Radioactive contamination of 7LiI(Eu) crystal scintillators

The radioactive contamination of two 26 g samples of low background lithium iodide crystal scintillators doped by europium and enriched in 7Li to 99.9% (7LiI(Eu)) has been investigated by scintillation method at the sea level, and by ultra-low background HPGe γ spectrometry deep underground. No radioactive contamination was detected. In particular, the contamination of the crystal scintillators by 226Ra and 228Th does not exceed 1 mBq/kg, and the activity of 40K is less than 0.5 Bq/kg