Basic study of single crystal fibers of Pr:Lu3Al5O12 scintillator for gamma-ray imaging applications

Single-crystalline fibers were grown from 0.25, 0.70, and 1.50 mol% Pr-doped Lu3Al5O12 (LuAG) melts by the micro-pulling down (μ-PD) method with a diameter of 0.3-0.5 mm and a length of about 200 mm. They were cut to 10 mm long specimens, and their scintillation properties, including light yield and decay time profile, were examined. These results were compared with corresponding properties of the specimens (0.8x0.8x10 mm3) cut from the bulk crystals produced by conventional Czochralski (CZ) growth. The μ-PD-grown fibers demonstrated relatively low light yield and had the same decay time constant when compared with those of the samples cut from the CZ-grown crystals. The fiber crystals were used to assemble scintillating arrays with dimensions of O 0.5x10 mm2x20 pixels and O 0.3x10 mm2x30 pixels coated by a BaSO4 reflector. After optical coupling with a position sensitive photomultiplier tube, the fiber-based arrays demonstrated acceptable imaging capability with a spatial resolution of about 0.5 mm.