Double-Chooz Neutrino
Experiment
Carmen Palomares
Ciemat (Spain)
For Double-Chooz Collaboration

Neutrino Oscillation
From ν µ → ν τ From nuclear
Atmospheric νµ reactor experiments0ν e   1  ν µ  =  0 c23
ν   0 − s23 τ 
where0  c13
s23  0c23  − s13e −iδFrom ν e → ν xSolar νe0 s13e −iδ  c12
10  − s120c13  0s12
c1200  ν 1  0 ν 2 1 ν 3 sij = sin θ ij cij = cos θ ij3 mixing angles
1 complex phase
2 mass differences

Vulcano08
30 MayC. Palomares
Double Chooz Neutrino Experiment2Current knowledge
SK+K2K+MINOS

Solar+KamLAND

θ 23 = 43.3+−43..38

θ12 = 33.7 ±1.3227∆m132 = 2.6 ± 0.2 ×10 −3 eV 2 ∆m12
@1σ arXiv:0704.1800= 7.9+−00..28×10−5 eV 2 @1σCHOOZ
experiment

Limit at 90% CL:(CHOOZ+atm+LBL+solar+KamLAND)

sin22θ13<0.11
arXiv:0710.5027
1km

M. Apollonio et. al., Eur.Phys.J. C27 (2003) 331-374

Vulcano08
30 MayThe main goal ofupcoming
experiments is thedetermination of θ13
C. Palomares
Double Chooz Neutrino Experiment3

Θ13 at nuclear reactors
experiments
ν e disappearance searchesP(ν e → ν e ) Independent of δ-CP, weak dependence on ∆m12

Matter effects negligible due to the small distances and the ν energy O(MeV) Unambiguous measurement ofΘ13 complementary to beams
 The only limitation comes fromstatistical and systematic errors
 These experiments must be carriedout on a short time scale toprovide an input for future beams

Vulcano0830 May

C. Palomares
Double Chooz Neutrino Experiment4

Neutrino detection at nuclear
reactor experiments
Detection by inverse β-decay

ν e + p → e+ + n

Signature Delayed coincidence of:Prompt e+ annihilation Ee+ = Eν-(Mn-Mp)
Photons from n capture on H Eγ= 2 MeV
on dedicated nuclei (Gd) Eγ = 8 MeV
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30 MayC. Palomares
Double Chooz Neutrino Experiment5

Backgrounds
Accidental:
 e+-like signal: radioactivity frommaterials and surrounding rock.
 n signal: n from cosmic µspallation, thermalized andcaptured on Gd.
Or another radioactivity event
Correlated: fast n (by cosmic µ) recoil on p(low energy) and captured onGd long-lived (9Li, 8He) β-decaying
isotopes induced by µ
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Double Chooz Neutrino Experiment

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Double Chooz Concept
To look for non-zero values of Θ13
Beyond the previous systematic limitations:
1. Two detectors to reduce uncertainties to the reactor flux
2. Identical detectors to reduce errors due to detector acceptance

NeardetectorνννVulcano08
30 MayνFarDetector

C. Palomares
Double Chooz Neutrino Experiment7Improving CHOOZ
CHOOZ: R=Nmeas/Nexp = 1.01 ± 2.8% (stat) ± 2.7% (sys)Statistical error
CHOOZ

Double Chooz

Target volume

5.55 m3

10.3 m3

Data taking period

Few months

3-5 years

Event rate

2700

Chooz-far 40000/3y
Chooz-near > 1 106/3y

Statistical error

2.8%

0.5%

Systematic errors
CHOOZ

Double Chooz

Reactor uncertainties

2.1%----

Number of protons

0.8%

0.2%

Detector Efficiency

1.5%

0.5%Vulcano08
30 May Improve detector design and knowledge
 Large S/B detector design (shielding andradiopurity materials) and increasing
overburden

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Double Chooz Neutrino Experiment8

The Double Chooz
Collaboration
Spokesman: Hervé de Kerret (APC)France: APC Paris, CEA/Dapnia Saclay,
Subatech Nantes, Strasburg

Germany: Aachen, MPIK Heidelberg, TU
München, EKU Tübingen, Hamburg



Spain: CIEMAT Madrid

UK: Sussex

Vulcano08
30 MayJapan: HIT, Kobe, MUE, Niigata, TGU, TIT,TMU, TohokuRussia: RAS, RRC Kurchatov InstituteUSA: Alabama, ANL, Chicago, Columbia,Drexel, Illinois, Kansas, LLNL, LSU, Notre
Dame, Sandia, Tennessee, UCD
Brazil: CBPF, UNICAMP

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Double Chooz Neutrino Experiment9

The Chooz site:
Near lab
400 m
115 m.w.e.

