1 Measurement of reactor antineutrino disappearance driven by  13 Steve Kettell Brookhaven National Lab NuFact 2013, IHEP, Beijing New results from all 3 this year

NuFact 8/22/132 Chooz, France RENO, Korea Daya Bay, China Reactor Neutrinos

NuFact 8/22/133 Neutrino Mixing U MNSP Matrix Maki, Nakagawa, Sakata, Pontecorvo Super-K, MINOS, T2K, NOvA SNO, Super-K, KamLAND  12 ~ 34°  23 = ~ 45°  13 = 9  Daya Bay, Double Chooz, RENO MINOS,T2K, NOvA ν e = cosθ 13 (cosθ 12 ν 1 + sinθ 12 ν 2 ) +e -iδ sinθ 13 ν 3 ν e  0.82 ν ν ν 3

4 Neutrino Mass Neutrinos have mass one small mass difference (solar) one large mass difference (atmospheric) Δm 2 sol= m 2 2 -m 1 2  7.5x10 -5 eV 2 Δm 2 atm ~=|m 3 2 -m 1 2 |  2.4x10 -3 eV 2 NuFact 8/22/13

5 Neutrinos from Nuclear Reactors Nuclear reactor fuel and subsequent fission fragments are neutron rich and decay by turning neutrons to protons and emitting antineutrinos. They produce a lot of antineutrinos: 6  e /s/3GW th We detect antineutrinos via the inverse beta decay (IBD) reaction E e+  E MeV NuFact 8/22/13 Expected Signal

6 Measuring  13 with reactor neutrinos NuFact 8/22/13 Measure relative rates in near and far detectors to remove reactor flux uncertainties Build functionally identical detectors to remove detector mass and efficiency uncertainties Measure distances accurately Measure detector mass accurately

NuFact 8/22/137 Experiment Power (GW th ) Detector(t) Near/Far Overburden (m.w.e.) Near/Far Sensitivity Goal (3-yr) (90%CL) Daya Bay17.480/80250/860~ Double Chooz 8.5 8/8120/300~ 0.03 RENO16.516/16120/450~ 0.02 Three active experiments

EH-1: Sep 23, 2011 EH-2: Nov 5, 2011 EH-3: Dec 24, 2011 Daya Bay 6  2.9 GW th 6 antineutrino detectors in 3 halls  8 since Oct  20 t + 3  20 t

The RENO Experiment Far Detector Near Detector 1380m 290m 6  GWth 16 ton, 120 m.w.e. 16 ton, 450 m.w.e.

Double Chooz Mid-2014

Antineutrino Detectors 11 ‘functionally identical’ detectors: Reduce systematic uncertainties 20t Gd-LS target 5m All detectors filled from common Gd-LS tanks. Target mass measured to 3 kg (0.015%) during filling. Reflectors improve light collection and uniformity. LS 192 8” PMTs: ~163 p.e./MeV. NuFact 8/22/13 MO

Automated Calibration System R=0 R= m R=1.35m Top view 3 sources in each ACU including: 10 Hz 68 Ge (0 KE e + = 2  MeV  ’s) 0.5 Hz 241 Am- 13 C neutron source (3.5 MeV n without  ) Hz 60 Co gamma source ( MeV  ) LED diffuser ball (500 Hz) for time calibration Temporary special calibration sources:  : 137 Cs (0.662 MeV), 54 Mn (0.835 MeV), 40 K (1.461 MeV) n: 241 Am- 9 Be, 239 Pu- 13 C Three axes: center, edge of target, middle of gamma catcher 12 3 Automatic calibration units (ACUs) on each detector

Muon Tagging System 13 Outer layer of water veto (sides and bottom) is 1m, inner layer >1.5m. Water extends 2.5m above ADs 288 8” PMTs per near hall 384 8” PMTs in Far Hall 4-layer RPC above pool 54 modules in near halls 81 modules in Far Hall Goal efficiency: > 99.5% with uncertainty <0.25% Dual tagging systems: 2.5 meter thick two-zone water shield and RPCs NuFact 8/22/13

Antineutrino (IBD) event selection Fast neutrons np→dγ Signal window Delayed Prompt No additional prompt-like 400us before delayed and no delayed-like 200us after

15 “ Identical” Antineutrino Detectors NuFact 8/22/13 Neutron Capture Time Prompt Spectra Expected ratio is due to reactor core distance. Gadolinium concentration is “identical” for the two detectors IBD near far

RENO Status  Data taking began on Aug. 1, 2011 with both near and far detectors. (DAQ efficiency : ~95%)  A (220 days) : First  13 result [11 Aug, 2011~26 Mar, 2012] PRL 108, (2012)  C (~700 days) : Shape+rate analysis (in progress) [11 Aug, 2011~31 Jul, 2013]  B (403 days) : Improved  13 result [11 Aug, 2011~13 Oct, 2012] NuTel 2013  Absolute reactor neutrino flux measurement in progress [reactor anomaly & sterile neutrinos] Near Far A B C

RENO Results  RENO obtained the first result in April 2,  RENO has continued data-taking & data-analysis in a steady state, and reported a new result in March,  A clear deficit in rate (7.1% reduction)  Consistent with neutrino oscillation in the spectral distortion

NuFact 8/22/1318 Double Chooz

NuFact 8/22/1319 Double Chooz New rate analysis with reactor rate modulation sin 2 2  13 =  0.035

