Characterization of x-ray lens for use in probing high energy density states of matter

Abstract

By using polycapillary lenses to focus laser-produced x-ray sources to high intensities, an improvement in signal-to-noise ratio can be achieved. Here the He-α line emission produced by driving a titanium backlighter target is focused by a polycapillary lens and the output characterized. The x-ray spot is measured to have a peak intensity of 4.5 × 107 photons, with a total photon count of 8.8 × 108 in 0.13 ± 0.01 mm2. This setup is equivalent to placing the backlighter target 3 mm from the sample with a 600 μm diameter pinhole. The polycapillary lens enables the placement of the backlighter target at a much larger distance from the sample to be studied and therefore has the ability to greatly improve the signal-to-noise ratio on detectors. We demonstrate this with two simple diffraction experiments using pyrolytic graphite and polycrystalline aluminium.