21-29 July 2022
US/Pacific timezone

Measurement of the $^{232}$Th/$^{235}$U fission cross section ratios at the Back-n white neutron source of CSNS

25 Jul 2022, 12:09
Folsom ()



Zhizhou Ren


Neutron-induced fission cross section of 232Th has important applications in the Th/U fuel cycle. A measurement of the 232Th/235U fission cross section ratios in 1-20 MeV energy region was carried out by the time-of-flight method and Fast Ionization Chamber Spectrometer for Fission Cross Section Measurement (FIXM) at the China Spallation Neutron Source (CSNS)- Back-n white neutron source (Back-n). The fission event-energy spectrum and amplitude spectrum of 232Th and 235U have been measured in the single-bunch and double-bunch operation modes. The time-of-flight (TOF) spectrum under double-bunch mode was unfolded by using Bayes method and the results of fission cross section ratios of 232Th/235U was obtained after various modifications. The results under single-bunch mode was also obtained and the experimental uncertainty of the two datasets was analyzed. The results of 232Th/235U fission cross section ratios under the two modes are in agreement in the range of experimental uncertainty. The results are compared with the main evaluation database and the previous experimental results. The current results can provide experimental data support for evaluation of relevant nuclear data and design of Th/U cycle nuclear system.

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