钙钛矿快中子闪烁成像屏的点扩散函数研究

Study on Point Spread Function of Perovskite Fast Neutron Scintillation Imaging Screen

  • 摘要: 钙钛矿闪烁体材料具有高含氢量、高光产额、能量响应线性的特征,可以用于制作快中子辐射成像屏,而点扩散函数则是评价闪烁体成像能力的重要参数。目前,钙钛矿闪烁体的点扩散函数研究较少,且难以通过快中子成像实验实现材料的有效设计筛选,因此,建立并发展点扩散函数研究方法对钙钛矿快中子成像技术发展有重要作用。本文利用Geant4与Matlab建立了快中子成像物理模型,使用蒙特卡罗方法模拟了快中子在闪烁体中的能量沉积分布,分别模拟计算了铅基、铜基钙钛矿闪烁体在不同能量中子、X射线辐射条件下的点扩散函数。通过对比不同点扩散函数的趋势,发现钙钛矿闪烁体材料点扩散函数的半高宽随着中子能量的上升而下降。最终借助该模型获得了C5H7Cu2I2N4实验成像照片的模拟转化结果,仿真结果与实验结果趋势一致。该点扩散函数计算方法可以理论评估新型钙钛矿快中子闪烁屏的中子成像能力,对开展新型快中子成像屏研究、快中子成像实验具有指导意义。

     

    Abstract: Perovskite scintillator materials exhibit high hydrogen content, photo yield and linear energy response, rendering them ideal materials for the fabrication of fast neutron radiation imaging screens. However, efficient screening of new scintillator imaging screen materials presents challenges due to the high cost of material preparation and performance testing, long cycle time, and large workload. Additionally, the limited availability of experimental machines for fast neutron imaging and the high cost of imaging systems hinders the efficient detection of large number of materials by using common fast neutron sources. The point spread function, which serves as a critical parameter for evaluating the imaging capability of scintillators, can be defined as the projected distribution of the energy deposited by a single vertical incident radiation on the exit plane of a thin scintillator. The point spread function can be used for theoretical simulation of the scintillator imaging capability. The design and screening of perovskite scintillator imaging screening materials and the estimation of fast neutron imaging performance through theoretical simulations are important for the development of perovskite scintillator-based fast neutron imaging technologies. At present, there is little research on the point spread function of perovskite scintillators. Therefore, with the help of their fast neutron imaging properties, it is necessary to simulate new materials, establish and develop the point spread function research methods, and promote the fast neutron imaging technology of perovskite scintillator materials. In this study, Geant4 and Matlab were used to build a physics model of fast neutron imaging, Monte Carlo methods were used to simulate the energy deposition distribution of fast neutrons in the scintillator, and the point spread function simulation results of various perovskite scintillators were carried out. The point spread functions of Pb and Cu based perovskite scintillators were simulated and calculated under various neutron and X-ray irradiation conditions. By comparing the trends of point spread function at different conditions, it is found that the half-width of the point spread function of perovskite scintillator material decreases with the increase of neutron energy. In addition, the simulation transformation results of C5H7Cu2I2N4’s experimental imaging photo are obtained by using this model, showing a consistent trend on the luminescence characteristics with the experimental results. The computational approach to the point spread function can theoretically assess the neutron imaging capability of the new perovskite fast neutron scintillator screens, providing valuable guidance for the study of novel neutron imaging screen materials and fast neutron imaging experiments.

     

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