Structured GdI3:Ce scintillators for X-ray and neutron imaging

Gadolinium iodide doped with cerium (GdI₃:Ce) is one of the recently discovered materials that exhibit excellent scintillation properties. With its high density of 5.2 gm/cm³, high effective atomic number of 57, its promising bright emission of ~100,000 photons/MeV in 550 nm green region of visible spectrum, GdI₃:Ce is an excellent candidate for X-ray detection and imaging. In addition, the presence of Gd, with its high cross-section for thermal neutrons, makes it an attractive candidate for neutron detection and imaging. While the GdI₃:Ce crystals, which are useful for neutron and γ detection/spectroscopy have previously been reported [1, 2], it is necessary to synthesize this material in a large area film format for imaging applications. Such films may then be coupled to high-resolution CMOS- or CCD-based sensors to construct imaging detectors. Here we report on the first ever fabrication of GdI₃:Ce films using hot wall evaporation (HWE). Specimens up to 5 cm diameter, 350 μm thick films have been grown. The films are fabricated in a microcolumnar form, which offsets the efficiency-resolution tradeoff in conventional imaging systems. These films exhibit characteristic bright emission of GdI₃:Ce, excellent spatial resolution, and anticipated response to thermal neutrons. In addition to their excellent scintillation properties, the high X-ray absorption efficiency, high thermal neutron cross-section, and the vapor deposition methods for its synthesis, are promising features of this development. This combination allows mass production of large-area, high-performance X-ray/neutron detectors in a uniquely time efficient manner.