Abstract
This Letter reports the first extraction of individual antineutrino spectra from and fission and an improved measurement of the prompt energy spectrum of reactor antineutrinos at Daya Bay. The analysis uses inverse beta-decay candidates in four near antineutrino detectors in 1958 days. The individual antineutrino spectra of the two dominant isotopes, and , are extracted using the evolution of the prompt spectrum as a function of the isotope fission fractions. In the energy window of 4–6 MeV, a 7% (9%) excess of events is observed for the () spectrum compared with the normalized Huber-Mueller model prediction. The significance of discrepancy is for spectral shape compared with the Huber-Mueller model prediction. The shape of the measured inverse beta-decay prompt energy spectrum disagrees with the prediction of the Huber-Mueller model at . In the energy range of 4–6 MeV, a maximal local discrepancy of is observed.
- Received 16 April 2019
- Revised 4 August 2019
DOI:https://doi.org/10.1103/PhysRevLett.123.111801
Published by the American Physical Society under the terms of the Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article’s title, journal citation, and DOI. Funded by SCOAP3.
Published by the American Physical Society