CsI crystal is widely used for gamma detection in diagnostic systems of nuclear power plant and their facilities because of its excellent properties. Due to the possibility of neutron collision in this environment with detection systems, it can cause atomic displacement damage. Therefore, the main factor of these defects in a CsI crystal are primary knock-on atoms, I-PKA and Cs-PKA. In this work, the probability of generating these neutron-induced-PKAs was calculated using Geant4, a Monte Carlo radiation transport code. In addition, molecular dynamic (MD) simulation was utilized to obtain displacement threshold energy and PKA-induced displacement damages. The calculation of the formation energy of created defects using density functional theory (DFT) was also used to validate the potential used in MD. The results showed that antisite defects play an effective role in producing damage. It was also determined that PKA emission increased the diffusion coefficients. Finally, mathematical models were derived to determine the number of equilibrium point defects at different PKA energies. According to these models, neutron-induced displacement damage in CsI crystals is almost independent of PKA type.

中文翻译：

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CsI 晶体中子诱导位移损伤综合建模的原子研究


CsI 晶体因其优异的性能而被广泛用于核电厂及其设施诊断系统中的伽马射线检测。由于在这种环境中与探测系统发生中子碰撞的可能性，它会导致原子位移损伤。因此，CsI 晶体中这些缺陷的主要因素是初级敲击原子 I-PKA 和 Cs-PKA。在这项工作中，使用 Geant4（一种蒙特卡洛辐射传输代码）计算产生这些中子诱导的 PKA 的概率。此外，利用分子动力学 （MD） 模拟获得位移阈值能量和 PKA 诱导的位移损伤。使用密度泛函理论 （DFT） 计算产生的缺陷的形成能也用于验证 MD 中使用的电位。结果表明，反位缺陷在产生损伤方面起着有效作用。还确定 PKA 发射增加了扩散系数。最后，推导出数学模型以确定不同 PKA 能量下平衡点缺陷的数量。根据这些模型，CsI 晶体中中子诱导的位移损伤几乎与 PKA 类型无关。