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为了研究γ射线反散射峰与散射体的物质成分、厚度、入射射线能量和几何布置之间的关系。本论文基于蒙特卡罗方法,运用MCNP5程序模拟放射源137Cs、60Co发出的γ射线经过不同厚度的石蜡、玻璃、Al、Fe、Cu和Pb散射后反散射谱的变化,所得结果与实验谱符合较好。结果显示:散射体厚度与原子序数同时增加且原子序数大约到26以后,反散射峰值才随原子序数增加而减小;探测器与放射源的距离为10 mm时,137Cs、60Co发出的γ射线经Fe、Cu散射后,Fe、Cu的厚度分别为1.6 cm和2.4cm时,铁的峰值高于铜;反散射峰值随源与探测器之间的距离增加而减小,与入射射线能量无关。试验结果对进一步开展反散射在工业,农业和医疗业的辐射屏蔽的研究有一定的指导作用。
In order to study the relationship between the γ-ray backscattering peak and the material composition, thickness, incident ray energy and geometry of the scatterer. Based on the Monte Carlo method, the MCNP5 program was used to simulate the changes of the backscattering spectra of γ-rays emitted from 60Co radioactive source after passing through different thicknesses of paraffin, glass, Al, Fe, Cu and Pb. The obtained results are consistent with the experimental spectra better. The results show that when the thickness of the scatterer increases with the atomic number and the atomic number is about 26, the peak of backscattering decreases with the increase of atomic number. When the distance between the detector and the source is 10 mm, After the scattering of Fe and Cu, the peak of Fe is higher than that of Cu when the thickness of Fe and Cu are 1.6 cm and 2.4 cm, respectively. The peak of backscattering decreases with the increase of the distance between the source and the detector, regardless of the incident beam energy . The results of the experiment can guide the further research of radiation shielding in the industry, agriculture and medical industry.