Double-Chooz: a search for Theta13
  The Double-Chooz experiment goal is to search for a non-vanishing value of the Theta13 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 $\sin(2\theta_{13})^{2}<0.2$ (90% C.L., $\Delta m_{atm}^{2}=2.0$ eV$^{2}$). Double-Chooz will explore the range of $\sin(2\theta_{13})^{2}$ 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 to 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 sensitivity sin$^{2}$$(2\theta_{13})$ of 0.05 in 2009, and 0.03-0.02 in 2011. 
Th. Lasserre