Influence of multiple coulomb scattering on the accuracy of muon transmission imaging of small-scale matter
Influence of multiple coulomb scattering on the accuracy of muon transmission imaging of small-scale matter
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DOI：
10.7498/aps.72.20221792
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发表时间：
2023
影响因子：
1
通讯作者：
Zhang Jian-Ming;Li Zhi-Wei;Liu Fang;Li Jing-Tai;Mao Xin;Cheng Ya-Ping;Pang Jie;Feng Xin-Zhuo;Ni Si-Dao;Ou-Yang Xiao-Ping;Han Ran
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文献类型：
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作者：
Zhang Jian-Ming;Li Zhi-Wei;Liu Fang;Li Jing-Tai;Mao Xin;Cheng Ya-Ping;Pang Jie;Feng Xin-Zhuo;Ni Si-Dao;Ou-Yang Xiao-Ping;Han Ran
缪子透射成像方法是一种基于宇宙线缪子穿过目标物体前后的通量变化, 进而获得其内部密度结构的无损探测成像方法.该方法假设μ子在低Z材料中沿着直线传播。但是，多次库仑散射使μ子在穿透材料时偏离直线有一定程度，可能对μ子透射成像的精度产生一定影响。为此，本文使用GEANT 4软件包开展了缪子透射成像蒙特卡罗模拟，针对数米尺度多种密度结构的模型，定量分析了打开和关闭多重库仑散射物理过程时对成像精度的影响.利用具有多密度结构和数米长的目标模型，分析了多次散射对透射成像精度的影响。在实验中，我们设置了不同能量的μ子垂直穿过一定厚度岩石的模型，可以直观地看到散射对μ子穿透路径的影响。通过建立厚度分别为0.8m、2.4m和4.0m的岩石-水块模型，分析了库仑散射对小尺度物质μ子透射成像的影响。结果表明，μ子透射成像方法能够较好地恢复数米尺度标准岩石密度异常的几何形态和空间分布特征。而μ子在近垂直方向上的多次库仑散射引起的通量偏差可达5%，在标准岩石和空气的边界区可达13%。我们对μ子的散射角进行了限制，选择了散射角小于或等于1 °的μ子进行成像。使用选定μ子的透射成像的结果得到了改善。该图像不具有由散射引起的模型周围的异常增加的通量的错觉，但是模型区域中的μ子通量减少得更多，这影响了利用通量差恢复物体的绝对密度的准确性。因此，在小尺度μ子透射成像研究中，为了更准确地恢复μ子的绝对密度，必须考虑多次库仑散射的影响。
The muon transmission imaging method is a non-destructive detection imaging method and can obtain the internal density structure of the target object by analyzing the flux change of cosmic ray muon before and after passing through the target object. This method assumes that muon travels along a straight line in low-Z materials. However, the multiple Coulomb scattering causes the muon deviate from the straight line to a certain extent when penetrating the material, which may have a certain impact on the accuracy of muon transmission imaging. This study uses the GEANT4 software package to carry out Monte Carlo simulation of muon transmission imaging. Object models with multiple density structures and several meters are used to analyze the effect of multiple scattering on the accuracy of transmission imaging. In the experiment, we setting a model in which muons of different energies vertically pass through a rock of a certain thickness, we can intuitively see the influence of scattering on the penetration path of muons. By setting up rock-water block models with thicknesses of 0.8m, 2.4m and 4.0m, the effect of Coulomb scattering on the transmission imaging of small-scale material muons is analyzed. The results suggests that the muon transmission imaging method can well restore the geometric shape and spatial distribution characteristics of density anomalies for objects with several-meter scale for standard rock materails with a scale of several meters. However, the flux deviation caused by multiple Coulomb scattering on the muons in the near-vertical direction can reache 5%, and upto 13% in the boundary areas of the standard rock and air. We have limited the scattering angle of the muon, and selected the muon with a scattering angle of less than or equal to 1 degree for imaging. The results of transmission imaging using selected muon have improved. The image does not have the illusion of an abnormally increased flux around the model caused by scattering, but the muon flux in the model area is reduced even more, this affects the accuracy of restoring the absolute density of an object using flux differences. Therefore, the effects of multiple coulomb scattering should be considered for recovering more accurate absolute density in small-scale muon transmission imaging study.