Spectral Structure of Antineutrinos from Nuclear Reactors

We reexamine calculations of energy spectrum of antineutrinos from nuclear reactors. Ab initio calculations rely on our collected knowledge of the nuclear processes involving $\sim$1000 isotopes present within a reactor. While this approach suffers from systematic uncertainties which are difficult to quantify, certain characteristics of the spectrum can be predicted. We examine these characteristics in light of recent high-statistics measurements of positrons from antineutrino inverse beta decay. Impacts on future measurements of reactor antineutrinos will also be discussed.