HIGH-SPATIAL-RESOLUTION SCINTILLATOR SCREENS COUPLED TO CCD DETECTORS FOR X-RAY-IMAGING APPLICATIONS

New generations of X-ray imaging detectors are being developed for X-ray diffraction studies using both conventional sources and synchrotron beam lines. In many cases, these detectors utilise a scintillator screen to convert the X-ray photon energy into scintillation light. However, the spatial resolution is limited due to the diffusion of light that occurs within the scintillator layer. Results are presented for a scintillation screen that improves the spatial resolution through the use of a specially prepared fibre optic surface where the clad glass has been selectively etched away to leave the protruding columns of core glass. When evaporated onto this surface, the scintillator grows as extensions of these pillars forming discrete columns which individually act as light guides for the scintillation light. A calculation of the system DQE is presented and used to predict the performance to 8 ke V X-rays. A Monte Carlo simulation of the X-ray interaction in CsI is also used to evaluate the system DQE above the K shell absorption edges (33 and 37 keV) and therefore determine the useful energy range of the scintillator.