Precise Determination of the U-235 Reactor Antineutrino Cross Section per Fission

Abstract

We investigate which among the reactor antineutrino fluxes from the decays of the fission products of ${}^{235}\text{U}$, ${}^{238}\text{U}$, ${}^{239}\text{Pu}$, and ${}^{241}\text{Pu}$ may be responsible for the reactor antineutrino anomaly if the anomaly is due to a miscalculation of the antineutrino fluxes. We find that it is very likely that at least the calculation of the ${}^{235}\text{U}$ flux must be revised. From the fit of the data we obtain the precise determination ${\sigma }_{f,235}=(6.33\pm 0.08)\times 10^{-43}{\text{cm}}^2/\text{fission}$ of the ${}^{235}\text{U}$ cross section per fission, which is more precise than the calculated value and differs from it by $2.2\sigma$. The cross sections per fission of the other fluxes have large uncertainties and in practice their values are undetermined by the fit.

Comments: 9 pages. Final version published in Physics Letters B 764 (2017) 145