Far lab1050 m
300 m.w.e.

Chooz-B reactors
8.4 GWth
Placed in the Ardennes(France)Vulcano08
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Double Chooz Neutrino Experiment

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The Detector(s)Outer muon Veto
Scintillator panels

Target: 10.3m3 Gd doped LS(Acrylic) R=1.15m
H=2.47m
th=8mmγ-Catcher: 22.6m3 LS(Acrylic) R=1.70m
H=3.55m
th=12mm

InnerVeto: 80m3 LS

Buffer: 114.2m3 mineral oil(Steel) 78 8” PMTs
R=3.27m
H=7 m
th=10mm(Stainless Steel) 390 10” PMTs
R=2.76m
H=5.67m
th=3mmShielding
15cm Steel

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Double Chooz Neutrino Experiment11

Current Status Current Activity: Far Detector Construction

and Integration
Civil engineering work completed.
Pit refurbished and access adapted.

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30 MayC. Palomares
Double Chooz Neutrino Experiment

Near detector:
 Location defined Preliminary study completed
 Lab ready end of 200912

Current Status
Liquid Scintillator
 Delivery Gd-complex completed
 PXE arrived in MPIK (Heidelberg)
tests and purification going on
 Scintillator hall ready, filling up withequipment

Vulcano08
30 MayVessels and mechanicalcomponents:
 Design approved The fabrication is on-going

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Double Chooz Neutrino Experiment13

Current Status
PMT 10” Hamamatsu R7081
PMT geometry baseline
390 PMTs/detector

Vulcano08
30 MayFirst 100 PMT batch delivered.
Test benches ready

PMT mechanical support& magnetic shield

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Double Chooz Neutrino Experiment14

Schedule Far detector assembly2008─Summer 2009
 Far detector commissioning
Summer 2009
 Near detector civil work complete
End 2009
 Near detector assembly2010 Near detector start
Beginning 2011

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Double Chooz Neutrino Experiment15

Expected Sensitivity
σsys=2.5%

Current limit @90%CL
sin22θ13<0.11

sin22θ13

Limit from Far Chooz (~2010)
sin22θ13<0.06
Limit from Double Chooz (~2012)
sin22θ13<0.035Far detector
alone

Vulcano08
30 MayBothdetectors

C. Palomares
Double Chooz Neutrino Experimentσsys=0.6%

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Summary

Double Chooz will be the first of a new generation ofneutrino experiments using identical detectors at
different distances from a reactor to measure Θ13

We will measure or set a strong limit in Θ13 within afew years

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Double Chooz Neutrino Experiment17

BackupNeutrino oscillations:present status

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30 MayC. Palomares
Double Chooz Neutrino Experiment19Θ13 Determination
sin22θ13—δ plane for the true values sin22θ13=0.1 and δ=90°
arXiv:0710.5027

Reactor experiment determines
sin22θ13 unambiguosly

Super beams

90% CL3σ♦▲
Vulcano08
30 MayBest fit normal hierarchy
Best fit inverted hierarchy

Combination:
 A relative good determination of θ13
 Some information on δ (corrupted by theambiguity in the mass hierarchy)
 CP violation cannot be established

C. Palomares
Double Chooz Neutrino Experiment20Θ13 Determination
Evolution of the 3σ discovery potentialof a non-zero value of θ13of upcoming
experiments

Vulcano08
30 MayLowest true value for which sin22θ13= 0
excluded at ≥3σ

C. Palomares
Double Chooz Neutrino Experiment21

Reactor experiments
proposals
Double Chooz
Daya BayReno

Angra

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30 MayC. Palomares
Double Chooz Neutrino Experiment22

Reactor experiments
proposals

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30 MayC. Palomares
Double Chooz Neutrino Experiment23

Double-Chooz:
Systematic errors

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30 MayC. Palomares
Double Chooz Neutrino Experiment24