W0236

Advanced Technologies for Next-Generation CCD Detectors. Y. Diawara, R.D. Durst, V. Valdna, Bruker Analytical X-ray Systems, Inc., 6300 Enterprise Ln., Madison, WI 53719 USA

A critical component of CCD-based x-ray imagers is the phosphor screen which converts the incident x-ray flux to visible light. The characteristics of an ideal x-ray phosphor include strong x-ray absorption, high conversion efficiency, good spectral matching to the CCD, good linearity, fast time response and extremely low afterglow levels. The characteristics of commercially available x-ray phosphors are discussed with particular attention given to lanthanide-doped Gd₂O₂S (which has become the defacto standard for CCD-based x-ray imaging). However, Gd₂O₂S was originally developed as an intensifier for ortho film and hence its time response, spectral output and conversion efficiency are not optimal for CCD imaging. The need for x-ray phosphors which are specifically optimized for CCD detectors has been recognized for some time. Here we report on studies of the underlying physical limits to x-ray phosphor performance and the development of a new class of x-ray phosphors which exhibit higher conversion efficiency, better spectral matching, lower afterglow levels and superior linearity compared to the best conventional phosphors.