New Antineutrino Spectra of Nuclear-Reactor Fissile Isotopes: Experiment and Calculations

New antineutrino spectra of fissile isotopes entering into the composition of nuclear-reactor fuel are obtained. A method that combines a calculation of antineutrino spectra and a fit of the results to the spectra obtained experimentally at the Rovno nuclear power plant in the 1980s is used. The cross sections calculated for fissile isotopes by employing these spectra describe well the cross section of ^DCσ_f=(5.71± 0.06)× 10^-43 cm ^2/ fission obtained in the Double Chooz experiment. The cross section obtained on the basis of the calculated spectra at the same composition of the reactor core is ^INRσ_f=(5.82± 0.12)× 10^-43 cm ^2/ fission. For the resulting spectra, there is no problem of a bump in the region around 5 MeV in the observed energy spectrum of positrons.