Double-Chooz A search for 13 Guillaume MENTION (PCC-Collège de France/APC) On behalf of the...
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Transcript of Double-Chooz A search for 13 Guillaume MENTION (PCC-Collège de France/APC) On behalf of the...
Double-ChoozA search for 13
Guillaume MENTION (PCC-Collège de France/APC)
On behalf of the Double-Chooz collaboration
NOW 2004 Conca Specchiulla, Italy
September 14th 2004
G. Mention (PCC/APC) -NOW04-
In this presentation
1. Current 13 physical context
2. Chooz site and detector
3. Improving Chooz
4. Backgrounds
5. Detector design
6. Sensitivity and discovery potential
7. Safeguard applications
G. Mention (PCC/APC) -NOW04-
Best current constraint: Chooz
World best constraint !
@m2atm = 2 10-3 eV2
sin2(2θ13) < 0.2
(90% C.L)
e x
M. Apollonio et. al., Eur.Phys.J. C27 (2003) 331-374
e e (disappearance experiment)
Pth= 8.4 GWth, L = 1.050 km, M = 5 toverburden: 300 mwe
R = 1.01 2.8%(stat)2.7%(syst)
G. Mention (PCC/APC) -NOW04-
The Double-Chooz concept
8.4 GWth
Chooz power station Near detector Far detector
e e,,
anti-e flux (uranium 235, 238 & plutonium 239, 241) Reaction: e + p e+ + n, <E>~ 4 MeV, Ethreshold =1.8 MeV Disappearance experiment: search for a departure from the 1/D2
behavior and shape distortion
D1 = 100-200 m D2 = 1,050 m
Improve the detector concept and backgrounds rejection
improve Chooz sensitivity 0.03
G. Mention (PCC/APC) -NOW04-
Letter of Intent (hep-ex/0405032)
ANDDrexel, Argonne and Universities ofAlabama, Louisiana and Tennessee
G. Mention (PCC/APC) -NOW04-
Near site: D~100-200 m, overburden 50-80 mweFar site: D~1.1 km, overburden 300 mwe
2Cores
EDFOperator
FramatomeConstructor
66, 57(%, in 2000)
1996/1997Couplage
8.4 GWthPower
PWRType
Chooz-Far
Chooz-Near
Double-Chooz, Ardennes, France
G. Mention (PCC/APC) -NOW04-
Near laboratory outlines
@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
G. Mention (PCC/APC) -NOW04-
Detectors design
7 m
Shielding: 0,15 m steel
7 m
Muon VETO: scintillating oil (r+0.6 m – V = 110 m3)
Non-scintillating buffer: same liquid (+ quencher?)(r+0.95m, , V = 100 m3)
-catcher: 80% dodecane + 20% PXE (acrylic, r+0,6m – V = 28,1 m3)
PMTs supporting structure
target: 80% dodecane + 20% PXE + 0.1% Gd (acrylic, r = 1,2 m, h = 2,8 m, 12,7 m3)
n
ep
Gd
~ 8 MeV
511 keV
511 keVe+
G. Mention (PCC/APC) -NOW04-
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
Number of events 2700Chooz-far : 60 000/3 y
Chooz-near: > 3 106/3 y
Statistical error 2.7% 0.4%
G. Mention (PCC/APC) -NOW04-
Decreasing systematical error
1. Improve the detector concept
2. Two identical detectors towards σrelative~ 0.6%
3. Backgrounds – improve S/N>100 error < 1%
Improving Chooz – Systematical error –
@Chooz : σsys = 2.7%
G. Mention (PCC/APC) -NOW04-
Reactor induced systematics
systematics Error type Chooz
2 identical detector
Low 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
G. Mention (PCC/APC) -NOW04-
Detector induced systematics
systematics Error type Chooz
2 identical detector
Low backgrounds
Detector
Scintillator density 0.3% O(0.1%)
% H 1.2% O(0.1%)
Target volume 0.3% 0.2%
Boundary effects 1.0% O(0.1%)
Live time n.g. 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
G. Mention (PCC/APC) -NOW04-
Main works on systematic errors
Solid angle- Reactor cores to near detector distance to be measured @10 cm- Monitoring of the source barycenter…
Target volume- @Chooz : 0.3% [simple measurement]- Goal ~ 0.2% [same apparatus for both detectors] – feasible but not
trivial…
Live time to be measured accurately by several methods KamLAND : dead-time 10% and σsyst = 0.6%
Double-Chooz: dead-time(near) 25% and goal: σsyst ~ 0.25%
G. Mention (PCC/APC) -NOW04-
Relative Normalization: Analysis @Chooz: 1.5% syst. err.
