Double-Chooz: a search for θ13

The Double-Chooz experiment goal is to search for a non-vanishing value of the θ13 neutrino mixing angle. This is the last step to accomplish prior moving towards a new era of precision measurements in the lepton sector. The current best constraint on the third mixing angle comes from the CHOOZ reactor neutrino experiment sin2(2θ13) < 0.2-0.14 (90% C.L., Δmatm2=2.0-2.410−3 eV2). Double-Chooz will explore the range of sin2(2θ13) from 0.2 to 0.03-0.02, within three years of data taking. The improvement of the CHOOZ result requires an increase in the statistics, a reduction of the systematic error below one percent, and a careful control of the backgrounds. Therefore, Double-Chooz will use two identical detectors, one at 150 m and another at 1.05 km distance from the Chooz nuclear cores. In addition, we will use the near detector as a “state of the art” prototype to investigate the potential of neutrinos for monitoring the civil nuclear power plants. The plan is to start operation with two detectors in 2008, and to reach a sin2(2θ13) sensitivity of 0.05 in 2009, and 0.03-0.02 in 2011.