Study on artificial radioactivity information extraction from airborne gamma-ray spectrum

[Background] Response spectrum of radiation sources can be extracted from airborne gamma-ray spectrum by the least square method, however, the analysis accuracy of artificial radioactivity information is affected by the accuracy of response spectrum of radiation sources. [Purpose] This study aims to improve accuracy of response spectrum of radiation sources by extracting artificial radioactivity information from airborne gamma-ray spectrum. [Methods] We obtained the linear law between peak intensity of annihilation radiation from cosmic gamma-rays and count rate of cosmic gamma-rays in the last channels by experiments at different detection altitudes and the response spectrum of cosmic gamma-rays by Monte Carlo (MC) simulation. Meanwhile, the response spectrum of radon daughters could be replaced by the response spectrum of stratum radiated from only ²³⁵U and ²³⁸U series, which was verified by experiments at eight detection altitudes. [Results] The above conclusions were applied to inverse activities of two point sources at different detection altitudes and locate radiation hotspot of artificial radioactivity nuclide. [Conclusion] These results show that the proposed approach can extract artificial radioactivity information better. And it provides a valid method to use airborne gamma-ray spectrometry in nuclear emergency. (authors)