O. V. Bogdanov

Tomsk Polytechnic University

We analyze channeling radiation in terms of twisted photons. We numerically calculate the average number of twisted photons produced by 255 MeV electrons channeled in (220) Si crystal. The periodicity of projection of the total angular momentum per photon with respect photon energy is revealed.

We study the radiation from charged particles crossing a cholesteric plate in the shortwave approximation when the wavelength of photons is much smaller than the pitch of the cholesteric helix, whereas the escaping angle of the photon and the anisotropy of the permittivity tensor can be arbitrary. The radiation of photons is treated in the framewor...

The band structure of photons in cholesteric liquid crystals (CLCs) is investigated in the shortwave approximation. The bound states or narrow resonances of photons in the CLC are formed by the extraordinary waves. The explicit expressions for the spectrum bands and the dispersion laws of photons in these bands are obtained. It is shown that these...

We study the radiation from charged particles crossing a cholesteric plate in the shortwave approximation when the wavelength of photons is much smaller than the pitch of the cholesteric helix whereas the escaping angle of the photon and the anisotropy of the permittivity tensor can be arbitrary. The radiation of photons is treated in the framework...

The radiation of twisted photons by charged particles traversing a cholesteric plate is studied in the framework of quantum electrodynamics in an anisotropic inhomogeneous dispersive medium. The complete set of solutions to the Maxwell equations in the cholesteric plate is constructed in the paraxial and small anisotropy approximations. The explici...

The computer simulations of relativistic heavy ions channeling through the half-wavelength crystal showed the similarity of trajectories and angular distributions for ions with close ratios of the mass number A and the ion charge Ze. We studied the deflection efficiency of 300 MeV/u and 30 GeV/u 129 Xe, 208 Pb, 238 U ions by a single tungsten half-...

The radiation of twisted photons by charged particles traversing a cholesteric plate is studied in the framework of quantum electrodynamics in an anisotropic inhomogeneous dispersive medium. The complete set of solutions to the Maxwell equations in the cholesteric plate is constructed in the paraxial and small anisotropy approximations. The explici...

We study the radiation of twisted photons by undulators filled with a homogeneous dielectric dispersive medium and obtain the general formulas for the average number of radiated twisted photons. We consider in detail the radiation of undulators in the dipole regime and the radiation of helical and planar wigglers. The selection rules for radiation...

The radiation of twisted photons by undulators filled with a homogeneous dielectric dispersive medium is considered. The general formulas for the average number of radiated twisted photons are obtained. The radiation of undulators in the dipole regime and the radiation of the helical and planar wigglers are studied in detail. It is shown that the s...

The computer simulations of the angular distributions of low-Z relativistic isotopes channeled in a half-wavelength-crystal (HWC) revealed that at equal beam energy, crystal thickness and its alignment, the HWC channeling is sensitive to a mass number A of the low-Z isotope. That means, besides well-known applications of relativistic channeling for...

The probability to detect a twisted photon produced by a cold relativistic particle bunch of charged particles is derived. The radiation of twisted photons by such particle bunches in stationary electromagnetic fields and in propagating electromagnetic waves is investigated. Several general properties of both incoherent and coherent contributions t...

We propose to use Vavilov-Cherenkov (VC) and transition radiations as a source of twisted photons in a wide range of energies. The experimental setup to observe the orbital angular momentum of photons constituting those radiations is described. The radiation produced by relativistic electrons and ions in passing dielectric plates is considered. The...

Simple formulas for the probability of radiation of twisted photons by scalar and Dirac particles with quantum recoil taken into account are derived. We show that the quantum recoil does not spoil the selection rule for the forward radiation of twisted photons in the planar undulator: $m+n$ is an even number, where $n$ is the harmonic number and $m...

In most cases, the twisted photons generated directly by charged particles in undulators and laser waves are produced by bunches of particles and not by one charged particle. However, up to now, the theoretical studies of such a radiation were mainly based on description of radiation produced by one charged particle. In the present paper, we invest...

The general formula for probability to record a twisted photon produced by a charged particle moving in an inhomogeneous isotropic dispersive medium is derived. The explicit formulas for probability to record a twisted photon are obtained for the radiation of a charged particle traversing a dielectric plate or an ideally conducting foil. It is show...

The general formula for probability to record a twisted photon produced by a charged particle moving in an inhomogeneous isotropic dispersive medium is derived. The explicit formulas for probability to record a twisted photon are obtained for the radiation of a charged particle traversing a dielectric plate or an ideally conducting foil. It is show...

The semiclassical general formula for the probability of radiation of twisted photons by ultrarelativistic scalar and Dirac particles moving in the electromagnetic field of a general form is derived. This formula is the analog of the Baier-Katkov formula for the probability of radiation of one plane wave photon with the quantum recoil taken into ac...

