Application of polycapillary optics to hard x-ray astronomy

Polycapillary x-ray optics, which are comprised of bundles of tens of thousands to millions of hollow glass capillary tubes, can be used as concentrators of astronomical x-rays for spectroscopic studies. Measurements have been performed of transmission efficiency of straight polycapillary fibers in the range of 10-80 keV. A geometrical optics simulation has been developed which accurately models experimental results and includes the effects of surface roughness and profile error. An optic designed for 8 keV photons has been tested as a concentrator for parallel beam synchrotron radiation. The results, a factor of 65 in intensity gain, are in good agreement with optics simulation. A prototype optic designed for 10-50 keV is currently under construction with a predicted gain of more than 100. Design requirements for higher energy photons are considered. By using a small or position sensitive detector, improvements of 2 orders of magnitude at 80 keV are expected from the use of this type of collector.