https://doi.org/10.1140/epja/s10050-022-00910-8
Regular Article - Experimental Physics
Measurement of the 236,238U(n,f) cross sections from the threshold to 200 MeV at CSNS Back-n
1
Department of Modern Physics, University of Science and Technology of China, 230026, Hefei, China
2
Institute of Nuclear Physics and Chemistry, China Academy of Engineering Physics, 621900, Mianyang, China
3
Institute of Applied Physics and Computational Mathematics, 100088, Beijing, China
4
Institute of High Energy Physics, Chinese Academy of Sciences (CAS), 100049, Beijing, China
5
Spallation Neutron Source Science Center, 523803, Dongguan, China
6
State Key Laboratory of Particle Detection and Electronics, University of Science and Technology of China, 230027, Hefei, China
7
State Key Laboratory of Nuclear Physics and Technology, School of Physics, Peking University, 100871, Beijing, China
8
Key Laboratory of Nuclear Data, China Institute of Atomic Energy, 102413, Beijing, China
9
University of South China, 421001, Hengyang, China
10
State Key Laboratory of Particle Detection and Electronics, Institute of High Energy Physics, Chinese Academy of Sciences, Beijing, China
11
Northwest Institute of Nuclear Technology, 710024, Xi’an, China
12
Department of Engineering and Applied Physics, University of Science and Technology of China, 230026, Hefei, China
13
School of Physics, Beihang University, 100083, Beijing, China
14
Xi’an Jiaotong University, 710049, Xi’an, China
c
liurongzy@163.com
m
yanjie@caep.cn
Received:
16
July
2022
Accepted:
14
December
2022
Published online:
13
January
2023
Neutron-induced uranium fission reactions play an essential role in advanced nuclear energy research, basic and applied nuclear science. Based on the China Spallation Neutron Source (CSNS) Back-streaming white neutron source (Back-n), the measurement of the 236,238U fission cross sections relative to 235U from the threshold to 200 MeV was carried out by using time-of-flight (TOF) method with a multi-cell fast fission ionization chamber in double-bunch mode. The TOF spectra in double-bunch mode were unfolded by using Bayesian method. The fission cross section ratios of 238U/235U and 236U/235U were obtained. The experimental data of the 236,238U/235U fission cross section ratios measured in single-bunch mode were re-analyzed in high energy region and the upper limit was extended to 200 MeV for comparison. The experimental results in double-bunch mode are in good agreement with those in single-bunch mode and the main evaluation data within experimental uncertainties. The 236,238U(n,f) cross sections were obtained from the measured ratios and the standard 235U(n,f) cross sections and they agree well with the theoretical calculation, previous experiments, main evaluations and IAEA NDS. The experimental results can provide technical support for further experimental researches in double-bunch mode and relevant nuclear data evaluations.
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