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Double-CH1313Z:
A search for 13
Thierry Lasserre (CEA/Saclay)On behalf the Double-Chooz collaboration
NuFact04, Osaka, JapanJuly 28th 2004
T. L. (Saclay) - NuFact04 -
Letter of Intent
T. L. (Saclay) - NuFact04 -
CHOOZ site &
Detector Overview
T. L. (Saclay) - NuFact04 -
Near site: D~100-200 m, overburden 50-80 mweFar site: D~1.1 km, overburden 300 mwe
Type PWR
Cores 2
Power 8.4 GWth
Couplage 1996/1997
(%, in to 2000) 66, 57
Constructeur Framatome
Opérateur EDF
Chooz-Far
Chooz-Near
Double-Chooz, Ardennes, France
T. L. (Saclay) - NuFact04 -
The CHOOZ-far site
September 2003
T. L. (Saclay) - NuFact04 -
The CHOOZ-far detector
CHOOZ existing pit
Non scintillating buffer: scintillator+quencher(r+0.95m, , V=100 m3)
-catcher: 80% dodecane + 20% PXE (acrylic, r+0,6m – V= 28,1 m3)
7 m
7 m
PMT supporting structure
Muon VETO: scintillating oil (r+0.6 m – V=110 m3)
7 m
Shielding: 0,15m steel
target: 80% dodecane + 20% PXE + 0.1% Gd (acrylic, r=1,2m, h = 2,8m, 12,7 m3)
T. L. (Saclay) - NuFact04 -
Full detector simulation
~500 PMTs/detector
T. L. (Saclay) - NuFact04 -
The CHOOZ-near site
250 m
125 m
Near detector @100-200 m from the coresExact position under study, in collaboration with EDF
T. L. (Saclay) - NuFact04 -
The CHOOZ-near laboratory
@DAPNIA
Distance Reactor-detector
Required overburden (m.w.e)
100 45-53
150 55-65
200 67,5-80
~10m
60 m.w.e. overburden•12 m compacted earth•3 meter high density material
5m
15m
T. L. (Saclay) - NuFact04 -
How to improve Chooz:statistics & systematics
T. L. (Saclay) - NuFact04 -
Improving CHOOZ – Statistical error -
Luminosity increase L = t x P(GW) x Vtarget
@CHOOZ: R = 1.01 2.8%(stat)2.7%(syst)
CHOOZ Double-Chooz
Target volume 5,55 m3 12,67 m3
Target composition 6,77 1028 H/m3 6,82 1028 H/m3
Data taking period Few months 3-5 years
Event rate 2700CHOOZ-far : 60 000/3 yCHOOZ-near: >3 106/3 y
Statistical error 2,7% 0,4%
T. L. (Saclay) - NuFact04 -
Decreasing systematical error
1. Improve the detector concept2. Two identical detectors towards σrelative~0,6%3. Backgrounds – improve S/B>100 error<1%
Improving CHOOZ – Systematical error -
@CHOOZ : σsys=2.7%
T. L. (Saclay) - NuFact04 -
Reactor induced systematics
systematics Error type CHOOZFuture
Experiment
2 identical detectorLow background
Reactor
Flux, cross section 1.9% - O(0.1%)
Thermal power 0.7% - O(0.1%)
E/Fission 0.6% - O(0.1%)
2.1% - O(0.1%)
2 detectors cancellation of the reactor physical uncertainties
T. L. (Saclay) - NuFact04 -
Relative Normalisation: Detector
Solid angle- Distance measured @10cm + Monitoring of the source
barycenter …
Target volume- @CHOOZ : 0.3% [simple measurement]- Goal ~0.2% [same apparatus for both detectors] - Not trivial
…
Density- 0.1% achievable, but accurate temperature control mandatory
H/C ratio & Gd concentration- Absolute measurement is difficult : 1% error @CHOOZ- Plan: use the same batch to fill both detectors
Boundary effect at the inner vessel interface (spill in/out)
- Neutron transport slightly different due to solid angle effect- MC study to be done to check that it is negligible
Live time to be measured accurately by several methods
T. L. (Saclay) - NuFact04 -
Detector induced systematics
systematics Error type CHOOZFuture
Experiment
Sim.Monte-Carlo
2 identical detectorLow backgrounds
Detector
