MCNP5模拟γ射线反散射谱的影响因素

MCNP5 study of the Influence Factor on Gamma-Ray Backscattering Spectrum

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。

This paper aims to study the correlation of the backscattering peak of gamma ray with the material composition,thickness of the scatter,incident（-ray energy and geometric arrangement. Based on the method of Monte Carlo,MCNP5 program was used to simulate the changes of the backscattering spectrum after gamma phone emitted by ^137 Cs,^60Co through different thickness of paraffin wax and glass,Al,Fe,Cu and Pb. The MCNP5 simulation result is in very good agreement with the experimental data. The results showed that the backscattering is increased with the thickness of scatter and with atomic number,until the atomic number about to 26 and later. When the distance between the detector and radiation source is 10 mm the peak value of the ^137 Cs and ^60Co scattered by Fe is higher than that of Cu with the thickness of 1. 6 cm and 2. 4 cm,respectively.When the distance between the source and the detector increases,the Backscattering peak is reduced and this has nothing to do with the incident ray energy. Our results are useful for applying the Backscattering method to the radiation shield of the industry,agriculture and medical industry.