Prompt fission neutron spectra of U238 and Th232 above emissive fission threshold

V. M. Maslov, Yu. V. Porodzinskij, M. Baba, A. Hasegawa, N. V. Kornilov, A. B. Kagalenko, and N. A. Tetereva
Phys. Rev. C 69, 034607 – Published 17 March 2004

Abstract

Statistical model calculations were performed to interpret the prompt fission neutron spectra (PFNS) from U238(n,f) and Th232(n,f) reactions for the incident neutron energies En618MeV. Spectra of the prefission (presaddle) (n,xnf) reaction neutrons were calculated with Hauser-Feshbach statistical model, fission and (n,xn) reaction cross section data being described consistently. Spectra of neutrons, evaporated from the fission fragments, were approximated as a sum of two Watt distributions. The reduced neutron velocity in the center-of-mass system due to the neutron emission during fragment acceleration was assumed. PFNS component due to presaddle neutrons is evidenced in the shape of the measured PFNS data. We show it to be strongly correlated with the emissive fission contributions to the observed fission cross sections. The dependence of these contributions on the target nuclide fissility and incident neutron energy is shown to be pronounced in the PFNS shapes for Th232(n,f) and U238(n,f) reactions. High-energy tails of the first neutrons of (n,nf) and (n,2nf) reactions are shown to be evidenced in the PFNS measured data trends.

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  • Received 13 March 2003

DOI:https://doi.org/10.1103/PhysRevC.69.034607

©2004 American Physical Society

Authors & Affiliations

V. M. Maslov1, Yu. V. Porodzinskij1, M. Baba2, A. Hasegawa3, N. V. Kornilov4, A. B. Kagalenko4, and N. A. Tetereva1

  • 1Joint Institute of Nuclear and Energy Research—“Sosny,” 220109 Minsk, Belarus
  • 2Cyclotron and Radioisotope Center, Tohoku University, Aramaki, Aza-Aoba, Aoba-ku, Sendai, Japan
  • 3Japan Atomic Energy Research Institute, Tokai, Japan
  • 4SSC RF Institute of Physics and Power Engineering, Obninsk, Russia

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Issue

Vol. 69, Iss. 3 — March 2004

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