Calibration of the UV/ion shields for the AXAF High-Resolution Camera

The high resolution camera (HRC) is one of AXAF's two focal plane instruments. It consists of two detectors: the HRC-I which is optimized for direct imaging of x-ray sources; and the HRC-S which is optimized as the spectroscopic read-out of the low energy transmission grating (LETG). Both detectors are comprised of a chevron pair of micro-channel plates (MCPs) with a crossed grid charge detector (CGCD) and a UV/ion shield (UVIS). The role of the UVIS is to minimize the detectors' sensitivity to low energy electrons, ions and UV light, while providing sufficient x-ray transmission in the 0.1 to 10 keV x-ray band. In this paper, we report on the results of the flight UVIS calibration measurements. Specifically, x-ray and UV transmission measurements obtained at the HRC X-ray Test Facility of the Smithsonian Astropysical Observatory, and x- ray transmission measurements of UVIS witness samples obtained at a synchrotron light source facility.