D-D中子源在聚乙烯球壳内反应率的绝对测量

利用D-D中子源/聚乙烯球壳模型，将裂变法和活化法结合，在聚乙烯球壳内水平方向的几个位置进行了反应率测量，获得了不同阈能的4种反应率的实验数据。裂变反应率结果的不确定度为2.5%~4.3%，活化反应率结果的不确定度约为6.3%。并利用MCNP程序进行了模拟计算，计算值均比测量值小，其中，²³⁸U的差别最大。

Absolute Reaction Rate Measurement With D-D Neutron Source in Polyethylene Spherical Shell

The absolute reaction rate distribution measurements in a polyethylene spherical shell with 38.6 cm outside diameter and 10 cm thickness were performed with D-D neutron source. By combining fission method and activation method, rich-uranium fission chamber, depleted-uranium fission chamber, ²³⁷Np fission chamber and ¹¹⁵In activation foils were placed at several positions on the equatorial line of the inner face of the shell, and the absolute reaction rates were obtained. The uncertainty of fission rates is 2.5%-4.3%, while the uncertainty of activation rates is about 6.3%. The reaction rates were calculated by MCNP and ENDF/B-Ⅶ.0. The calculated results are lower than the measured results and ²³⁸U is typical.