Yuri Kamyshkov

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Double Chooz
New reactor antineutrino experiment
Yuri Kamyshkov University of Tennessee Knoxville
FRONTIERS IN CONTEMPORARY PHYSICS - III
Vanderbilt University, May 23-28, 2005
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Survival probability of reactor antineutrinos in
case of three flavor oscillations
(no CP phase, no matter effect)
Is ?13 ? 0 ? Future of neutrino physics will
depend on this answer.
We need this answer asap!
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First ?13 limit came from Chooz experiment
?e ? ?e (disappearance experiment) Pth 8.4
GWth,L 1.050 km, Mass 5 toverburden 300 mwe
World best constraint ! _at_?m2atm 2?10?3
eV2 sin2(2?13) lt 0.2 (90 C.L)
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Reactor ?-experiments before KamLAND
First KL publication
Second KL publication
Lev Mikaelyan (Kurchatov Inst) in 2000 proposed
to use one source and two detectors as a method
for further reduction of systematic errors in
reactor antineutrino disappearance measurements
for ?13
R(Chooz) 1.01 ? 2.8 (stat) ? 2.7 (syst)
Alabama 03?München 03??13 White paper?Niigata
04?APS study?Angra 05
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Double Chooz Collaboration (February 2005)
a group of Saclay, APC, Subatech, TUMunich,
MPIK-Heidelberg,Tubingen Univ., Univ. Hamburg,
Kurchatov, INR, LNGS, Louisiana State, Argonne,
Drexel, Univ. Alabama, Univ. Notre Dame, Kansas
State, Univ. Tennessee
a group with integrated experience from Chooz,
Palo Verde, KamLAND, Borexino, LENS, Super-K,
IMB, SNO, MINOS, Brookhaven 704, LSND, MiniBooNE,
Fermilab E1A, E594
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Double Chooz ideas
Timely measurement of ?13 is needed
Existing Chooz reactor and site facilities
can be very efficiently used for ?13
measurement
Two-detector Double Chooz most naturally
should be utilizing the experience of the
previous most precise reactor antineutrino
experiment Chooz (you practically know what
need and can be improved)
The Chooz detector in many respects is a
prototype of DC detectors (one can avoid an
RD stage)
The goal is to improve sensitivity limit of
Chooz down to sin2(2?13) gt 0.03 in a fast
proceeding experiment with a reasonably low
cost
Will take a reasonable next step in improving
accuracy of antineutrino measurements
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Study done by Double Chooz Colleagues P. Huber,
M. Lindner, T. Schwetz, and W. Winter,
arXivhep-ph/0303232
400 tGWy
8,000 tGWy
?70
DC 3yr
One can say that to reach 0.01 is 70 times more
difficult than to reach 0.03 However, factor of
70 need not all be in Luminosity either L can be
improved or the systematics can be better
controlled
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The Double-Chooz concept
Existing Chooz site
New site
?e,?,?
D1 150 m
8.4 GWth Chooz PWR station
D2 1,050 m
Near detector
Far detector

• Measure neutrino flux before and after
  oscillation
• Measure deviation from 1/D2 dependence
• Improve detector design to reduce systematics

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Double-Chooz, Ardennes, France
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Far site at 1050 m
Near site at 150 m

• 60 m.w.e. overburden
• 12 m compacted earth
• 3 meter high density material
• Design is in progress
• Construction by CEA/Saclay

DAPNIA
300 m.w.e. overburden
Near Detector site
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Understanding Mechanical Construction
Acrylic Target vessel (R1,2m, h2,8m, t 12mm)
Acrylic Gamma catcher vessel (R 1,8m, H 4
m, t 8mm)
LS 0,1Gd
LS
Stainless steel Buffer (R 2,75m, h 5,6m, t
4mm)
Muon VETO (shield) Thickness 150mm
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Mechanical Studies at Saclay
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Statistics e spectrum
?m2atm 2.0 10-3 eV2
sin2(2?13)0.04 sin2(2?13)0.1 sin2(2?13)0.2
sin2(2?13)0.04 sin2(2?13)0.1 sin2(2?13)0.2
Events/200 KeV/3 years
E (MeV)
E (MeV)
Near Detector 1.8 106 events -Reactor
efficiency 80 -Detector efficiency 80 -Dead
time 50
Far Detector 34 000 events -Reactor
efficiency 80 -Detector efficiency 80
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New DC detectors design
7 m
7 m
Old Chooz 5-t detector Double Chooz two 10-t
detectors
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Gd doped scintillator must be stable
3Gd
Gd-Acac Gd-Dmp
Gd-Carboxylate
Loaded LS stability tested for gt 6-12 months.
More tests are in progress
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Double Chooz calibration plans
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Candidate PMTs radio assay results
J.B., Alabama U, April05
Expected activity for ETL 9354 (ultra-low) is
1.02 ? 0.52 Bq per PMT Expected activity for
Hamamatsu R5912 (low) is 5.2 ? 0.9 Bq per PMT
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Gamma Singles Rates From Radioactivity
Scintillaltor
Buffer
Veto
Sand
Rock
Chooz
Vessel
PMTs
Acrylic
LS
Double Chooz
Steel
? - Catcher
Rock
Veto
Buffer
Scintillaltor
Y.E., May, 2005
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Muon fluxes
NEAR detector ( 60 mwe) ltE?gt 19 GeV 420 Hz
(flat) 770 Hz (hemi) FAR (300 mwe) 25
Hz ltE?gt 63 GeV
Near
From Bugaev et. al
Far
Spallation production of 9Li, ... vs muon energy
is not well known (see J. Beacom talk).
But since the muon rate in the FAR detector is
not very large, production of some isotopes
(e.g.9Li) can be measured (like e.g. in KamLAND)
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Background measurements in Chooz
in Chooz 42 of time both reactors were OFF
What can be reasonably expected for DC 78 of
time full power 18 of time 1/2 power 4 of
time both reactors OFF
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Some numbers estimated from Chooz performance
most of these are removed by efficient veto and
coincidence requirement accidental background
is measurable correlated background is
measurable with two reactors OFF
Monte Carlo simulations give better numbers
10 accuracy of correlated background
determination is required
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Comparison of detector systematics
e

• _at_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
• ?R distance (e n ) level of accidentals
• ?t (e n)

n
?t
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How Good is Good Enough?
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Expected Sensitivity 2007-2012
90 C.L. contour of sin2(2?13)0 ?m2atm 2.8
103 eV2
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If you are desperate to know the value ?13, you
will be interested
in our Schedule and Milestones

• May 04-Jun 05 Project Definition
• 05 Full Approval (assumption)
• Jul 05 Call for Bids
• Jul 05-Oct 07 Production
• Mid 06 Start on site installation
• May 07 Far Detector Completion
• Oct 07 Sin22q13 lt (0.19) with far detector
  alone
• Nov 07 Near Detector Completion
• Dec 08 Sin22q13 lt ( 0.05) sensitivity - 2
  detectors
• Dec 10 Sin22q13 lt ( 0.03)

By the end of 2010 one can know that sin22?13 lt
0.03 or to learn earlier the non-zero value