Future Neutrino Oscillation Experiments

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Future Neutrino Oscillation Experiments
Ed Blucher

• Neutrino oscillations, CP violation, and
  importance of ?13
• Accelerator vs. reactor experiments
• Future reactor experiments to measure sin22?13

2
Neutrino Oscillations

• During last few years, oscillations among
  different flavors of neutrinos have been
  established physics beyond the S.M.
• Mass eigenstates and flavor eigenstates are not
  the same (similar to quarks)

mass eigenstates
flavor eigenstates
MNSP matrix

• Raises many interesting questions including
  possibility of CP violation in neutrino
  oscillations.
• CP violation in neutrino sector could be
  responsible for the matter-antimatter asymmetry.

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Quark and Neutrino Mixing Matrices
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2 Flavor Neutrino Mixing
The time evolution of the flavor states is
For a beam that is pure ?? at t0,
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MNSP Matrix
?12 30
?23 45
sin2 2?13 lt 0.2 at 90 CL
What is ?e component of ?3 mass eigenstate?
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CP Violation in Neutrino Oscillations
Minakata and Nunokawa, hep-ph/0108085
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Methods to measure sin22?13

• Appearance nm?ne (Accelerator Exp)
• Use fairly pure, accelerator produced nm beam
  with a detector at long distance (300 km - 900
  km) from the source
• Look for the appearance of ne events
• Use near detector to measure background nes (beam
  and misid)

150m
1500m

• Disappearance (Reactor Exp)
• Use a set of reactors as a source of
• ne's with a detector at few km
• Look for a non- 1/r2 behavior of the ne rate
• Use near detector to measure the unoscillated
  flux

Diablo Canyon, CA
overburden
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Accelerator and reactor measurements of ?13
Accelerator experiments measure
Reactor measurement of ?13 is independent of
matter effects and CP violation
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Reactor Measurements of Neutrino Oscillations
Reactors are copious sources of
per second.
Detection of antineutrino by
followed by
or for Gd-loaded scintillator
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Long history of neutrino experiments at reactors
20 m
KamLAND
6 m
CHOOZ
Current interest is focused mainly on possibility
of measuring ???
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Reactor Measurements of
Future Search for small oscillations at 1-2 km
distance (corresponding to
Pee
Reactor experiments allow direct measurement of
sin22??? no matter effects, no CP
violation, almost no correlation with other
parameters.
Sensitivity goal sin22???0.01. Level at which
long-baseline superbeams can be used to measure
mass hierarchy, CPV sensitivity goal of
proposed accel. expts.
Distance to reactor (m)
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Previous Reactor ??? Experiments
CHOOZ Systematic Errors

• CHOOZ and Palo Verde Experiments
• Single detector experiments
• Detectors used liquid scintillator with
  gadolinium and buffer zones for background
  reduction
• Shielding
• CHOOZ 300 mwe
• Palo Verde 32 mwe
• Fiducial mass
• CHOOZ 5 tons _at_ 1km, 5.7 GW
• 2.2 evts/day/ton with 0.2-0.4 bkg evts/day/ton
  
• 3600 n events
• Palo Verde 12 tons _at_ 0.85km, 11.6 GW
• 7 evts/day/ton with2.0 bkg evts/day/ton
• 26000 n events

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CHOOZ
Target 5 ton Gd-doped scintillator
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Is it possible to improve the Chooz experiment by
order of magnitude (i.e., sensitive to sin22???
0.01)? Add second detector bigger detectors
better control of systematics.
200 m
1500 m

• What systematic error is attainable?
• Efficiency and energy calibration strategy
  (movable detectors?)
• Backgrounds
• Multiple reactor cores
• Site / depth
• Choice of scintillator (stability of
  Gd-loaded scintillator)
• Size, distance of detectors

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Normalization and spectral information
Predicted spectrum ?130
Observed spectrum sin22?130.04

• Counting Experiment
• Compare number of events in near and far detector
• Energy Shape Experiment
• Compare energy spectrum in near and far detector

