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Published April 1, 2016 | Published + Submitted
Journal Article Open

New measurement of θ_(13) via neutron capture on hydrogen at Daya Bay


This article reports an improved independent measurement of neutrino mixing angle θ_(13) at the Daya Bay Reactor Neutrino Experiment. Electron antineutrinos were identified by inverse β-decays with the emitted neutron captured by hydrogen, yielding a data set with principally distinct uncertainties from that with neutrons captured by gadolinium. With the final two of eight antineutrino detectors installed, this study used 621 days of data including the previously reported 217-day data set with six detectors. The dominant statistical uncertainty was reduced by 49%. Intensive studies of the cosmogenic muon-induced ^9Li and fast neutron backgrounds and the neutron-capture energy selection efficiency, resulted in a reduction of the systematic uncertainty by 26%. The deficit in the detected number of antineutrinos at the far detectors relative to the expected number based on the near detectors yielded sin^22θ_(13) =0.071±0.011in the three-neutrino-oscillation framework. The combination of this result with the gadolinium-capture result is also reported.

Additional Information

© 2016 American Physical Society. Received 14 March 2016; published 21 April 2016. The Daya Bay Experiment is supported in part by the Ministry of Science and Technology of China, the United States Department of Energy, the Chinese Academy of Sciences, the CAS Center for Excellence in Particle Physics, the National Natural Science Foundation of China, the Guangdong provincial government, the Shenzhen municipal government, the China General Nuclear Power Group, the Key Laboratory of Particle & Radiation Imaging (Tsinghua University), Ministry of Education, the Key Laboratory of Particle Physics and Particle Irradiation (Shandong University), Ministry of Education, the Research Grants Council of the Hong Kong Special Administrative Region of China, the MOST fund support from Taiwan, the U.S. National Science Foundation, the Ministry of Education, Youth and Sports of the Czech Republic, the Joint Institute of Nuclear Research in Dubna, Russia, the NSFC-RFBR joint research program, the National Commission for Scientific and Technological Research of Chile, and the Tsinghua University Initiative Scientific Research Program. We acknowledge Yellow River Engineering Consulting Co., Ltd. and China Railway 15th Bureau Group Co., Ltd. for building the underground laboratory. We are grateful for the ongoing cooperation from the China Guangdong Nuclear Power Group and China Light & Power Company.

Attached Files

Published - PhysRevD.93.072011.pdf

Submitted - 1603.03549v2.pdf


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