There exists a persistent local deviation in the reactor antineutrino spectra between those measured directly at power reactors through the νe+p→n+e+ reaction and the currently used reference data. In order to interpret the origin of this spectral anomaly with its peak at 6 MeV, the gross theory of β decay was applied to calculate the antineutrino spectra for about 500 fission products (FPs) where the measured spin parities were introduced into calculations for 178 odd(-N)-odd(-Z) FPs in the framework of the gross theory and the recently measured ground-to-ground transition rate for two FPs dominating the spectrum shaping above 5 MeV. The overall consistency between the calculated and the reference spectra is reasonable, and our result supports the direct measurements of the νe spectra at power reactors. The anomaly is suggested to originate first with the plutonium isotopes Pu239 and Pu241, which are closely followed by U235.
ASJC Scopus subject areas
- Nuclear and High Energy Physics