Spectra and mean energies of prompt neutrons from 238U fission induced by primary neutrons of energy in the region E n <20 MeV

The time-of-flight technique is used to measure the ratios R(E, E n )=N(E, E n )/N Cf(E) of the normalized (to unity) spectra N(E, E n ) of neutrons accompanying the neutron-induced fission of 238U at primary-neutron energies of E n =6.0 and 7.0 MeV to the spectrum N Cf(E) neutrons from the spontaneous fission of 252Cf. These experimental data and the results of their analysis are discussed together with data that were previously obtained for the neutron-induced fission of 238U at the primary energies of E n =2.9, 5.0, 13.2, 14.7, 16.0, and 17.7 MeV.