arXiv subjects

A. V. Solov'yov

Publications and source records attributed to A. V. Solov'yov.

47 records · Page 3Linked to original sources

arXiv2001

Photon emission by ultra-relativistic positrons in crystalline undulators: the high-energy regime

This paper discusses the undulator radiation emitted by high-energy positrons during planar channeling in periodically bent crystals. We demonstrate that the construction of the undulator for positrons with energies of 10 GeV and above is only possible if one takes into account the radiative energy losses. The frequency of the undulator radiation depends on the energy of the particle. Thus the decrease of the particle's energy during the passage of the crystal should result in the destruction of the undulator radiation regime. However, we demonstrate that it is possible to avoid the destructive influence of the radiative losses on the frequency of the undulator radiation by the appropriate variation of the shape of the crystal channels. We also discuss a method by which, to our mind, it would be possible to prepare the crystal with the desired properties of its channels.

physics.acc-ph↗

arXiv2001

Coherent radiation of an ultra-relativistic charged particle channeled in a periodically bent crystal

We suggest a new type of the undulator radiation which is generated by an ultra-relativistic particle channeled along a periodically bent crystallographic plane or axis. The electromagnetic radiation arises mainly due to the bending of the particle's trajectory, which follows the shape of the channel. The parameters of this undulator, which totally define the spectrum and the angular distribution of the radiation (both spontaneous and stimulated), depend on the type of the crystal and the crystallographic plane (axis), on the type of a projectile and its energy, and on the shape of the bent channel, and, thus, can be varied significantly by varying these characteristics. As an example, we consider the acoustically induced radiation (AIR) which is generated by ultra-relativistic particles channeled in a crystal which is bent by a transverse acoustic wave. The AIR mechanism allows to make the undulator with the main parameters varying in wide ranges, which are inaccessible in the undulators based on the motion of particles in the periodic magnetic fields and also in the field of the laser radiation. The intensity of AIR can be easily made larger than the intensity of the radiation in a linear crystal and can be varied in a wide range by varying the frequency and the amplitude of the acoustic wave in the crystal. A possibility to generate stimulated emission of high-energy photons (in keV - MeV region) is also discussed.

physics.acc-ph↗

arXiv2001

Total spectrum of photon emission by an ultra-relativistic positron channeling in a periodically bent crystal

We present the results of numerical calculations of the channelling and undulator radiation generated by an ultra-relativistic positron channelling along a crystal plane, which is periodically bent. The bending might be due either to the propagation of a transverse acoustic wave through the crystal, or due to the static strain as it occurs in superlattices. The periodically bent crystal serves as an undulator. We investigate the dependence of the intensities of both the ordinary channelling and the undulator radiations on the parameters of the periodically bent channel with simultaneous account for the dechannelling effect of the positrons. We demonstrate that there is a range of parameters in which the undulator radiation dominates over the channelling one and the characteristic frequencies of both types of radiation are well separated. This result is important, because the undulator radiation can be used to create a tunable source of X-ray and gamma-radiation.

physics.acc-ph↗

arXiv2001

The influence of the dechanneling process on the photon emission by an ultra-relativistc positron channeling in a periodically bent crystal

We investigate, both analytically and numerically, the influence of the dechanneling process on the parameters of undulator radiation generated by ultra-relativistic positron channelling along a crystal plane, which is periodically bent. The bending might be due either to the propagation of a transverse acoustic wave through the crystal, or due to the static strain as it occurs in superlattices. In either case the periodically bent crystal serves as an undulator which allows to generate X-ray and gamma-radiation. We propose the scheme for accurate quantitative treatment of the radiation in presence of the dechanneling. The scheme includes (i) the analytic expression for spectral-angular distribution which contains, as a parameter, the dechanneling length, (ii) the simulation procedure of the dechanneling process of a positron in periodically bent crystals. Using these we calculate the dechanneling lengths of 5 GeV positrons channeling in Si, Ge and W crystals, and the spectral-angular and spectral distributions of the undulator over broad ranges of the photons. The calculations are performed for various parameters of the channel bending.

physics.acc-ph↗

arXiv2001

Channeling of Charged Particles Through Periodically Bent Crystals: on the Possibility of a Gamma Laser

