  It has recently been widely recognized that a reactor anti-neutrino
disappearance experiment with two or more detectors is one of the most
cost-effective ways to extend our reach in sensitivity for the neutrino mixing
angle theta-13 without ambiguities from CP violation and matter effects. The
physics capabilities of a new reactor experiment together with superbeams and
neutrino factories have also been studied but these latter are considered by
many to be more ambitious projects due to their higher costs, and hence to be
farther in the future.
  We propose to contribute to an international collaboration to modify the
existing neutrino physics facility at the Chooz-B Nuclear Power Station in
France. The experiment, known as Double-CHOOZ, is expected to reach a
sensitivity of sine squared of twice the mixing angle > 0.03 over a three year
run, 2008-2011. This would cover roughly 85% of the remaining allowed region.
The costs and time to first results for this critical parameter can be
minimized since our project takes advantage of an existing infrastructure.
