Thermoluminescence of LaBr3:Ce and LaCl3:Ce crystals

LaCl3:Ce and LaBr3:Ce scintillators are characterized by a high light yield and very fast nanosecond primary emission. To study scintillation mechanisms in these materials, we have measured low-temperature thermoluminescence. Both crystals exhibited prominent glow peaks below 100 K: LaCl3:10%Ce sample showed multiple glow peaks with two major ones at 65 and 66 K, whereas the LaBr3:0.5%Ce sample showed two major peaks at 65 and 75 K. Assuming first-order kinetics, the traps responsible for those peaks can be described by the following parameters: E=0.168 eV, s=1×1012 s−1; E=0.135 eV, s=1×109 s−1 for LaCl3:Ce and E=0.144 eV, s=1×1010 s−1; E=0.166 eV, s=1×1010 s−1 for LaBr3:Ce. The lifetimes of listed traps at RT are in the range of radiative lifetime of Ce3+ emission (0.5-50 ns).