Improvement of LaBr₃:5%Ce scintillation properties by Li⁺, Na⁺, Mg²⁺, Ca²⁺, Sr²⁺, and Ba²⁺ co-doping

This paper reports on the effects of Li⁺, Na⁺, Mg²⁺, Ca²⁺, Sr²⁺, and Ba²⁺ co-doping on the scintillation properties of LaBr₃:5%Ce³⁺. Pulse-height spectra of various gamma and X-ray sources with energies from 8 keV to 1.33 MeV were measured from which the values of light yield and energy resolution were derived. Sr²⁺ and Ca²⁺ co-doped crystals showed excellent energy resolution as compared to standard LaBr₃:Ce. The proportionality of the scintillation response to gamma and X-rays of Ca²⁺, Sr²⁺, and Ba²⁺ co-doped samples also considerably improves. The effects of the co-dopants on emission spectra, decay time, and temperature stability of the light yield were studied. Multiple thermoluminescence glow peaks, decrease of the light yield at temperatures below 295 K, and additional long scintillation decay components were observed and related to charge carrier traps appearing in LaBr₃:Ce³⁺ with Ca²⁺, Sr²⁺, and Ba²⁺ co-doping.