摘要:
为能够快速评判实验测试方案和预估实验结果,建立了中子体通量的快速估算模型.理论上,封闭空间中子平均体通量与特征长度的平方成反比,且中子体通量的大小能反映散射中子注量强弱.采用蒙特卡罗模拟方法,计算得到了密闭实验大厅内中子的体通量,以及不同位置处的散射中子注量,并将模拟得到的体通量和散射中子注量拟合成便于工程实践中应用的解析表达式,拟合结果与模拟结果的相对偏差小于10%.研究结果表明,球形空间内中子的体通量与球半径的1.905次方成反比;密闭实验大厅的中子体通量与大厅横截面宽度的1.948次方成反比,与长宽比的0.775次方成反比;球形空间结构内,每个源中子的平均径迹长度约为半径的5.4倍,而长方体密闭实验大厅内,单个源中子的平均径迹长度为大厅特征尺度的2~3倍.
Abstract:
To evaluate the detection cases and predict experiment results rapidly,a fast estimation model of neutron cell flux was established.Theoretically,the neutron cell flux in an enclosed space is inversely proportional to the square of the characteris-tic length,and the magnitude of neutron cell flux can reflect the intensity of scattering neutron flux.The neutron cell flux in en-closed experimental hall was calculated by Monte Carlo method,and the scattering neutron flux at different distances from neu-tron source was obtained.The relationship between the neutron cell flux and the hall size is obtained by fitting the simulation re-sults.The relationship between the scattering neutron flux at different distances from neutron source x and the hall size L is also fitted,and the relative deviation between the fitting results and Monte Carlo simulation results is within 10%.The results show that the neutron cell flux in spherical structure is inversely proportional to the 1.905 power of the sphere radius;the neutron cell flux in strip experimental hall is inversely proportional to the 1.948 power of cross section width of experimental hall,also in-versely proportional to the 0.775 power of ratio of length to width of experimental hall.The average track length of each single source neutron in spherical structure is 5 times the sphere radius,while in the enclosed experimental hall,the average track length of each source neutron is 2~3 times the characteristic size of experimental hall.
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