Antineutrino Spectra of U and Pu Taken from the Double Chooz Experiment

U, U, Pu, and Pu antineutrino spectra were obtained from the measurement done by the near detector in Double Chooz experiment. Method of converting the experimental positron spectrum into the antineutrino one has been developed. The spectrum conversion function obtained from Monte Carlo calculations is used. The experimental antineutrino spectrum taken by this method corresponds to a certain fuel composition of a nuclear reactor core in parts of fission. It is possible to split the experimental antineutrino spectrum on nuclear fuel components spectra. Nuclear fuel individual isotope antineutrino spectra from uranium and plutonium were fitted by the calculated ones obtained by summation of individual fragment spectra. In the calculation, a strength function was used to describe the probability distribution of beta transitions for unknown fragments. The most accurate experimental cross sections of inverse beta decay reaction measured in a number of experiments are consistent with sections calculated on base of our experimental and calculated U, U, Pu, and Pu antineutrino spectra.