PrBr$_3$: Ce$^3+$: A New Fast Lanthanide Trihalide Scintillator

We present PrBr $_3$ : Ce $^3+$ as a new member of the lanthanide trihalide scintillator family. This compound has the same crystal structure as its cousin LaBr $_3$ : Ce $^3+$ . The calculated density $rho_r$ (5.33 g/cm $^3$ ) and the effective atomic number $Z_ eff$ (48.27) are higher than those of LaBr $_3$ : Ce $^3+$ ( $rho_r = 5.07$ g/cm $^3$ and $Z_ eff = 46.90)$ . This results in a shorter total attenuation length of 2.09 cm for 511 keV $gamma$ -ray excitation. Lower light yield than that of LaBr $_3$ : Ce $^3+$ is observed for prBr $_3$ :5%Ce $^3+$ (16 000 photons/MeV) and 20% Ce $^3+$ (21 000 photons/MeV) versus 70 000 photons/MeV in LaBr $_3$ : Ce $^3+$ . Scintillation decay curves of those crystals are non exponential and their decay times are faster than 10 ns. The scintillation properties of undoped PrBr $_3$ are also presented.