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The X-ray ring at NSLS in normal operation mode accelerates electrons to energies of about 2.5 GeV for optimized X-ray emission in the range of 1 to 10 keV. A table of the operating parameters of the NSLS X-ray storage ring is provided at their Web site (http://www.nsls.bnl.gov/). Our experiment was set up on beamline X8A, one of 56 X-ray beamlines attached to the X-ray storage ring. The beam energy incident on the filters was selected by adjusting the orientation of the crystal element of a double crystal monochromator located upstream from the vacuum chamber. Each crystal element spans a certain energy range. In particular a W/Si multilayer covers the energy range 0.26-2.0 keV with energy resolution () of 2x10-2 a Si(111) crystal covers the range 2.1-5.9 keV with a resolution of 5x10-4 and a Beryl(1010) crystal covers the range from 0.8-2.0 keV with a resolution of 8x10-4. In Table 5.1, we list the energies surveyed and the monochromator crystal elements used for the transmission measurements of the ACIS-I and ACIS-S UV/Optical blocking filters. Detailed fine energy scans were performed above the absorption K edges of C, N, O, and Al to investigate extended X-ray absorption fine structure (EXAFS) and shifts in the location of the Al-K edge due to possible Al2O3 contamination.
|Energy Range (eV)||Step Size (eV)||Monochromator||Beam Filter||Absorption Edge|
|300-600||5||W Si Multilayer||Chromium||N-K(401.6eV)|
The configuration of the test set up is shown in Figure 5.1. The ACIS filters were placed into the UC/SAO spectrometer-reflectometer chamber and mounted onto a mechanical fixture. The fixture was made to support both image and spectrometer filters and was mounted on a rotary stage that allowed for the selection of the portion of the filter to be intercepted by the X-ray beam. The X-ray beam was collimated with a set of vertical and horizontal entrance slits to a size of 2 mm by 2 mm. The beam flux was monitored using a detector that was moved in and out of the X-ray beam with a computer controlled actuator.