Reactor electron antineutrino disappearance in the Double Chooz experiment

TL;DR

The Double Chooz experiment observed a deficit in electron antineutrinos consistent with neutrino oscillations, measuring a non-zero mixing angle and excluding no-oscillation at high confidence.

Contribution

This paper reports the first measurement of electron antineutrino disappearance at the Double Chooz experiment, providing precise values for the mixing angle theta13.

Findings

Measured sin^2 2θ13 = 0.109 ± 0.030 (stat) ± 0.025 (syst)

Excluded no-oscillation hypothesis at 99.8% CL

Observed 8,249 candidate events with a deficit compared to expectation

Abstract

The Double Chooz experiment has observed 8,249 candidate electron antineutrino events in 227.93 live days with 33.71 GW-ton-years (reactor power x detector mass x livetime) exposure using a 10.3 cubic meter fiducial volume detector located at 1050 m from the reactor cores of the Chooz nuclear power plant in France. The expectation in case of theta13 = 0 is 8,937 events. The deficit is interpreted as evidence of electron antineutrino disappearance. From a rate plus spectral shape analysis we find sin^2 2{\theta}13 = 0.109 \pm 0.030(stat) \pm 0.025(syst). The data exclude the no-oscillation hypothesis at 99.8% CL (2.9{\sigma}).