Investigating the minimum detectable activity concentration and contributing factors in airborne gamma-ray spectrometry

In this study,the theory of minimum detectable activity concentration(MDAC)for airborne gamma-ray spectrometry(AGS)was derived,and the relationship between the MDAC and the intrinsic effi-ciency of a scintillation counter,volume,and energy res-olution of scintillation crystals,and flight altitude of an aircraft was investigated.To verify this theory,experi-mental devices based on NaI and CeBr 3 scintillation counters were prepared,and the potassium,uranium,and thorium contents in calibration pads obtained via the stripping ratio method and theory were compared.The MDACs of AGS under different conditions were calculated and analyzed using the proposed theory and the Monte Carlo method.The relative errors found via a comparison of the experimental and theoretical results were less than 4%.The theory of MDAC can guide the work of AGS in probing areas with low radioactivity.

无人机航空γ能谱测量在地形高起伏地区异常查证中的应用

针对地形高起伏地区大比例尺放射性矿产勘查的需要,研制了基于小体积NaI(Tl)晶体的航空伽马能谱探测器,与F-120无人直升机集成了航空γ能谱测量系统。利用该系统在南方某地区开展了铀矿异常检查测量,与地面γ能谱测量结果比对,两者的高异常区域位置、形态基本一致,且前者的异常形态更细致,特别是与铀含量直接相关的铀道数据对区内已知铀矿点反应更明显,数据质量更优。据此认为,无人机航空γ能谱测量有望替代地形起伏大的地区铀矿异常查证工作中的现有地面γ能谱测量。