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基于硼转换的GEM(Gas Electron Multiplier)探测器性能突出,计数率高达10 MHz以上,耐辐射,信号读出方式简单、灵活,位置与时间分辨率高,是下一代中子束流监测器极具优势的候选者。这种新型中子束流监测器主要由硼中子转换层、气体电离粒子放大的GEM以及二维读出电极组成。通过Geant4程序包对探测器物理过程进行蒙特卡罗(Monte Carlo)模拟,主要研究了硼中子转换层转换效率与厚度及中子波长的关系、出射粒子的能谱、不同气体比分不同气体厚度中的能量沉积、以及γ的能量沉积,计算比较了不同厚度GEM膜对快中子产生的影响。模拟结果表明,出射粒子在漂移区的能量沉积几乎与气体比分无关,硼层厚度取0.1μm以下,漂移区厚度6 mm时,可以确保出射粒子在漂移区能量完全沉积,同时具有最佳n/γ区分能力。
GEM (Gas Electron Multiplier) based on boron conversion performance outstanding, counting rate up to 10 MHz or more, resistance to radiation, the signal readout is simple, flexible, high position and time resolution, is the next generation neutron beam monitor pole Advantageous candidates. The new neutron beam monitor is mainly composed of boron neutron conversion layer, GEM with gas ionized particles and two-dimensional readout electrode. The Monte Carlo simulations of the physical process of the detector were carried out by using the Geant4 package. The relationships between the conversion efficiency of the neutron conversion layer and the thickness and the neutron wavelength were studied. The energy spectra of the emitted particles, different gases with different gas concentrations In the energy deposition, and γ energy deposition, the calculation of different thickness of the GEM film on the impact of fast neutrons. The simulation results show that the energy of the exiting particles in the drift region is almost independent of the gas fraction. When the thickness of the boron layer is less than 0.1μm and the drift region is 6 mm, the energy of the exiting particles can be completely deposited in the drift region while the best n / γ distinguish ability.