Engineering Department, Lancaster University , Lancaster LA1 4YR, UK.
Environ Sci Technol. 2011 Oct 1;45(19):8262-7. doi: 10.1021/es201619r. Epub 2011 Sep 9.
A method to determine the depth of buried localized radioactive contamination nonintrusively and nondestructively using principal component analysis is described. The γ-ray spectra from two radionuclides, cesium-137 and cobalt-60, have been analyzed to derive the two principal components that change most significantly as a result of varying the depth of the sources in a bespoke sand-filled phantom. The relationship between depth (d) and the angle (θ) between the first two principal component coefficients has been derived for both cases, viz. d(Φ) = x + y log(e) Φ where x and y are constants dependent on the shielding material and the γ-ray energy spectrum of the radioactivity in question, and φ is a function of θ. The technique enables the depth of a localized radioactive source to be determined nonintrusively in the range 5 to 50 mm with an accuracy of ±1 mm.
描述了一种使用主成分分析非侵入式、非破坏性地确定埋藏局部放射性污染深度的方法。分析了铯-137 和钴-60 两种放射性核素的γ射线谱，得出了两个主成分，它们在特定的沙填充模型中随源深度的变化而变化最大。针对两种情况，推导了深度（d）与前两个主成分系数之间夹角（θ）之间的关系，即 d(Φ) = x + y log(e) Φ，其中 x 和 y 是常数，取决于屏蔽材料和放射性核素的γ射线能谱，φ 是θ的函数。该技术可以非侵入式地在 5 至 50 毫米的范围内准确确定局部放射性源的深度，精度为±1 毫米。
