Novel high efficiency microcolumnar LuI3:Ce for hard X-ray imaging

We report on the development of microcolumnar films of an extremely fast and bright cerium-doped lutetium iodide (LuI₃:Ce) scintillator that can resolve the 153 ns bunch structure of the Advanced Photon Source (APS) at Argonne National Laboratory (ANL). Due to the fast, afterglow-free decay, and high efficiency of LuI₃:Ce, during the experiments performed at the 1-ID hard X-ray beamline at the APS, single 65 keV X-ray photons could be resolved with high signal-to-noise ratio and with temporal resolution better than 20 ns, revealing the 153 ns bunch structure of the APS. LuI₃:Ce has high density (~5.6 g/cm³), high effective atomic number (59.7), bright green emission (540 nm range, well matched to commercial optics and CCD sensors), light yield exceeding 115,000 ph/MeV, and rapid, afterglow-free decay (~28 ns). We have developed the scintillator using a vacuum deposition technique that is suitable for manufacturing large area scintillators in a microcolumnar form which provides high absorption efficiency and allows high temporal and spatial resolution imaging. Details of the scintillator fabrication and characterization, and imaging experiments performed at the Sector 1-ID hard X-ray beamline at the APS will be presented in the paper.