19 July 1996 ACIS UV/optical blocking filter calibration at the National Synchrotron Light Source
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Abstract
Measurements of the transmission properties of the AXAF CCD imaging spectrometer (ACIS) UV/optical blocking filters were performed at the National Synchrotron Light Source at Brookhaven Laboratories. The X-ray transmissions of two Al:Si/LEXAN/Al:Si three layer filters were measured between 260 and 3000 eV. The main purpose of the calibration was to determine a model transmission function with an accuracy of better than 1 percent. We present results from fits of model transmission functions to the measured x-ray transmission data. Detailed fine energy scans above the Al-K and C-K absorption edges revealed the presence of fine oscillations of the x-ray transmission. These features are most likely extended x-ray absorption fine structures (EXAFS). The amplitude of the EXAFS oscillations above the Al absorption edge is about 5 percent of the mean value of the x-ray transmission. EXAFS theory predicts a temperature dependence on the amplitude of the EXAFS oscillations. This dependence arises from the fact that thermal vibrations of the atoms in a solid produce a phase mismatch of the backscattered electron wave function. Since the ACIS filters will be at a much lower temperature on orbit we provide a prediction of the EXAFS component for the expected on orbit temperature of the ACIS filters.
© (1996) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
George Chartas, George Chartas, Gordon P. Garmire, Gordon P. Garmire, John A. Nousek, John A. Nousek, Leisa K. Townsley, Leisa K. Townsley, Forbes R. Powell, Forbes R. Powell, Richard L. Blake, Richard L. Blake, Dale E. Graessle, Dale E. Graessle, } "ACIS UV/optical blocking filter calibration at the National Synchrotron Light Source", Proc. SPIE 2805, Multilayer and Grazing Incidence X-Ray/EUV Optics III, (19 July 1996); doi: 10.1117/12.245111; https://doi.org/10.1117/12.245111
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