We discuss radiation generated by positrons channeling in a crystalline undulator. The undulator is produced by periodically bending a single crystal with an amplitude much larger than the interplanar spacing. Different approaches for bending the crystal are described and the restrictions on the parameters of the bending are established. We present the results of numeric calculations of the spectral distributions of the spontaneous emitted radiation and estimate the conditions for stimulated emission. Our investigations show that the proposed mechanism provides an efficient source for high energy photons, which is worth to be studied experimentally.

physics.acc-ph↗

arXiv2001

Total energy losses due to the radiation in an acoustically based undulator: the undulator and the channeling radiation included

This paper is devoted to the investigation of the radiation energy losses of an ultra-relativistic charged particle channeling along a crystal plane which is periodically bent by a transverse acoustic wave. In such a system there are two essential mechanisms leading to the photon emission. The first one is the ordinary channeling radiation. This radiation is generated as a result of the transverse oscillatory motion of the particle in the channel. The second one is the acoustically induced radiation. This radiation is emitted because of the periodic bending of the particle's trajectory created by the acoustic wave. The general formalism described in our work is applicable for the calculation of the total radiative losses accounting for the contributions of both radiation mechanisms. We analyze the relative importance of the two mechanisms at various amplitudes and lengths of the acoustic wave and the energy of the projectile particle. We establish the ranges of projectile particle energies, in which total energy loss is small for the LiH, C, Si, Ge, Fe and W crystals. This result is important for the determination of the projectile particle energy region, in which acoustically induced radiation of the undulator type and also the stimulated photon emission can be effectively generated. The latter effects have been described in our previous works.

physics.acc-ph↗

arXiv2001

Photon emission by an ultra-relativistic particle channeling in a periodically bent crystal

This paper is devoted to a detailed analysis of the new type of the undulator radiation generated by an ultra-relativistic charged particle channeling along a crystal plane, which is periodically bent by a transverse acoustic wave, as well as to the conditions limiting the observation of this phenomenon. This mechanism makes feasible the generation of electromagnetic radiation, both spontaneous and stimulated, emitted in a wide range of the photon energies, from X- up to gamma-rays.

physics.acc-ph↗

arXiv2001

Acoustically induced radiation of a charged particle channeling in a crystal

We suggest a new type of radiation (acoustically induced radiation - AIR), which is generated by ultrarelativistic particles channeling in crystal along a crystal plane (or axis), which is bent by a transverse acoustic wave. The AIR mechanism allows to make an undulator with characteristics inaccessible in the undulators based on the motion of particles in the periodic magnetic fields and also in the field of the laser radiation. The intensity of AIR can easily be made larger than the intensity of the radiation in a linear crystal and can be varied in a wide range by varying the frequency and the amplitude of the acoustic wave.

physics.acc-ph↗

arXiv2001

Finslerian N-spinors: Algebra

New mathematical objects called Finslerian N-spinors are discussed. The Finslerian N-spinor algebra is developed. It is found that Finslerian N-spinors are associated with an N^2-dimensional flat Finslerian space. A generalization of the epimorphism SL(2,C) --> O^\uparrow_+(1,3) to a case of the group SL(N,C) is constructed. Particular examples of Finslerian N-spinors for N=2,3 are considered in detail.

math-ph↗

arXiv1999

On SL(3,C)-covariant spinor equation and generalized Duffin-Kemmer algebra

The SL(3,C)-covariant 9-dimensional equation for a free 3-spinor particle is transformed into the Dirac-like form (p_Aδ^A - M)Ψ=0. However, the corresponding δmatrices do not satisfy the Dirac algebra. It is shown that δ^A lead to a Finslerian generalization of the Duffin-Kemmer algebra. The Appendix contains an explicit realization of the δmatrices.

math-ph↗

arXiv1998

Finslerian N-spinor algebra

New mathematical objects called Finslerian N-spinors are discussed. The Finslerian N-spinor algebra is developed. It is found that Finslerian N-spinors are associated with an N^2-dimensional flat Finslerian space. A generalization of the epimorphism SL(2,C) --> SO^\uparrow(1,3) to a case of the group SL(N,C) is constructed.

math-ph↗