E? (MeV)
E? (MeV)
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Analysis Using Counting and Energy
Spectrum(Huber et al. hep-ph/0303232)
scal relative near/far energy calibrationsnorm
relative near/far normalization
90CL at Dm2 310-3 eV2

• Counting exp. region

• Spectrum Rate region

ScenariosReactor I 12ton7GW5yrsReactor II
250ton7GW5yrs
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Worldwide interest in two-detector reactor
experiment
Workshops Alabama, June 2003 Munich, October
2003 Niigata, Japan, March 2004
Based on early workshops, a whitepaper
describing physics possibilities of reactor
experiment has been written.
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• Sites under discussion
• Kraznoyarsk (Russia)
• Chooz (France)
• Kashiwazaki (Japan)
• Diablo Canyon (California)
• Braidwood, Byron (Illinois)
• Wolf Creek (Kansas)
• Brazil
• Taiwan
• China

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Kr2Det Reactor ?13 Experiment at Krasnoyarsk
Features - underground reactor - existing
infrastructure
Detector locations constrained by existing
infrastructure
Reactor
Ref Marteyamov et al, hep-ex/0211070
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Proposal for Reactor ?13 Experiment in Japan
Kashiwazaki -7 nuclear power stations worlds
most powerful reactors - requires
construction of underground shaft for detectors
far
near
near
Kashiwazaki-Kariwa Nuclear Power Station
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Kashiwazaki Proposal for Reactor ?13 Experiment
in Japan
far
near
near
70 m
70 m
200-300 m
6 m shaft, 200-300 m depth
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The Chooz site, Ardennes, France
Double-CH?13?13Z
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The Chooz site
Type PWR
Cores 2
Power 8.4 GWth
Couplage 1996/1997
(, in to 2000) 66, 57
Constructeur Framatome
Opérateur EDF
?
Near site D100-200 m severall options under
study Far site D1.1 km, overburden 300 mwe
former experimental hall

• Positive signs from EDF for reusing the former
  CHOOZ site. Near site ? civil engineering
• 2x11.5 tons, D1100-200m, D21050m. Sensitivity
  3 years ? sin2(2?13) lt 0.03

• Chooz, 2x10 tonnes, D10.7 km, D21.1 km, 3 ans
  (70 kevts) ? sin2(2?13)lt0.037

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CHOOZ-Far
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CHOOZ-Far detector
3.5 m
Existing CHOOZ tub
7 m
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CHOOZ-Near new Laboratory
10-15 m
High-Z material
5- 15 m
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U.S. Nuclear Power Plants
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Braidwood, Illinois 7.17 GW 24 miles SW of Joliet

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Braidwood site
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Diablo Canyon Nuclear Power Plant
1500 ft
Powerful Two reactors (3.1 3.1 GW Eth)
Overburden Horizontal tunnel could give 800 mwe
shielding Infrastructure Construction roads.
Controlled access. Close to wineries.
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• Weve formed a small collaboration to develop a
  proposal for a
• midwest site
• Chicago, Columbia, ANL, FNAL, Kansas, Michigan,
  Oxford, Texas

Chicago involvement Kelby Anderson, Ed Blucher,
Juan Collar, Jim Pilcher, Matt Worcester
(postdoc), Erin Abouzaid (grad), Abby Kaboth
(undergrad), Jennifer Seger (undergrad)

• Significant effort also underway at LBNL to
  investigate feasibility
• of experiment at Diablo Canyon.

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Conclusions

• Extremely exciting time for neutrino physics!
• The possibility of observing CP violation in the
  neutrino sector presents a great experimental
  challenge.
• Reactor and accelerator experiments are
  complementary.
• Reactor experiment has potential to be faster,
  cheaper, and better for establishing value of ???.

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Was baryogenesis made possible by leptonic CP
violation?
Leptogenesis may have been the result of direct
CP violation in decays of heavy Majorana
particles
This antilepton excess in converted to a baryon
excess through nonperturbative Standard Model B-L
conserving processes.
- Fukugita and Yanagida, Phys. Lett. B174 (1986)