First Double Chooz $\mathbf{\theta_{13}}$ Measurement via Total Neutron Capture Detection

Abstract

The establishment of the neutrino oscillations phenomenon as a solution to both solar and atmospheric neutrino anomalies had two consequences: a new oscillation mode, labelled $\mathbf{\theta_{13}}$, and the possibility to observe CP violation, if $\mathbf{\theta_{13}}$ was sizeable. CP violation implies that neutrino oscillations behave differently for neutrinos and anti-neutrinos -- a rare fundamental phenomenon key for our understanding of the Universe. The experimental demonstration of $\mathbf{\theta_{13}}$ has aided the completion of a quest lasting half a century. The best $\mathbf{\theta_{13}}$ knowledge is today inferred from high-precision reactor neutrino disappearance. The Double Chooz (DC) experiment has played a pioneering role in this channel by providing the first positive evidence, in 2011, in combination with the T2K experiment appearance data. The establishment of $\mathbf{\theta_{13}}$ awaited the Daya Bay experiment's observation in 2012; confirmed soon after by the RENO experiment. Today's best knowledge on $\mathbf{\theta_{13}}$ from reactor experiments is a key input to many neutrino experiments. Here DC reports its first multi-detector $\mathbf{\theta_{13}}$ measurement exploiting several unprecedented techniques for a major precision improvement.