Abstract:
In this talk we present the first results from 100 days of running of the Double Chooz detector. This experiment searches for the last unmeasured mixing angle, \theta_{13}, in the three-neutrino mixing matrix, via the disappearance of \bar\{\nu_e} produced by the dual 4.27 GWth Chooz B Reactors. We demonstrate that the detector is running well. With this data set, we fit total interaction rate and energy dependence to extract the mixing parameter at \Delta m2_{31} = 2.4 × 10^{−3} eV^2. We find sin^2 2\theta_{13} = 0.085 ± 0.051. This is an important first step in our multi-year program to establish the magnitude of \theta_{13} and a valuable input to today’s global fits to the three-neutrino oscillation model.