POLYCAPILLARY X-RAY OPTICS FOR X-RAY ASTRONOMY

High-energy x-ray spectrometry from astronomical sources is difficult due to low flux rates and high background. Polycapillary x-ray optics can be used to increase the signal-to-noise ratio by focusing photons onto a small energy dispersive detector. Two optics, both designed for x-ray astronomy, have been built and tested as collimating optics with a microfocus x-ray source for x-ray energies up to 70 keV and as focusing optics with parallel x-rays up to 50 keV. Results from these tests show that polycapillary x-ray optics have transmission efficiencies ranging from 5 % to 40 % and signal gains ranging from 5 to over 100 for energies up to 50 keV. Furthermore the results show that these optics have potential for use up to 100 keV. The experimental results as well as simulations for the measured and for optimized optics will be discussed.