Prompt-fission-neutron spectra in the Pu239(n,f) reaction
| Autor: | K.J. Kelly, B. Laurent, D. Etasse, P. Morfouace, Matthew Devlin, Paola Marini, R. C. Haight, G. Belier, A. Chatillon, J.A. Gomez, Kyle Schmitt, John M. O'Donnell, J. Taieb |
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| Rok vydání: | 2020 |
| Předmět: |
Physics
010308 nuclear & particles physics Fission Astrophysics::High Energy Astrophysical Phenomena Nuclear Theory Center (category theory) Kinetic energy 01 natural sciences 7. Clean energy Neutron temperature Nuclear physics Neutron research facility 0103 physical sciences Neutron Nuclear Experiment 010306 general physics Energy (signal processing) Spontaneous fission |
| Zdroj: | Physical Review C. 101 |
| ISSN: | 2469-9993 2469-9985 |
| DOI: | 10.1103/physrevc.101.044614 |
| Popis: | Prompt-fission-neutron spectra from $^{239}\mathrm{Pu}$ ($\mathit{n},\phantom{\rule{0.16em}{0ex}}\mathit{f}$) were measured with respect to $^{252}\mathrm{Cf}$ spontaneous fission for incident neutron energies from 0.7 to $700\phantom{\rule{0.16em}{0ex}}\mathrm{MeV}$ at the Weapons Neutron Research facility (WNR) of the Los Alamos Neutron Science Center. A newly designed high-efficiency fission chamber was coupled to the highly segmented Chi-Nu neutron liquid scintillator array to detect neutrons emitted in fission events. The double time-of-flight technique was used to deduce the incident neutron energies from the spallation target and the outgoing-neutron energies from the fission chamber. Prompt-fission-neutron spectra (PFNS) were measured with respect to $^{252}\mathrm{Cf}$ spontaneous fission down to $200\phantom{\rule{0.16em}{0ex}}\mathrm{keV}$ and up to about $12\phantom{\rule{0.16em}{0ex}}\mathrm{MeV}$ for all the incident neutron energies with typical total uncertainties well below $2%$ up to about 7-MeV outgoing-neutron energy. The general trend of PFNS is well reproduced by JEFF3.3 and ENDF evaluations, although a better agreement is found with JEFF3.3. Discrepancies were observed for the low-energy part of the spectra, especially around the opening of the second-, third- and fourth-chance fission. Neutron average kinetic energies as a function of incident neutron energy are obtained experimentally with reported total uncertainties below $0.5%$. The measured values agree with the most recent data. The trend is fairly well reproduced by the JEFF3.3 evaluation, although it fails to reproduce the experimental values within their uncertainties. |
| Databáze: | OpenAIRE |
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