Scintillator density 0.3% 0.3% O(0.1%)
% H 1.2% 1.2% O(0.1%)
Target volume 0.3% 0.2% 0.2%
« Spill in/out » effect 1.0% 1.0% X O(0.1%)
Live time ? 0.25% 0.25%
M. Apollonio et. al., Eur.Phys.J. C27 (2003) 331-374
A single scintillator batch will be prepared to fill both detectors with the same apparatus
T. L. (Saclay) - NuFact04 -
Relative Normalisation: Analysis
@CHOOZ: 1.5% systematic error - 7 analysis cuts- Efficiency ~70%
Sélection cuts - positron energy [energy threshold]
- e+ position/géode (30cm) [position reconstruction] - neutron energy [energy cut - calibration] - n pos./géode (30 cm) [position reconstruction] - distance e+ - n [position reconstruction] - t e+ - n [neutron capture on Gd] - n multiplicity [level of accidental bkg]
Goal Double-CHOOZ: <0.5% systematic error - 2 to 3 analysis cut
Sélection cuts - neutron energy
(- distance e+ - n ) [level of accidentals] - t e+ - n
e+
n
t
e+
T. L. (Saclay) - NuFact04 -
Systematics uncertainties
T. L. (Saclay) - NuFact04 -
Backgrounds
T. L. (Saclay) - NuFact04 -
- CHOOZ: N/S ~ 4%
- Double-CHOOZ-Far (300 mwe): 12.7 tons Signal x 3
-Modification of the detector design + expensive
-Uncorrelated: N/S(chooz) ~ 4% : Double-Chooz: Sx3 & N/3 < 0.5%
-Correlated events: N/S < 1%CHOOZ : ~<1 recoil proton per day Double-CHOOZ: liquid active buffer +30cm ~0.3 events per day
- Double-CHOOZ-near (50 mwe): Signal x 50-100 S(CHOOZ-Far)
-Key advantage: Dnear ~ 100-200m Signal x 50-100 !
-Uncorrelated: CHOOZ-Far backgrounds x 50 N/S < 1%
-Correlated events: CHOOZ-Far x <30 N/S < 1%
(but not a comprehensive list of backgrounds …)
Backgrounds Estimates
T. L. (Saclay) - NuFact04 -
Neutron Induced Background
Surrounded by 100 mwe rock shielding
Cosmic muons create fast neutrons through spallation and muon capture in the rock surrounding the detector
Fast neutron slowns down by scattering into the scintillator; it could deposit between 1-8 MeV and be later captured on Gd !
Full simulation – Geant + Fluka
Old Chooz simulation: 300 m.w.e. 31hours – MC is reliable !
• Simulated: Nb<1.6 evts/day (90% C.L.)• Measured in-situ: Nb=1.1 evts/day
Double-Chooz simulation:• 338 106 tracked – 580 103 neutrons tracked• 1 neutron created a muon event• Far detector: Nb<0.5 evt/day (90% C.L.)• Near detector: Nb<3.2 evts/day (90%C.L.)
T. L. (Saclay) - NuFact04 -
Overview of Scintillator developement
& Acrylic vessel design
T. L. (Saclay) - NuFact04 -
Gd-Acac
3+Gd
Goal: 0.1% Gd loaded scintillator (follow up of LENS R&D)
Light yield ~8000 /MeV + attenuation length > 5m STABLE & Compatible with acrylic
Gd doped scintillator development
3+Gd(R-C
OO
H)
x R
-CO
O-
R-COO- -O
OC-R
Carboxylate
Ongoing: 1/ Long term stability 2004 2/ scintillator-acrylic compatibility
~80 days Ageing test @40-50o [x2-4 each 100] Material compatibility test + acrylic design
70
75
80
85
90
95
100
105
300 350 400 450 500 550 600l [nm]
T [
%]
Gd(2MVA)3 inPC(35%)+Dod(65%)[2MVA]=0.05M [Gd]=2g/ laf ter 1 month
af ter T-test (6 days @ 40°C)
af ter T-test (14 days@40°C)
af ter T-test (20 days @50°C)
T. L. (Saclay) - NuFact04 -
Scintillator liquid baselineVolume
[m3]Type
-target 12,7 0,1% Gd loaded scintillator
-Catcher 28,1 Unloaded scintillator
Buffer 100 Non scintillating oil
Veto 110 Scintillating oil
