【摘要】 活化法测量硅单晶中子嬗变掺杂的辐照热中子注量时,由于活化探测器与硅的目标反应截面随中子能量的变化曲线存在一定差异,导致测量值可能存在较大偏差。为了抑制反应截面差异引入的测量影响,基于Stoughton-Halperin约定关系,确立了二元一次方程组求解法和线性最小二乘拟合法,并使用多种活化探测器进行了实验。结果表明:同一位置的不同探测器测量值存在显著差异,基于合理的探测器组合,采用上述方法能够显著减小测量值偏差,偏差可达3%以内。因此,两种方法均能有效抑制截面差异引入的测量影响,并且方程组法仅需要两种探测器,相比最小二乘法更有一定的优势。此外,该方法还适用于其他热中子辐照样品。更多还原

【Abstract】 [Background] When the activation method is used to measure the irradiated thermal neutron fluence of single-crystal silicon neutron transmutation doping, the measured value may have a certain deviation due to the difference in the curve shapes of the target reaction cross-section as a function of neutron energy between activated detector and silicon. [Purpose] This study aims to suppress the measurement influence caused by reaction crosssection difference between activation detector and silicon, and to reduce the measurement deviation. [Methods]Based on the Stoughton-Halperin convention relation, the binary first-order equations solution method and a linear least-squares fitting method were established. A variety of activation detectors and their combinations were applied to experimental measurement to verify their feasibility. These activation detectors were placed in the irradiation facility and irradiated in the Minjiang test reactor at Sichuan province. Finally, all of detectors were taken out from the reactor, and the radioactive activity was measured by high purity germanium γ spectrometer. [Results] The results show that obvious differences exist in the measurement values of different activated detectors at the same position,and the measurement deviation based on suitable detector combination is greatly reduced to be less than 3% by using above two methods. [Conclusions] The two methods proposed in this study can effectively suppress the influence of the reaction cross-section difference on measurement. The equation method has certain advantages over the leastsquare method with only two kinds of compulsory detectors, it can also be applied to other thermal neutron irradiation samples.更多还原