Accurate Measurement of the Electron Antineutrino Yield of ^{235}U Fissions from the STEREO Experiment with 119 Days of Reactor-On Data.

H Almazán,V Savu,L Bernard,A Letourneau,A Bonhomme,R Rogly,J Haser,T Materna,V Sergeyeva,M Lindner,H Pessard,A Stutz,T Salagnac,A Minotti,I El Atmani,M Vialat,D Lhuillier,P Del Amo Sanchez,C Roca,L Labit,J Lamblin,C Buck,S Schoppmann,M Licciardi,Adrien Blanchet ,T Söldner ,J S Réal ,A Onillón

doi:10.1103/physrevlett.125.201801

Abstract

We report a measurement of the antineutrino rate from the fission of ^{235}U with the STEREO detector using 119days of reactor turned on. In our analysis, we perform several detailed corrections and achieve the most precise single measurement at reactors with highly enriched ^{235}U fuel. We measure an IBD cross section per fission of σ_{f}=(6.34±0.06[stat]±0.15[sys]±0.15[model])×10^{-43} cm^{2}/fission and observe a rate deficit of (5.2±0.8[stat]±2.3[sys]±2.3[model])% compared to the model, consistent with the deficit of the world average. Testing ^{235}U as the sole source of the deficit, we find a tension between the results of lowly and highly enriched ^{235}U fuel of 2.1 standard deviations.

Highlights

Accurate Measurement of the Electron Antineutrino Yield of 235U Fissions from the STEREO Experiment with 119 Days of Reactor-On Data
Experiments at reactors with highly and lowly enriched 235U fuel [2,3,4,5] confirm the ∼6% deficit of observed electron antineutrinos when compared to stateof-the-art antineutrino energy spectrum calculations, known as the reactor antineutrino anomaly (RAA) [6,7]
The Daya Bay and RENO collaborations have reported an observation of correlation between the reactor core evolution and changes in the deficit of the reactor antineutrino flux [3,4]

Summary

Introduction

Accurate Measurement of the Electron Antineutrino Yield of 235U Fissions from the STEREO Experiment with 119 Days of Reactor-On Data. We report a measurement of the antineutrino rate from the fission of 235U with the STEREO detector using 119 days of reactor turned on.

Results

Conclusion