Spectra of Prompt Fission Neutrons in the Reactions U() and Pu()

The influence of exclusive prefission neutron spectra, , on the observed spectra of prompt fission neutrons (PFN), the total kinetic energy (TKE) of fission fragments (products), and the average number of prompt fission neutrons is studied. The exclusive neutron spectra correspond to a self-consiste...

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Veröffentlicht in:Physics of atomic nuclei 2023-10, Vol.86 (5), p.627-669
1. Verfasser: Maslov, V. M.
Format: Artikel
Sprache:eng
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Zusammenfassung:The influence of exclusive prefission neutron spectra, , on the observed spectra of prompt fission neutrons (PFN), the total kinetic energy (TKE) of fission fragments (products), and the average number of prompt fission neutrons is studied. The exclusive neutron spectra correspond to a self-consistent description of the fission reactions (neutron emission) U( ) ( U( )) and Pu( ) ( Pu( )) for neutrons of energy extending up to 20 MeV. An extensive experimental database of PFN spectra made it possible to study in detail (confirm) an intricate dependence of the shape of observed PFN spectra on the fissility of U and Pu compound nuclei. This effect is found to be correlated with the contributions of ( ) emissive fission reactions and with the competition of ( ) and ( ) reactions. The exclusive prefission neutron spectra of reactions and the exclusive neutron spectra of ( ) and reactions were calculated by means of the Hauser–Feshbach formalism simultaneously with the ( ) and ( ) cross sections. It is shown that the angular anisotropy of exclusive neutron spectra of ( ) reactions has a substantial effect on the observed spectra of prompt fission neutrons and their average energies . The ratio of the average PFN energies for the forward and backward emission of prefission neutrons in the reactions U( ) and Pu( ) agrees with experimental data. Partial components associated with ( ) and ( ) reactions are singled out in the observed PFN spectra. The input values of model parameters are fixed in describing PFN spectra of thermal-neutron-induced fission reactions. The potential of the approach being considered for predictions of PFN spectra and their average energies in the reactions U( ) and Pu( ) is demonstrated.
ISSN:1063-7788
1562-692X
DOI:10.1134/S1063778823050307