Double Chooz

ダブルショー実験
概要およびその準備状況
川崎健夫（新潟大学）
・Double Chooz:
Collaboration, Experimental concept,
Detector, Physics Prospect,
Status & Schedule,
・Summary
ニュートリノ研究会、宇宙線研２０１０年２月１０日
Neutrino oscillations
(e,,)T = U (1,2,3)T :U=MNS Matrix
atmospheric 
0
 e   1
  
     0 c23
   0  s
23
  
0  c13

s23 
0
c23   s13e id
Super-K+K2K+MINOS P(→)
sin  23  0.50
2
m23
 2.5 103 eV 2
2

0.08
0.07
0.20
0.25
Reactor 
sij  sin qij , cij  cosqij
solar 
0 s13e id c12

1
0   s12
0
c13  0
CHOOZ
sin2(2q13)<0.2
s12
c12
0
0  1 
 
0  2 
1  3 
Solar+KAMLAND P(e→x)
0.02
sin2  12  0.300.03
m122  7.9  0.3 105 eV 2
@1
hep-ph/
0606060
6 parameters can be accessible from
neutrino oscillation.

Remains
2
2
m12
, m23
,q12,q 23,q13,d
(2 mass differences, 3 angles,1complex phase)
Small q13
leptonic CP phase d
Reactor neutrino experiment
CHOOZ reactor experiment
Chooz B reactor
e  e
(disappearance experiment)
Pth= 4.5 GWth, L = 1.050 km, M = 5 t
overburden: 300 mwe
2 cores
e
L=1.05km
sin22q13=0.1
E=4MeV
D=300mwe
Reactor Neutrino Oscillation
1.2
P(e --> e )
1
0.8
0.6
0.4
0.2
0
0.1
Measure very small deficit
1
10
100
1000
L(km)
2
m13
L
Pe  e   1 sin 2q13sin
4E
2
2
e Detection
Gd doped liquid scintillator
Chooz data
(0.511MeV)
Prompt signal
Ee = E + 1.8 MeV + O(Ee/mn)
(0.511MeV)
30μs
CHOOZ
hep-ex/0301017v1
Delayed signal
 Eg ~ 8MeV
E=1~8MeV
Gd
E=8MeV
n
e+
~30s
sin2(2q13)=0.04
sin2(2q13)=0.1
sin2(2q13)=0.2
Chooz Result
CHOOZ : Rosc = 1.01 ± 2.8% (stat) ± 2.7% (syst)
sin22q<0.15 @m2=2.5x10-3eV2
World best constraint
The next quest for q13
Accelerator
Reactor
P e   e 
P(    e )


