Measurement of the prompt neutron spectrum from thermal-neutron-induced fission in U-235 using the recoil proton method

He, Tao; Peng, Zheng; Xiao, Jun

doi:10.1007/s41365-019-0633-z

Cited by 3 publications

(1 citation statement)

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“…Early attempts at such measurements were necessarily primitive, but interest in these spectra was such that the first numbered report from the then secret program at Los Alamos was titled A Discussion of the Fission Neutron Spectrum [2]; this document is no longer classified. More recently, there has been a renewed interest in improved PFNS data, with numerous experimental efforts (see, for example, [3][4][5][6][7][8][9][10][11]) and related evaluations [12][13][14] for neutron-induced fission of the major actinides. Improved data on PFNS are needed, particularly for fast neutrons, to improve nuclear data libraries [15,16] used in neutronics calculations for fast systems.…”

Section: Introductionmentioning

confidence: 99%

Prompt Fission Neutron Spectra for Neutron-Induced Fission of ²³⁹Pu and ²³⁵U

et al. 2020

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We report the current results of a large effort to accurately measure the Prompt Fission Neutron Spectra (PFNS) for neutron-induced fission of 235U and 239Pu for incident neutrons with energies from 1 to 20 MeV. The Chi-Nu experiment at the Los Alamos Neutron Science Center used an unmoderated, white spectrum of neutrons to induce fission in actinide samples that were placed inside a parallel plate avalanche counter to provide a fast fission signal. A double time-of-flight technique was used to determine the incoming and outgoing neutron energies. Two neutron detector arrays, one with 54 liquid scintillators and another with 22 lithium glass detectors, were used to detect the outgoing neutrons and measure the PFNS distributions over a wide range in outgoing neutron energy, from below 100 keV to 10 MeV. Extensive Monte Carlo modeling was used to understand the experiment response and extract the PFNS. Systematic errors and uncertainties in the method have been examined and quantified. A summary of these results for incoming energies from 1 to 5 MeV is presented here.

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