The X-ray spectrometer (XRS), which is being developed for one of the focal plane instruments of the Advanced X-ray Astrophysics Facility (AXAF), requires filters with high X-ray transmittance, high background rejection, and operation at cryogenic temperatures. Thin foil filters can provide high X-ray transmittance and the required rejection for low energy radiation. The results of the test program demonstrate that these filters are fully successful at cryogenic temperatures and therefore can provide blocking filters for the XRS with the required performance.
Ritva A. M. Keski-Kuha,
"X-Ray Thin Foil Filters At Cryogenic Temperatures", Proc. SPIE 1160, X-Ray/EUV Optics for Astronomy and Microscopy, (28 July 1989); doi: 10.1117/12.962629; https://doi.org/10.1117/12.962629