基于GEM-TPC的快中子能谱仪的研究
发布时间：2019-01-18 13:26
【摘要】：在未来的核工业、核物理实验和国土安全领域中,快中子能谱仪将扮演着重要的角色,它有望用于快中子反应堆的状态监控、特殊核材料的监测、以及热核聚变等离子体的诊断等实践中。但是,传统快中子能谱仪面临着探测效率和能量分辨率难以同时达到优良性能的困境,或是对探测器的介质材料、中子源和中子束流有着特殊的要求,这些因素都限制了传统快中子能谱仪的广泛应用。因此,需要一类新型快中子能谱仪,同时具备较高的能量分辨率、较好的探测效率、很好的n/γ抑制比、介质材料易获得、以及适用范围广等特征。论文提出了基于GEM-TPC(基于气体电子倍增器的时间投影室)的快中子能谱仪(中子TPC)的设想,试图解决传统快中子能谱仪所面临的困惑。对照传统快中子能谱仪的性能指标,并结合中子TPC自身特性,提出了中子TPC的预期指标:(1)对于5MeV中子,能量分辨率(FWHM)≤5%,探测效率≥10-5;(2)对于2.5MeV中子,能量分辨率(FWHM)≤7%,探测效率≥10-5。论文完成了国际上第一套中子TPC系统的模拟计算、理论分析、设计搭建和实验研究,具体研究内容包括:1)基于Geant4、Garfield和ROOT等模拟软件对中子TPC的性能进行模拟计算;模拟结果表明,中子TPC对5MeV和2.5MeV中子的性能响应可以满足预期指标。2)构建了中子TPC的数学解析模型,分析了影响中子TPC性能的重要因素,为提高中子TPC的性能指明了理论方向。3)完成了中子TPC的设计、搭建和测试,并采用基于宇宙线测量的中子TPC通道增益不一致性的修正方法,实现了对圆弧形读出pad的通道增益的标定和修正。4)完成了中子TPC系统的中子束流实验,并独立编写了实验数据处理程序,分析并解决了以下几个难点:通过选用信号波形的积分面积和时间重心来表征信号的能量和时间信息,消除了弹道亏损对信号能量和时间信息的影响;采用基于数学公式和实验数据散点拟合的修正方法校正了电子漂移速度;通过Hough变换排除了反冲质子主径迹外的本底干扰信号,实现质子主径迹点的筛选;通过比较粒子径迹起始位置和粒子平均电离能量损失率,排除了本底粒子对有效质子事例的影响。最后,中子束流实验结果表明,对于1.2MeV、1.81MeV和2.5MeV中子束流,中子TPC的能量分辨率(FWHM)可以分别达到15.7%、10.3%和7.0%,同时探测效率优于10-5,性能指标达到了预期设想。
[Abstract]:In the future nuclear industry, nuclear physics experiments and homeland security, fast neutron spectrometer will play an important role, it is expected to be used in fast neutron reactor state monitoring, monitoring of special nuclear materials, And the diagnosis of thermonuclear fusion plasma. However, the traditional fast neutron spectrometer is facing the dilemma that the detection efficiency and energy resolution are difficult to achieve good performance at the same time, or there are special requirements for the dielectric material, neutron source and neutron beam current of the detector. These factors limit the wide application of traditional fast neutron spectrometers. Therefore, a new type of fast neutron spectrometer is needed, with high energy resolution, good detection efficiency, good N / 纬 suppression ratio, easy to obtain dielectric materials and wide range of application. In this paper, the conception of fast neutron energy spectrometer (TPC) based on GEM-TPC (time projection chamber based on gas electron multiplier) is proposed to solve the puzzlement of traditional fast neutron spectrometer. Comparing with the performance of traditional fast neutron spectrometer and combining with the characteristics of neutron TPC, the expected index of neutron TPC is put forward: (1) for 5MeV neutron, the energy resolution (FWHM) 鈮，
本文编号：2410765
[Abstract]:In the future nuclear industry, nuclear physics experiments and homeland security, fast neutron spectrometer will play an important role, it is expected to be used in fast neutron reactor state monitoring, monitoring of special nuclear materials, And the diagnosis of thermonuclear fusion plasma. However, the traditional fast neutron spectrometer is facing the dilemma that the detection efficiency and energy resolution are difficult to achieve good performance at the same time, or there are special requirements for the dielectric material, neutron source and neutron beam current of the detector. These factors limit the wide application of traditional fast neutron spectrometers. Therefore, a new type of fast neutron spectrometer is needed, with high energy resolution, good detection efficiency, good N / 纬 suppression ratio, easy to obtain dielectric materials and wide range of application. In this paper, the conception of fast neutron energy spectrometer (TPC) based on GEM-TPC (time projection chamber based on gas electron multiplier) is proposed to solve the puzzlement of traditional fast neutron spectrometer. Comparing with the performance of traditional fast neutron spectrometer and combining with the characteristics of neutron TPC, the expected index of neutron TPC is put forward: (1) for 5MeV neutron, the energy resolution (FWHM) 鈮，
本文编号：2410765
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