Scintillation properties of ⊘ 1x1 inch3 LaBr3:: 5%Ce3+ crystal

The Scintillation properties of the first large circle divide 1 x 1 inch(3) LaBra(3):5%Ce3+ scintillator were studied under gamma-ray excitation. This crystal is a LaBr3:5%Ce3+ standard product from Saint Gobain company. The sample was cut and polished by the manufacturer from a larger size crystal boule. It was then assembled in a cylindric aluminum case with a front glass window. The results are compared with those recorded with a 0.4 x 0.3/, x 0.5 inch(3) unpacked crystal. The highest light yield of 21500 +/- 2200 photoelectrons per MeV (60500 +/- 6000 photons per MeV) of absorbed gamma-ray energy was measured for the unpacked crystal-compared to 16800 +/- 1700 photoelectrons per MeV for the circle divide 1 X 1 inch(3) sample. At room temperature the scintillation decays with a decay time of 16 +/- 1 us. The 0.4 x 0.3 x 0.5 inch 3 unpacked crystal-coupled to photomultiplier tube (Hamamatsu R1791) and measured at 662 keV-exhibited an energy resolution of 2.8%, better than the one of the circle divide 1 x 1 inch(3) crystal (3.1%). Special attention was devoted to energy and temperature dependencies of scintillation properties: the results show a good proportionality for light output versus gamma-ray energy. The light output deviates from the linear response of 5% between 20 keV and 2 MeV. Furthermore temperature dependency of gamma-ray excited decay time (80-700 K) does not indicate the presence of thermal quenching from the cerium 5d state. These characteristics suggest a broad range of applications for the LaBr3:5%Ce3+ scintillator.