STEREO: Search for sterile neutrinos at the ILL

Recent studies have shown that there are discrepancies between observations and the theoretical predictions in some neutrino experiments at short distances. In the so-called "Reactor Antineutrino Anomaly" and in the "Gallium Anomaly", these differences from the expectations are at the $\sim$3 $\sigma$ level in both cases. Oscillations into a light sterile neutrino state ($\Delta m^{2} \sim 1eV^{2}$) could account for the deficits in observed rates. The STEREO experiment has been conceived to confirm or reject the sterile neutrino hypothesis. It will search for an oscillation pattern at short baselines (9-11 m) in the energy spectrum of the antineutrinos emitted by the research nuclear reactor of the Institut Laue Langevin. To this end, the detector is filled with two tons of Gd-loaded liquid scintillator read out by an array of PMTs and is segmented into 6 cells in the direction of the antineutrino's propagation. STEREO should be capable of excluding the best fit parameters region of a candidate sterile neutrino at 5 $\sigma$. Data taking will start at the end of 2016 and the first physics results are expected by the first semester of 2017.