Radiopurity of a CeBr3 crystal used as scintillation detector

Cerium bromide (CeBr3) has recently been shown to exhibit several properties making it a suitable material as a scintillation detector in nuclear physics applications. The intrinsic activity of gamma-ray emitting radionuclides in a 38.1 mm×38.1 mm (diameter×height) crystal of CeBr3 was investigated. The measurements were carried out in the HADES underground laboratory located 225 m underground. Two primordial radionuclides were detected; 227Ac (and its daughters) with massic activity of 0.30±0.02 Bq/kg and 138La with massic activity of 7.4±1.0 mBq/kg. Two activation products were also detected; 139Ce and 82Br. Their massic activities (assuming a homogeneous distribution in the crystal) just before taking the CeBr3 crystal underground were 4.3±0.3 mBq/kg and 18±4 mBq/kg correspondingly. None of the other common primordial radionuclides (40K, 226Ra, 228Ra, 228Th, and 235U) were detected and their detection limits were below 2 mBq/kg except for 238U for which the upper limit was 135 mBq/kg and 210Pb with an upper limit of 600 mBq/kg.