Alpha-gamma discrimination by pulse shape in LaBr3:Ce and LaCl3:Ce

The line-shape of the signals from LaBr3:Ce and LaCl3:Ce detectors coupled to PM tubes were studied. The possibility of discriminating the type of interacting radiation was investigated making use of Pulse Shape Analysis (PSA) techniques. The study was performed measuring the self-activity present in lanthanum halide crystals in coincidence with gamma-rays in a HPGe crystal. A small but significant difference between alpha- and gamma-induced signals was directly observed for both the crystals. Using a simple PSA algorithm, it was possible to emphasize the differences in the pulse shape of gamma-rays and alpha-particles. This resulted in a rather clear identification of these two types of radiations.