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为了提高PGNAA系统中D-T中子管的中子慢化效率,获得更高的热中子产额,借助蒙特卡罗模拟,确定了以铅为中子反射层、5个聚乙烯层和铅层相互交替作为中子慢化层、碳化硼含量为5%的含硼聚乙烯作为中子吸收层以及铅作为γ屏蔽层的中子慢化装置模型。针对中子产额为3×107n/s的D-T中子管,该慢化装置出射方向低于5 e V的中子产额可达5.28×106n/s,占总中子产额的30.8%,有效提高了中子慢化效率。经过验证模拟结果能够满足实验要求。
In order to improve the neutron moderation efficiency of DT neutron tube in PGNAA system and obtain higher thermal neutron yield, it was confirmed by means of Monte Carlo simulation that lead as neutron reflecting layer, five polyethylene layers and lead layer A neutron moderator model that alternates as a neutron moderator layer, a boron-containing polyethylene with a boron carbide content of 5% as a neutron absorber layer, and a lead as a gamma shielding layer. For the DT neutron tube with neutron yield of 3 × 107n / s, the neutron yield of this moderating device with the exit direction less than 5 eV can reach 5.28 × 106n / s, accounting for 30.8% of the total neutron yield. , Effectively improve the neutron moderation efficiency. Verified simulation results to meet the experimental requirements.