Measurement of the a ratio and ( n , ? ) cross section of U 235 from 0.2 to 200 eV at n_TOF
Measurement of the a ratio and ( n , ? ) cross section of U 235 from 0.2 to 200 eV at n_TOF
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在 n_TOF 下从 0.2 到 200 eV 测量 U 235 的 a 比率和 (n,?) 横截面
DOI：
10.1103/physrevc.102.044615
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发表时间：
2020
影响因子：
3.1
通讯作者：
Balibrea-Correa J
中科院分区：
文献类型：
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作者：
Balibrea-Correa J
我们在CERN的n_TOF装置上测量了0.2 - 200 eV的中子俘获裂变截面比和俘获截面。用n_TOF总吸收量热计（TAC）和一组微兆气体探测器（裂变示踪探测器）同时测量中子俘获率和裂变率。利用标准反应确定n_TOF中子注量，得到俘获截面的能量依赖关系，然后用7.8 ~ 11 eV的截面积分进行绝对归一化。用稍高的统计波动获得的比直接确定，而不需要任何参考截面。为了进行这种测量的分析，我们开发了一种新的方法来校正实验观察到的效果，即在TAC和micromegas探测器中探测裂变反应的概率不是独立的。这项工作的结果已被用于一个新的评估的范围内进行的合作国际评价图书馆组织（CIELO）项目，并与ENDF/B-VIII.0和JEFF-3.3捕获截面低于4 eV和高于100 eV的一致。然而，测量的捕获截面在4和100 eV之间平均大10%。
We measured the neutron capture-to-fission cross-section ratio (ratio) and the capture cross section ofbetween 0.2 and 200 eV at the n_TOF facility at CERN. The simultaneous measurement of neutron-induced capture and fission rates was performed by means of the n_TOFTotal Absorption Calorimeter (TAC), used for detection ofrays, in combination with a set of micromegas detectors used as fission tagging detectors. The energy dependence of the capture cross section was obtained with help of thestandard reaction determining the n_TOF neutron fluence; the well-known integral of thecross section between 7.8 and 11 eV was then used for its absolute normalization. Theratio, obtained with slightly higher statistical fluctuations, was determined directly, without need for any reference cross section. To perform the analysis of this measurement we developed a new methodology to correct the experimentally observed effect that the probabilities of detecting a fission reaction in the TAC and the micromegas detectors are not independent. The results of this work have been used in a new evaluation ofperformed within the scope of the Collaborative International Evaluated Library Organisation (CIELO) Project, and are consistent with the ENDF/B-VIII.0 and JEFF-3.3 capture cross sections below 4 eV and above 100 eV. However, the measured capture cross section is on average 10% larger between 4 and 100 eV.