A high precision reactor neutrino detector for the Double Chooz experiment

Double Chooz is a reactor neutrino experiment which investigates the last neutrino mixing angle; θ13. It is necessary to measure reactor neutrino disappearance with precision 1% or better to detect a finite value of θ13. This requirement is the most strict compared to other reactor neutrino experiments performed so far. The Double Chooz experiment makes use of a number of techniques to reduce the possible errors to achieve the sensitivity. The detector is now under construction and it is expected to take first neutrino data in 2009 and to measure sin22θ13 with a sensitivity of 0.03 (90%C.L.) In these proceedings, the technical concepts of the Double Chooz detector are explained stressing on how it copes with the systematic errors.