X rays from relativistic electrons in a multilayer structure

Abstract

A dynamic diffraction theory of x-ray emission by relativistic electrons crossing a finite-thickness multilayer mirror (e.g., alternating layers of W and B4C) is developed, taking into account both diffracted transition and parametric radiation mechanisms. Simple formulas describing the characteristics of the total emission from either thin nonabsorbing or thick absorbing multilayers are derived. These formulas show that a multilayer radiator can be brighter and more efficient than crystalline ones. Good agreement between theory and prior experimental results is also shown. Thus the theory and its experimental verification demonstrate the possibility of a tunable quasimonochromatic x-ray source whose efficiency can be larger than that of other novel x-ray sources.

Diffracted transition radiation of relativistic electrons in an artificial periodic structure

“…For further analysis of the radiation, we repre sent dynamic additions (9) in the form: (16) where (17) The parameter in (17) determining the degree of field reflection asymmetry with respect to the target surface is important and can be represented in the form (18) where θ B is the angle between the electron velocity and the reflecting layers and δ is the angle between the tar get surface and the reflecting layers. We note that the angle δ -θ B of electron incidence on the target sur face increases if the parameter ε decreases, and vice versa (Fig.…”

“…Radiation in periodic layered structures was usually regarded as resonant transition radiation [5,16]. In [17], radiation from an artificial periodic structure was represented as the sum of DTR and PXR. In the cited papers, relativistic particle radi ation in an artificial periodic structure was considered only in Bragg scattering geometry in the particular case of symmetric reflection of a particle field from a target surface, in which diffracting layers are parallel to the target surface.…”

Cr/Sc multilayer radiator for parametric EUV radiation in “water-window” spectral range

“…The angular and spectral-angular densities of radiation were calculated using different theories [3,5]. The calculation shows that the maximum PR intensity is emitted near the direction  Dy = 1/ ( is the Lorentz factor) with respect to the plane of diffraction.…”

Manifestation of the effects of dynamic diffraction in the coherent X-ray radiation of relativistic electrons in a periodic layered medium

“…Coherent X ray radiation in a periodic layered structure was regarded as the resultant effect of two mechanisms of radiation, namely, PXR and diffracted transition radiation (DTR). The dynamic theory of relativistic electron radiation in periodic layered media [21] well described the experimental data in [22], where layers of a struc ture with a thickness of about 1 nm were used and pho tons with a frequency of 15 keV were generated. We note that, in all cited papers , the process of emission in a periodic layered medium was regarded only in the Bragg scattering geometry in the case of symmetric reflection, where the angle between the surface and reflecting planes was zero and emitted photons escaped through the front target boundary.…”

“…Parametric radiation (PXR), together with RTR, was considered in [13]. It is necessary to note that various methods were used to describe the process of relativis tic electron radiation in a periodic layered structure [14][15][16][17][18][19][20]; however, the authors of [21] were the first to consider radiation from a multilayer periodic layered structure in the dynamic approximation as the scatter ing of pseudophotons of the Coulomb field of relativ istic electrons at amorphous layers by analogy with the process of coherent radiation produced by relativistic electrons in a crystalline medium. Coherent X ray radiation in a periodic layered structure was regarded as the resultant effect of two mechanisms of radiation, namely, PXR and diffracted transition radiation (DTR).…”