Wide energy range efficiency calibration for a lanthanum bromide scintillation detector

Abstract

In recent years a new type of scintillation detector based on the LaBr 3 :Ce crystal has been developed. This detector offers a substantial advantage over the standard NaI(Tl) detector. In comparison the energy resolution (about 3% at 662 keV) is better and the efficiency for high-energy gamma rays is higher. The detector crystal has other advantages such as a high scintillation light output with a fast decay time. Due to the favorable characteristics and ease of use, the lanthanum bromide detector is likely to gain acceptance quickly in a variety of applications. We use the detector for activation analysis in conjunction with a 14-MeV neutron generator. This includes the detection of prompt gamma rays from neutron inelastic scattering and neutron capture. The elements of our interest include oxygen, hydrogen, nitrogen, carbon, fluorine and chlorine which emit characteristic gamma energies in the range of 1–10 MeV. The paper presents the absolute full-energy peak efficiency calibration of a 38.1 mm × 38.1 mm ( 1.5 in × 1.5 in ) LaBr 3:Ce crystal for gamma-ray energies up to 5 MeV. For the present calibration the detector/source distance was set to 250 mm.