Neutron radiation detector for nuclear reactor applications plays an important role in getting information about the actual neutron flux. Such a detector must be able to operate at high neutron flux levels (>109 cm-2 s-1) and discriminate the neutron and gamma responses in the nuclear reactor's mixed neutron-gamma environment. Silicon carbide and diamond are the most attractive semiconductor materials for neutron detection, thanks to their outstanding properties, such as high displacement threshold energy and wide bandgap energy, which allow them to operate in high radiation levels and high temperature. The aim of this article is to compare the ability to detect thermal neutrons of these two semiconductors at the same irradiation conditions. For this purpose, the neutron irradiation tests of detectors were implemented at MINERVE research reactor at CEA Cadarache. The 4H-silicon carbide (SiC) p+n diode has demonstrated better neutron-gamma discrimination at 0-V bias voltage than at -200 V which is explained by its increased sensitivity to gamma photons at -200 V caused by a wider charge collection region than at 0 V. Therefore, it is preferable to use the 4H-SiC p+n diode without an external electric field for applications in the mixed neutron-gamma environment such as nuclear reactor environment. The results show that the single-crystal chemical vapor-deposited (sCVD) diamond-based detector has better neutron to gamma discrimination, thanks to the use of 6Li as a neutron converter instead of 10B. However, the study of the radiation stability of detectors showed that the sCVD diamond-based detector suffers from the “polarization effect” when it operates at a high neutron flux (~109 cm-2 · s-1).

中文翻译：

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碳化硅与金刚石室温热中子探测比较


用于核反应堆应用的中子辐射探测器在获取实际中子通量信息方面发挥着重要作用。这种探测器必须能够在高中子通量水平 (>109 cm-2 s-1) 下运行，并区分核反应堆混合中子-伽马环境中的中子和伽马响应。碳化硅和金刚石是用于中子探测的最具吸引力的半导体材料，这要归功于它们出色的特性，例如高位移阈值能量和宽带隙能量，这使得它们能够在高辐射水平和高温下工作。本文的目的是比较这两种半导体在相同辐照条件下检测热中子的能力。为此，探测器的中子辐照测试在 CEA Cadarache 的 MINERVE 研究堆进行。 4H-碳化硅 (SiC) p+n 二极管在 0V 偏置电压下比在 -200V 偏置电压下表现出更好的中子伽马辨别力，这是因为它在 -200V 下对伽马光子的灵敏度更高，这是由于更广泛的电荷收集所致因此，对于核反应堆环境等混合中子-伽马环境中的应用，优选使用没有外部电场的4H-SiC p+n二极管。结果表明，由于使用 6Li 而不是 10B 作为中子转换器，单晶化学气相沉积 (sCVD) 金刚石探测器具有更好的中子与伽马辨别能力。然而，对探测器辐射稳定性的研究表明，sCVD金刚石基探测器在高中子通量（~109 cm-2·s-1）下工作时会受到“极化效应”的影响。