Improved measurement of the reactor antineutrino flux and spectrum at Daya Bay
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摘要
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 GWth 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. A reactor antineutrino spectrum weighted by the IBD cross section is extracted for model-independent predictions.
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 GWth 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. A reactor antineutrino spectrum weighted by the IBD cross section is extracted for model-independent predictions.
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 GWth 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. A reactor antineutrino spectrum weighted by the IBD cross section is extracted for model-independent predictions.
引文
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60 L.Groshev et al.,Nuclear Data Tables 5(1968)
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5 F.Boehm et al.,Phys.Rev.Lett.84,3764(2000),ar Xiv:hepex/9912050[hep-ex]
6 K.Eguchi et al.,Phys.Rev.Lett.90,021802(2003)
7 F.P.An et al.(Daya Bay Collaboration),Phys.Rev.Lett.108,171803(2012)
8 K.Abe et al.(T2K Collaboration),Phys.Rev.D 88,032002(2013)
9 P.Adamson et al.(MINOS Collaboration),Phys.Rev.Lett.110,171801(2013)
10 Y.Abe et al.(Double Chooz),Phys.Rev.Lett.108,131801(2012),ar Xiv:1112.6353[hep-ex]
11 J.K.Ahn et al.(RENO),Phys.Rev.Lett.108,191802(2012),ar Xiv:1204.0626[hep-ex]
12 F.An et al.(JUNO),(2015),ar Xiv:1507.05613[physics.ins-det]
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16 N.Ryder,“The Solid Experiment,”AAP 2014,Paris,France(2014)
17 M.Pequignot,“The STEREO Experiment,”AAP 2014,Paris,France(2014)
18 P.Vogel,L.Wen,and C.Zhang,(2015),10.1038/ncomm-s7935,ar Xiv:1503.01059[hep-ex]
19 K.Schreckenbach,G.Colvin,W.Gelletly,and F.Von Feilitzsch,Phys.Lett.B160,325(1985)
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26 G.Mention et al.,Phys.Rev.D83,073006(2011)
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29 F.P.An et al.(Daya Bay),Phys.Rev.Lett.116,061801(2016),ar Xiv:1508.04233[hep-ex]
30 Y.Abe et al.(Double Chooz),JHEP 10,086(2014),[Erratum:JHEP02,074(2015)],ar Xiv:1406.7763[hep-ex]
31 F.Capozzi,E.Lisi,and A.Marrone,(2015),ar Xiv:1508.01392[hep-ph]
32 F.P.An et al.(Daya Bay),Phys.Rev.Lett.115,111802(2015),ar Xiv:1505.03456[hep-ex]
33 F.P.An et al.(Daya Bay),Nucl.Instrum.Methods A811,133(2016),ar Xiv:1508.03943[physics.ins-det]
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37 Application of Orifice Plates for Measurement of Feedwater Flow:EDF Plant Experience,Tech.Rep.(EPRI)
38 J.Cao,Nucl.Phys.B-Proceedings Supplements 229-232,205(2012),Neutrino 2010
39 C.R.Xu et al.,Chinese Journal of Nuclear Science and Engineering 23,26(2003)
40 APOLLO2,“APOLLO2:Vailidation/Quali cation,”http://nucleaire-saclay.cea.fr/Phocea/Vie des labos/Ast/ast technique.php?id ast=351
41 F.P.An et al.(Daya Bay Collaboration),Chin.Phys.C 37,011001(2013)
42 R.Sanchez et al.,Nucl.Eng.Tech.42,474(2010)
43 R.R.G.Marleau,A.Hebert,and R.Roy,Report IGE-236(2001)
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46 D.A.Dwyer and T.J.Langford,Phys.Rev.Lett.114,012502(2015)
47 N.Haag et al.,Phys.Rev.Lett.112,122501(2014)
48 V.Kopeikin,L.Mikaelyan,and V.Sinev,Phys.Atom.Nucl.67,1892(2004)
49 X.B.Ma et al.,Phys.Rev.C88,014605(2013)
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51 F.P.An,X.C.Tian,L.Zhan,and J.Cao,Chin.Phys.C33,711(2009)
52 B.Zhou et al.,Chin.Phys.C36,1(2012)
53 P.Huber and P.Jaffke,Phys.Rev.Lett.116,122503(2016),ar Xiv:1510.08948[hep-ph]
54 J.Liu et al.,Nucl.Instrum.Meth.A750,19(2014),ar Xiv:1305.2248[physics.ins-det]
55 F.P.An et al.(Daya Bay Collaboration),Nucl.Instrum.Meth.A685,78(2012)
56 S.Agostinelli,et al.(GEANT4 Collaboration),Nucl.Instrum.Meth.A506,250(2003)
57 Gaudi,“The gaudi project,”http://proj-gaudi.web.cern.ch/proj-gaudi/
58 H.X.Huang et al.,JINST 8,P09013(2013)
59 W.Q.Gu,G.F.Cao,X.H.Chen,X.P.Ji,G.S.Li,J.J.Ling,J.Liu,X.Qian,and W.Wang,(2015),ar Xiv:1512.00295[physics.ins-det]
60 L.Groshev et al.,Nuclear Data Tables 5(1968)
61 ENDF,“Evaluated Nuclear Data File,”http://www.nndc.bnl.gov/endf/
62 C.Zhang,X.Qian,and P.Vogel,Phys.Rev.D87,073018(2013)
63 M.Apollonio et al.,Phys.Lett.B466,415(1999)
64 F.Boehm et al.,Phys.Rev.D64,112001(2001)
65 F.P.An et al.(Daya Bay Collaboration),Phys.Rev.Lett.112,061801(2014)
66 G.Dietze and H.Klein,Nucl.Instrum.Methods,193,549(1982)
67 A.A.Sonzogni,T.D.Johnson,and E.A.Mc Cutchan,Phys.Rev.C 91,011301(2015)
68 A.Hocker and V.Kartvelishvili,Nucl.Instrum.Methods,A372,469(1996)
69 V.Blobel,“Unfolding-Linear Inverse Problems,Notes for the Terrascale workshop at DESY May 2010,”
70 T.Adye,Proceedings of the PHYSTAT 2011 Workshop,CERN,Geneva,Switzerland,January 2011,CERN-2011-006,pp 313-318,313(2011),ar Xiv:1105.1160[physics.data-an]
71 G.D’Agostini,Nucl.Instrum.Meth.A362,487(1995)