Background-independent measurement of θ13 in Double Chooz

Abe, Y.; Dos Anjos, J. C.; Barriere, J. C.; Baussan, E.; Bekman, I.; Bergevin, M.; Bezerra, T. J. C.; Bezrukov, L.; Blucher, E.; Buck, C.; Busenitz, J.; Cabrera, A.; Caden, E.; Camilleri, L.; Carr, R.; Cerrada, M.; Chang, P. -J.; Chauveau, E.; Chimenti, P.; Collin, A. P.; Conover, E.; Conrad, J. M.; Crespo-Anadon, J. I.; Crum, K.; Cucoanes, A.; Damon, E.; Dawson, J. V.; Dietrich, D.; Djurcic, Z.; Dracos, M.; Elnimr, M.; Etenko, A.; Fallot, M.; Von Feilitzsch, F.; Felde, J.; Fernandes, S. M.; Fischer, V.; Franco, D.; Franke, M.; Furuta, H.; Gil-Botella, I.; Giot, L.; Goger-Neff, M.; Gonzalez, L. F. G.; Goodenough, L.; Goodman, M. C.; Grant, C.; Haag, N.; Hara, T.; Haser, J.; Hofmann, M.; Horton-Smith, G. A.; Hourlier, A.; Ishitsuka, M.; Jochum, J.; Jollet, C.; Kaether, F.; Kalousis, L. N.; Kamyshkov, Y.; Kaplan, D. M.; Kawasaki, T.; Kemp, E.; De Kerret, H.; Konno, T.; Kryn, D.; Kuze, M.; Lachenmaier, T.; Lane, C. E.; Lasserre, T.; Letourneau, A.; Lhuillier, D.; Lima, H. P.; Lindner, M.; Lopez-Castano, J. M.; Losecco, J. M.; Lubsandorzhiev, B. K.; Lucht, S.; Maeda, J.; Mariani, C.; Maricic, J.; Martino, J.; Matsubara, T.; Mention, G.; Meregaglia, A.; Miletic, T.; Milincic, R.; Minotti, A.; Nagasaka, Y.; Nakajima, K.; Nikitenko, Y.; Novella, P.; Obolensky, M.; Oberauer, L.; Onillon, A.; Osborn, A.; Palomares, C.; Pepe, I. M.; Perasso, S.; Pfahler, P.; Porta, A.; Pronost, G.; Reichenbacher, J.; Reinhold, B.; Rohling, M.; Roncin, R.; Roth, S.; Rybolt, B.; Sakamoto, Y.; Santorelli, R.; Sato, F.; Schilithz, A. C.; Schonert, S.; Schoppmann, S.; Shaevitz, M. H.; Sharankova, R.; Shimojima, S.; Sibille, V.; Sinev, V.; Skorokhvatov, M.; Smith, E.; Spitz, J.; Stahl, A.; Stancu, I.; Stokes, L. F. F.; Strait, M.; Stuken, A.; Suekane, F.; Sukhotin, S.; Sumiyoshi, T.; Sun, Y.; Svoboda, R.; Terao, K.; Tonazzo, A.; Trinh Thi, H. H.; Valdiviesso, G.; Vassilopoulos, N.; Veyssiere, C.; Vivier, M.; Wagner, S.; Watanabe, H.; Wiebusch, C.; Winslow, L.; Wurm, M.; Yang, G.; Yermia, F.; Zimmer, V.

doi:10.1016/j.physletb.2014.04.045

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. © 2014 The Authors.