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中子水分仪的标定是中子测水技术的基础。是子法测定土壤的水分,虽是利用快中子与土壤中水的氢核直接作用,但所测得的结果是快中子经氢核慢化后生成的热中子计数。为了要得到土壤水分含量,就必须明确热中子计数与含水量的关系。这是利用中子水分仪测定土壤含水量的先决条件。一般地说,生成的热中子密度与土壤含水量有一定的直线关系。实践也证明了这一事实。但在实际应用时,不同的仪器(主要是探头的结构和源的几何位置不同),土壤理化性质的差异(如化学组成、质地、容重等),对标定曲线的形状、截距和斜率都有影响。所以,严格地说,对于每一台仪器和每一种类土壤都需要有其特定的标定曲线,这样才能得到较准确的测定结果。
Neutron moisture meter calibration is the basis of neutron measurement technology. It is the sub-method to determine the soil moisture. Although it utilizes the direct interaction between fast neutrons and water protons in soil, the measured result is the thermal neutron count generated by the fast nuclei moderated by hydrogen nuclei. In order to obtain soil moisture content, it is necessary to clarify the relationship between thermal neutron count and water content. This is a prerequisite for the determination of soil moisture using neutron moisture meters. In general, the generated thermal neutron density and soil moisture have a certain linear relationship. Practice also proves this fact. However, in practical applications, the shape, intercept and slope of the calibration curve are different for different instruments (mainly the structure of the probe and the geometry of the source), differences in the physical and chemical properties of the soil (such as chemical composition, texture and bulk density) influential. Therefore, strictly speaking, for each instrument and each type of soil need to have its specific calibration curve, so as to get more accurate measurement results.