Probing the reactor antineutrino anomaly and the search for a sterile neutrino at the Institut Laue-Langevin nuclear research reactor

PPRC Seminars
Stephane Zsoldos (Queen Mary)
Teppei Katori
September 29th, 2017 at 13:30
GO Jones Room 410

The re-evaluation of the theoretical antineutrino flux emitted by nuclear reactors revealed a deficit of about 6% between the observed flux and the expected one. This so-called reactor antineutrino anomaly has a statistical significance of 2.7 sigma, and one possible explanation for this deficit could be the existence of a light sterile neutrino state into which reactor antineutrino oscillate at very short distances. The STEREO project aims to find an evidence of such oscillation.

The measurement will take place at only few meters ~10m from the compact core of the Institut Laue-Langevin (ILL) research reactor in Grenoble, France, which provides a large flux of electron antineutrinos with an energy range from 1 to 10MeV.

The sensitive volume of the STEREO detector is 2 m cube of organic liquid scintillator doped with Gadolinium, segmented in 6 cells stacked along the direction of the core and detecting anti-neutrinos via inverse beta decay.

This setup will provide excellent sensitivity to short-baseline oscillations effects by precisely measuring any relative distortion of the antineutrino spectrum as a function of both energy and baseline.

The close proximity to the reactor yield a high background environment from the reactor and also generated in nearby experiments which is managed by the means of heavy shielding surrounding the detector. An active water-Cherenkov muon veto located above STEREO allows to tag incoming cosmic particle and to remove from the analysis events who might be produced by correlated fast neutrons.

In this presentation I will introduce the experiment and its scientific context. Then I will focus more about the study on background on site and the resulting sensitivity of the detector. I will conclude by giving a brief status on the on-going data taking, where first preliminary results are expected for the summer 2017.