【摘要】 碘化锂晶体闪烁体具有中子测量效率高、探测器尺寸小等优点,它是目前相当成熟和用途广泛的探测器,在中子测量及环境监测等各方面均有广泛应用,它由闪烁体、光导、光电倍增管、高压四部分组成。本工作利用Monte Carlo程序研究了6LiI/natLiI闪烁体探测器尺寸与探测效率的关系,并通过GEANT4及MCNP程序模拟计算了高富集度的6LiI晶体和天然LiI晶体及纯7LiI晶体的探测效率。从理论模拟结果可以看出10 mm厚度的两种探测器对热中子探测效率都很高,6LiI达到98%,而natLiI也能达到65%。利用反应堆热中子刻度了6LiI/natLiI闪烁体探测器的热中子探测效率,考虑了铅砖及高密度聚乙烯的散射,以及环境中子的贡献后,实际测量6LiI探测器探测效率在90%左右,natLiI探测器探测效率在70%左右。更多还原

【Abstract】 Background: Being of very high detection efficiency and small size, Lithium iodide(LiI) scintillator detector is used extensively in neutron measurement and environmental monitoring. Purpose: Using thermal reactor, neutron detectors will be tested and calibrated. And a new neutron detector device will be designed and studied. Methods: The relationship between the size and detection efficiency of the thermal neutron detector 6LiI/natLiI was studied using Monte Carlo code GEANT4 and MCNP5 package, and the thermal neutron efficiency of detector was calibrated by reactor neutrons. Results: The theoretical simulation shows that the thermal neutron detection efficiency of detector of 10-mm thickness is relatively high, the enriched 6LiI is up to 98% and the nature natLiI 65%. The thermal neutron efficiency of detector is calibrated by reactor thermal neutrons. Considering the neutron scattering by the lead brick, high density polythene and environment neutron contribution, the detection efficiency of 6LiI detector is about 90% and natLiI detector 70%. Conclusion: The detector efficiency can reach the efficiency value of theoretical calculations.更多还原