K.B. Korotchenko

Basic channeling with Mathematica©: A new computer code

The Mathematica© software is a powerful tool to solve numerous problems in physics, essentially when the analytical solution is not possible. The channeling and related phenomena is just that case. Here we suggest to introduce a standard in calculations of channeling and related phenomena using Mathematica© software. The new computer code Basic Channeling with Mathematica© BCM-1.0, at the first stage, will include a set of packages to make symbolic calculation of the planar channeling phenomena.

Angular Distribution of Diffracted X Rays from (111) Channeled Electrons in Si: The Effect of the Band Structure of Energy Levels

It has been shown that the inclusion of the band structure of the energy levels of channeled electrons qualitatively changes the angular distributions of x rays at the Bragg angles, which can be useful for the experimental detection of the effect.

Quantum effects for parametric X-ray radiation during channeling: Theory and first experimental observation

The theory of X-ray radiation from relativistic channeled electrons at the Bragg angles—parametric X-ray radiation (PXR) during channeling (PXRC)—is developed while accounting for two quantum effects: the initial population of bound states of transverse motion and the transverse “form-factor” of channeled electrons. An experiment was conducted using a 255 MeV electron beam from a linac at the SAGA Light Source. We have identified a difference in the angular distributions of PXR and PXRC and obtained a fairly good agreement between the theoretical and experimental results.

Angular Distributions of DCR from Axially Channeled Electrons in ‹110› LiF Crystal

The formulae and new computation method for calculation of angular distributions of diffracted channeling radiation (DCR) from relativistic electrons axially channeled in a crystal are presented. Numerical results are obtained for y = 20 electrons channeled in 110 LiF crystal.

Effect of the band structure of energy levels on the angular distribution of diffracted X-ray radiation for positron plane channeling in silicon

It is shown that the inclusion of the band structure of energy levels of channeled positrons (as in the case of electrons) leads to a qualitative change in the angular distribution of X-ray radiation.

Peculiarities of channelling radiation spectra from 100 to 800 MeV electrons and positrons in (1 1 1) Si crystal

By means of numerical calculations, the channelling radiation spectra from relativistic electrons and positrons have been studied in detail for channelling along (1 1 1) double planes in a Si crystal. The evolution of the shape of radiation spectrum is studied under an increase of particles energies from 100 to 800 MeV and a change of the angle of incidence with respect to (1 1 1) double planes. It is shown that the (1 1 1) channelling radiation spectra have much more complicated structure and radiation yield is several times greater compared to the channelling along (1 0 0) or (1 1 0) planes.

Quantum features of the angular distributions of parametric X-ray radiation of channeled relativistic electrons in a crystal

The appearance of sharp stepwise changes (quantum jump) in the angular distribution of parametric X-ray radiation from channeled electrons has been predicted at the appearance of each new quantum state of the channeled electron at the corresponding increase in the energy of an electron beam.

Quantum Features of PXRC Angular Distributions From Relativistic Channeled Electrons in a Crystal

We predict quantum features in angular distributions of parametric X-radiation from channeled relativistic electrons (PXRC). The effect is connected with the number of quantum states of channeled electrons, form-factors of the transverse quantum channeling states and initial populations of these quantum states. The main motivation of this work is theoretical prediction for the future experiment at the SAGA-LS facility.

Modification of the theory of diffracted channeling radiation for axial electron and positron channeling

A new type of combinational channeling radiation induced by subbarrier (interband) transitions for the transverse motion of relativistic electrons (positrons) is studied. It is known as diffracted channeling radiation (DCR). The formula describing the DCR angular distribution in the case of axial channeling is obtained by taking into account the band structure of energy levels for the transverse motion of electrons (positrons). It is shown that, in the two-wave approximation of the wave function A(r) of virtual photons, the DCR matrix elements in the dipole approximation for axial and plane channeling coincide formally (with the dimension of the problem taken into account). However, the formulas for DCR angular distributions in the cases of axial and plane channeling differ considerably.

Comparison of the quantum and classical calculations of flux density of (220) channeled positrons in Si crystal

Simulation of flux-peaking effect of the 255 MeV positrons channeled in (220) Si crystals is performed in the frame of classical and quantum mechanics. Comparison of the results obtained using both approaches shows relatively good agreement.