Calibration procedures in airborne gamma-ray spectrometry

The various calibration procedures adopted for airborne gamma-ray spectrometric measurements in Atomic Minerals Division are: (1) Over calibration pads for calculating sensitivities, stripping, and reverse stripping coefficients. Sensitivities are essential for converting the count rates into ground concentrations i.e. ppm (parts per million) in case of uranium and thorium and into percentage for potassium. In order to apply inter-channel corrections to radiometric data, stripping coefficients are essential. (2) Over test strip for calculating linear attenuation coefficients. These linear attenuation coefficients are used for applying height correction to the radiometric data. (3) Computation of sensitivities at nominal flying altitude (122 m) from the data obtained over the test strip for gamma-rays of different energies. In this paper computation of linear attenuation coefficients using test strip data and sensitivities, stripping, and reverse stripping coefficients using calibration pads data have been discussed in detail and results have been reported. The accuracy of the results have been ascertained and errors have been reported. (author). 12 refs., 7 tabs., 6 figs