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在脉冲辐射混合场(n,γ)中进行γ射线参数测量,要求探测器系统必须有很快的时间响应,还应有很高的γ/n分辨能力。本文详述了切伦科夫(Cherenkov)辐射原理,用蒙特卡罗软件MCNP模拟计算了γ、中子在不同光纤阵列材料中的能量沉积,根据计算结果选择铅玻璃作为光纤阵列切伦科夫辐射体,配合常聚甲基丙烯甲酯(polymethylmethacrylate,PMMA)塑料光纤光导传输,由光电倍增管转换为电信号输出,研制了一种γ灵敏切伦科夫铅玻璃光纤阵列探测器。在中国原子能科学研究院的600 k V高压倍加器上进行了14.1 MeV中子灵敏度实验,又在西北核技术研究所60Co源上完成了1.25 MeVγ灵敏度实验。实验数据与模拟结果推算得出的数据基本相符,表明该探测器系统具有较高的γ/n分辨能力,可满足在脉冲中子、γ辐射混合场中对γ射线参数测量的分辨能力要求。
The measurement of γ-ray parameters in the pulsed radiation mixing field (n, γ) requires that the detector system must have fast time response and high gamma / n resolving power. In this paper, the principle of Cherenkov radiation is described in detail. The energy deposition of γ and neutron in different fiber array materials is simulated by Monte Carlo software MCNP. According to the calculation results, lead glass is selected as the fiber array Cerenkov Radiator, coupled with a conventional polymethylmethacrylate (PMMA) plastic optical fiber light guide, is converted into an electrical signal output by a photomultiplier tube. A γ sensitive Cherenkov lead glass optical fiber array detector is developed. A 14.1 MeV neutron sensitivity experiment was performed on a 600 kV high voltage doubler at China Institute of Atomic Energy, and a 1.25 MeV γ sensitivity experiment was performed on a 60Co source at the Northwestern Institute of Nuclear Technology. The experimental data are in good agreement with those obtained from the simulation results, indicating that this detector system has high γ / n resolving power and can meet the resolving power requirement of γ-ray parameter measurement in pulsed neutron and γ-radiation mixing fields.