轴向位置的精确测量是快中子探测领域的挑战和难题,对高分辨率的快中子成像具有重要意义。改进位置和时间响应能使快中子成像获得更好的成像分辨率和对比度,而提升时间分辨的困难主要来自相互作用深度(depth of interaction,DOI)的不确...轴向位置的精确测量是快中子探测领域的挑战和难题,对高分辨率的快中子成像具有重要意义。改进位置和时间响应能使快中子成像获得更好的成像分辨率和对比度,而提升时间分辨的困难主要来自相互作用深度(depth of interaction,DOI)的不确定性。针对位置改进的问题,设计了一种基于有机闪烁体阵列的双端读出快中子探测器,提出了一种用于校准DOI的方法。该校准方法基于快中子探测器双端读出的数据来进行系列计算和拟合,最终得到轴向位置校准曲线。研究结果表明,该校准方法解决了快中子探测中轴向定位不准确的问题,提高了快中子探测器的位置分辨率。展开更多
对特殊核材料等进行无损检测时,快中子探测器的时间分辨率对系统的成像时间和图像质量等方面具有重要影响。提高时间分辨率的主要困难在于无法精准测量入射中子与物质相互作用深度(depth of interaction,DOI)。为了减小DOI效应对快中子...对特殊核材料等进行无损检测时,快中子探测器的时间分辨率对系统的成像时间和图像质量等方面具有重要影响。提高时间分辨率的主要困难在于无法精准测量入射中子与物质相互作用深度(depth of interaction,DOI)。为了减小DOI效应对快中子探测的影响,利用Geant4模拟软件构建了基于塑料闪烁体的双端读出快中子探测器模型,系统地研究了闪烁体厚度对探测器时间分辨率性能的影响。在此基础上,提出了平均两端定时和重建中子作用点2种提高时间分辨率的方法。研究结果表明,这2种校准方法均能降低DOI测量不准确对快中子探测产生的影响,提高快中子探测器的时间分辨率。对于厚度为100 mm的闪烁体探测器,利用重建中子作用点法对光电倍增管(photomultiplier tube,PMT)定时补偿后,探测器的时间分辨率由(1030±5)ps提高到(612±2)ps。展开更多
An intrinsic sensor （diameter 16 ram, thickness 300 μm ） based on chemical vapor deposition derived polycrystailine diamond was developed. Ultra low dark current under 100 pA and high n/γ discrimination of 15.8 we...An intrinsic sensor （diameter 16 ram, thickness 300 μm ） based on chemical vapor deposition derived polycrystailine diamond was developed. Ultra low dark current under 100 pA and high n/γ discrimination of 15.8 were obtained on this device, which enable it to be used for neutron detection in multi-radiation field. Moreover, the neutron sensitivity of this detector was characterized theoretically and experimentally. And for fast and ultra-fast neutron, the detection sensitivity is in the magnitude of 10^-17 to 10^-16 C cm^2/n with good stability and negligible pump effect. All these results indicate that the as-prepared sensor to be ideal for fast and ultra-fast neutron monitoring, and it may pave the way to build neutron detector with low cost and large sensitive area with diamond.展开更多
文摘轴向位置的精确测量是快中子探测领域的挑战和难题,对高分辨率的快中子成像具有重要意义。改进位置和时间响应能使快中子成像获得更好的成像分辨率和对比度,而提升时间分辨的困难主要来自相互作用深度(depth of interaction,DOI)的不确定性。针对位置改进的问题,设计了一种基于有机闪烁体阵列的双端读出快中子探测器,提出了一种用于校准DOI的方法。该校准方法基于快中子探测器双端读出的数据来进行系列计算和拟合,最终得到轴向位置校准曲线。研究结果表明,该校准方法解决了快中子探测中轴向定位不准确的问题,提高了快中子探测器的位置分辨率。
文摘对特殊核材料等进行无损检测时,快中子探测器的时间分辨率对系统的成像时间和图像质量等方面具有重要影响。提高时间分辨率的主要困难在于无法精准测量入射中子与物质相互作用深度(depth of interaction,DOI)。为了减小DOI效应对快中子探测的影响,利用Geant4模拟软件构建了基于塑料闪烁体的双端读出快中子探测器模型,系统地研究了闪烁体厚度对探测器时间分辨率性能的影响。在此基础上,提出了平均两端定时和重建中子作用点2种提高时间分辨率的方法。研究结果表明,这2种校准方法均能降低DOI测量不准确对快中子探测产生的影响,提高快中子探测器的时间分辨率。对于厚度为100 mm的闪烁体探测器,利用重建中子作用点法对光电倍增管(photomultiplier tube,PMT)定时补偿后,探测器的时间分辨率由(1030±5)ps提高到(612±2)ps。
基金supported by the National Natural Science Foundation of China (Grant Nos. 11175142,11175141 and 11105106)the National Hi-Tech Project of China (Grant No. 2009AA050705)the State Key Laboratory of Multiphase Flow (Xi’an Jiaotong University)
文摘An intrinsic sensor （diameter 16 ram, thickness 300 μm ） based on chemical vapor deposition derived polycrystailine diamond was developed. Ultra low dark current under 100 pA and high n/γ discrimination of 15.8 were obtained on this device, which enable it to be used for neutron detection in multi-radiation field. Moreover, the neutron sensitivity of this detector was characterized theoretically and experimentally. And for fast and ultra-fast neutron, the detection sensitivity is in the magnitude of 10^-17 to 10^-16 C cm^2/n with good stability and negligible pump effect. All these results indicate that the as-prepared sensor to be ideal for fast and ultra-fast neutron monitoring, and it may pave the way to build neutron detector with low cost and large sensitive area with diamond.
