The oscillation results published by the Double Chooz Collaboration in 2011 and 2012 rely on background models substantiated by reactor-on data. In this analysis, we present a background-model-independent measurement of the mixing angle θ13 by including 7.53 days of reactor-off data. A global fit of the observed antineutrino rates for different reactor power conditions is performed, yielding a measurement of both θ13 and the total background rate. The results on the mixing angle are improved significantly by including the reactor-off data in the fit, as it provides a direct measurement of the total background rate. This reactor rate modulation analysis considers antineutrino candidates with neutron captures on both Gd and H, whose combination yields sin2(2θ13) = 0.102 ± 0.028(stat.) ± 0.033(syst.). The results presented in this study are fully consistent with the ones already published by Double Chooz, achieving a competitive precision. They provide, for the first time, a determination of θ13 that does not depend on a background model.
|Original language||English (US)|
|Number of pages||6|
|Journal||Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics|
|State||Published - Jul 30 2014|
Bibliographical noteFunding Information:
We thank the French electricity company EDF ; the European fund FEDER ; the Région de Champagne Ardenne ; the Département des Ardennes ; and the Communauté des Communes Ardennes Rives de Meuse . We acknowledge the support of the CEA , CNRS/IN2P3 , the computer center CCIN2P3 , and LabEx UnivEarthS in France; the Ministry of Education, Culture, Sports, Science, and Technology of Japan (MEXT) and the Japan Society for the Promotion of Science (JSPS); the Department of Energy and the National Science Foundation of the United States; the Ministerio de Ciencia e Innovación (MICINN) of Spain; the Max Planck Gesellschaft , and the Deutsche Forschungsgemeinschaft DFG ( SBH WI 2152 ), the Transregional Collaborative Research Center TR27 , the excellence cluster “Origin and Structure of the Universe”, and the Maier-Leibnitz-Laboratorium Garching in Germany; the Russian Academy of Sciences , the Kurchatov Institute and RFBR (the Russian Foundation for Basic Research); the Brazilian Ministry of Science, Technology and Innovation (MCTI) , the Financiadora de Estudos e Projetos (FINEP) , the Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) , the São Paulo Research Foundation (FAPESP), and the Brazilian Network for High Energy Physics (RENAFAE) in Brazil.