- 7 analysis cuts- Efficiency ~70%
Goal Double-Chooz: ~0.3% syst. err. - 2 to 3 analysis cuts
Selection cuts - neutron energy
(- distance e+ - n ) [level of accidentals] - t (e+ - n)
e+
n
t
ne
p Gde+
G. Mention (PCC/APC) -NOW04-
Uncorrelated and correlated backgrounds
n
ep
Gd
~ 8 MeV
511 keV
511 keVe+
neutrino identification (signal)
n Gd
~ 8 MeV
n deposits energy
correlated background
accidental background (uncorrelated)
prompt signal + n capture on Gd
n
Gd
~ 8 MeV
+
E >~ 1 MeV
+-n cascades
G. Mention (PCC/APC) -NOW04-
- Chooz: N/S ~ 4%
- Double-Chooz-Far (300 mwe): 12.7 m3 Signal x 2.4
- Uncorrelated (, + n capt. on Gd):N/S(Chooz) ~ 4% : Double-Chooz: Sx3 & N/3 can be measured and
subtracted
- Correlated events (neutrons):Chooz : ~<1 recoil proton per day Double-Chooz: liquid active buffer +30 cm
~0.3 events per day N/S<1%
- Double-Chooz-near (50 mwe): Signal x 50-100 SFAR
- Key advantage: Dnear ~ 100-200 m Signal x 50-100 !
- Uncorrelated: Chooz-Far backgrounds x 50 can be measured and subtracted
- Correlated events: Chooz-Far x <30 N/S < 1%
(but not a comprehensive list of backgrounds …)
Backgrounds Estimates
G. Mention (PCC/APC) -NOW04-
Neutron Induced BackgroundCosmic muons create fast neutrons through spallation and muon capture in the rock surrounding the detector
Fast neutron slows 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.)
n Gd
~ 8 MeV
G. Mention (PCC/APC) -NOW04-
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)
G. Mention (PCC/APC) -NOW04-
DAPNIAta
rget
: 2
.8 m
-ca
tche
r:
4.0
m
-catcher: 1.8 m
target: 1.2 m
Acrylic vessels (preliminary)
single acrylic pieceintegration (-target + -catcher set)
G. Mention (PCC/APC) -NOW04-
Spectrum deformation @Double-Chooz1σ statistical errors only
rate info:
no-osc excluded@ 2.66σ
shape info:
flat shape excluded@ 5.98σ
G. Mention (PCC/APC) -NOW04-
Global normalization: 2%
Detector N Detector F
σabs=2%
Detector N Detector F
σrel=0.6%
Relative normalization: 0.6%
Detector N Detector F
σshape=2%
Spectrum shape uncertainty: 2%
Detector N Detector F
σbkg=1%
Backgrounds subtraction: 1%
Systematical errors influence on spectra
G. Mention (PCC/APC) -NOW04-
Potential limit if sin2(213)=0
• Efficiencies included
• 1% of background in Near & Far detectors
• Syst. uncert.:σabs = 2.0%σrel = 0.6%σscl = 0.5%σshp = 2.0%σΔm
2= 20% m2=2.4 10-3 eV2
3 years (efficiencies included) sin2(213)<0.024
Det. Bins k
2
k
k
2
kk
2
σ
α
Error Uncor.
BiasesαTheoryDataχ
FN,A
N
1i
K
1k
2
Ak
Aki,
2
Ai
K
1k
Aki,
Aki,
Ai
Ai
2bins
σ
α
U
SαTOχ
G. Mention (PCC/APC) -NOW04-
Complementarity of Double-Chooz with T2K (3σ discovery potential)
sin22θ13 = 0.08
Double-Chooz 1 year 3 years 7 yearsJ-Parc / 1 year 5 years
m2 = 2.0 10-3 eV2
Lindner et al.
G. Mention (PCC/APC) -NOW04-
Double-Chooz & IAEA IAEA: International Agency for Atomic Energy
Missions: Safety & Security, Science & Technology, Safeguard & Verification Control that member states do not 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 !
IAEA 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:
• Perform new antineutrino spectrum measurement @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
G. Mention (PCC/APC) -NOW04-
Double-Chooz sensitivity:can set sin2(213)<0.025-0.03, 90% C.L. (if m2 = 2.0-2.5 10-3 eV2)& can see sin2(213)>0.04-0.05, 3σ C.L. (if 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: APC Paris, Saclay, Subatech, TU Munich, MPIK Heidelberg, Tubingen Univ. Hamburg Univ., Kurchatov, RAS Moscow, Univ. Alabama, Univ. Tennessee, Univ. Louisiana, Univ. Drexel, Argonne, + Italian groups discussing… (maxi-)letter of intent (May 2004) final proposal end of 2004
Approved in France. Our Goal @Double-Chooz: Construction starts in 2006
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