基于SiC的裂变靶室中子灵敏度标定技术

Calibration of Neutron Sensitivity in Fission Target Chamber of SiC Detector

为实现对基于SiC探测器的裂变靶室极低中子灵敏度的准确标定,提出了利用不同的中子源分别测量中子探测效率与裂变碎片的等效平均沉积能量,再将实验结果合成得到中子灵敏度的标定方法。利用该方法,获得了SiC探测器与不同厚度^(235) U或^(238) U裂变靶组成的探测系统对14.9 MeV中子的响应灵敏度,灵敏度的相对标准不确定度为7.5%(k=1),较好地满足了应用需求。与传统带屏蔽体的标定方法相比,该方法测得的中子灵敏度可标定下限拓展了1个量级以上,同时,散射本底的影响可以通过挡影锥的方法准确扣除,显著提高了标定结果的精度。

To accurately calibrate the low neutron sensitivity in the fission target chamber(FTC)of the SiC detector,a method with which the neutron detection efficiency and the equivalent average deposition energy of the fission fragment can be measured respectively on different neutron sources is proposed to calibrate the neutron sensitivity.Based on this method,the corresponding neutron sensitivities of neutron of 14.9 MeV are measured by the detection system composed of SiC detector and 235 U or 238 U fission target with different thickness.The relative standard uncertainty of the measured sensitivity is 7.5%(k=1),and the calibration lower limit of the neutron sensitivity is extended over one order of magnitude.Meanwhile,the effect of the scattering background can be deducted accurately by adding a shadow cone between the FTC and the source,and thus the accuracy of the calibration results can be greatly improved.