Letter of Intent for Double-CHOOZ: a Search for the Mixing Angle Theta13

TL;DR

The paper proposes the Double-CHOOZ experiment to precisely measure the neutrino mixing angle theta13 by using two detectors at different distances, aiming to improve sensitivity and reduce systematic errors over three years.

Contribution

It introduces a new experimental setup with dual detectors to significantly improve the measurement sensitivity of theta13 compared to previous experiments.

Findings

Projected sensitivity of 0.05 in 2009

Projected sensitivity of 0.03 in 2011

Enhanced control of systematic errors and background

Abstract

Tremendous progress has been achieved in neutrino oscillation physics during the last few years. However, the smallness of the $\t13$ neutrino mixing angle still remains enigmatic. The current best constraint comes from the CHOOZ reactor neutrino experiment $\s2t13 < 0.2$ (at 90% C.L., for $\adm2=2.0 10^{-3} \text{eV}^2$). We propose a new experiment on the same site, Double-CHOOZ, to explore the range of $\s2t13$ from 0.2 to 0.03, 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 cosmic ray induced background. Therefore, Double-CHOOZ will use two identical detectors, one at $\sim$150 m and another at 1.05 km distance from the nuclear cores. The plan is to start data taking with two detectors in 2008, and to reach a sensitivity of 0.05 in 2009, and 0.03 in 2011.