Journal Article

Measurement of θ13 in Double Chooz using neutron captures on hydrogen with novel background rejection techniques

Dracos, M., Furuta, H., Jochum, J., Jollet, C., Oberauer, L., Brugière, T., Gil-Botella, I., Goodman, M.C., Hofmann, M., Sharankova, R., Haser, J., Mariani, C., Kemp, E., Lima, H.P., Matsubara, T., Milincic, R., Kawasaki, T., Miletic, T., Hourlier, A., Palomares, C., Suekane, F., Lucht, S., Sumiyoshi, T., Hellwig, D., Mention, G., Skorokhvatov, M., Chauveau, E., Yermia, F., Cabrera, A., Shaevitz, M.H., Sukhotin, S., Bezerra, T.J.C., Letourneau, A., Reinhold, B., Pepe, I.M., Haag, N., Reichenbacher, J., Meregaglia, A., Dawson, J.V., Baussan, E., Franco, D., Collin, A.P., Hara, T., Schoppmann, S., LoSecco, J.M., Tonazzo, A., Osborn, A., Zimmer, V., von Feilitzsch, F., Fernandes, S.M., dos Anjos, J.C., Schönert, S., Smith, E., Stancu, I., Schilithz, A.C., Vassilopoulos, N., Yang, G., Lubsandorzhiev, B., Camilleri, L., Lachenmaier, T., Röhling, M., Wurm, M., Wagner, S., Buck, C., Kaether, F., Onillon, A., Spitz, J., Stahl, A., Sibille, V., Fischer, V., Sakamoto, Y., Giot, L., Santorelli, R., Watanabe, H., Crespo-Anadón, J.I., Porta, A., Lasserre, T., Pronost, G., Bezrukov, L., Sinev, V., Navas-Nicolás, D., Blucher, E., Dhooghe, J., Kamyshkov, Y., Goodeno

2016

Overview

A bstract The Double Chooz collaboration presents a measurement of the neutrino mixing angle θ 13 using reactor ν e ¯ observed via the inverse beta decay reaction in which the neutron is captured on hydrogen. This measurement is based on 462.72 live days data, approximately twice as much data as in the previous such analysis, collected with a detector positioned at an average distance of 1050 m from two reactor cores. Several novel techniques have been developed to achieve significant reductions of the backgrounds and systematic uncertainties. Accidental coincidences, the dominant background in this analysis, are suppressed by more than an order of magnitude with respect to our previous publication by a multi-variate analysis. These improvements demonstrate the capability of precise measurement of reactor ν e ¯ without gadolinium loading. Spectral distortions from the ν e ¯ reactor flux predictions previously reported with the neutron capture on gadolinium events are confirmed in the independent data sample presented here. A value of sin 2 2 θ 13  = 0.095 − 0.039 + 0.038 (stat+syst) is obtained from a fit to the observed event rate as a function of the reactor power, a method insensitive to the energy spectrum shape. A simultaneous fit of the hydrogen capture events and of the gadolinium capture events yields a measurement of sin 2 2 θ 13 = 0 . 088 ± 0 . 033(stat+syst).

• Publisher: Springer Berlin Heidelberg
• Subject: Classical and Quantum Gravitation / Elementary Particles / Physics / Physics and Astronomy / Quantum Field Theories / Quantum Field Theory / Quantum Physics / Regular Article - Experimental Physics / Relativity Theory / String Theory