The probability to record a twisted photon produced by a cold relativistic particle bunch of charged particles is derived. The radiation of twisted photons by such particle bunches in stationary electromagnetic fields and in propagating electromagnetic waves is investigated. It is shown that the incoherent radiation by bunches of particles traversi...

Aiming to develop a Time-of-Flight (TOF) detector with a precision down to about 50 ps (σ) in time, radiation hard and operating with a high radiation rate of relativistic heavy ions of up to 10⁷ per spill of 1 to 10 s., we have constructed a new Time-of-Flight Cherenkov detector based on an Iodine-Naphthalene liquid radiator. This fluid with high...

The semiclassical general formula for the probability of radiation of twisted photons by ultrarelativistic scalar and Dirac particles moving in the electromagnetic field of a general form is derived. This formula is the analog of the Baier-Katkov formula for the probability of radiation of one plane wave photon with the quantum recoil taken into ac...

The effect of a finite width of a particle bunch on radiation of twisted photons is studied. The general formulas connecting the radiation probability distribution of twisted photons produced by bunches of identical particles with the radiation probability distribution of twisted photons generated by one particle are obtained for axially symmetric...

We propose to use channeling radiation (CR) from relativistic electrons as a source of high energy twisted photons in the MeV range. We calculate numerically the orbital angular momentum (OAM) of radiation produced by electrons with the energies 155÷2500 MeV for the axial and planar channeling in the thin Si crystal. We obtain that the average OAM...

The infrared asymptotics of probability of radiation of twisted photons in an arbitrary process of quantum electrodynamics (QED) in a vacuum is investigated. This asymptotics is universal and corresponds to the radiation produced by a classical current. Such a radiation is known as the edge radiation. We represent it in terms of the twisted photons...

The first proof of principle experiment with a prototype of a Time-of-Flight (TOF) - Cherenkov detector of relativistic heavy ions (RHI) exploiting a liquid Iodine Naphthalene radiator has been performed at Cave C at GSI (Darmstadt, Germany). A conceptual design for a liquid Cherenkov detector was proposed as a prototype for the future TOF measurem...

The general formula for the probability of radiation of a twisted photon by a classical current is derived. The general theory of generation of twisted photons by undulators is developed. It is proved that the probability to record a twisted photon produced by a classical current is equal to the average number of twisted photons in a given state. T...

The perspective atomic physics experiments are the part of Super-FRS collaboration program [1], in particular for the first time to observe the nuclear Okorokov effect of resonant coherent excitation (RCE) of relativistic nuclei passing through a crystal [2]. The RHI beam energy at Super-FRS is up to 1500 MeV/u, and perturbation harmonic energy at...

The hybrid scheme of positron source involving channeling radiation from 0.1 ÷ 1.6 GeV 〈1 0 0〉 channeled electrons in a crystalline W target (radiator) and subsequent electron-positron pair production in a downstream thick amorphous W target (converter) is investigated by means of computer simulation using the BCM-1 code. Computer simulation is car...

The properties of radiation created by a classical ultrarelativistic scalar charged particle in a constant homogeneous crossed electromagnetic field are described both analytically and numerically with radiation reaction taken into account in the form of the Landau-Lifshitz equation. The total radiation naturally falls into two parts: the radiation...

We consider the radiator-converter approach at 200 MeV channeled electrons (the SPARC_LAB LNF facility energies) for the case of using W crystalline radiator and W amorphous converter. A comparison of the positron production by the axial channeling radiation and the bremsstrahlung is performed. The positron stopping in the convertor is studied by m...

New experimental data on planar channeling of 255 MeV electrons in a 0.74 µm Si Half-Wave Crystal (HWC) obtained at SAGA-LS facility are presented. The computer simulation showed that the angular distribution of electrons after penetration through the HWC revealed the number of unknown before peculiarities is connected with specific electron trajec...

A hybrid positron-source scheme based on an electron beam of the Sorgente Pulsata e Amplificata di Radiazione Coerente test facility installed at the Laboratori Nazionali di Frascati (Frascati, Italy) is proposed. In the case of a thin (0.1-mm-thick) amorphous converter, the positron yields per primary electron are compared at positron energies of...

The new symbolic-numerical code devoted to investigation of the channeling phenomena in periodic potential of a crystal has been developed. The code has been written in Wolfram Language taking advantage of analytical programming method. Newly developed different packages were successfully applied to simulate scattering, radiation, electron-positron...

New experiments on channeling of 255 MeV electrons in a half-wavelength crystals (HWC) were performed at SAGA Light Source facilities. The simulations of trajectories for (2 2 0) and (1 1 1) planar channeling in Si were performed using the computer code BCM-1.0. Comparison of experimental and theoretical results shows a good agreement. The results...

The relations among the components of the exit momenta of ultrarelativistic electrons scattered on a strong electromagnetic wave of a low (optical) frequency and linear polarization are established using the exact solutions to the equations of motion with radiation reaction included (the Landau-Lifshitz equation). It is found that the momentum comp...

