free electrons in substances have been studied. It is shown that photon absorption by electrons, coherent photon scattering, noncoherent photon scattering, and electron-stopping after interaction with photons can be observed in substances. The dependence of the photon-wavelength variation after interaction with electrons on substance parameters and electron propagation velocity is obtained.     

Cooperative scattering effect between Stokes and anti-Stokes field stimulated by a stream of atoms

This paper is devoted to the study of the cooperative two-photon scattering processes between two resonator modes stimulated by an excited atomic beam. It has been proved that these collective scattering phenomena between the Stokes and anti-Stokes resonator modes are taking place due to the energy transfer between these fields. The statistical properties of the Stokes and anti-Stokes photons have been described using the photon correlation functions. The numerical solution of this equation describes the statistical transformation of n-Stokes photons into anti-Stokes photons.     

On the role of secondary interactions in the production of bremsstrahlung spectra from a thick target

Bremsstrahlung emission, or radiation loss, is the dominant mechanism of energy dissipation of electrons at relativistic energies greater than a few MeV when it is subjected to acceleration in the field of the nucleus or of the electrons. In this study, the Monte Carlo calculations for bremsstrahlung spectra have been described for the case of a thick tungsten target with incident electron beams from 10 to 50 MeV, where secondary interactions induced by the electrons and photons in the target, such as energy loss, absorption, scattering, and (e ⁺, e ⁻)-pair production effects, were taken into account. The text was submitted by the authors in English.     

Search for supersymmetric particles in photon-electron interactions at high energy

We discuss the production of gauge fermions and scalar electrons in high energy scattering of real photons off electrons. We propose to perform scattering experiments with polarized photons to discriminate between left and right partners of electrons and thus test more stringently the supersymmetry character of these particles.     

Collision operator for relativistic electrons in a cold gas of atomic particles

The collision operator of relativistic electrons with a cold gas of atomic particles is derived consistently taking into account elastic interactions, excitation of electron shells, and ionization. The creation of secondary electrons is described accurately. In the range of energies exceeding the binding energy of atomic electrons, the operator implicates only the angular scattering by nuclei and the ionization integral that automatically allows for scattering by atomic electrons. The collision operator used earlier for studying the kinetics of avalanches of relativistic runaway electrons is analyzed. A more exact operator derived in the present study is simpler in form and saves time in computer calculations.     

Relativistic Compton scattering from a relativistic maxwellian distribution of electrons

Using an earlier developed relativistic differential cross section formula for Compton scattering of photons from a given momentum distribution of electrons, an expression for the differential cross section is derived for the case of a relativistic Boltzmann distribution.     

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用KMR模型研究了等离子体中多光子非线性Compton散射下电子相轨道的演化,发现电子与光子进行能量交换后,只有未被俘获电子的相轨道才能从周期性向非周期性、随机型演化,其演化剧烈程度随电子吸收光子数的增大而加剧,随电子与光子碰撞非弹性成分和碰撞前初始速度的增大而迅速减弱,但低于强激光场中的剧烈程度。当电子被光场俘获时,这种演化过程结束并做稳定的运动,光子不再为电子提供能量。     

Compton散射下等离子体中电子相轨道的演化

用KMR模型研究了等离子体中多光子非线性Compton散射下电子相轨道的演化,发现电子与光子进行能量交换后,只有未被俘获电子的相轨道才能从周期性向非周期性、随机型演化,其演化剧烈程度随电子吸收光子数的增大而加剧,随电子与光子碰撞非弹性成分和碰撞前初始速度的增大而迅速减弱,但低于强激光场中的剧烈程度。当电子被光场俘获时,这种演化过程结束并做稳定的运动,光子不再为电子提供能量。     

The role of Compton scattering in the low‐Z elements X‐ray fluorescence formation

The paper reviews the ionization of elements with low atomic numbers (boron, carbon, nitrogen, oxygen, and fluorine) by incoherent scattering of primary radiation and under the influence of Compton electrons. It is shown that at high energy of primary photons, the total contribution of these processes to X‐ray fluorescence formation becomes significant; at the energy of 80 keV, it becomes dominant. Copyright © 2013 John Wiley & Sons, Ltd.     

Computational improvements in phase shift calculations of elastic electron scattering

A method of calculating the scattering phase shifts from the Dirac radial equations containing a rather general potential is described. The method takes advantage of the fact that a system of linear differential equations can be solved with the help of power series. Application of the method is demonstrated for the case of low-energy scattering (uniformly distributed nuclear charge screened by the atomic electrons) and for the case of high-energy scattering (uniform or more complicated nuclear charge distribution without atomic screening).     

Qualitative difference between the angular anisotropy parameters in fast electron scattering and photoionization

It is demonstrated for the first time that in spite of well known big similarities between atomic ionization by photons and fast electrons, a qualitative difference exists in angular anisotropy parameters of electrons knocked out in these processes. The difference is disclosed here and attributed to distinction between normal (transverse) and virtual (longitudinal) photons. Formulas are derived for dipole and non-dipole angular anisotropy parameters in fast electron-atom scattering. The ratio of quadrupole-to-dipole matrix elements is determined by the parameter ωR/v < 1, where ω is the transferred in collision energy, R is the ionized shell radius, and v is the speed of projectile. This factor can be much larger than that in the case of photoionization, where one has the speed of light c that is much higher than v. We illustrate general formulas by concrete results for outer s subshells of noble gas atoms Ar and Xe. Even for very low momentum transfer q, in the so-called optical limit, the deviation from photoionization case is prominent and instructive.     

Intensity of intersubband electron scattering by polar optical phonons in semiconductor quantum wires with account of energy level broadening

An approach describing the effect of energy level broadening in semiconductor quantum wires on the intensity of intersubband electron scattering by polar optical phonons is suggested. As a broadening mechanism, scattering by atomic thermal vibrations and by the roughness of the confining surfaces of a quantum system is considered. It is shown that in this case the dependence of the intensity of intersubband scattering of electrons on their kinetic energy has no singularities.     

Inelastic electron scattering from a Coulomb potential in a laser field

We present a theoretical study of inelastic electron scattering from a fixed Coulomb potential in the presence of a laser field, based on analytic expressions for the two-photon continuum-continuum transition matrix element. We present here the particular case of incident and scattered light polarizations orthogonal to each other and to the incident electron momentum. Results are given for the cross sections corresponding to the detection of electrons and polarized photons in coincidence, and for the detection of polarized photons only.     

Most probable and average energy losses of the beam of monoenergetic charge particles with average and low energies at multiple scattering

The results of statistical modeling of the discrete process of multiple inelastic scattering are presented. This process is modeled to find the most probable and average energy losses of a beam of charged particles (electrons and protons) passing through a material layer with a given thickness. The proposed approach is based on determining the most probable energy loss at single small-angle scattering, on including the effect of the statistical probability on this quantity at multiple scattering, and on determining the average number of inelastic interactions for particles in a film with a known thickness. The dependence of the particle energy lost during interaction with atomic electrons on their relative motion is taken into account for low-energy particles. A new interpretation is offered for the parameter J in the logarithmic term in the formulas for the average and most probable energy losses of charged particles. A computational scheme for this parameter as an average potential energy of atomic electrons is given.