2 

2  m23L 
 sin q 23sin 2q13  0.05  sin 2q13sind sin
 4E 


2
No effect from d
Small Matter effect
2
2 

2  m13L 
 1  sin 2q13sin
 4E 


Complementary
2
Double Chooz
Detecctor Design/
Physics Prospects
How to improve CHOOZ result?
CHOOZ Result :sin2(2q13)<0.2
Rosc = 1.01 ± 2.8% (stat) ± 2.7% (syst)
Double Chooz Experiment
Ardennes, France
CHOOZ B Reactor
Power = 4.27GWth x 2
Reactor Neutrino Oscillation
1.2
P(e --> e )
1
0.8
0.6
0.4
0.2
~0.4km
Near Site
115 m.w.e
500/day
0
0.1
Near
Far
1
10
100
1000
L(km)
Far Site
Overhaul CHOOZ
Exp. Hall
©2009 Google
~1.05km
300 m.w.e
70/day
Double Chooz Collaboration
France
Saclay
APC (collège de France)
Subatech Nantes
IPHC Strasbourg
Germany
Max planck Heidelberg
Munich TU
Hamburg U
Tubingen U
Aachen U
Spain
CIEMAT Madrid
USA
Livermore nat lab
Argonne
Columbia Univ
Chicago Univ
Kansas U
Notre Dame U
Tennesse U
Alabama U
Drexel U
Illinois Inst tech
MIT
Japan
Tohoku U
Tokyo Metropolitan U
Niigata U
Tokyo Institute of Tech.
Kobe U
Tohoku Gakuin U
Hiroshima Inst. of Tech.
England
Sussex Univ
Russia
Kurchatov inst
Sc. Acad.
Brasil
CBPF
UNICAMP
~150 people
35 institutes, 8 countries
Very Experienced members: Chooz, Bugey,
KamLAND, Super-Kamiokande, SNO, Borexino
Double Chooz: 2 phases
We are here now!
2007
Design
2008
2009
2010
Construction Far
2011
Improve statistics
Large target volume
Longer stable operation
Improve systematics
Better detector design
Low BG PMT/material
Buffer oil/Gamma catcher
Improved Cosmic-Veto detectors
2013
Timeline
Data Taking (Phase 1)
Cstr.
Near
Phase 1:Far Detector Only
2012
Data Taking (Phase 2)
Phase 2:Far + Near Detector
Identical detectors cancel
systematics on.
Neutrino flux/Reactor power
Acceptance, Cross section and etc..
Better understand of Background
and Energy scale is important
for the further reduction of systematic
errors
CHOOZ Result :sin2(2q13)<0.2
Rosc (=Observe/Expect)= 1.01 ± 2.8% (stat) ± 2.7% (syst)
Electronics
& DAQ
Detector Design
New 4-region
large detector concept
Outer Veto: plastic scintillator strips (400 mm)
-Target: 10,3 m3 scintillator doped with 4.5g/l
CEA-DSM-IRFU (thechnical coordination)
of Gd compound in an acrylic vessel (8 mm)
g-Catcher: 22,3 m3 scintillator in an acrylic
vessel (12 mm)
Buffer: 110 m3 of mineral oil in a stainless
steel vessel (3 mm) viewed by 390 PMTs
Inner Veto: 90m3 of scintillator in a steel
vessel equipped with 78 PMTs
Veto Vessel (10mm) & Steel Shielding
The detector design
7 m
Muon Outer-VETO:
Scintillators Panels
7 m
-target: Volume for -interaction
80% dodecane + 20% PXE + PPO + Bis-MSB
+ 0.1% Gd
g-catcher: Extra-volume for -interaction
80% dodecane + 20% PXE + PPO + Bis-MSB
511 keV
e
511 keV
p e+
n
Gd
g ~ 8 MeV
Acrylic vessels  «hardware»
definition of fiducial volume
Non-scintillating buffer: Mineral Oil
Isolate PMTs from target area
Muon Inner-VETO: LS
Shielding: steel 17 cm: >7 g
 Improved background reduction
PMT support structure:
insulation target/veto
steel tank, optical
How much can we improve?
@CHOOZ: R = 1.01  2.8%(stat)  2.7%(syst)
– Statistical error –
Luminosity incerase L = t x P(GW) x Np
Large detection volume & Long stable operation are necessary
CHOOZ
Double-Chooz
5.55 m3
10.2 m3
Target composition
6.77 1028 H/m3
6.82 1028 H/m3
Data taking period
Few months
3-5 years
Event rate
2700
CHOOZ-far : 50,000/3 y
CHOOZ-near: ~2.5x105/3 y
Statistical error
2.8%
0.5%
Target volume
Gd doped scintillator
• Solvent: 20% PXE – 80% Dodecane
• Gd loading: being developed @MPIK
Gd(dpm)3
MPI-K product and purify scintillators
-All liquids are on site.
UV-VIS-IR scintillator transmission
• 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
Stable@20-40℃ for 2 years
Systematic on Analysis/Selection
@CHOOZ: 1.5% syst. err. (Efficiency ~70% )
Goal Double Chooz:
•2 layer design (no fiducial cut)
• Low BG PMT/Material
• Improve Veto detector
⇒ Reduce # of cuts in Analysis
e
pe+Gd
n
Efficiency is INSENSITIVE to the energy scale error
In total, 0.2~0.3% syst. err.:
Better Energy calibration (depends on position) realize further reduction
e+Energy
Neutron
Energy
t
Backgrounds
