Application Research On Low Energy Section Of Airborne Gamma-ray Spectrometry Use To Geological Mapping

Airborne gamma measurement method has advantages like good results, high efficiency, low costs, and adapted to the traffic inconvenient places such as gobi, desert, grassland, and complex terrain conditions. On most application and study of airborne gamma energy spectrum is focused onprocessing and utilization of the high energy period informationof U, Th, K count. In the spectrum of low energy section, although more difficult to distinguish characteristics gamma ray peak, however after Compton scatteringof the stratum substances form the low-energy scattering peak, with the corresponding formation information, such as the stratum material equivalent atomic coefficient, density, etc., and with large counting, small statistical fluctuation.This paperby using MCNP 5 software, on the basis of the principle of equivalent mass thickness, build the many sub-item sources superposition model, with different energy gamma rays, the density of different strata, different detection height, and different lithology respectively simulated calculation, and the calculation results comparing with the measured airborne spectrum. Using correlation ofthe low-energy scattering peak position and the stratum material equivalent atomic coefficient, make the peak left counts as S1, peak right counts as S2, with S1: S2 as marked volume, after revised and fitted, got the low-energy count lithology inversion scheme.This inversion scheme was applied to the test zone near the Baiyun Obo mine, after a small model validation, field geological reconnaissance, the ground gamma ray spectrometry, eventually applied in the test zone of airborne gamma ray energy spectrum, the equivalent atomic number coefficientfigure compared with geological reconnaissance and ground gamma inversion effect. Demonstrated the research significance, the inversion scheme to geological mapping and so on the ground geological work provides the beneficial reference.