基于特征伽马谱线测量的中子俘获截面测量方法研究

Background]: Neutron capture reaction cross sections are of significant importance in various fields, including fundamental physics, nuclear astrophysics, nuclear engineering, and materials science. Traditionally, the measurement of neutron capture reaction cross sections involves detecting all gamma rays produced from the target nucleus after reacting with neutrons. Theoretical methods are then used to calculate the proportion of the neutron capture reaction, thus obtaining the cross section. This method relies heavily on theoretical predictions and the combined effects of multiple reaction channels, which can obscure the structural features of the target reaction, resulting in smoothed cross section data in the resonance regions predicted by theory. [Purpose]: To overcome the limitations of the traditional method and reduce dependency on theoretical predictions, a more precise method utilizing high-energy resolution gamma detectors is needed to accurately measure the neutron capture reaction cross sections by identifying the yields of individual reaction channels. [Methods]: By analyzing the decay scheme of reaction products, high-energy resolution gamma detectors were employed to measure one or more characteristic gamma lines that can represent the reaction effects. This approach excludes interference from other reaction channels, thereby providing accurate neutron capture reaction cross sections. The 91Zr(n,)92Zr reaction was used to compare the advantages and disadvantages of this method with the traditional method. The experiment was conducted at the China Spallation Neutron Source. [Results]: In this work, clear resonance phenomena was observed in the theoretically predicted resonance regions. The results in non-resonance regions were consistent with previous data within error margins. This demonstrates that the new method provides accurate and reliable data for neutron capture reaction cross sections. [Conclusions]: The proposed method has significant advantages over traditional methods, offering a new approach for measuring neutron capture reaction cross sections. It reduces reliance on theoretical predictions and provides more detailed and accurate cross section data, especially in the resonance regions. This new method offers a promising direction for future research in neutron capture reactions.