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在石油、化工、冶金等工业领域,γ射线连续料位计有着较为广泛的应用。进口一套这种料位计要耗资近万美元。国内已研制使用的连续料位计采用点探测器——连续源型式。连续源防护困难,源体笨重,剂量较大;点探测器闪烁计数器探头稳定性差,误差较大。因而有必要研制点源——长电离室型连续料位计。目前国外多采用此种型式,并用微机控制,处理数据。基本原理利用γ射线通过物质时强度减弱的规律性,将C_s-137或C_o-60γ射线点源放在被测装置一端,另一端以长圆柱型电离室探测器测量穿过被测物料的射线强度。当料面高度连续变化时,探测器被物料的屏蔽程度也随之变化。即到达探测器处的γ射线总注量强度发生变化。测量探测器输出电流I_(out),即可测定被测物料在容器内的料面高度,如图1所示。推导探侧器输出电流I_(out)=I_o exp(-μ·ρ·I)及相关的几何因子,其中I_o为H=0时探测器的输出
In the oil, chemical, metallurgical and other industrial fields, γ-ray continuous level meter has a more extensive application. The import of such a level meter to cost nearly ten thousand US dollars. The domestic level has been developed using continuous level meter point detector - continuous source type. Continuous source protection difficulties, the source body bulky, larger doses; point detector scintillation counter probe stability is poor, the error is large. It is necessary to develop point source - long ionization chamber continuous level meter. At present, more use of this type of foreign countries, and computer control, data processing. Fundamentals The use of γ-rays through the material intensity weakened the regularity, the C_s-137 or C_o-60γ ray point source on the side of the device under test, the other end of the long cylindrical ionization chamber probe through the measured material radiation strength. When the level of continuous changes in the material, the detector is also the degree of material shielding changes. That is, the total amount of γ-ray emission at the detector changes. Measuring the detector output current I_ (out), you can measure the measured material in the container of the material height, as shown in Figure 1. Derive the sonde output current I out (out) = I_o exp (-μ ρ I) and related geometry factors, where I_o is the detector output at H = 0