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Measurement of reactor antineutrino disappearance driven by 13

Steve KettellBrookhaven National LabNuFact 2013, IHEP, Beijing

New results from all 3 this year

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Chooz, France RENO, Korea

Daya Bay, China

Reactor Neutrinos

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Neutrino MixingUMNSP MatrixMaki, Nakagawa, Sakata, Pontecorvo

U Ue1 Ue2 Ue3

U1 U2 U 3

U1 U 2 U 3

0.8 0.5 Ue3

0.4 0.6 0.7

0.4 0.6 0.7

1 0 0

0 cos23 sin23

0 sin23 cos23

cos13 0 e iCP sin13

0 1 0

e iCP sin13 0 cos13

cos12 sin12 0

sin12 cos12 0

0 0 1

1 0 0

0 e i / 2 0

0 0 e i / 2i

Super-K, MINOS, T2K, NOvA

SNO, Super-K, KamLAND

12 ~ 34° 23 = ~ 45° 13 = 9

Daya Bay, Double Chooz, RENOMINOS,T2K, NOvA

νe = cosθ13 (cosθ12 ν1 + sinθ12 ν2) +e-iδ sinθ13 ν3

νe 0.82 ν1 + 0.55 ν2 - 0.16 ν3

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Neutrino Mass

• Neutrinos have mass • one small mass

difference (solar) • one large mass

difference (atmospheric)

Δm2sol=m2

2-m127.5x10-5eV2

Δm2atm~=|m3

2-m12|2.4x10-3eV2

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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: 61020 e/s/3GWth

• We detect antineutrinos via the inverse beta decay (IBD) reaction• Ee+ E - 0.8 MeV

Expected Signal

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Measuring 13 with reactor neutrinos

Pee 1 sin2 213 sin2 m312L

4E

cos4 13 sin2 212 sin2 m21

2L

4E

• 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

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ExperimentPower(GWth

)

Detector(t)

Near/Far

Overburden (m.w.e.) Near/Far

Sensitivity Goal (3-

yr)(90%CL)

Daya Bay 17.4 80/80 250/860 ~ 0.008

Double Chooz 8.5 8/8 120/300 ~ 0.03

RENO 16.5 16/16 120/450 ~ 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 GWth

6 antineutrino detectors in 3 halls 8 since Oct 2012

320 t + 320 t

The RENO ExperimentThe RENO Experiment

Far Detector

Near Detector

1380m

290m

6 2.7 16.7 GWth16 ton,

120 m.w.e.

16 ton,450 m.w.e.

Double Chooz

Mid-2014

Antineutrino Detectors

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‘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.

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MO

Automated Calibration System

R=0R=1.7725 m R=1.35m Top view

3 sources in each ACU including:• 10 Hz 68Ge (0 KE e+ = 20.511 MeV ’s)• 0.5 Hz 241Am-13C neutron source (3.5 MeV n without )

+ 100 Hz 60Co gamma source (1.173+1.332 MeV )• LED diffuser ball (500 Hz) for time calibration

Temporary special calibration sources: : 137Cs (0.662 MeV), 54Mn (0.835 MeV), 40K (1.461 MeV) n: 241Am-9Be, 239Pu-13C

Three axes: center, edge of target, middle of gamma catcher

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3 Automatic calibration units (ACUs) on each detector

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Muon Tagging System

• 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

Antineutrino(IBD) event selection

Fast neutronsnp→dγ

Signalwindow

Delayed

Prompt

No additional prompt-like 400us before delayed and no delayed-like 200us after

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“Identical” Antineutrino Detectors

Neutron Capture Time

Prompt Spectra

Expected ratio is 0.981 due to reactor core distance.

Gadolinium concentration is “identical” for the two detectors

IBD

near

far

RENO StatusRENO Status

Data taking began on Aug. 1, 2011 with both near and far detectors.

(DAQ efficiency : ~95%)

A (220 days) : First q13 result [11 Aug, 2011~26 Mar, 2012] PRL 108, 191802 (2012)

C (~700 days) : Shape+rate analysis (in progress) [11 Aug, 2011~31 Jul, 2013]

B (403 days) : Improved q13 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 ResultsRENO Results

RENO obtained the first result in April 2, 2012.

)(019.0)(013.0113.02sin 132 syststat

RENO has continued data-taking & data-analysis in a steady state, and reported a new result in March, 2013.

