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This paper considers the features of coherent synchrotron radiation generated when relativistic electron bunches pass the field of short magnets. A significant contribution to the spectral and angular characteristics of radiation can be made by a factor of the limited length of the magnetic field disposed along the trajectory of the electrons. Furthermore, a substantial contribution to these features can be made by a radiation coherence factor. This work comprises the theoretical analysis of these effects and the results of experimental studies in the millimeter wavelength range

The possibility of using radiation of relativistic electrons in optical fibers using the properties of dielectric materials for diagnosing beams was theoretically suggested by the authors X. Artru and C. Ray. (Nucl. Instrum. Meth. B vol. 309 (2013). The aforementioned work studies the properties of various types of radiation induced in fibers by the electromagnetic field of relativistic electrons. In this paper, we present the experimental research of the influence of surface waves on the radiation propagating along a fiber. The work also investigates the properties of various types of coherent millimeter wave radiation that was induced in dielectric fibers by the electromagnetic field of relativistic electrons. The results also include the experimental analysis of nature and properties of coherent radiation in fibers, the analysis being performed for different positions of fiber in relation to the electron beam.

The article discusses the problem of radiation generated during the interaction between the field of relativistic charged particles and metamaterials based on a one-dimensional periodic wire structure. The work includes the experimental study of the reverse coherent transition radiation emitted by these structures in the millimeter wavelength range for two orthogonal directions of radiation polarization. Under the same experimental conditions, authors also compared the intensity of this radiation with the reverse transition radiation from solid conductive targets. The study elucidates the asymmetrical polarization of radiation emitted by a metamaterial wire structure.

The formalism of form factors is the basis for the describing the coherent radiation of bunches that comprise relativistic charged particles. The general theory of coherent radiation for synchrotron and bremsstrahlung radiation, when radiation is generated directly by charged particles, but not by the material of a target, was developed long ago. However, there is no general model of coherent radiation for such polarization radiation as transition, diffraction and other types of radiation, when the radiation is generated by the material of a target polarized by the electromagnetic field of relativistic particles. This often causes the misapplication of the form factors of synchrotron radiation to other types of radiation. In this paper, we suggest the simplified algorithm for construction of form factors for different types of polarization radiation of relativistic electrons in the material of a target.

Two simple approaches for evaluating the transversal beam size using a slit and a grating are presented. A model for calculating the resonant diffraction radiation (RDR) characteristics from grating consisting of perfectly conducting strips spaced by vacuum gaps is developed. The proposed model allows calculating the RDR characteristics for a beam passing through a big slit between two gratings. It is noted that quasimonochromatic maxima appear in the RDR spectral–angular distribution, whose position is determined by the grating’s period and observation geometry. The peak shape depends on the beam parameters. Having measured the RDR angular distribution at a fixed wavelength, one may evaluate the beam size using simple formulas obtained.

At KEK-ATF extraction line detailed investigation of backward optical diffraction radiation (ODR) and its implementation to transversal beam parameter diagnostics is planned. We designed and constructed a target chamber with a precise target movement mechanism, a precise laser alignment system and an optical system. The first step to achieve success in the experiment is the tuning of the optical system using backward optical transition radiation (OTR). We believe that, if we are able to measure OTR spectral-angular characteristics with a proper accuracy, we may obtain good results for ODR measurements as the OTR effect is well experimentally and theoretically studied. Therefore, the first stage of our experiment assumes the measurements of backward OTR to analyze all possible types of radiation coming from the target, which could be obstacles for the ODR measurements. In the first series of experiments we have found that the angular distribution of the detected optical radiation is strongly asymmetric. One of the possible reasons for the asymmetry is the synchrotron radiation contribution from bending or steering magnets.

The efficiency of positron production by a 1.2-GeV electron beam incident on a tungsten single crystal oriented in an axially channeling condition has been experimentally studied. Positron yields from a 1.2-mm-thick crystal have been measured to be ,2.5 3.0 times larger than those from amorphous targets with the same thickness. A simple model simulation of the positron production process shows that coherent bremsstrahlung, as well as channeling radiation, contributes to the enhancement of the positron yields. [S0031-9007(98)05357-5]

Channeling radiation has been used for excitation of the 15.1 MeV resonance gamma level of a 12C nucleus. Multiplicity effects occuring during radiation emission from (100) silicon crystal at 900 MeV electron incidence were considered.

An experiment on the investigation of optical diffraction radiation (ODR) from a slit target as a possible tool for noninvasive electron beam-size diagnostics has been performed at the KEK accelerator test facility. The experimental setup has been installed at the diagnostics section of the extraction line. We have performed the first incoherent ODR observation from a slit target. The measured angular distributions are in reasonable agreement with the theoretical expectation. The beam-size effect onto the ODR angular pattern has been observed. Moreover, the sensitivity to the beam size as small as 14 microm has been achieved.