The Double Chooz experiment

Double Chooz is a reactor neutrino experiment that aims at a precise measurement of the last unknown neutrino mixing angle θ13. This is conducted by investigating a deficit of electron anti-neutrinos from EDF Chooz nuclear power station in France. Observation of θ13 is moreover important since this value impacts a feasibility to make a future measurement of the leptonic CP violation parameter. The 1 km baseline experiment with reactor neutrinos is advantageous in that this leads to a simple 2 flavor neutrino oscillation formalism, where the clean measurement of θ13 is achievable. To fulfill precisely a θ13 observation, reduction of possible uncertainties and suppression of backgrounds are required. Double Chooz utilizes various techniques for these aspects including two identical detectors at different baselines with each composed of four-layer liquid structure. The goal of Double Chooz is to measure sin2(2θ13) with a sensitivity of 0.03 at 90 % confidence level. The construction of the Double Chooz far detector was successfully completed that is placed at 1 km baseline, and its physics data-taking was started in spring, 2011. In this talk, the experimental concept, results of the first neutrino oscillation analysis, and future prospects of Double Chooz are presented.