Ultra-fast LuI₃:Ce scintillators for hard x-ray imaging

We have developed ultra-fast cerium-coped lutetium-iodide (LuI₃:Ce) films thermally evaporated as polycrystalline, structured scintillator using hot wall epitaxy (HWE) method. The films have shown a 13 ns decay compared to the 28 ns reported for crystals. The fast speed coupled with its high density (∼5.6 g/cm³), high effective atomic number (59.7), and the fact that it can be vapor deposited in a columnar form makes LuI₃:Ce an attractive candidate for high frame rate, high-resolution, hard X-ray imaging. In crystal form, LuI₃:Ce has demonstrated bright (>100,000 photons/MeV) green (540 nm) emission, which is well matched to commercial CCD/CMOS sensors and is critical for maintaining high signal to noise ratio in light starved applications. Here, we report on the scintillation properties of films and those for corresponding crystalline material. The vapor grown films were integrated into a high-speed CMOS imager to demonstrate high-speed radiography capability. The films were also tested at Advanced Photon Source, Argonne National Laboratory beamline 1-ID under hard X-ray irradiation. The data show a factor of four higher efficiency than the reference LuAG:Ce scintillators, high image quality, and linearity of scintillation response over a wide energy range. The films were employed to perform hard X-ray microtomography, the results of which will also be discussed.