Investigation of the properties of a 1 00 1 00 LaBr 3 :Ce scintillator

The properties of a cylindrical 1 00 � 1 00 LaBr3:Ce scintillator (Brillance 380) were investigated. The energy resolution at g-ray energy of 662 keV was measured to be smaller than 3% and the intrinsic time resolution was found to be E230 ps. Two different aspects were investigated. The first is the detailed study of the crystal self-activity, emitting a and b particles and g-rays, by measuring coincidences with g-rays in HPGe, BGO and BaF2 detectors. In particular, the coincidence with an HPGe detector allowed to isolate clearly the different contributions from 227 Ac (chemical homologue of lanthanum) and its daughter nuclei down to the stable 207 Pb. The second aspect is the determination of the efficiency for g-ray detection, measured at 1 MeV and simulated using GEANT4 up to 15 MeV as a function of the detector size.