ABSTRACT The aim of this work is to help inform the decision for choosing a convenient material for the PGAA (Prompt Gamma Analysis Activation) collimator plug to be installed at the tangential channel of the Moroccan Triga Mark II Research Reactor. Two families of materials are usually used for collimator construction: a mixture of high-density polyethylene (HDPE) with boron, which is commonly used to moderate and absorb neutrons, and heavy materials, either for gamma absorption or for fast neutron absorption. An investigation of two different collimator designs was performed using N-Particle Monte Carlo MCNP6.2 code with the ENDF/B-VII.1 and MCLIP84 libraries. For each design, carbon steel and lead materials were used separately as collimator heavy materials. The performed study focused on both the impact on neutron beam quality and the neutron–gamma background at the exit of the collimator beam tube. An analysis and assessment of the principal findings is presented in this paper, as well as recommendations.

中文翻译：

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使用蒙特卡罗模拟确定 PGAA 准直器插头设计

摘要这项工作的目的是帮助决定为 PGAA（快速伽马分析激活）准直器插头选择一种方便的材料，以安装在摩洛哥 Triga Mark II 研究反应堆的切向通道上。准直器结构通常使用两类材料：高密度聚乙烯 (HDPE) 与硼的混合物，通常用于缓和和吸收中子，以及重材料，用于伽马吸收或快速中子吸收。使用 N-Particle Monte Carlo MCNP6.2 代码和 ENDF/B-VII.1 和 MCLIP84 库对两种不同的准直器设计进行了调查。对于每个设计，碳钢和铅材料分别用作准直器重材料。所进行的研究集中在对中子束质量和准直束管出口处的中子-伽马背景的影响上。本文对主要调查结果进行了分析和评估，并提出了建议。