)(015.0)(010.0100.02sin 132 syststat

)(009.0)(006.0929.0exp

syststatRFarected

Farobserved

A clear deficit in rate (7.1% reduction)

Consistent with neutrino oscillation in the spectral distortion

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Double Chooz

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Double Chooz

New rate analysis withreactor rate modulationsin2213 = 0.097 0.035

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Double Chooz

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A. Two AD Comparison: arXiv:1202:6181 - Sep. 23, 2011 – Dec. 23, 2011 NIM A685:78 - Side-by-side comparison of 2 detectors B. First Oscillation result: arXiv:1203:1669 - Dec. 24, 2011 – Feb. 17, 2012 (6 ADs)- 1st observation of νe dis. PRL108:171803

C. Improved Result: arXiv:1210:6327 - Dec. 24, 2011 – May 11, 2012 - 2.5x original data, CPC37:011001 D.New analysis - Dec. 24, 2011 – July 28, 2012 - 4x original data; shape, m2

ee analysis

E. Full experiment (8 AD)- Oct. 19, 2012 – present

A

B

C

D

Data Overview

Results described in this talkFor details see Soeren Jetter in Friday 12:10 WG-1 Jiajie Ling talk at BNL http://www.phy.bnl.gov/~partsem/fy13/BNL_Ling_dayabay.pdf

E

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Data Summary

Over 300,000 antineutrino eventsConsistent rates for side-by-side detectors

Uncertainty dominated by statistics

EH-1 EH-2 EH-3

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Backgrounds

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Constrain fast-n rate usingIBD-like signals in 10-50 MeV

Near Halls Far Hall

B/S %

σB/S

%B/S%

σB/S

%

Accidentals 1.5 0.01 4.0 0.04

Fast neutrons 0.1 0.07 0.06 0.039Li/8He 0.4 0.1 0.3 0.08241Am-13C 0.04 0.02 0.36 0.1613C(α, n)16O 0.01 0.01 0.05 0.03

Total backgrounds are 5% (2%) in far (near) halls.

Background uncertainties are 0.3% (0.2%) in far (near) halls.

Simulated Am-Csource neutroncapture position

Estimate 9Li rate usingtime-correlation with muon

Hot AmC sourcedeployment

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Uncertainty Summary

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

Absolute Relative

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Antineutrino Rate vs. Time

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 reactorflux expectations.

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Shape and mass splitting

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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. 108:171803 (2012) 615 citations (~1.5 per day) sin22θ13=0.092±0.016(stat)±0.005(syst)

Updated result (55139 days) June 6, 2012 Chinese Physics C37:011001 (2013) sin22θ13=0.089±0.010(stat)±0.005(syst)

6-AD (2-1-3) data (12/11-7/12) sin22θ13=0.090+0.008-0.009

Full 6-AD data analysis (217 days, shape & m232) |mee

2 |=2.59+0.19-0.2010-3

Final two ADs installed, calibration campaign completed 7-10/12 Taking data with all 8-AD since Oct 19, 2012

Future Plans

RENO’s Projected Sensitivity of q13 RENO’s Projected Sensitivity of q13

.)(015.0.)(010.0100.02sin 132 syststat

018.0100.0 (5.6 s)

(402 days) 007.0 (5 years)(~ 14 s)

(7 % precision)

2013. 3

3 years of data : ±0.007 (7% precision)

- statistical error : ±0.010 → ±0.006 - systematic error : ±0.015 → ±0.005

(7 % precision)

ssyst =0.015 Goals - sin22q13 to 7% precision - direct measurement of Dm2

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- precise measurement of reactor neutrino flux and spectrum

- study for reactor anomaly and sterile neutrinos

(18 % precision)

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Double Chooz plans

NuFact 8/22/13 32Projected uncertainty in sin22θ13<4%. Reduction in uncertainty will improve CP reach of LBNE.

Expect to achieve mee2 precision

better than 110-4 eV2 after 3 years.

Daya Bay Plans • Measure of 13 with high precision

• Measure mee2 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

8-AD run

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Daya Bay

n-H coming soonRENO

Double Chooz n-Gd

n-H

Summarysin22θ13=0.090+0.008

-0.009

|mee2|= (2.59+0.19

-0.20)10-3 eV2

sin22θ13=0.100±0.010(stat)±0.015(sys)

sin22θ13=0.109±0.030(stat)±0.025(sys)

sin22θ13=0.097±0.034(stat)±0.034(sys)

Accelerator experiments:— normal, — inverted, CP=0, 23=45Reactor 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

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Backup

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Daya Bay

Selected as one of Science’s top 10 breakthroughs of 2012. “…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.”

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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

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– 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 sin2213

– Improve ultimate precision on JCPν and allow tests of unitarity

Definitive sin22θ13 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 CP0,. 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.