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本文分析了在应用双滤膜法测定氡(气土)浓度的一般条件下采用直线速度分布的合理性,在这个基础上,建立起一个既考虑射气本身在职样管内飞行时的衰变又考虑了其子体在飞行时的积累和衰变的扩散方程,给出了一个完整的计算公式。只要用通用的扩散系数值(D=0.06 cm~2/s)代入公式,理论计算结果与 J.W.Thomas 的实验结果很好地一致,从而克服了 C.W.Tan 的扩散理论中对飞行时间限制很严的缺点和在选择扩散系数 D 值上的困难。因而使计算公式的适用性和结果的精确度都相应地得到了改善。
In this paper, we analyze the rationality of using linear velocity distribution under the general conditions of applying double-membrane method to determine radon (soil) concentration. On the basis of this, we establish a model that considers both the decay of the projectile in flight The diffusion equation of its daughter’s accumulation and decay during flight gives a complete formula. As long as the common diffusion coefficient value (D = 0.06 cm ~ 2 / s) is substituted into the formula, the theoretical calculation result is in good agreement with the experimental result of JW Thomas, thus overcoming the limitation of flight time in CWTan’s diffusion theory Disadvantages and Difficulties in Choosing Diffusion Coefficient D Therefore, the applicability of the calculation formula and the accuracy of the results are correspondingly improved.