Abstract
This Letter reports one of the most precise measurements to date of the antineutrino spectrum from a purely U235-fueled reactor, made with the final dataset from the PROSPECT-I detector at the High Flux Isotope Reactor. By extracting information from previously unused detector segments, this analysis effectively doubles the statistics of the previous PROSPECT measurement. The reconstructed energy spectrum is unfolded into antineutrino energy and compared with both the Huber-Mueller model and a spectrum from a commercial reactor burning multiple fuel isotopes. A local excess over the model is observed in the 5-7 MeV energy region. Comparison of the PROSPECT results with those from commercial reactors provides new constraints on the origin of this excess, disfavoring at 2.0 and 3.7 standard deviations the hypotheses that antineutrinos from U235 are solely responsible and noncontributors to the excess observed at commercial reactors, respectively.
| Original language | English |
|---|---|
| Article number | 021802 |
| Journal | Physical Review Letters |
| Volume | 131 |
| Issue number | 2 |
| DOIs | |
| State | Published - Jul 14 2023 |
Funding
This material is based upon work supported by the following sources: U.S. Department of Energy (DOE) Office of Science, Office of High Energy Physics under Grants. No. DE-SC0016357 and No. DE-SC0017660 to Yale University, under Grant No. DE-SC0017815 to Drexel University, under Grant No. DE-SC0008347 to Illinois Institute of Technology, under Grant No. DE-SC0016060 to Temple University, under Grant No. DE-SC0010504 to University of Hawaii, under Contract No. DE-SC0012704 to Brookhaven National Laboratory, and under Work Proposal No. SCW1504 to Lawrence Livermore National Laboratory. This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract No. DE-AC52-07NA27344 and by Oak Ridge National Laboratory under Contract No. DE-AC05-00OR22725. Additional funding for the experiment was provided by the Heising-Simons Foundation under Grant No. 2016-117 to Yale University. J. K. G. is supported through the National Science Foundation Graduate Research Fellowship Program. This work was also supported by the Canada First Research Excellence Fund (CFREF), the Natural Sciences and Engineering Research Council of Canada (NSERC) Discovery program under Grant No. RGPIN-418579, and Province of Ontario. We further acknowledge support from Yale University, the Illinois Institute of Technology, Temple University, University of Hawaii, Brookhaven National Laboratory, the Lawrence Livermore National Laboratory LDRD program, the National Institute of Standards and Technology, and Oak Ridge National Laboratory. We gratefully acknowledge the support and hospitality of the High Flux Isotope Reactor and Oak Ridge National Laboratory, managed by UT-Battelle for the U.S. Department of Energy.