Asymmetry of formation of π+-mesons by linearly polarized photons in the region of the first pion-nucleon resonance

This article presents measurements of the asymmetry of formation of ⁺ mesons on a proton by linearly polarized photons in the energy region from 220 to 320 MeV and for pion emission angles 90–135° in the c.m.s. Aphenomenological analysis is carried out on the basis of 25 measured values of the asymmetry and the data of other laboratories. As a result of the analysis, five independent values are obtained for the multipole amplitude functions.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 5, pp. 94–101, May, 1978.     

Variation of γ-ray spectra with the energy of channeled electrons

The spectral dependence of the γ-radiation produced by channeled electrons of different energies, E = 600, 750 and 900 MeV in 0.35 mm thick diamond was measured with a NaI(Tl) photon spectrometer. The energy dependences of the basic spectral features of the channeling radiation were determined.     

Kinematic grouping of reflections of parametric X-ray radiation

A model of parametric X-ray radiation (PXR) of moderately relativistic particles is developed within the kinematic theory taking into account radiation absorption. The model allows calculation of the PXR reflection intensity in a given direction taking into account diffraction of virtual photons on a set of “incidental” low-index crystallographic planes. It is shown that when a charged particle moves along certain crystallographic directions, the effect of kinematic grouping of reflections, at which lines of parametric radiation from various planes practically coincide, is observed.     

Feasible Design of a Free Electron Laser Based on the Smith–Parsell Effect

A free electron laser design is considered in which coherent radiation is generated during the flight of a bunched electron beam near a periodic metal target (Smith–Parsell radiation). If the target (array) is placed in a special resonator, optical feedback can be realized. It is proposed to use an array made of thin conductive strips separated with vacuum gaps, since the radiation output in this case is much higher than that attainable with conventional arrays. Varying the array parameters, one can choose the necessary direction and required spectral distribution of the Smith–Parsell radiation. When radiation is generated in the direction normal to the trajectory of the electron beam, the array acts as one of the resonator mirrors.     

Interference of the transient radiation fields produced by an electric charge and a magnetic moment

The conditions for the occurrence of interference of the transient radiation fields produced by an electric charge and a magnetic moment are analyzed. The contribution of the transient radiation of a charge – magnetic moment system, depending on the orientation of the magnetic moment, to the total output has been calculated for the case of a particle escaping from a titanium target in vacuum for a photon energy of 454 eV. The possibility of harnessing the effect under consideration in developing a new type of polarimeter has been evaluated.     

Channeling radiation of 4.9 MeV electrons in crystals

Measurements of the channeling radiation of 4.9 MeV electrons in Si and KCl crystals are presented. For the first time the orientational maxima of the radiation yield in the X-ray and optical spectral regions are obtained.     

Investigation of resonance diffractive radiation from relativistic electrons in conducting periodic targets

Optical resonance diffractive and transition radiation from 200-MeV electrons in conducting periodic targets with spaced strips are investigated experimentally at the Tomsk synchrotron. The orientation and spectral properties of the radiation are measured.     

Observation of spectral line splitting for parametric X-rays

The spectral distribution and energy dependence of the yield of parametric X-rays for 200 to 900 MeV electrons transmitted through a silicon crystal have been measured. The measurements were performed in the Bragg geometry at an angle θ = 19° to the electron beam direction. The effect of spectral line splitting for parametric X-rays was observed.     

Energy characteristics of planar-channeling radiation for high-energy electrons in diamond

γ-ray spectra have been measured for (110) and (111) planar channeling of 600–900 MeV electrons in a diamond crystal. It is shown that in the case of (111) crystallographic planes the influence of molecular-type motion on the formation of the spectra is predominant.     

Observation of monochromatic X-ray radiation from 900 MeV electrons transmitting through a diamond crystal

A new source of monochromatic X-ray radiation from a relativisti? electron beam transmitted through a crystal target is experimentally observed.