A sourceless efficiency calibration model of airborne γ-spectrometry based on Geant4

The calibration facility process for the airborne γ-spectrometer, which is built at the Shijiazhuang Dagou Village Airport of China, is time-consuming and labor-intensive. In this paper, a sourceless efficiency calibration model based on the Monte Carlo method using the Geant4 software has been established. The proposed model allows for the acquisition of the γ-spectrum response curve of the airborne γ-spectrometer above a cylindrical γ-radiation source containing uranium, thorium, and potassium elements in any proportion. It is applied to perform Compton scattering calibration and height attenuation correction for UGRS-10 airborne gamma spectrometer. The relative errors between the calibration parameters obtained by Geant4 simulation and those obtained by UGRS-10 airborne gamma spectrometer at Daguocun airport calibration facility are between 3 % and 27 %. The experiment demonstrates the Monte Carlo-based sourceless efficiency calibration model is suitable to calibrate airborne γ-spectrometers and provides technical support for airborne γ-spectrometry.