用于快中子探测的裂变电离室实验及模拟结果比较(英文)

本文报道了一种用于快中子测量的裂变电离室的实验及模拟结果对比，该电离室的裂变材料为238U，分别电镀在电离室的阳极和阴极。裂变电离室通常有三种工作模式:脉冲模式、均方电压模式和电流模式，从而在大动态范围内实现中子注量测量。我们利用252Cf中子源对工作在脉冲模式的裂变电离室效率进行了测量，同时为了评估均方电压模式和电流模式，测量了裂变电离室在不同气压下的脉冲幅度，并通过Geant4蒙特卡罗软件对裂变电离室的脉冲幅度进行了模拟。模拟可以解释实验结果，当工作气压是2.64×105 Pa时探测效率最高（4.30±0.7）×10-7]，且裂变碎片能谱清晰，表明裂变电离室可以工作在不同模式下。

Comparison Between Experiment and Simulation for the Fission Chamber Used in Fast Neutron Detection

A fission chamber coated with two layers of 238U fissile materials has been developed for the measurements of fast neutrons. The developed fission chamber can operate in the pulse mode, the mean square voltage mode, and the current mode to perform the flux measurement over a large dynamic range. The pulse mode of the fission chamber has been tested with a 252Cf neutron source by measuring the detection efficiency. To evaluate both the mean square voltage mode and the current mode, the pulse amplitudes from the fission chamber in different gas pressures have been measured with the 252Cf source. Then, the pulse amplitudes from the fission chamber have also simulated with the Geant4 Monte Carlo software tool. The simulation can explain measured results, detection efficiency is highest(4.30±0.7)×10-7] when gas pressure is 2.64×105 Pa and energy spectrum of fission fragments is clearly, so the fission chamber can work in different modes.