New High Stopping Power Thin Scintillators Based on ${rm Lu}_{2}{rm O}_{3}$ and ${rm Lu}_{3}{rm Ga}_{5-{rm x}}{rm In}_{rm x}{rm O}_{12}$ for High Resolution X-ray Imaging

摘要

X-ray computed tomography devices and X-ray diffraction techniques are powerful tools: the former provide volumetric data of samples during a non-destructive examination for biology and material science, and the latter measure grain orientation and strain, as well as crystalline phase identification and structure refinement. Today, the European Synchrotron Radiation Facility (ESRF) provides increasingly higher energy beams, up to 150 keV combined with higher brilliance ($10^{13}$ X-ray photons/sec). This means that detectors suffer from low X-ray absorption at high spatial resolution (1–10 $mu{rm m}$) and from radiation damage in tomography and diffraction applications. In addition, more and more experiments in medicine require the absorbed dose by the sample to be reduced. In this context, more efficient scintillators are developed and evaluated at the ESRF. In order to perform sub-micrometer and micrometer resolution imaging scintillators 1 $mu{rm m}$ to 500 $mu{rm m}$ thin are required. Single Crystal Film scintillators (SCF), 1 $mu{rm m}$ to 100 $mu{rm m}$ can be obtained via Liquid Phase Epitaxy for sub-micrometer resolution. Transparent ceramics, 100 $mu{rm m}$ to 500 $mu{rm m}$ thick are promising candidates for X-ray imaging requiring high X-ray absorption and good contrast with micrometer resolution. Commonly available scintillators, such as ${rm CdWO}_{4}$ and YAG:Ce suffer from low efficiency, therefore new scintillators with higher light yield and stopping-power are required. A first test was carried out to evaluate an Europium doped Lutetium Oxide ceramic for micrometer resolution and new SCFs of ${rm Lu}_{3}{rm Ga}_{5-{rm x}}{rm In}_{rm x}{rm O}_{12}:{rm Eu}$ for sub-micrometer resolution are investigated. Performance of ${rm Lu}_{2}{rm O}_{3}$ and LuInGG, i.e absorption, light yield, afterglow, spatial resolution will be presented and compared to standard screens (YAG, GGG). First results will be illustrated with X-ray images and will demonstrate the absorption efficiency improvement at high spatial resolution.