Tchakoua Tchouaso Modeste
Department of Physics, North Carolina A&T State University, Greensboro, NC, 27411, USA.
Appl Radiat Isot. 2021 Jul;173:109716. doi: 10.1016/j.apradiso.2021.109716. Epub 2021 Apr 20.
Semiconductor thermal neutron detectors are increasingly been used in in-core thermal neutron flux measurements in nuclear reactors. One limitation of these detectors is that they suffer from low detection efficiency. In this work, the maximum efficiency of a planar structure thermal neutron detector was determined using two widely used computer codes: Geant4 and MCNP6. Diamond and SiC are used as based materials in this work because of their large electron-hole pair production efficiency which generally translates to high detection efficiency. The electron-hole pair production efficiency is the fraction of energy that goes into electron-hole pair creation and depends on the band-gap energy and the W-values. These two materials are also not susceptible to radiation damage which makes them suitable for high radiation environments such as nuclear reactors. Thermal neutron detection is achieved using B and LiF conversion layers coated on the surface of the detector. The maximum efficiency for B conversion layer was achieved at a thickness of 2 μm. The efficiency at this thickness is 5.57 ± 0.09% and 5.49±0.09% for diamond and silicon carbide, respectively. When LiF was used as a thermal neutron conversion layer, the maximum thickness of the conversion layer was determined to occur at 17 μm. The efficiency at this thickness is 5.47 ±0.06% and 5.38±0.06% for diamond and SiC, respectively.
半导体热中子探测器越来越多地用于核反应堆堆芯内热中子通量的测量。这些探测器的一个局限性在于它们的探测效率较低。在这项工作中，使用两种广泛使用的计算机代码Geant4和MCNP6确定了平面结构热中子探测器的最大效率。在这项工作中，金刚石和碳化硅被用作基础材料，因为它们具有较高的电子 - 空穴对产生效率，这通常会转化为较高的探测效率。电子 - 空穴对产生效率是进入电子 - 空穴对产生的能量分数，它取决于带隙能量和W值。这两种材料也不易受到辐射损伤，这使得它们适用于诸如核反应堆等高辐射环境。热中子探测是通过涂覆在探测器表面的硼和氟化锂转换层来实现的。硼转换层在厚度为2μm时达到最大效率。对于金刚石和碳化硅，该厚度下的效率分别为5.57±0.09%和5.49±0.09%。当使用氟化锂作为热中子转换层时，转换层的最大厚度确定为17μm。对于金刚石和碳化硅，该厚度下的效率分别为5.47±0.06%和5.38±0.06%。
