Double Chooz Double Chooz A Reactor A Reactor θ θ13 13 Experiment Experiment M.Motoki M.Motoki Tohoku Univ. Tohoku Univ. On behalf of the Double Chooz Collaboration On behalf of the Double Chooz Collaboration • Reactor θ Reactor θ 13 13 measurement measurement • Description and Status of Description and Status of Double Chooz Double Chooz • Expected schedule and Expected schedule and sensitivities sensitivities • Summary Summary
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Double Chooz A Reactor θ 13 Experiment M.Motoki Tohoku Univ. On behalf of the Double Chooz Collaboration Reactor θ 13 measurementReactor θ
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Tohoku Univ.Tohoku Univ.On behalf of the Double Chooz CollaborationOn behalf of the Double Chooz Collaboration
• Reactor θReactor θ 13 13 measurementmeasurement• Description and Status of Double ChoozDescription and Status of Double Chooz• Expected schedule and sensitivitiesExpected schedule and sensitivities• Summary Summary
2
Reactor Neutrino Oscillations
P(ee) ~ 1
– cos413 sin2 212 sin2(m212 L/4E)
- sin2 213 sin2(m213 L/4E)
(Ignores tiny matter effect)
P
L/E(km/MeV)
m21 3 dominated
m212
dominated
L = E/(2.54 m2) ~ 1-2 km
KamLAND(180km)
3
Best current limitBest current limit is from CHOOZ is from CHOOZ
sinsin220.19 0.19
Only ran 199 daysOnly ran 199 daysTotal live time 341daysTotal live time 341days(Reactor off: 142days)(Reactor off: 142days)
Hep-ex/0301017
@CHOOZ: R = 1.01 2.8%(stat)2.7%(syst)
Double Chooz Experiment
Reactor Neutrino Oscillation
0
0.2
0.4
0.6
0.8
1
1.2
0.1 1 10 100 1000
L(km)
P(e
-->
e )
FarNear
P=8.4GWth
1.05km
0.4 or 0.31km
sin2(2θ13)=0.1
Collaboration
• Japan– Tohoku U.– Tokyo Metropolitan U.– Niigata U.– Tokyo Institute of Technology– Kobe U.– Tohoku Gakuin U.– Miyagi University of Education– Hiroshima Inst. of Technology
Delayed photons from n capture on dedicated nuclei (Gd)t ~ 30 s E ~ 8 MeV
111111 1026 WsPsNsN Fiss
P=8GWth N~1021s-1 on all solid angle
Gd doped scintillator
• Solvent: 20% PXE(phenyl-xylyl ethane)– 80% Dodecane• Gd loading: being developed @MPIK
• 0.1% Gd loading of Gd-BDK (Beta Diketonate)• Long term Stability promising• LY ~7000 ph/MeV: 6 g/l PPO + 50 mg/l Bis-MSB• Attenuation length: 5-10 m meters at 420 nm• Radiopurity U: 10-12 g/g - Th: 10-12 g/g - K: 10-9 g/g
UV
-VIS
-IR
sci
nti
llat
or
tran
smis
sio
n
- Heidelberg MPIK Transition to industrial production of 100 kg of Gd Summer 2007- On-site storage building available at Chooz Upgrade will be done in 2007
MPIK new building for storage and purification of scintillators
Gd(dpm)3
dipivaloymethane
Stable@20-40 for 2 years℃
PMT System
High performancelow background10" PMT (Oil proof)[Japan]
Magnetic ShieldSupport Structure[Spain]
(Option)LC(Light concentrator)[England]
390 10‘‘ PMTs at Buffer Vessel
(70 8‘‘ PMTs for Inner Muon Veto)
13 % coverage
Energy resolution goal: 7 % at 1 MeV
PMT configuration
a candidate
BackgroundsCHOOZ OFF data & Simulation ( represent CHOOZ results well)
Accidental BackgroundPrompt Signal: radio activity dominated by PMTs (Rate=Rp)Delayed Signal: Neutrons from cosmic spallation (Rate=Rd) ⇒ Accidental coincidence Rate = Rp x Rd x Δt
Correalated background(cosmic induced)
Fast Neutrons (recoil p and thermalized N) caputure Long-lived (9Li) -(N)decaying isotopes
Spallation fast
neutron
μ capture
Recoil p n capture on Gd
Gd
Gd
Recoil p n from capture
μμ
Nbkg = ~1.4 evts/day (Far) 2% of signal = ~10 evts/day (Near) 0.9% of signal
Ee
En
CHOOZ OFF data
Nbkg = ~1.6 evts/day (Far) 2.3% of signal = ~17 evts/day (Near) 1.7% of signal
Sensitivity
Double-Chooz Far Detector starts in 2008Double-Chooz Near detector follows 16 months later
90% C.L. contour if sin2(2)=0m2
atm = 2.8x10-3 eV2 is supposed to be known at 20% by MINOS
Far detector
only
Far & Near detectors
2009
sys=2.5%
sys=0.6%
2010
Double Chooz R&D's are in final stages & Detector Construction just started.
First data taking expected to start in 2008 with far detector only => sin2(213) < 0.06 in 1,5 year
In 2010 take data with both near and far
detectors => sin2(213) < 0.03 in 3 years
We will know or set a strong limit on the size of 13 within a few years & the neutrino oscillation studies will go in a new phase.