16 September 1994 Efficiency measurements and modeling of the Advanced X-ray Astrophysics Facility (AXAF) high-energy transmission gratings
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Abstract
As part of the calibration for the High Energy Transmission Grating Spectrometer (HETGS) on AXAF, we conducted several studies at synchrotrons in an effort to measure the resolving power and the quantum efficiency of gratings over a range of x- ray energies. Gratings that have been thoroughly studied can be used as calibration transfer standards at MIT to evaluate the quality and repeatability of our testing procedures. Synchrotron studies also enable us to evaluate our theoretical prediction of grating performance and thereby obtain a more accurate model of the gratings. In this paper we discuss studies made of 0.2 micrometers and 0.4 micrometers period gratings with gold grating bars supported by thin polyimide films. The goal of this experiment was to measure and accurately model the efficiencies of several grating facets over much of the energy range for which they would be used in space. Our tests were performed in January and July of 1994 at the National Synchrotron Light Source at Brookhaven National Laboratory. We used beam line X8A to illuminate sample gratings that were inserted in the UC/SAO Reflectometer Test Station (the same device that is used to study witness samples for the AXAF mirrors). A double crystal monochromator was used to select narrow energy bands over the range 0.6-6 keV. We measured the diffraction efficiencies as a function of energy for the first order x-rays. Results are in good agreement with predicted efficiencies calculated using gold optical constants that we recently measured, and confirm the energy shift of the MIV and MV edges from the standard values, as measured by Blake et al. (J. X-ray Sci. Technol., in press).
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Christie S. Nelson, Christie S. Nelson, Thomas H. Markert, Thomas H. Markert, Y. S. Song, Y. S. Song, Mark L. Schattenburg, Mark L. Schattenburg, Dale E. Graessle, Dale E. Graessle, Kathryn A. Flanagan, Kathryn A. Flanagan, Richard L. Blake, Richard L. Blake, James M. Bauer, James M. Bauer, Eric M. Gullikson, Eric M. Gullikson, } "Efficiency measurements and modeling of the Advanced X-ray Astrophysics Facility (AXAF) high-energy transmission gratings", Proc. SPIE 2280, EUV, X-Ray, and Gamma-Ray Instrumentation for Astronomy V, (16 September 1994); doi: 10.1117/12.186811; https://doi.org/10.1117/12.186811
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