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当标准源本身的集合尺寸在所研究的问题里可不加考虑时,这类源称为“点源”;另一类标准源具有较大的几何尺寸,有一定的体积,且是在靠近放射源的某一表面测量它的照射量率,标准源的几何尺寸在所研究的问题中必须考虑,这类标准源统称为体状标准源(体源)。实验所用的2个体源是一个标准密封模型,半径均为1.1 m,高0.6 m,基质为混凝土材料。所含天然放射性核素为238U系、232Th系及40K,平衡系数100%。点源在距离它某处某点的γ剂量率与距离的平方成反比,为研究体源上方随距离的变化,本文通过实地测量和软件模拟了不同距离处的γ剂量率(表1)。
When the size of the standard source itself is not considered in the study of the collection size, this type of source is called “point source”; another type of standard source has a larger geometry, a certain volume, and is in Its exposure rate is measured near a surface of a radioactive source. The standard source geometry must be considered in the study. The standard sources are collectively referred to as the standard source of somatic body (body source). The two sources used in the experiment are a standard seal model with a radius of 1.1 m and a height of 0.6 m. The matrix is a concrete material. The natural radionuclides contained 238U series, 232Th series and 40K, the balance coefficient of 100%. The γ dose rate is inversely proportional to the square of the distance at a point somewhere away from it. In order to study the change of distance with the distance above the body source, the γ dose rate at different distances was simulated by field measurements and software (Table 1).