Estimated with CHOOZ OFF data & Simulation ( represent CHOOZ data well)
Fast neutrons
g ~ 8 MeV
Correlated
proton recoils
μ
μ
Gd
μ capture
“Positron” Energy spectrum
Recoil p
n from 
capture
Gd
μ → (9Li, 8He) → β-n
Gd
n capture Recoil p
on Gd
Spallation
fast
neutron
Accidentals
PM + rocks
γ
Nbkg = ~1.6 evts/day (Far) 2% of  signal
⇒0.7% syst err.
=10~20evts/day (Near) 0.5%
⇒ 0.2% syst err.
Due to the different overburden, BG is not fully canceled.
+ neutron-like event Better understand of BG reduces sys. errors. (To be
measured within a few tens of percent If we can take ~a few
weeks reactor OFF data.)
How much can we improve?
@CHOOZ: R = 1.01  2.8%(stat)  2.7%(syst)
– Systematic errors –
Systematic error
CHOOZ
Dobule Chooz
Reactor Cross section
1.9%
-
Number of protons
0.8%
0.2%
Detection efficiency
1.5%
0.5%
Reactor power
0.7%
-
Energy per fission
0.6%
-
Total systematic error
2.7%
<0.6%
Double Chooz Goal in Phase 2 (Far+Near)
Thanks to improved detector design and 2 detectors concept
Achievable sensitivity of sin22θ13
m2atm = 2.5x10-3 eV2 (20% uncertainty by MINOS)
Spectrum Analysis is
necessary for confidence
e+ spectrum
Achievable sensitivity
of sin22θ13(90%CL)
2010
2011
2012
2013
CHOOZ: sin22θ13 < 0.15(0.12@global)
5 times better than current limit
(5 year measurement)
2014
Far/Near ratio
Status of construction/
Schedule in the future
Far detector construction
Material
Status of installation
Steel shield
Complete ✔
Inner veto tank
Complete ✔
Inner veto PMT (8” 78PMTs)
Complete ✔
Buffer tank
Complete ✔
Buffer tank PMT(10” 390PMTs)
Complete ✔
Gamma catcher and Target vessels
Complete ✔
Close Lids
Complete ✔
Electronics/DAQ installation
On going
Liquid filling
Soon
・・・・・・・
・・・・
Far site construction
February 2009
Overhaul CHOOZ Exp. Hall
Lab cleaning
Installation Veto and Veto-PMTs
Installation Buffertank
PMT installation
400High performance low background 10" PMTs(Oil proof)
(HAMAMATSU R7081MOD-ASSY)
Final test at Exp. site
Test
Assembly
Installation to detector
May 2009
July 2009
PMT installation report
Buffer PMT complete
Acrylic vessel installation
Sept 2009
Gamma Catcher transport
Gamma Catcher installation
Acrylic vessels in lab
Acrylic vessels in buffer tank
Oct 2009
Current status
2009
Construction Far
Lid closed
2010
2011
Data Taking (Phase 1)
Start Data taking!!!
In parallel, start filling of Liquid Scintillator
to Acrylic Vessels, Buffer and Inner Veto.
Dec 2009
DAQ/Electronics installation
will start in the Next week!
 DAQ/Electronics:
Deadtime less
Splitter(Installed), PMT HV supplies
Trigger electronics
500MHz FADC, DAQ PCs
Run control PCs
Soon..
2009
Construction Far
Data taking start.
Then….
2010
2011
Data Taking (Phase 1)
Cstr.
Near
Data Taking (Phase 2)
Calibration:
- Target fish-line & articulated arm
- g-catcher and buffer guide tubes
- Embedded LEDs (Installed)
 Outer veto:
Panels of strips of
coextruded plastic scintillator with
wavelength shifting fiber.
Improve data quality and reduce systematic errors.
Status of the Near site
• Site engineering study completed
⇒Start excavation 2010
Site will be ready 2011
Laboratory
•Neutrino fluxes: 2.5 x105 events in 3 years
•Depth: 120 m.w.e. ( flux: ~ 3-4 /m-2s-1)
Open ramp (85 m),
14% slope
Liquid storage
160m
Tunnel (155 m),
12% slope
Summary for Double Chooz
• The Double Chooz experiment
– Double Chooz will be the first of a new generation of reactor
neutrino experiments. It is the one of the best experimental
concept to measure q13
• The status of DoubleChooz Experiment
– Detector Construction are close to the final stages.
• Installation of DAQ/Electronics starts in the next week.
• Filling of Liquid Scintillator follows.
– We should observe the neutrino from reactor in this year!
– Construction of the near site/detector will be started soon.
• Prospects for the future
– First data taking expected to start in 2010 with far detector only
⇒sin2(2q13) < 0.06 in 1.5 year
– From year 2011~, take data with the both near and far detectors
⇒sin2(2q13) < 0.03 in 3 years

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