New method of electron beam transverse size measurement by angular distribution of emission in a thin crystal

Abstract

A technique is proposed for determining beam dimensions on a target by measuring two-dimensional angular distributions of the radiation for two distances between the crystal where the radiation is generated and a coordinate detector. The dimensions are determined from the results of a least squares method procedure with varying parameters, where the adjustable function is the distribution for a shorter distance and the fitting function is the convolution of the angular distribution at a greater distance with a twodimensional Gaussian distribution whose parameters are uniquely related to the beam dimensions on the target and the distances between the crystal and the detector. The minimum measured beam sizes are about 50-60 μm for the parametric x-ray mechanism and an electron energy of less than 1 GeV and 10-15 μm for the mechanism of diffracted transition radiation and electrons with an energy above several GeV.

Method of spatial size measurement of relativistic electrons beams with small bunch length

“…Therefore, all the results and conclusions obtained above and in ref. [13] remain valid for shorter wavelengths. Furthermore, a decrease in the radiation wavelength by a factor of more than 10 to λ ∼ 0.01 nm is achievable, since in the experiment in ref.…”

“…This allows the photon energy to be increased by reducing the viewing angle while maintaining the ability to protect the detector from bremsstrahlung from the crystal; see ref. [13] for details.…”

“…In ref. [13], it was shown that the error in determining the beam sizes by the method of ref. [10] does not exceed 5-7%, and the minimum measured dimensions σ x,y are determined by the conditions σ x,y > δ and σ x,y /R > 0.1Θ ch , where δ is the pixel size of the coordinate detector, R is the distance between the crystal and detector, and Θ ch is the characteristic radiation angle.…”

“…Reference [13] investigated the use of radiation with a photon energy of ω ∼ 11 keV and a wavelength of λ ∼ 0.1 nm, which is comparable to the size of microbunches of the particle beam of an X-ray free-electron laser [3]. It is desirable to reduce the wavelength of the detected radiation to apply the technique of [10,13] for FEL diagnostic purposes.…”

Diffracted transition radiation as a new diagnostic tool for relativistic electron beam emittance

“…The abovementioned coherent effects in the optical radiation requires the not exceed 5%-7%, and the minimum measured dimensions 𝜎 𝑥,𝑦 were determined by the conditions 𝜎 𝑥,𝑦 > 𝛿 and 𝜎 𝑥,𝑦 ∕𝑅 2 > 0.1𝛩 ch , where 𝛿 is the pixel size of the coordinate detector, 𝑅 2 is the shorter distance between the crystal and the detector, and 𝛩 ch is the characteristic radiation angle. The minimum measured transverse dimensions are limited by the distance between the detector and the electron beam and cannot be less than 50-100 μm [21].…”