LSO-Based Single Crystal Film Scintillator for Synchrotron-Based Hard X-Ray Micro-Imaging

X-ray detector systems are powerful tools: in combination with tomographic methods they provide volumetric data of samples in a non-destructive manner which is of high interest for, e.g., biology, medicine or materials research. The detector able to provide images with submicrometer spatial resolution frequently consists of a scintillator screen, light microscopy optics and a digital camera. Here, the scintillator converts the X-rays into a visible light image which is projected onto the camera by the light optics. In order to perform high resolution imaging Single Crystal Film (SCF) scintillators 1 mum to 30 mum thin are required due to the limited depth of focus of the microscopy optics. Thin SCFs can be obtained via liquid phase epitaxy (LPE). A drawback is that a detector working with SCFs suffers from low efficiency (2% at 50 keV) owing to their limited thickness. The detective quantum efficiency (DQE) is here mainly limited by the low absorption of X-rays and the light yield in the thin scintillator layer. Performances, i.e absorption, light yield, afterglow of operational systems at the European Synchrotron Radiation Facility (ESRF) using YAG:Ce (Y₃Al₅O₁₂:Ce), LAG:Eu (Lu₃Al₅O₁₂:Eu) and GGG:Eu (Gd₃Ga₅O₁₂:Eu) scintillators will be presented and compared to new LSO:Tb (Lu₂SiO₅:Tb) scintillators developed in the framework of an European project , . A new concept to improve the efficiency of detection in the 20 keV - 40 keV energy range with 1 mum spatial resolution will be presented. This concept based on multilayer scintillators is realised by the LPE process as well. First results will be illustrated with X-ray images and will demonstrate the absorption efficiency improvement of the X-ray detector. The expected performance is 7 times better than the LAG-based scintillators.