From double Chooz to triple Chooz — neutrino physics at the Chooz reactor complex

We discuss the potential of the proposed Double Chooz reactor experiment to measure the neutrino mixing angle sin²2θ₁₃. We especially consider systematical uncertainties and their partial cancellation in a near and far detector operation, and we discuss implications of a delayed near detector startup. Furthermore, we introduce Triple Chooz, which is a possible upgrade scenario assuming a second, larger far detector, which could start data taking in an existing cavern five years after the first far detector. We review the role of the Chooz reactor experiments in the global context of future neutrino beam experiments. We find that both Double Chooz and Triple Chooz can play a leading role in the search for a finite value of sin²2θ₁₃. Double Chooz could achieve a sensitivity limit of ∼ 2.10⁻² at the 90% confidence level after 5 years while the Triple Chooz setup could give a sensitivity below 10⁻².