The neutron leakage spectra were measured at 60° by using time-of-flight (TOF) method from three different sizes of polyethylene samples.The measured spectra were compared with the calculated ones simulated with MCNP using three different models (simplified point detector model,complex point detector model,complicated ring detector model),respectively.The result shows that for small sized sample (φ13 cm× 6 cm),the calculated results from different models all agree well with experimental ones in n-p scattering peak.For large sized samples (30 cm× 30 cm× 6 cm,40 cm×40 cm × 6 cm),the calculated results from complicated ring detector model agree better with the experiment.This conclusion is very important for the next step benchmark experiment with large sized sample.%采用T(d,n)4He脉冲中子源和中子飞行时间法测量了3种不同尺寸聚乙烯样品在60.方向的泄漏中子飞行时间谱.通过3种模拟模型(点探测器简化模型、点探测器复杂模型和环探测器复杂模型),应用MCNP程序分别模拟得到了泄漏中子飞行时间谱,并与实验数据进行比较.结果显示:对于小体积样品(φ13 cm×6 cm),3种模型的模拟数据和实验结果在n-p散射峰符合均很好;对于大体积样品(30 cm×30 cm×6 cm,40 cm×40 cm×6 cm),采用环探测器复杂模型的计算结果更加接近实验值.该研究工作为将来开展大体积样品基准检验奠定了基础.
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