铜活化法诊断神光Ⅲ主机装置氘氚中子产额

介绍了铜活化诊断氘氚中子产额的测量原理,分析了62 Cu和64 Cu两种活化核素在符合测量中的贡献。针对不同范围内的中子产额测量,提出了系统灵敏度相对标定法和64 Cu活化核标定法。通过添加中子屏蔽锥测量了标定场所散射中子影响。计算评估了63 Cu(n,γ)64 Cu反应过程对活化测量的影响。在神光Ⅲ主机装置上,利用该系统测量了直接驱动氘氚中子产额。实验结果表明:氘氚中子产额在109~1013范围采用相对标定方法较为合适,64 Cu活化核的标定方法适用于1012~1016范围内产额测量。标定场所散射中子对灵敏度标定因子影响约0.4%。63 Cu俘获辐射反应在64 Cu活化核标定中贡献小于1%。目前神光Ⅲ主机装置直接驱动氘氚中子产额约8×1012。

DT neutron yield diagnosis by copper activation on Shenguang-Ⅲ laser facility

This paper presents the principle of DT neutron yields diagnostic by copper activation and analyses the contributions of two kinds of nuclei 62Cu and 64Cu in the coincidence measurement. Two calibration methods of the diagnostic system are introduced for different ranges of neutron yields, which are the relative method and the 64Cu nuclei method. The scattered neutron of the accelerator room is measured by placing a polypropylene shield in front of a copper sample. The effect of the reaction 63Cu(n, )64Cu on the copper activation measurement is calculated and evaluated. This system is used to measure neutron yields from directly-driven implosions on Shenguang-Ⅲ laser facility. The experimental results show the relative method and the 64Cu nuclei method are fit in the range of DT neutron yield 109-1013 and 1012-1016, respectively. The effect of the scattered neutrons from the accelerator room on the calibrated sensitivity is about 0.4%, and the contribution of 63Cu capture reaction on the calibrated sensitivity using the 64Cu nuclei method is less than 1%. At present, DT neutron yields from directly-driven implosions on Shenguang-Ⅲ laser facility is about 81012.