裂变中子辐射场反冲质子探测系统的优化设计

Optimization of Recoil-Proton Detection System Used in Fission Neutron Field

在强脉冲裂变中子-伽马混合辐射场中,通常利用反冲质子探测系统对高能中子进行测量,如何提高探测系统的信噪比是设计的关键。采用MCNPX程序,模拟输入watt谱,对系统的结构进行了优化设计,其中包括:靶和PIN探测器的直径、厚度、放置角度,靶腿角度,靶室镍窗厚度以及辐射屏蔽结构等。结果表明,减小PIN探测器厚度以及靶腿角度可显著改善系统的信噪比;减小镍窗厚度以及采用阶梯状喇叭口屏蔽也可有效提高系统信噪比。

The key problem in measurement of high energy neutron fluence in intense pulsed fission neutron-gamma mixed field using recoil-proton detection system is to improve its sig-nal-to-noise ratioSNR.In this paperwe use MCNPX code and the watt spectrum as input spectrum to investigate the possibility of improving the SNR of a recoil-proton detection sys-tem by changing the structure of the detection system.The study includes the influence of the dimension of the target and the PIN detectorthe angle of the wings of the target cham-berthe thickness of the Ni window of the chamberas well as the shield structure of the de-tection system.The results show that SNR can be obviously improved by decreasing the thickness of the detector or the angle of the wings of the chamberand decreasing the thick-ness of the Ni window or using the bell-mouthed shield are also helpful.