Post on 30-Dec-2015
Christian Buck, MPIK Heidelberg for the Double Chooz Collaboration
LAUNCH
March 23rd, 2007
The Double Chooz experiment
Why Double Chooz?
Improved knowledge of mixing matrix
Θ13 controls 3 flavor effects (e.g. CP violation only for Θ13 > 0)
Discovery potential: models often close to experimental bound
Complementarity to beam experiments
- Degeneracies + parameter correlations
- Optimize future experiments
Discrimination power for normal hierarchy in 0νββ depends on Θ13
Δmsol2 ~ 8∙10-5 eV2, sin2(2Θ12) ~ 0.86
Δmatm2 ~ 2.5∙10-3 eV2, sin2(2Θ23) ~ 1
ν2
Δmatm2
Δmsol2 ν1
ν3
sin2Θ13
sin2Θ23
sin2Θ12
νe
νμ
ντ
ν eν μν τ =U e1 U e2 U e3Uμ1 Uμ2 Uμ3U τ1 U τ2 U τ3
ν 1
ν 2
ν 3
Interest of International Atomic Energy Agency (IAEA) in νe detection
- Monitoring of single reactors
- Monitoring of countries
Intensity and shape of spectrum depend on isotopic composition Pu content!
Use Double Chooz near detector as prototype for reactor monitoring
Thermal power (1% ?)
Non-proliferation
Current proposals
December 2002: 1st European meeting, MPIK April 2003 – February 2005: 4 int. workshops in U.S., Germany, Japan and Brazil 1st Double Chooz Meeting: Nov 2003
Angra
Double-Chooz
KaskaDaya bay
RENO
Double Chooz collaboration
Spokesman: H. de Kerret (APC) France: CEA/Dapnia Saclay, APC, Subatech (Nantes) Germany: MPIK Heidelberg, TU München, EKU Tübingen, Universität
Hamburg, RWTH Aachen Italy: LNGS (Gran Sasso) Russia: RAS, Kurchatov Institute (Moscow) USA: Alabama, ANL, Chicago, Drexel, Kansas State, LLNL, LSU, Notre
Dame, Tennessee Spain: CIEMAT Japan: HIT, Kobe, MUE, Niigata, Tohoku, TGU, TIT, TMU England: University of Oxford
The labs
Far detector (300 m w.e., 1.05 km) Near detector (75 m w.e., 280 m)
Δm2atm = 2.8·10-3 eV2
(MINOS best fit)
Constant flux ratios
Improving Chooz
0.3 %1.5 %Det.eff.
< 0.6%2.7 %Σ system.
0.4%2.8%Statistical
0.2 %0.8 %# protons
<0.1 %0.7 %Power
<0.1 %0.6 %E/fission
<0.1 %1.9 %Flux, σ
DCChoozerror
CHOOZ limit
sin2(2θ13) < 0.12 – 0.20R = 1.01 2.8%(stat)
2.7%(syst)
Reactor
Detector
ν e ν x
Δm
2 (eV
)2
sin2(2Θ)
10-2
10-3
Sensitivity
2008
Sensitivity 2008 – 2013 (near detector starts 16 months after far) for m2
atm = 2.8·10-3 eV2
Detector design
TARGET: (th = 2,3m)- Acrylic vessel (th = 8mm)
- 10,3 m3 LS (1 g/l Gd)
γ-catcher: (th = 0,55m) -Acrylic vessel (th = 12mm)
- 22,6 m3 LS
Buffer: (th = 1,05m) -Steel vessel (th = 3 mm)
-114 m3 mineral oil
Inner veto: (th = 0,5m) -Steel vessel th = 10 mm)
-~80 m3 LS
SHIELDING (th = 17 cm)- Steel
7m
7m
Neutrino signal
n
e
p511 keV
511 keVe+
~ 8 MeV
Gd
Target: Gd-loaded liquid scintillator
Eve
nts/
200
KeV
/3 y
ears
sin2(213)=0.04 sin2(213)=0.1 sin2(213)=0.2
Energy [MeV]
Neutrino rates: - far: ~70/day- near: ~1000/day
Correlated backgrounds
n
~ 8 MeV
n deposits energy
Gd
Fast neutrons
Chooz rate: ~1/day
Double Chooz simulation:
Far: Nb < 0.6/day (90% CL)
Near: Nb ~ 3.3/day (90% CL)
β-n-cascades (spallation products: 9Li, 11Li, 8He)
Expected rate:
Far: 1.4/day, Near: 9/day
Long-lived
Mockup
Goal:
- Find technical solutions
- Define interfaces
- Material compatiblity
- Test filling procedure
Volumes:
- 100 liter Target
- 200 liter Gamma Catcher
- 700 liter Buffer
Match scintillator properties:
- Densities (1 % in DC)
- Light yield
Mockup results
400 420 440 460 480 500 520 540 560 580 6000,000
0,005
0,010
0,015
0,020
0,025
0,030
0,035
0,040
0,045
0,050Target
5 m
Abs
orba
nce
wavelength [nm]
Dec 05 Jan 06 Feb 06 Mar 06 Apr 06
400 420 440 460 480 500 520 540 560 580 6000,000
0,005
0,010
0,015
0,020
0,025
0,030
0,035
0,040
0,045
0,050-catcher
Dec 05 Jan 06 Feb 06 Mar 06 Apr 06
5 m
Abs
orba
nce
wavelength [nm]
0 1 2 3 4 50,0
0,1
0,2
0,3
0,4
0,5
0,6
0,7
0,8
0,9
1,0Target
Gd-
conc
. [g/
l]
months
Gd-concentration unchanged
Optical properties stable
Metal loaded scintillators
Development at MPIK since 2000 (C.Buck, F.X.Hartmann, D.Motta, T.Lasserre, S.Schönert, U.Schwan)
Wide interest in different fields:- Solar neutrino physics (In, Yb,…)
- Reactors experiments (Gd)
- Geo-neutrinos (Gd)
- 0νββ-decay (150Nd)
400 425 450 475 500 525 550 575 600 625 6500
5
10
15
20
25
mo
l.ext
.[l/(
mo
l*cm
)]
wavelength [nm]
Nd(acac)3nH
2O
NdCl3
Scintillator development at MPIK
Metal-β-diketonates:R1
3+M
R2
O
OO
O
O
O
HC-
C-
H
C-H
R1 R1
R2
R2
How to dissolve metal in organic scintillator? Method 1: Organometallic compound
Requirements: solubility no light quenching optical transparency radiopurity low reactivity (stability!)
