Escape peak ratios in silicon X-ray charge coupled devices (CCDs)

The intensity of the escape peak from the CCDs developed for the Joint European X-ray Telescope (JET-X) has been investigated over the energy range 2–10 keV. Both measured and calculated escape peak ratios (i.e., the ratio of counts in the escape peak to the sum of the counts in the escape and main peaks) are found to be in excellent agreement for all event sizes (i.e., single pixel events, 1 and 2 pixel events, etc.). Using a Monte Carlo simulation the escape peak ratio has been investigated as a function of pixel size and depletion depth. For completeness, we list the energy dependent parameterised forms for five CCDs used in three major astronomy missions.