Determination of the lead concentration of Pb---Zn ores in laboratory boreholes using gamma-gamma techniques with very low activity sources

The low activity spectrometric gamma-gamma technique was extended to the determination of lead concentration in Pb---Zn ore in boreholes. The tool uses a 38 mm diam. × 76 mm NaI(T1) scintillation detector and has an external diameter of 60 mm. Two source-detector configurations were tested in the present work. The two 137Cs gamma-ray sources used in these configurations had activities of 1.8 and 1.1 MBq, respectively.