Peculiarities of intrinsic background in LaBr 3 : Ce and CeBr 3 scintillating crystals

The intrinsic background was measured in LaBr 3 :Ce and CeBr 3 scintillating crystals grown at the Institute of Solid-State Physics of the Russian Academy of Sciences. The measurements were taken in the range of γ-ray energies from 20 keV to ∼5 MeV. Cylindrical samples with dimensions of Ø 1.5 × 1.8 cm for LaBr 3 :Ce and Ø 0.5 × 1.5 cm for CeBr 3 were used. Well-known peculiarities due to the 138 La radioactive iso-tope and actinide contaminants were reproduced in the recorded background spectrum of the LaBr 3 :Ce crystal. The detailed spectrum of the intrinsic background in the CeBr 3 crystal was measured for the first time. At energies of >200 keV, the background rate of CeBr 3 appeared to be much lower than that of LaBr 3 :Ce both in the continuum and in the peculiarities associated with the radioactivity of possible contaminants.