Investigating new activators for small-bandgap LaX3 (X = Br, I) scintillators.

Luminescence and scintillation properties of Bi 3+ , Sb 3+ , and Eu 2+ -doped LaI 3 and LaBr 3 were explored. Out of the three dopants investigated, Eu 2+ was the most promising new activator for small-bandgap LaX 3 (X = Br, I) and was further studied in the mixed-halide LaBr 3−x I x . Crystals were grown from the melt using the vertical Bridgman method. LaBr 3 :Eu 2+ 0.5% (mol) had the most favorable scintillation properties with a light output of 43,000 ph/MeV and 6% energy resolution at 662 keV. Performance of LaBr 3−x I x :Eu 2+ worsened for most samples as iodide concentration was increased. Room-temperature scintillation of LaI 3 :Eu 2+ 0.1% and 0.5% was observed and is the first case of room-temperature emission reported for doped LaI 3 . [ABSTRACT FROM AUTHOR]