Abstract:

Gadolinium iodide doped with Cerium (GdI₃:2%Ce) and undoped gadolinium iodide (GdI₃) crystals were grown by vertical Bridgman method with sealed quartz crucible. Crystal ingots with dimension of ϕ15 mm×20 mm were cut and polished to be plates of 12 mm×10 mm×2.5 mm and 11 mm×8 mm×2.5 mm. GdI₃:2%Ce without crack and inclusion were encapsulated for all the measurements. X-ray diffraction analysis shows that the Ce³⁺-doped GdI₃ and undoped GdI₃ crystal have the same structure. X-ray and ultraviolet excited luminescence spectra of GdI₃:2%Ce present broad emission bands peaking at 520 nm and 550 nm, respectively, which correspond to 5d-4f transition luminescence of Ce³⁺. Three peaks located at 262, 335 and 440 nm can be observed in excitation spectra when photoluminescence is monitored at 550 nm. The GdI₃:2%Ce crystal presents an excellent energy resolution of 3.4% and decay time of (58±3) ns under excitation of 662 keV gamma-rays from ¹³⁷Cs source. The results show the GdI₃:2%Ce crystal is a promising scintillator for gamma ray and neutron detection.

Key words: GdI3:2%Ce crystal, Bridgman method, scintillation property