Evaluation of production samples of the scintillators LaBr3:Ce and LaCl3:Ce

We report on the evaluation of the performance of two recently developed scintillator materials, LaCl3:Ce and LaBr3:Ce, at the task of gamma ray spectroscopy. Their performance is compared to a standard scintillator used for gamma ray spectroscopy--a 25 mm diameter 25 mm tall cylinder of NaI:Tl. We measure the pulse height, energy resolution, and full-energy efficiency of production LaBr3:Ce and LaCl3:Ce scintillation crystals of different sizes and geometries for a variety of gamma-ray energies. Using production rather than specially selected crystals will establish whether immediate large-scale use is feasible. The crystal is excited by gamma rays from one of six isotopic sources (125I, 241Am, 57Co, 22Na, 137Cs, and 60Co) placed 15 cm away from the scintillator. Our measurements show that both LaCl3 and LaBr3 outperform NaI:Tl in almost all cases. They outperform NaI:Tl at all energies for the photopeak fraction and counting rate measurements, and for energy resolution at higher energies (above 200 keV for LaCl3 and 75 keV for LaBr3). The performance of production crystals is excellent and these scintillators should be considered for immediate use in systems where stopping power and energy resolution are crucial