SoLid

The Neutrino team, in collaboration with researchers from France, Belgium and England, is at the origin of the international experiment SoLid [1]. After a large prototype installed at the BR2 reactor in Mol, Belgium [2], built at Subatech, the team has been nationally coordinating an ANR project starting in 2016, which with the support of the technical services, has notably ensured the mechanical design of the detector, the calibration and the coordination of the analysis. The experiment, installed at the BR2 research reactor, had the main goal of probing the flux of antineutrinos at very short distances to test the hypothesis of a sterile neutrino with a mass around eV.

[1] “A novel segmented-scintillator antineutrino detector", JINST , volume 12, (2017), 04024
[2] “Performance of a full scale prototype detector at the BR2 reactor for the SoLid experiment", JINST, volume 13, (2018), 05005

Double Chooz

The international Double-Chooz collaboration has succeeded in obtaining the value of the parameterθ13 with the best systematic error in the world, the last to be measured among those that characterize neutrino oscillations. These results were published in the journal Nature Physics [1]. This study of θ13 in turn served to demonstrate very robustly that the evel of uncertainty in flux predictions was greatly underestimated, possibly by a factor of 4 strongly disfavoring the reactor anomaly that appeared when comparing the measured flux to the predicted flux. The experiment also provides the most accurate measurement of the neutrino flux from nuclear reactions in reactors, which is proportional to the measurement of the average cross section per fission reaction.

The Neutrino team of Subatech played a central role in the physics analyses that led to this major result, in continuity with previous analyses published in JHEP [2] and in Nuclear Physics B [3]. Notable contributions included detailed studies of the cosmic ray background and the final statistical fit of the oscillation to extract the mixing angle θ13.

[1] “Double Chooz θ13 measurement via total neutron capture detection", Nature Physics, Volume 16, (2020) 558
[2] “Measurement of θ13 in Double Chooz using neutron captures on hydrogen with novel background rejection techniques", Journal of High Energy Physics, Volume 1, (2016), 1-29
[3] Double Chooz and a history of reactor θ13 experiments, Nuclear Physics B Proceedings Supplement, Volume 908, (2016) 74-93