X-ray CCD response functions, front to back

For some applications, particularly in X-ray astronomy, one requires accurate knowledge of the charge-coupled device (CCD) spectral redistribution function, with errors of order 1%. We describe some recent advances in response function measurement and modeling. In particular, we show that it is now possible to isolate and separately measure the response contributions of many of the component volumes that comprise the CCD. We describe how we have deployed this capability to determine X-ray photon response functions for front-illuminated detectors, and indicate how these measurements can improve understanding of the response function of the back-illuminated CCD.