Progress in fabrication of long transparent YAG:Ce and YAG:Ce,Mg single crystalline fibers for HEP applications

A significant enhancement in the light attenuation length in 22 cm long YAG:Ce and YAG:Ce, Mg fibers grown by the micro-pulling-down method has been reported. This progress has been achieved by the introduction of Al excess into the melt, optimization of thermal conditions of crystallization and post growth annealing. Attenuation length clearly correlates with surface roughness of the fibers. Al excess addition over the stoichiometric composition enhances the fiber surface smoothness. An increase in axial thermal gradient and melt pressure in the crucible capillary die improves the crystallization process stability. Mg codoping provides a Ce3+ scintillation decay time decrease down to 80 ns.