A computer code is developed to calculate the radiation energy losses (RELs) of electrons during both 〈100〉 axis and (100) plane channeling in a thin Si crystal. A computer simulation of these losses is carried out by taking the initial angular divergence of the beam into account, and the REL dependences on the angle of electron entry into the crys...

The hybrid scheme of the positron source for SPARC_LAB LNF facility (Frascati, Italy) is proposed. The comparison of the positron yield in a thin amorphous W converter of 0.1 mm thickness produced by bremsstrahlung, by axial and planar (110) channeling radiations in a W crystal is performed for the positron energy range of 1 3 MeV. It is shown that...

Orientation dependences of channeling radiation total yield from relativistic 155-855 MeV electrons at both < 1 0 0 > axial and (1 0 0) planar channeling in thin silicon and tungsten crystals are studied by means of computer simulations. The model as well as computer code developed allows getting the quantitative results for orientation dependence...

a b s t r a c t We performed calculations of Vavilov–Cherenkov radiation (VChR) angular distributions from relativistic heavy ions (RHI) taking account of their slowing-down in a radiator. The results of calculations show that the slowing-down of RHI in radiator leads to specific broadening of VChR ring thus forming specific VChR angular distributi...

Numerical methods are used to study the dependence of the structure and the width of the angular distribution of Vavilov-Cherenkov radiation with a fixed wavelength in the vicinity of the Cherenkov cone on the radiator parameters (thickness and refractive index), as well as on the parameters of the relativistic heavy ion beam (charge and initial en...

A new method and theoretical base for calculation of the Cherenkov Radiation (ChR) angular distribution from relativistic heavy ions (RHI) taking into account stopping in radiator is suggested. Our method is based on the thin radiator approximation and the Bethe-Bloch formula for ionization energy loss (stopping) and provides fast calculations with...

Dechanneling processes for electrons in a (111) Si crystal based on the solution of Fokker-Planck equation have been studied. The dynamics of particle distribution density has been investigated in dependence on both energy and initial scattering distribution of electron beams. The influence of dechanneling process on spectral intensity of channelin...

The properties of both angular and spatial distribution of 255 MeV electrons at channeling in silicon crystal has been investigated experimentally at the linac injector of SAGA light source and by computer simulations. The simulation of trajectories, angular and spatial distributions of electrons on the screen monitor has been performed taking into...

We studied numerically the structure of angular distributions of Cherenkov radiation (ChR) from moderately relativistic heavy ions (RHI) taking into account the decrease of the ion velocity due to stopping in the radiator. The calculations clearly show that both the width and fine structure of the ChR angular distribution in the vicinity of the Che...

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...

Concept of using crystal targets as complementary X-ray and gamma ray sources at synchrotron light facilities is considered. Calculations of channeling radiation, parametric X-radiation and bremsstrahlung from relativistic electrons in the crystal targets are performed for parameters of synchrotrons operating in Moscow (Kurchatov Center for Synchro...

Typical trajectories of relativistic electrons and the corresponding radiation spectra at axial channeling in silicon and diamond crystals are revealed and constructed using the ©Mathematica 6.01 computer code. The radiation spectrum of 300 MeV electrons averaged over the trajectories in the 〈100〉 direction in a diamond crystal well coincides with...

A model of planar channeling of 400 MeV electrons taking into account the dechanneling processes in a crystal is developed. The dynamics of the initial angular distribution of relativistic electrons as a function of standard deviation has been studied. The simulation results for the density function of channeled projectiles distribution in a thick...

The spectral intensity of (111) channeling radiation from electrons is numerically calculated at the energy varying from 100 to 900 MeV and different electron incidence angles relative to the (111) planes in thin Si crystals. The calculation results show that the channeling radiation’s spectra have a more complicated structure, and the total channe...

Combining the SRIM’06 computer code and the formula for spectral-angular distribution of radiation from a particle moving in a medium in arbitrary trajectory, we studied numerically the structure of angular distributions of Cherenkov radiation from moderately relativistic heavy ions (RHI) taking into account the decrease of ions velocity due to sto...

The influence of the tails of particle trajectories on planar channeling radiation (CR) spectra from relativistic (800–2000 MeV) electrons and positrons in a thin silicon crystal is investigated. It is shown that the trajectory tails significantly change the CR spectra from electrons and positrons in specific parts of the spectra compared to calcul...

Calculation of channeling radiation from relativistic electrons under (1 1 1) planar channeling conditions in a LiF crystal is performed using both classical and quantum methods. The complicated shape of the periodic (1 1 1) planar potential allows the existence of a different number of discrete energy levels (quantum states) in the potential well...

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...

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.

Based on this idea, in this report we are discussing the features of 20-800 MeV e-/e+ channeling in various crystals. Namely, paying attention to the complex character of radiation origin, the new peculiarities of channeling radiation from relativistic particles have been described in details; the processes of multiple scattering have been studied...

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.