Smith-Purcell effect is well known as a source of monochromatic electromagnetic radiation. In this paper we present the generalized theory of Smith-Purcell radiation from periodic beams. The ...form-factors describing both coherent and incoherent regimes of radiation are calculated. The radiation characteristics are investigated in two practically important frequency ranges, THz and X-ray, for two modulation profiles, most frequently used in practice - a train of microbunches and a Gaussian-shaped one, characterized by sinusoidal modulation with an arbitrary modulation depth. On the base of the theory developed we show that a modulated electron beam consisting of a set of bunches makes it possible to improve significantly the spectral line monochromaticity of the light emitted, reaching values better than 1% for short gratings. We demonstrate as well that Smith-Purcell radiation can be used for non-destructive diagnostics of the depth of modulation for partially modulated beams. These findings not only open up a new way to manipulate the light emission using Smith-Purcell effect but also promise a profound impact for other radiation sources based on charged particle beams, such as undulator radiation in FELs, next-generation X-ray radiation source based on inverse Compton scattering, in a wide range from THz to X-rays.
In this work, we construct for the first time the theory of small-angle transition radiation from multilayered structures. The theoretically obtained spectral and angular distributions of radiated ...photons are compared with those predicted by Geant4, a very popular package used today for numerical simulation of different physical processes. We demonstrate that, while spectral distributions ideally coincide, the angular ones differ. We argue that transition radiation from the multilayered structure must contain sharp spikes having the interference nature and caused by the effect of merging two maximum frequencies in dispersive media, and thus Geant4 needs improving in this respect. The transition radiation theory developed here for the small-angle case can play a vital part for the possible future Small Angle Spectrometer at the LHC, other experiments of this kind, and detectors for hadrons of the tera-electron-volt energy range.
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This book deals with diffraction radiation, which implies the boundary problems of electromagnetic radiation theory. It presents different analytical models of diffraction radiation and results of ...recent experimental studies.
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4.
Crab crossing in inverse Compton scattering Potylitsyn, A. P.; Gavrilenko, D. V.; Strikhanov, M. N. ...
Physical review. Accelerators and beams,
04/2023, Volume:
26, Issue:
4
Journal Article
Peer reviewed
Open access
Inverse Compton scattering is a promising x-ray source, very bright, quasi-monochromatic, and compact. In this paper, we present a generalized theory of Compton backscattering in terms of luminosity, ...suitable for both classical and quantum regimes. We show that the optimal parameters, which require a certain mutual orientation and inclination of the fronts of the laser and electron beams described by 3D Gaussians, correspond to the crab scheme. This scheme is widely used in particle physics but is not yet used for x-ray sources. The constructed theory not only predicts the optimal geometry for laser and electron beams but also describes the luminosity. Our results reveal the opportunity to sharply increase the luminosity of compact x-ray sources based on Compton/Thomson backscattering.
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Smith-Purcell radiation is a well-known phenomenon, which provides a noninvasive scheme for diagnostics of charged particle beams and is used as an effective source of electromagnetic waves, e.g., in ...the orotron, the free electron laser, etc. In this paper we develop the theory of Smith-Purcell radiation (SPR) for the little-investigated case of arbitrary angles between the charged particle trajectories and the rulings of a grating. The effect of conical diffraction arising here changes drastically the space distribution of the radiation. By contrast to the only existing approach, described by Haeberle et al. Phys. Rev. E 55, 4675 (1997), which requires difficult numerical calculations, we give a fully analytic theory of SPR. Also, in this paper we present for the first time the theory of x-ray Smith-Purcell radiation. Evanescent waves on the surface are shown to lead to strong enhancement of Smith-Purcell radiation, through a resonant mechanism. The results are important for the description of real divergent high-brightness beams and for the development of novel noninvasive diagnostic schemes based on the Smith-Purcell effect.
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An analysis of spectral-angular characteristics of diffraction radiation, both incoherent and coherent, has been performed. It is shown that radiation processes can be interpreted as Cherenkov ...radiation, which is produced by a region of dynamic polarization moving along a target edge with superluminal velocity vSL. Such radiation is generated if the condition vSL > c is fulfilled, which is the conventional 'threshold' Cherenkov condition.
X-ray transition radiation detectors (TRDs) are used for particle identification in both high energy physics and astroparticle physics. In most of the detectors, emission of the X-ray transition ...radiation (TR) starts at Lorentz factors above γ∼500 and reaches saturation at γ∼2÷3⋅103. However, many experiments require particle identification up to γ∼105, which is very difficult to achieve with conventional detectors. Semiconductor pixel detectors offer a unique opportunity for precise simultaneous measurements of spectral and angular parameters of TR photons. Test beam studies of the energy and the angular distributions of TR photons emitted by electrons and muons of different momenta crossing several types of radiators were performed at the CERN SPS with a 480 μm thick silicon detector bonded to a Timepix3 chip. High resolution images of the energy−angle phase space of the TR produced by different radiators were obtained and compared with MC simulations. The characteristic interference patterns are in agreement with the theoretical models with an unprecedented level of details. The studies presented in this paper also show that simultaneous measurements of both the energy and the emission angles of the TR X-rays could be used to enhance the particle identification performances of TRDs.
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Polarization radiation, which includes diffraction radiation, transition radiation, Smith-Purcell radiation, and others, can be a good instrument for beam diagnostics. All information about the beam ...size is contained in the so-called form-factor of the beam. The form-factor represents the sum of two parts corresponding to the coherent and incoherent radiation. Contrary to the general opinion the incoherent part does not always equal unity. In this report we give theoretical description of the incoherent part of the form-factor both for Gaussian and uniform distribution of the ultrarelativistic particles in the bunch. We show that the incoherent form-factor depends on the transverse size of the beam, and discuss the new opportunities for non-invasive diagnostics of ultrarelativistic electron beams.
Diffraction radiation from divergent beam is considered in terms of radiation in UV and X-ray range. Scedastic form of Gaussian distribution of the particle in the bunch, i.e. Gaussian distribution ...with changing dispersion has been used, which is more adequate for description of divergent beams than often used Gaussian distribution with constant dispersion. Both coherent and incoherent form-factors are taken into account. The conical diffraction effect in diffraction radiation is proved to make essential contribution in spectral-angular characteristics of radiation from a divergent beam.
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10.
Conical effect in diffraction radiation Sergeeva, D.Yu; Tishchenko, A.A.; Strikhanov, M.N.
Nuclear instruments & methods in physics research. Section B, Beam interactions with materials and atoms,
07/2015, Volume:
355
Journal Article
Peer reviewed
When light is scattered on a grating, the scattered waves are distributed over a cone surface, which is called “conical diffraction effect”. In the present work the similar effect in theory of ...diffraction radiation (DR) from a charged particle moving near a target at some angle to its edge is predicted and described for the first time. The equation describing the surface of maximal radiation, which is conical surface, is derived from the first principles. The effect is illustrated by spectral-angular distributions of DR from a thin target (screen) in X-ray, EUV, optical and lower frequency regions for two cases: (a) the particle moves in the plane perpendicular to the screen; (b) the particle moves in the plane parallel to the screen. The radiation for these two orientations of the target is shown to differ mainly in direction of mirror reflection to the trajectory of the particle. Due to similar nature of DR and transition radiation (TR) the same effects should arise for TR from targets of limited transversal size.
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