Final Measurement of the U235 Antineutrino Energy Spectrum with the PROSPECT-I Detector at HFIR

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 5MeV to 7MeV energy region. Comparison of the PROSPECT results with those from commercial reactors provides new constraints on the origin of this excess, disfavoring at 2.2 and 3.2 standard deviations the hypotheses that antineutrinos from U235 are solely responsible and non-contributors to the excess observed at commercial reactors respectively.

The paper has been updated to match publication at PRL

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• Long term remote reactor power and fuel composition monitoring using antineutrinos
• Measurement of cosmic muon-induced neutron background with ISMRAN detector in a non-reactor environment
• Directional Response of Several Geometries for Reactor-Neutrino Detectors
• Analysis of reactor burnup simulation uncertainties for antineutrino spectrum prediction
• Water-based Quantum Dots Liquid Scintillator for Particle Physics