Composition, decomposition and analysis of reactor antineutrino and electron spectra based on gross theory of β-decay and summation method

• We calculated the reactor lepton spectra fully based on nuclear theory successfully.
• The present methodology is independent of and complementary to the summation calculations ever conducted on the the experimental decay data.
• We made it clear what kinds of beta-transition types and nuclides are important to shape the lepton spectra. Important role of the odd(Z)-odd(N) nuclides is argued.
• The reactor antineutrino problem provides a good incentive and testing-basis for improvement of the theory, especially for odd-odd nuclides.

We applied the gross theory of β-decay to compose and decompose the reactor electron and antineutrino spectra emitted from 235,238 U and 239,241 Pu by summing up all the contributions from a large number of decaying fission-products (FPs). We make it clear what kinds of transition types and FP nuclides are important to shape the lepton spectra. Important role of the odd(Z)-odd(N  ) nuclides is also argued from the view point of the gross theory of β-decay. After taking the ambiguity in the current data for fission yields and QβQβ-values into account, we suggested a possibility that the high-energy part of the widely referred electron-spectra by Schreckenbach et al. might be too low. Our calculation supports the old experiment at University of Illinois.