水泥材料的反射中子实验研究

Experimental research on reflected neutrons from cement material

采用铀核裂变法和活化法实验研究D-T聚变中子在水泥材料上的反射中子。在铁球壳外表面水平赤道方向上,用小型浓缩铀和贫化铀裂变电离室结合俘获探测器测量了反射中子引起的235U(包镉)和238U裂变反应率,实验不确定度分别为6.1%-7.3%和6.4%-7.4%。用5种高阈能活化箔测量了反射中子引起的活化反应率,实验不确定度为7.2%-8.0%。比较了252Cf自发裂变中子在水泥材料上反射中子引起的235U(包镉)裂变反应率测量结果。讨论和分析了实验结果。

Neutrons reflected by the cement material were studied by nuclear fission and activation methods with a D-T neutron source. With the small enriched uranium and depleted uranium fission ionization chambers combining to the capturing detector, the ^235U（wrapped by Cd foil） and ^238U fission reaction rates induced by reflected neutrons are measured on the horizontal equator of the Fe shell＇s outer surface. The standard experimental uncertaininties of fission reaction rates were 6.1%-7.3% for ^235U（wrapped by Cd foil） and 6.4%-7.4% for ^238U. With five kinds of activation foils of different threshould energy, the 56Fe, 27Al, 93Nb, 19F and 63Cu reaction rates induced by reflected neutrons were measured. The standard experimental uncertaininties of activation reaction rates were 7.2%- 8.0%. The ^235U（wrapped by Cd foil） fission reaction rates with a ^252Cf neutron source were compared to the ones with a D-T neutron source. The experimental results were discussed and analyzed.