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1 问题的提出提及辐射场中任何一点的射线强度时,都常涉及两个衰减因素,即:①距离衰减或称扩散衰减,衰减的定量适用平方反比定律.②射线穿过物质(厚度为T)后的衰减,其计算式如下I=I_0e~(-μT) (1)式中I_0——入射射线强度I——透过物质后的射线强度T——射线透过的物质厚度μ——物质对射线的衰减系数现在多将公式(1)称为射线强度衰减律.现在有些教材,在讲述射线强度衰减时,只讲到射线穿透物质T后的衰减,且假定射线束是平行的,见图1.
1 PROBLEM PROBLEMS There are two attenuation factors involved when referring to the radiation intensity at any point in the radiation field, namely: (1) The law of inverse square distance is applied to the quantitative determination of the attenuation or diffusion attenuation, (2) T) after the decay, which is calculated as follows I = I_0e ~ (-μT) (1) where I_0 - incident ray intensity I - the ray intensity after transmission T - the ray thickness of the material through μ- - Attenuation Coefficient of Material to Ray Nowadays the formula (1) is called the law of attenuation of radiation intensity. Now some textbooks tell the attenuation of the intensity of the radiation only the attenuation after the ray penetrates the material T, and it is assumed that the beam is parallel See figure 1.