Double Chooz θ13 measurement via total neutron capture detection

Neutrinos were assumed to be massless particles until the discovery of the neutrino oscillation process. This phenomenon indicates that the neutrinos have non-zero masses and the mass eigenstates ( ν 1 , ν 2 , ν 3 ) are mixtures of their flavour eigenstates ( ν e , ν μ , ν τ ). The oscillations between different flavour eigenstates are described by three mixing angles ( θ 12 , θ 23 , θ 13 ), two differences of the squared neutrino masses of the ν 2 / ν 1 and ν 3 / ν 1 pairs and a charge conjugation parity symmetry violating phase δ CP . The Double Chooz experiment, located near the Chooz Electricité de France reactors, measures the oscillation parameter θ 13 using reactor neutrinos. Here, the Double Chooz collaboration reports the measurement of the mixing angle θ 13 with the new total neutron capture detection technique from the full data set, yielding sin 2 (2 θ 13 ) = 0.105 ± 0.014. This measurement exploits the multidetector configuration, the isoflux baseline and data recorded when the reactors were switched off. In addition to the neutrino mixing angle measurement, Double Chooz provides a precise measurement of the reactor neutrino flux, given by the mean cross-section per fission 〈 σ f 〉 = (5.71 ± 0.06) × 10 −43 cm 2 per fission, and reports an empirical model of the distortion in the reactor neutrino spectrum. The Double Chooz collaboration reports the neutrino oscillation parameter θ 13 from a measurement of the disappearance of reactor anti-electron neutrinos with the total neutron capture technique.