Double Chooz: Optimizing CHOOZ for a possible theta 13 measurement
  The proposed Double Chooz theta 13 experiment is described. Double Chooz will be an optimized reactor disappearance experiment similar to the original CHOOZ. The optimization includes an increase in the signal to noise by increasing the target volume to twice the original CHOOZ, reducing singles background with a non-scintillating oil buffer region around the target and carefully controlling systematic uncertainties by measuring the electron antineutrino flux of the source with a near detector. The Double Chooz far detector will be situated in the same cavern as CHOOZ but will detect ~50000 electron antineutrinos in three years of operation. We estimate a systematic uncertainty of 0.6%, and a reduction of the upper limit on theta 13 to 5 degrees. 
S. A. Dazeley (for the Double Chooz Collaboration)