Measuring radon progeny and thoron progeny in air by absolute beta counting subsequent to grab sampling
Measuring radon progeny and thoron progeny in air by absolute beta counting subsequent to grab sampling
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DOI：
10.1016/j.radmeas.2005.10.011
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发表时间：
2006-05-01
影响因子：
2
通讯作者：
Dezso, Z.
中科院分区：
文献类型：
--
作者：
Papp, Z.;Dezso, Z.
本文第一作者几年前提出了一种同时测定空气中氡子体和氡子体的新的抓取进样方法。文中详细讨论了该方法的特点和性能。该方法基于使用端窗盖革-穆勒计数器在连续时间间隔上计数的过滤气溶胶样品的总β计数。通过将衰变产物的理论衰变曲线的线性组合与计数效率和其他一些量的知识进行拟合，分析了所测得的计数率随时间的变化曲线。定义的立体角绝对β计数用于逐个评估衰变产物的计数效率。因此，该方法是一种绝对的方法，不需要进一步的校准。可以分别和同时测定氡和钍的衰变产物。与基于α计数的方法相比，由于对计数效率的不准确评估而导致的结果的系统误差可能更低，并且可以更可靠地估计。该方法灵敏度高，即使在室外也能获得准确的铅-214、铋-214、铅-212、EEDC222和EEDC220的结果。然而，Po-218和Bi-212的结果更不准确，Tl-208根本无法测定。根据从一些理论考虑和模型中获得的信息，使用条件计算可以显著提高测定的可靠性。该方法可以在很大的活动浓度范围内使用，同样可以在洞穴、矿山、房屋或户外使用。本文通过对室内、洞穴和室外三次采样结果的详细介绍和分析，论证了该方法的上述特点和能力。文中还详细分析了该方法的已知优点和缺点。(C)2005爱思唯尔有限公司。保留所有权利。
A new grab sampling method for the simultaneous determination of radon progeny and thoron progeny in air has been developed and demonstrated by the first author of this paper a few years ago. The characteristics and capabilities of this method are discussed in the present paper in detail. The method is based on gross beta counting of filtered aerosol samples counted over successive time intervals using an end-window Geiger-Muller counter. The measured counting rate versus time curve is analyzed by fitting to it some linear combination of the theoretical decay curves of the decay products with the knowledge of the counting efficiencies and some other quantities. Defined solid angle absolute beta counting was used to evaluate the counting efficiencies for the decay products one by one. So, the method is an absolute one that does not demand further calibration. The decay products of radon and thoron can be determined separately and simultaneously. The systematic error of the results, deriving from the inaccurate evaluation of the counting efficiencies, is probably lower and can be estimated more surely than that of the methods based on alpha counting. The method is highly sensitive: accurate results can be obtained for Pb-214, Bi-214, Pb-212, EEDC222 and EEDC220 even outdoors. However, the results for Po-218 and Bi-212 are much more inaccurate and Tl-208 cannot be determined at all. The reliability of the determinations can be raised significantly using conditional computations based on the information obtainable from some theoretical considerations and models. The method can be used in a broad activity concentration range, equally in caves, mines, houses or outdoors. The above characteristics and capabilities of the method are demonstrated in this paper through the detailed presentation and analysis of the results obtained for three samplings performed indoors in a house, in a cave, and outdoors, respectively. The known advantages and drawbacks of the method are also surveyed in detail. (c) 2005 Elsevier Ltd. All rights reserved.