NuFact 8/22/1320 Double Chooz

A.Two AD Comparison: arXiv:1202: Sep. 23, 2011 – Dec. 23, 2011 NIM A685:78 - Side-by-side comparison of 2 detectors B.First Oscillation result: arXiv:1203: Dec. 24, 2011 – Feb. 17, 2012 (6 ADs) - 1 st observation of ν e dis. PRL108 : B.Improved Result: arXiv:1210: Dec. 24, 2011 – May 11, x original data, CPC37: D.New analysis - Dec. 24, 2011 – July 28, x original data; shape,  m 2 ee analysis E.Full experiment (8 AD) - Oct. 19, 2012 – present A B C D Data Overview 21 Results described in this talk For details see Soeren Jetter in Friday 12:10 WG-1 Jiajie Ling talk at BNL NuFact 8/22/13 E

Data Summary 22 Over 300,000 antineutrino events Consistent rates for side-by-side detectors Uncertainty dominated by statistics EH-1 EH-2 EH-3 NuFact 8/22/13

Backgrounds 23 Constrain fast-n rate using IBD-like signals in MeV Near HallsFar Hall B/S % σ B/S % B/S % σ B/S % Accidentals Fast neutrons Li/ 8 He Am- 13 C C(α, n) 16 O Total backgrounds are 5% (2%) in far (near) halls. Background uncertainties are 0.3% (0.2%) in far (near) halls. Simulated Am-C source neutron capture position Estimate 9 Li rate using time-correlation with muon Hot AmC source deployment NuFact 8/22/13

Uncertainty Summary 24 NuFact 8/22/13 Influence of uncorrelated reactor systematics reduced by far vs. near measurement. AbsoluteRelative

Antineutrino Rate vs. Time 25 Predicted Rate: –Assume no oscillation –Absolute normalization is determined by data fit. –Normalization is within a few percent of expectations. Detected rate strongly correlated with reactor flux expectations. NuFact 8/22/13

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Shape and mass splitting 27NuFact 8/22/13

Daya Bay Status  Near Site Operations (6/11-12/11)  AD#1-2 comparison paper published  NIM A685:78 (2012)  First  13 : March 8, 2012 Discovery of reactor e disappearance at ~2 km  Phys.Rev.Lett. 108: (2012)  615 citations (~1.5 per day) sin 2 2θ 13 =0.092±0.016(stat)±0.005(syst)  Updated result (55  139 days) June 6, 2012  Chinese Physics C37: (2013) sin 2 2θ 13 =0.089±0.010(stat)±0.005(syst)  6-AD (2-1-3) data (12/11-7/12) sin 2 2θ 13 =  Full 6-AD data analysis (217 days, shape &  m 2 32 ) |  m ee 2 |=   Final two ADs installed, calibration campaign completed 7-10/12  Taking data with all 8-AD since Oct 19, NuFact 8/22/13

Future Plans

RENO’s Projected Sensitivity of  13 (5.6  ) (402 days) (5 years) (~ 14  ) (7 % precision)  3 years of data : ±0.007 (7% precision) - statistical error : ±0.010 → ± systematic error : ±0.015 → ±0.005 (7 % precision)  syst =0.015  Goals - sin 2 2  13 to 7% precision - direct measurement of  m precise measurement of reactor neutrino flux and spectrum - study for reactor anomaly and sterile neutrinos (18 % precision)

NuFact 8/22/1331 Double Chooz plans

Projected uncertainty in sin 2 2θ 13 <4%. Reduction in uncertainty will improve CP reach of LBNE. Expect to achieve  m ee 2 precision better than 1  eV 2 after 3 years. Daya Bay Plans Measure of  13 with high precision Measure  m ee 2 complementary to accelerator-based experiments. Further scientific goals: – Measure reactor flux/spectrum: possibly resolve ambiguities in reactor predictions and anomaly. – Multi-year measurement of reactor flux throughout fuel cycles. – Measure neutron and spallation production for various muon energies across DB depths. Run for at least 3 years (thru 2015) August 2012 NuFact 8/22/ AD run

Daya Bay n-H coming soon RENO Double Chooz n-Gd n-H Summary 33NuFact 8/22/13 sin 2 2θ 13 = |  m ee 2 |= ( )  eV 2 sin 2 2θ 13 =0.100±0.010(stat)±0.015(sys) sin 2 2θ 13 =0.109±0.030(stat)±0.025(sys) sin 2 2θ 13 =0.097±0.034(stat)±0.034(sys) Accelerator experiments: — normal, — inverted,  CP =0,  23 =45  Reactor experiments: rate only, rate+shape, n-Gd, n-H Electron neutrino contains 2 mass-splittings (3 mass states) and the large splitting agrees with that measured from muon neutrinos

34 Backup NuFact 8/22/13

35

Daya Bay Selected as one of Science’s top 10 breakthroughs of “…result suggests that in the coming decades neutrino physics will be every bit as rich as physicists had hoped…neutrino physics could be the future of particle physics — as the fact that neutrinos have mass is not even part of the standard model. If so, the Daya Bay result may mark the moment when the field took off.” 36NuFact 8/22/13

Experimental Halls complete 12/24/11 Hall 1 (Aug 11) Hall 3 (Dec 11) Daya Bay Ling Ao Ling Ao 2 810m 465 m 900m Hall 2 (Nov 11) Configuration until July 2012 NuFact 8/22/13 37

38 – Important measurement of a fundamental parameter Daya Bay will have the best measurement for the foreseeable future – Improve extraction of mass hierarchy and  CP from accel. expts. – Overconstrain PMNS matrix thru precision measurement of sin 2 2  13 – Improve ultimate precision on J CP ν and allow tests of unitarity Definitive sin 2 2θ 13 measurement Significance with which CP violation can be observed by NOvA+T2K+LBNE, as a function of the true value of  CP. Observation of CP violation is equivalent to the measurement  CP  0, . The significance is calculated by minimizing over both the normal and inverted hierarchies, as the mass hierarchy is not assumed to be known. The effects of external constraints on  13 from Daya Bay are shown. NuFact 8/22/13