Method 2:
Carboxylate system stabilized by pH (since 2000)
Attenuation length / stability
380 400 420 440 460 480 500 5200
10
20
30
40
50
60
70
80
90
100
atte
nuat
ion
leng
th [m
]
wavelength [nm]
solvent Gd-solution final scintillator
Stability tests up to 3 years
Tests of concentrates
Temperature tests
Cross check in Saclay
Measured by UV/Vis
10 cm cells
Absorption + Scattering!
No fluors: > 10 m in ROI
ROI
Scintillator stability
Palo Verde:
A.G.Piepke, S.W.Moser, V.M.NovikovNIM A 342 (1999) 392-398
Chooz: Time variation fit of attenuation length:
L att t =L 0
1 v⋅t
Parameter v
Chooz: (4.2 ± 0.4)∙10-3 /d *
BDK-system: ≤ 7.5∙10-5 /d
* Chooz Coll., Eur. Phys. J. C27, (2003) 331-374
[v = (1.5 – 2.8)·10-3 /d)]
Gd complex
0 500 1000 1500 2000 2500
0,02
0,04
0,06
0,08
0,10
0,12
0,14
coun
ts/(
h*kg
*keV
)
Energy [keV]
Approach: Gd-β-diketone
Purification by sublimation
Full scale production started!
8·10-108.7·10-13< 2.4·10-13Conc.[g/g]
0.25 0.032 < 0.03A/det. [Bq]
0.00065
Th
0.005< 0.0006A/kg
[Bq]
K U
GeMPI at LNGS (M.Laubenstein)
Scintillator solvent
PXE/dodecane mixture (20/80 Vol):
Optimized ratio
- PXE improves light yield
- Dodecane improves material compatibility + number of H
Column purification
High flash point, low toxicity
Solvents used in KamLand (Dodecane), Borexino (PXE in CTF)
Backup Linear alkylbenzene
350 400 450 500 550 600-0,0020,0000,0020,0040,0060,0080,0100,0120,0140,016
abso
rban
ce
wavelength [nm]
unpurified b1 unpurified b2 purified
10 m
Fluor choice
Primary fluor properties:
Light yield
Emission spectrum
Energy transfer parameters
Transparency
Radiopurity 380 400 420 440 460 480 500 520 540 560 580 6000
100
200
300
400
500
600
700
light
inte
nsity
[a.u
.]wavelength [nm]
Scintillator emission spectrum
Energy transfer model
0 20 40 60 80 1000
10
20
30
40
50
60
70 2 % In 5 % In
Ligh
t yie
ld [%
BC
505]
Fluor concentration [g/l]
I c , q = I 0⋅1
1 k s⋅c⋅
11K⋅q /c
0 10 20 30 40 500
10
20
30
40
50
60
70
80
90
100
rel.
light
yie
ld
Indium [g/l]
M
D A*excitation
.
.. . ..M
.........
.M
M
O
CH
I n
OO
O
O
O
Me .
C.Buck, F.X.Hartmann, D.Motta, S.Schönert, Chem.Phys.Lett.435 (2007) 252 – 256
Developed for Indium system
Scintillator Summary
2000 – 2003: Development metal loaded scintillator (In, Yb, Nd, Gd)
2003: First tests Gd-loaded scintillators– Gd(acac)3 scintillator
– pH controlled carboxylate (TMHA) scintillator
2004: Optimization synthesis 2005: Double Chooz mockup 2006: Outsourcing of Gd-BDK production
– Successful sublimation at company– First radiopurity measurements
Summer 2006: New division
3 x 24m3 Iso-containers Large scale production Gd-material
Scintillator building
60 m³ liquids
Summary
Double Chooz searches for the neutrino mixing angle θ13
- Sensitivity: sin2(2Θ13) < 0.02 - 0.03 (90% CL) (Chooz bound sin2(2Θ13) < 0.2)
- Start data taking: 2008
Main hardware contribution of MPIK:
- Development + production target Gd-scintillator (10.3 m³)
- Tuning + production of γ-catcher scintillator (22 m³)
- Design and construction scintillator mixing system
Status
- Major components ordered
- Construction of scintillator hall