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Title: Improved measurement of the reactor antineutrino flux and spectrum at Daya Bay

Here, a new measurement of the reactor antineutrino flux and energy spectrum by the Daya Bay reactor neutrino experiment is reported. The antineutrinos were generated by six 2.9 GW th nuclear reactors and detected by eight antineutrino detectors deployed in two near (560 m and 600 m flux-weighted baselines) and one far (1640 m flux-weighted baseline) underground experimental halls. With 621 days of data, more than 1.2 million inverse beta decay (IBD) candidates were detected. The IBD yield in the eight detectors was measured, and the ratio of measured to predicted flux was found to be 0.946 ± 0.020 (0.992 ± 0.021) for the Huber+Mueller (ILL+Vogel) model. A 2.9σ deviation was found in the measured IBD positron energy spectrum compared to the predictions. In particular, an excess of events in the region of 4$-$6 MeV was found in the measured spectrum, with a local significance of 4.4σ. Finally, a reactor antineutrino spectrum weighted by the IBD cross section is extracted for model-independent predictions.
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Publication Date:
Report Number(s):
BNL-113493-2017-JA
Journal ID: ISSN 1674-1137; R&D Project: PO-022; KA2201020; TRN: US1701050
Grant/Contract Number:
SC0012704; AC02-05CH11231
Type:
Accepted Manuscript
Journal Name:
Chinese Physics. C, High Energy Physics and Nuclear Physics
Additional Journal Information:
Journal Volume: 41; Journal Issue: 1; Journal ID: ISSN 1674-1137
Publisher:
IOP Publishing
Research Org:
Brookhaven National Laboratory (BNL), Upton, NY (United States); Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
Sponsoring Org:
USDOE Office of Science (SC), High Energy Physics (HEP) (SC-25); Ministry of Science and Technology of China; Chinese Academy of Sciences; U.S. National Science Foundation (NSF); Joint Institute of Nuclear Research in Russia; Ministry of Education, Youth and Sports of the Czech Republic; National Commission for Scienti c and Technological Research of Chile
Contributing Orgs:
Daya Bay Collaboration
Country of Publication:
United States
Language:
English
Subject:
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS; antineutrino; flux energy; spectrum; reactor; Daya Bay
OSTI Identifier:
1341712
Alternate Identifier(s):
OSTI ID: 1408413