1. The Double Chooz reactor neutrino experiment
Thomas Mueller – CEA Saclay Irfu/SPhN
19 March 2009
Thomas Mueller - Workshop AAP09

2. Thomas Mueller - Workshop AAP09
Overview
Neutrino oscillation
Theory & status
Neutrino reactor
The Double Chooz experiment
From Chooz to Double Chooz
Neutrino detection and detector design
Present status of the experiment
Errors & expected sensitivity
Summary & conclusion
19 March 2009
Thomas Mueller - Workshop AAP09

3. Neutrino oscillations
Super-Kamiokande (1998) → first evidence of neutrino oscillation, non-zero mass
Oscillations are described by a mixing of flavour and mass eigenstates through unitary PMNS matrix
6 parameters: 3 mixing angles, 2 mass differences & 1 complex phase
Atmospheric ν
CHOOZ experiment
Solar ν
19 March 2009
Thomas Mueller - Workshop AAP09

4. Current knowledge on neutrino mixing parameters
T. Schwetz et al.
NewJ.Phys.10:113011,2008
Experimental measurements
Best global limit on θ13
Global (90% CL)
sin2θ13 < 0.035
G.L. Fogli et al.
Phys.Rev.Lett.101:141801,2008
Hints for θ13 > 0
sin2θ13 = ± (1σ)
19 March 2009
Thomas Mueller - Workshop AAP09

5. Reactor neutrino oscillations
DC near detector
DC far detector
Nucifer
Chooz
KamLAND
19 March 2009
Thomas Mueller - Workshop AAP09

6. From Chooz (1997-1998) to Double Chooz
Neutrino disappearance experiment
5 m3 of Gd-doped liquid scintillator
L = 1.05 km
Highest systematic uncertainty → antineutrino flux emitted by reactor
Double Chooz: from absolute to relative measurement
R = 1.01 ± 2.8% (stat) ± 2.7% (syst)
sin22θ13 < Δm312= eV2 (90% CL)
19 March 2009
Thomas Mueller - Workshop AAP09

7. The Double Chooz collaboration
Spokesman: Hervé de Kerret (APC)
France: APC Paris, CEA/Irfu Saclay, Subatech Nantes, Strasbourg
Japan: HIT, Kobe, MUE, Niigata, TGU, TIT, TMU, Tohoku
Germany: Aachen, MPIK Heidelberg, TU München, EKU Tübingen, Hamburg
Russia: RAS, RRC Kurchatov Institute
USA: Alabama, ANL, Chicago, Columbia, Drexel, Illinois, Kansas, LLNL, LSU, Notre Dame, Sandia, Tennesses, UCD
Spain: CIEMAT Madrid
UK: Univ. Sussex
Brazil: CBPF, UNICAMP
Collaboration Chooz (June 2008)
19 March 2009
Thomas Mueller - Workshop AAP09

8. The Double Chooz experiment
2 « identical » detectors
Far detector (1050m) ν oscillation
300 m.w.e.
Near detector (400m) Flux normalization 115 m.w.e.
Phase I
( )
Far detector only
Phase II
(2011…)
2 detectors near and far
2 PWR-N4
2 x 4.27 GW
~ 1021 ν/s
Chooz B nuclear power plant
Ardennes, France
19 March 2009
Thomas Mueller - Workshop AAP09

9. Antineutrinos detection
Inverse β decay:
Clear signature of an antineutrino reaction in the detector → powerful background suppression
Prompt signal:
photons from e+e- annihilation
Delayed signal:
photons from n capture on Gd
Δt ~ 30 µs, E ~ 8 MeV
19 March 2009
Thomas Mueller - Workshop AAP09

10. Thomas Mueller - Workshop AAP09
Detector design
Acrylic target vessel
10.3 m3 Gd-doped LS
Acrylic γ-catcher vessel
22.6 m3 LS
Stainless steel Buffer
110 m3 mineral oil ~ 400 PMT
Inner veto
90 m3 LS ~ 80 PMT
Shielding
15 cm steel
Outer veto
plastic scintillator panels
Calibration glove-box
(εdet ~ 80%)
19 March 2009
Thomas Mueller - Workshop AAP09

11. Far lab integration (1/2)
June 08: Start of the work
Sept 08: Shielding installation
Nov 08: IV integration
Dec 08 - Jan 09: Lab cleaning
19 March 2009
Thomas Mueller - Workshop AAP09

12. Far lab integration (2/2)
Feb 09: IV cleaning…
… ISO6 class tent mounting…
… and IV PMTs installation
Presently: Buffer installation
First neutrino planned for end 2009
19 March 2009
Thomas Mueller - Workshop AAP09

13. Thomas Mueller - Workshop AAP09
Near lab preparation
Site engineering study complete
Tender process for construction soon
Schedule: lab is finished in 2010
19 March 2009
Thomas Mueller - Workshop AAP09

14. Statistical & systematic errors
CHOOZ: R = 1.01 ± 2.8% (stat) ± 2.7% (syst)
CHOOZ
Double Chooz
Target volume
5.55 m3
10.3 m3
Target composition
H/m3
H/m3
Data taking period
few months
3-5 years
Event rate
2700
FD 40000/3y - ND 106/3y
Statistical error
2.8%
0.5%
Statistical error
Systematic error
Two identical detectors σsys=0.6%
19 March 2009
Thomas Mueller - Workshop AAP09

15. Expected θ13 sensitivity
CHOOZ limit is reached in 1 month!
Phase I
Phase II
σsys=2.5%
σsys=0.6%
sin22θ13 < 0.03
sin22θ13 < 0.06
19 March 2009
Thomas Mueller - Workshop AAP09

16. Summary and conclusions
First new generation neutrino experiment using two identical detectors at different distances to measure θ13
Far detector installation in progress → first neutrino end 2009
Far detector only:
sin22θ13 < 0.06 in 1.5 years (90% CL) if no oscillation
Far and near detectors:
sin22θ13 < 0.03 in 3 years (90% CL) if no oscillation
19 March 2009
Thomas Mueller - Workshop AAP09