Next: 1 Introduction
Using Tritium and x-ray tubes as x-ray calibration sources for
the AXAF CCD imaging spectrometer
Stephen E. Jones, Marshall Bautz, Steven Kissel, and Michael Pivovaroff
Center for Space Research, Massachusetts Institute of Technology
Cambridge, Massachusetts, 02139
Abstract:
Accurate quantum efficiency calibrations for CCDs require stable
sources of known x-ray energies. Radioactive sources are the most stable
although some stable commercial x-ray tubes are available. However,
sealed, stable x-ray tubes include windows which filter low energy
x-rays to which our CCDs are sensitive. Therefore we have developed a
windowless radioactive source using the beta spectrum from tritium to
fluoresce low-energy x-rays from low Z targets. The potential drawback
of tritium outgassing is also investigated. This source is coupled
with an additional system based on a stable commercial x-ray tube to
produce higher energy x-rays. Together these sources form a system for
comparative quantum efficiency measurements with two CCDs mounted on
translation stages. We report on the physics and development of these
x-ray sources.
KEYWORDS: ACIS, AXAF, calibration, CCD, tritium, x-ray source
sjones@space.mit.edu