Assessment of the flux and monochromaticity characteristics of a polarized X-ray source

Abstract

This paper presents an apparatus designed for the generation of polarized X-rays utilizing crystal Bragg diffraction techniques, which produces polarized X-rays energies within the range of 4-10 keV, facilitating the calibration of detection efficiency, energy resolution, polarization degree, and other parameters pertinent to polarized X-ray detectors. The apparatus comprises of a radiation source, a diffractive crystal, a rotating control mechanism, a detector and other components. High-precision generation of polarized X-rays can be achieved by diffracting through crystals with varying lattice constants at an angle of 45° using an X-ray tube and a Bragg diffraction apparatus. Monte Carlo simulations were conducted to evaluate air absorption effects on X-rays at varying energy levels, revealing an optimal measurement distance of 30 cm. Key metrics such as energy output, flux rate, energy resolution and mono-chromaticity for the generated polarized X-rays were evaluated through experimental measurements. The polarized X-ray flux rates were measured as: 4.135×106 m-2s-1 at 4.59 keV, 2.210×107 m-2s-1 at 6.39 keV, and 1.958×107 m-2s-1 at 10.029 keV. Monochromaticity values were: 1.48 % at 4.59 keV, 0.96 % at 6.39 keV, and 0.15 % at 10.029 keV. The apparatus is applicable to ground calibration of astronomical satellite payloads and detector development.

Keywords

• polarized x-ray
• bragg diffraction
• monochromaticity
• flux rate