Measurements of x-ray emission from photoabsorption-edge transition radiation

This article describes the measurements of x-ray power, spatial, and spectral distributions from transition radiators whose spectra are narrowed by the foil material’s K-shell photoabsorption edge. We used two foil stacks, one composed of 10 foils of 2-μm-thick titanium and the other composed of 18 foils of 2-μm-thick copper. The x-ray flux produced by a foil stack was compared with the flux produced by a single foil of equivalent thickness. The Ross-filter technique was used for measuring the magnitude of the flux within specific energy bands, 1.56–4.96 keV, and 4.96–9.66 keV. The maximum flux from the titanium radiator was 4.8 mW. The maximum flux from the copper radiator was 3.6 mW. In addition both the flux distribution as a function of photon energy and the spatial flux distribution of the titanium radiator were measured. The x-ray emission was measured by pulse height analysis to be between 3.8 and 6 keV. The spatial measurements showed the x rays to be emitted in an annular cone with angular divergence of approximately 5 mrad. These measurements compared well with calculations.