Deep penetration effects are a major source of uncertainty in airborne gamma ray spectrometry because gamma rays can travel long distances through air and interact with detectors at a wide range of incident angles. To address this, the team designed a fast sourceless efficiency calibration algorithm that uses Geant4 based ray deposition modeling and Boolean operations to simulate how gamma rays deposit energy in the detector. By capturing intrinsic efficiency variations with incident direction, the method provides a more realistic detector response model without relying on physical calibration sources.

Traditional correction schemes often treat the survey area with uniform assumptions or simple two dimensional approximations. In contrast, the new method constructs a fully three dimensional terrain correction model dynamically along the aircraft flight path, allowing the inversion process to respond to real time changes in terrain height and surface geometry. This dynamic response matrix improves the stability of inversion results and reduces systematic bias in quantitative estimates of ground radioelement distributions.

Comparative experiments reported by the researchers show that the dynamic terrain correction approach outperforms conventional altitude based corrections, especially in mountainous and undulating regions where terrain effects are strongest. By better accounting for overlapping fields of view and changing detector geometry relative to the ground, the method yields more spatially consistent results across flight lines. The improved performance is particularly evident in tests of equivalent uranium content inversion, where dynamic terrain correction produces distributions that more closely match ground measurements.

Accurate airborne mapping of natural radionuclides such as potassium, uranium and thorium is essential for geological mapping, mineral resource exploration and environmental baseline studies. The higher quantitative reliability achieved with the combined sourceless calibration and dynamic terrain modeling approach supports clearer anomaly delineation and more robust interpretation of radiometric data. This is especially important in complex landscapes where conventional corrections can introduce artifacts or mask subtle geological signals.

The research team is now focusing on refining theoretical models of airborne gamma ray measurements and radiation field inversion under increasingly complex radiation environments. Their goal is to further enhance the adaptability of airborne gamma ray spectrometry for diverse survey conditions, including variable flight geometries and heterogeneous geological settings. Professor Hexi Wu commented that "This study further enhances the practical applicability of airborne gamma-ray measurements and represents a key step toward accurate quantitative analysis."

Research Report:Research on dynamic three dimensional terrain correction methods of quantitative inversion for airborne gamma ray spectrometer

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