Nuclear structure insights into reactor antineutrino spectra

Antineutrino spectra following the neutron induced fission of U-235, U-238, Pu-239, and Pu-241 are calculated using the summation approach. While each system involves the decay of more than 800 fission products, the energy region of the spectra most relevant to neutrino oscillations and the reactor antineutrino anomaly is dominated by fewer than 20 nuclei, for which we provide a priority list to drive new measurements. The very-high-energy portion of the spectrum is mainly due to the decay of just two nuclides, Rb-92 and Y-96. The integral of the signal measured by antineutrino experiments is found to have a dependence on the mass and proton numbers of the fissioning system. In addition, we observe that similar to 70% of the signal originates from the light fission fragment group and about 50% from the decay of odd-Z, odd-N nuclides.