First measurement of ?13 from delayed neutron capture on hydrogen in the Double Chooz experiment

The Double Chooz experiment has determined the value of the neutrino oscillation parameter ?13 from an analysis of inverse beta decay interactions with neutron capture on hydrogen. This analysis uses a three times larger fiducial volume than the standard Double Chooz assessment, which is restricted to a region doped with gadolinium (Gd), yielding an exposure of 113.1 GW-ton-years. The data sample used in this analysis is distinct from that of the Gd analysis, and the systematic uncertainties are also largely independent, with some exceptions, such as the reactor neutrino flux prediction. A combined rate- and energy-dependent fit finds sin22?13=0.097±0.034 (stat.)±0.034 (syst.), excluding the no-oscillation hypothesis at 2.0. This result is consistent with previous measurements of sin22?13

Reactor ? ¯e disappearance in the Double Chooz experiment

The Double Chooz experiment has observed 8249 candidate electron antineutrino events in 227.93 live days with 33.71GW-ton-years (reactor power×detector mass×live time) exposure using a 10.3m3 fiducial volume detector located at 1050m from the reactor cores of the Chooz nuclear power plant in France. The expectation in case of ? 13=0 is 8937 events. The deficit is interpreted as evidence of electron antineutrino disappearance. From a rate plus spectral shape analysis we find sin22? 13=0.109±0.030(stat)±0.025(syst) . The data exclude the no-oscillation hypothesis at 99.8%CL (2.9s)