摘要
采用飞行时间技术测量了氘氚(D-T)源中子穿过不同厚度板状聚乙烯样品后40°方向的泄漏中子时间到达谱,样品的长和宽均为100cm,厚度分别为4.5,9,18和27cm。本底谱测量采用了无样本底测量和无样堵孔本底测量2种方案,利用MCNP-4C程序模拟了相同实验条件下的泄漏中子时间到达谱,模拟过程中考虑了源中子的能谱与角分布、脉冲中子束宽度、探测器的效率以及样品的有效面积。通过比较发现,采用无样测量谱作为本底时,计算值/实验值(C/E)值大于1,并且随着样品厚度的增加而偏离1;而本底谱采用无样堵孔测量谱时,C/E小于1,并且随着样品厚度的增加而接近1。通过对两套本底谱的分析,并结合蒙特卡罗模拟,计算求得了相应样品厚度下比较接近实际的本底谱,采用该模拟计算本底谱后,C/E值有了明显的改善。
The neutron leakage spectrum were measured at 40~ by time-of-flight method for polyethylene slabs with the thicknesses of 4.5, 9, 18 and 27 cm, respectively. The experimental results were compared with the MCNP-4C simulations, which carefully considered many effects, such as the angle and energy dis- tributions of the source neutrons, the width of the beam pulse, the detection efficiency and the effective measured area. The sample out and collimator-filled spectra were measured as the background, and the re- sults showed that C/E values were larger than 1 when using the sample out background spectra, but smal- ler than 1 when using the collimator-filled background spectra. Combine these two different background spectra, a new method was used to calculate the background spectrum, and the results have a better agree- ment with the simulations.
出处
《原子核物理评论》
CAS
CSCD
北大核心
2012年第3期310-315,共6页
Nuclear Physics Review
基金
中国核工业集团公司核数据专题基金资助(4160109)~~
