Journal Article

STEREO neutrino spectrum of 235U fission rejects sterile neutrino hypothesis

Lamblin, J., Letourneau, A., Bonhomme, A., Soldner, T., Salagnac, T., Labit, L., Vialat, M., Almazán, H., del Amo Sanchez, P., Schoppmann, S., Réal, J.-S., Blanchet, A., Lindner, M., Savu, V., Pessard, H., Bernard, L., Lhuillier, D., Licciardi, M., Materna, T., Buck, C., Stutz, A., Roca, C., El Atmani, I., Ricol, J.-S., Chalil, A., Rogly, R.

2023

Overview

Anomalies in past neutrino measurements have led to the discovery that these particles have non-zero mass and oscillate between their three flavours when they propagate. In the 2010s, similar anomalies observed in the antineutrino spectra emitted by nuclear reactors have triggered the hypothesis of the existence of a supplementary neutrino state that would be sterile, that is, not interacting by means of the weak interaction 1 . The STEREO experiment 2 – 6 was designed to investigate this conjecture, which would potentially extend the standard model of particle physics. Here we present an analysis of the full set of data generated by STEREO, confirming observed anomalies while rejecting the hypothesis of a light sterile neutrino. Installed at the Institut Laue–Langevin (ILL) research reactor, STEREO accurately measures the antineutrino energy spectrum associated to the fission of 235 U. The segmentation of the detector and its very short distance to the compact core are crucial properties of STEREO for our analysis. The measured antineutrino energy spectrum suggests that anomalies originate from biases in the nuclear experimental data used for the predictions 7 , 8 . Our result supports the neutrino content of the standard model and establishes a new reference for the 235 U antineutrino energy spectrum. We anticipate that this result will allow progress towards finer tests of the fundamental properties of neutrinos but also to benchmark models and nuclear data of interest for reactor physics 9 , 10 and for observations of astrophysical or geoneutrinos 11 , 12 . Accurate measurements of the antineutrino energy spectrum of 235 U fission by the STEREO detector reject the sterile neutrino hypothesis and point to biases in the nuclear data to explain the discrepancies with the prediction.

• Publisher: Nature Publishing Group UK,Nature Publishing Group
• Subject: 639/766/387/1126 / 639/766/419/1131 / Anomalies / Calibration / Cosmic rays / Energy / Energy spectra / Experiments / Flavor (particle physics) / Humanities and Social Sciences / Hypotheses / multidisciplinary / Neutrinos / Nuclear reactors / Particle physics / Reactors / Science / Science (multidisciplinary) / Segmentation / Sensors / Spectral emittance / Standard model (particle physics)