Subjects: Physics >> Nuclear Physics submitted time 2024-06-25
Abstract： [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,γ)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.
Subjects: Physics >> Nuclear Physics submitted time 2024-05-10
Abstract： [Background]: The China Spallation Neutron Source (CSNS) provides a white neutron beam with an energy range from 0.5 eV to 300 MeV and a total beam intensity of up to 107n/s/cm2, serving as an excellent experimental platform for the measurement of neutron capture reaction cross sections. During normal operation, the CSNS generates two proton bunches separated by 410 ns, consecutively striking the target, resulting in a mixed neutron beam composed of two bunches with a 410 ns interval. To avoid interference between the effects of the two bunches and maintain the energy precision of neutron capture cross sections, experimental data need to be analyzed and reconstructed to restore the effects of individual bunches. [Purpose]: The existing parsing method can yield very refined unfolding results, but it is relatively complex and has a certain usage threshold. Therefore, a more convenient data processing method needs to be found. [Methods]: This work utilized mathematical operations to analyze and reconstruct the data, with 410 ns as the unit time, and processed the data with a channel width of 4100 ns. Additionally, a comparison was made of the impacts of this method and existing methods on the accuracy of neutron incident energy. [Results]: This work proposes a simplified data processing method that achieves the same energy resolution as existing methods in the low-to-medium energy range, providing a new data processing approach for similar experimental work. [Conclusions]: The simplified data processing method presented in this study effectively addresses the issue of excessive computational costs in analyzing low to medium energy neutron data from the CSNS. It offers a practical solution for experimental work requiring accurate analysis of neutron capture reactions in this energy range.
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