Reference recipe- PC (C9H12), PXE (C16H18) attack acrylics- Dodécane + PXE more resistant …- R&D Saclay+MPIK+Gran Sasso (08/2004)Baseline: 80% dodecane + 20% PXE + 6 g/l PPO + 20 mg/l BisMSB + 0.1% Gd
LY~8000 /MeV , L = 5-10 m
Fluors concentration- Match scintillation light to PMTs - PPO : 6g/l- BisMSB: 20mg/l
Vtot = 250 m3 (200 tons)
T. L. (Saclay) - NuFact04 -
Acrylic vessels
4m
2m
2.4m
3.6m
2.8m
Gamma catcher Target
Final assembly on Chooz’s site Assembly at the manufacturer
Target
Gamma catcher
•Empty weight:– Target = 220kg– Gamma catcher = 470kg
Maximum stress: 12 MPa
Thickness: 6 mm
T. L. (Saclay) - NuFact04 -
Sensitivity &
Discovery Potential
T. L. (Saclay) - NuFact04 -
Spectrum deformation @Double-CHOOZ
sin2(213)=0.15
T. L. (Saclay) - NuFact04 -
90% C.L. sensitivity if sin2(213)=0
m2=2.4 10-3 eV2
3 years (efficiency included) sin2(213)<0.024
T. L. (Saclay) - NuFact04 -
Attempt to compare Double-Chooz with Beams & Superbrams
Th. Lasserre
P. Huber et. al. hep/0403068
Double-CHOOZ starts with two detectors in January 2008T2K starts at FULL intensity in January 2010
m2=2.0 10-3 eV2
T. L. (Saclay) - NuFact04 -
Attempt to compare Double-Chooz with T2K (3σ discovery potential)
sin22θ13 = 0.14 sin22θ13 = 0.08 sin22θ13 = 0.04
T. L. (Saclay) - NuFact04 -
Double-Chooz & IAEA IAEA :Intenational Agency for Atomic Energy
Missions: Safety & Security, Science & Technology, Safeguard & Verification Control that member states do no use civil installations with military goals (production of plutonium !)
•Control of the nuclear fuel in the whole fuel cycle *•Fuel assemblies, rods, containers * (*Anti-neutrinos could play a role!)•Distant & unexpected controls of the nuclear installations *
Why IAEA is interested to antineutrino ? •IAEA wants the « state of the art »methods for the future !•Cost issue … 10,000$/day/inspector …
AIEA wants a feasibility study on antineutrinos•Monitoring of the reactors with a Double-Chooz like detector ?•Monitoring a country – new reactors “à la KamLAND”
Double-CHOOZ-IAEA: CEA/Saclay + Subatech Nantes + Kurchatov
•Perform new antineutrino spectrum @ILL reactor (Mini-Inca + -spectrometer)•Use Double-Chooz near as a ‘prototype’ for nuclear reactor monitoring•Other studies like large and very large underwater antineutrino detectors …
Mini-Inca
T. L. (Saclay) - NuFact04 -
Strong Support for the EDF power company & local authorities to perform a 2nd
experiment at Chooz (castle available again for physicists !!!)Double-CHOOZ sensitivity: sin2(213)<0.025-0.03, 90% C.L. (m2 = 2.0-2.5 10-3 eV2)Current limit: CHOOZ : sin2(213)<0.2 discovery potential !
Technology / design well known (CHOOZ, BOREXINO, KamLAND, …) few R&D needed : Gd loading (stability) + material compatibility (Started, to be completed in half a year)
Collaboration: Saclay, APC, Subatech, TUM, MPIK, Tubingen Univ. Hamburg Univ., Kurchatov, Univ. Alabama, Univ. Tennessee, Univ. Lousiana, Univ. Drexel, Argonne, + Italian groups soon … (maxi-)letter of intent (May 2004) final proposal end of 2004
Approved in France. Detector cost ~7 Million euros (Civil engineering cost not included)
Our Goal @Double- CHOOZ: Construction starts end of 2005 Start data taking in 2007 (far) & 2008 (near +
far)
Summary & outlook
2003 2004 2005 2006 2007 2008 2009Site Data takingProp. Construction ?design
in 2009: sin2(213) < 0.05
in 2011sin2(213) < 0.025
Far detector starts Near detector starts