航空伽玛能谱测量大气氡校正方法研究

The Radon is the unique radioactive natural gas.Its decay product suspends in the atmospheric environment,desintegrating spontaneously and releasing the gamma ray,which has a great effect on prospecting and measurement of the airborne gamma-ray spectrum.It limits applied depth and scope the airborne gamma-ray spectrometry.The radon correction technique is the key issue in the aerea of airborne gamma-ray spectrometry.The domestic research is basically still staying in the satiuation of realising the radon correction issue by increasing the hardware,and the interrelated approach theory rereach is till at a low level; meanwhile in order to make up the shortage of the technique,the foreign scientists have launched the rereach of the mathematic correction method of airborne gamma-ray spectrometry in 1980's. And they have got a great achievements,at which they have already successfully put the mathematic correction method of the radon into practice on comercial airborne gamma-ray spectrometry system. Due to the domestic researchers' long-term dependance on the import of the airborne gamma-ray spectrometry system,and the protection of the intellectual property rights, they hardly can get the radon correction method which is consider as the core technique. Therefore, the research on the atmospheric radon correction mathematic method of airborne gamma-ray spectrometry can make up the shortage in this field of our country,and it can also prove the level of the technique theory in our airborne gamma-ray spectrometry aerea.This has a great acodemic significance and economic benefit for providing the theory and the scientific evidence to broaden the applied scope.

氡是自然界唯一的天然放射性气体，其衰变子体悬浮于大气环境中自发衰变并且释放伽玛射线，对航空伽玛能谱勘查测量有较大的影响，限制航空伽玛能谱测量的应用深度和应用范围。大气氡影响校正方法技术作为航空伽玛能谱测量领域的关键问题，国内基本停留在通过增加硬件技术来实现大气氡的校正问题，相关方法理论研究水平较低；而国外为弥补该技术的不足，从二十世纪80年代就开展了航空伽玛能谱测量大气氡校正数学方法的研究工作，并达到了较高的水平，已将大气氡校正数学方法成功应用在商品化的航空伽玛能谱测量系统中。由于我国航空伽玛能谱测量系统长期依赖于进口，国外大气氡校正方法作为核心技术限于知识产权保护无法获得。因此，对航空伽玛能谱测量大气氡影响校正方法开展研究，能够弥补我国在该领域科研水平的不足，极大提高我国航空伽玛测量领域的技术理论水平，为拓宽航空伽玛能谱测量的应用范围提供理论和科学依据，具有重大的学术意义和经济效益。

氡是自然界唯一的天然放射性气体，大气氡校正方法研究对提高我国航空伽玛测量领域技术理论水平和拓宽其应用范围具有重要意义。项目组提出了扣除散射射线的新谱线比大气氡校正方法，并建立了谱线比大气氡校正的数学模型。大气氡校正方法中的校正系数是该方法能否准确扣除大气氡影响的关键。过对校正系数的分析，从理论推导了各组分校正系数随测量高度、地面铀组分校正系数与大气氡校正系数的关系。在此基础上，设计了基于饱和基准模型测量的校正系数刻度方法。避免了使用对谱形的数学拟合或矩阵运算而可能导致校正系数错误和物理含义模糊的问题，且无需大量的实际刻度飞行数据，提高了刻度效率。采用了蒙特卡罗方法代替数值分析和实验测量对航空伽玛能谱测量大气氡校正进行了研究。在对校正系数的刻度中，为提高模拟效率，采用了分步的模拟过程：（1）模拟了探测器对不同组分伽玛射线的参考射线和特征能窗射线本征峰探测效率之间关系；（2）模拟了航空伽玛能谱测量大气氡组分、陆地铀组分和钍组分低、高能射线入射至探测器通量的比值随高度变化关系。对两种校正系数刻度结果进行了讨论和初步的误差分析。将刻度结果应用在高度测量试验结果中，获得满意的结果，经过氡校正后铀能窗和低能参考能窗的高度衰减系数更符合理论分析值。