The Physics and Uncertainties of Reactor Antineutrino Spectra*

In this talk I present the physics determining reactor antineutrino spectra, including the uncertainties in the spectra. There are two methods commonly used to determine the expected antineutrino spectra, the summation method and the conversion method. The summation method sums up all individual contributions to the aggregate spectra, while the conversion method converts measured aggregate beta electron spectra into antineutrino spectra. Both methods introduce uncertainties. The current status of the expected spectra suggests a need for improved nuclear data, particularly improved cumulative fission yields.