The study of a neutron spectrum unfolding method based on Particle Swarm Optimization combined with Maximum Likelihood Expectation Maximization

• 作者： 肖鸿飞 ¹ 张庆贤 ¹ 谭河益 ¹ 石斌 ² 陈军 ² 程志强 ¹ 张建 ¹ 杨芮 ¹
• 作者单位：
  1.  成都理工大学

  2.  中国原子能科学研究院计量与校准技术重点实验室
• 提交时间：2023-05-31

摘要: Bonner多球谱仪(BBS)求解中子能谱是一个复杂的多维模型，需要使用复杂的优化算法求解第一类Fredholm积分方程。针对极大似然期望最大化(MLEM)算法容易陷入局部最优，粒子群优化(PSO)算法易得到粒子飞行方向和步长不合理，导致迭代无效，影响效率和精度的问题，提出了一种改进的PSO-MLEM算法用于中子能谱展开。利用动态加速因子平衡全局和局部搜索能力，提高算法的收敛速度和精度。首先，采用蒙特卡罗方法对BBS进行模拟，得到BBS的响应函数和计数率。模拟计数率时，采用了国际原子能机构403号技术报告中的4个参考光谱作为蒙特卡罗方法的输入参数。采用PSO-MLEM算法对中子能谱展开，通过展开能谱与参考能谱的差异进行验证。最后，利用BBS对252Cf中子源进行测量，并采用PSO-MLEM算法展开实验中子谱。与最大熵反卷积(MAXED)、PSO和MLEM算法相比，PSO-MLEM算法参数更少，并自动调整动态加速因子以解决局部最优问题。PSO-MLEM算法的收敛速度分别是MLEM和PSO算法的1.4倍和3.1倍。与PSO、MLEM和MAXED算法相比，PSO-MLEM算法的相关系数分别提高了33.1%、33.5%和1.9%，相对平均误差分别降低了98.2%、97.8%和67.4%。

Abstract: The neutron spectrum unfolding by Bonner Spheres Spectrometer (BSS) is considered a complex multidimensional model, which requires complex mathematical methods to solve the first kind of Fredholm integral equation. In order to solve the problem of the Maximum Likelihood Expectation Maximization (MLEM) algorithm which is easy to suffer the pitfalls of local optima and the particle swarm optimization (PSO) algorithm which is easy to get unreasonable flight direction and step length of particles, which leads to the invalid iteration and affect efficiency and accuracy, an improved PSO-MLEM algorithm, combined of PSO and MLEM algorithm, is proposed for neutron spectrum unfolding. The dynamic acceleration factor is used to balance the ability of global and local search, and improves the convergence speed and accuracy of the algorithm. Firstly, the Monte Carlo method was used to simulated the BSS to obtain the response function and count rates of BSS. In the simulation of count rate, four reference spectra from the IAEA Technical Report Series No. 403 were used as input parameters of the Monte Carlo method. The PSO-MLEM algorithm was used to unfold the neutron spectrum of the simulated data and was verified by the difference of the unfolded spectrum to the reference spectrum. Finally, the 252Cf neutron source was measured by BSS, and the PSO-MLEM algorithm was used to unfold the experimental neutron spectrum. Compared with maximum entropy deconvolution (MAXED), PSO and MLEM algorithm, the PSO-MLEM algorithm has fewer parameters, and automatically adjusts the dynamic acceleration factor to solve the problem of local optima. The convergence speed of the PSO-MLEM algorithm is 1.4 times and 3.1 times that of the MLEM and PSO algorithms. Compared with PSO, MLEM and MAXED, the correlation coefficients of PSO-MLEM algorithm increase by 33.1%, 33.5% and 1.9%, and the relative mean errors decreased by 98.2%, 97.8% and 67.4%.

• 来自： 肖鸿飞
• 分类： 物理学 >> 核物理学
• 投稿状态： 已被期刊接收
• 引用： ChinaXiv:202305.00279 (或此版本 ChinaXiv:202305.00279V1)
  DOI:10.12074/202305.00279V1
  CSTR:32003.36.ChinaXiv.202305.00279.V1
• 推荐引用方式： 肖鸿飞,张庆贤,谭河益,石斌,陈军,程志强,张建,杨芮.(2023).The study of a neutron spectrum unfolding method based on Particle Swarm Optimization combined with Maximum Likelihood Expectation Maximization.中国科学院科技论文预发布平台.doi:10.12074/202305.00279V1 (点此复制)