Directional Sensitivity in Double Chooz

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Directional Sensitivity in Double Chooz

• Kathrin A. Hochmuth
• Max-Planck-Institut für Physik

LAUNCH Workshop Heidelberg 23.3.2007
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Outline

• Neutrino Direction Measurements
• CHOOZ measurements
• Two Reactors
• - separation of sources?
• - monitoring power output?
• analytical estimates and maximum likelihood
  analysis
• - for Double Chooz setup with 30 separation
• - for hypothetical setup with 90 separation

in collaboration with M. Lindner and G. Raffelt
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Neutrino Direction
average displacement for reactor energies 1.9
cm
Note uncertainty of locating the positron
annihilation and neutron absorption points is
large!
Uncertainty of displacement
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Setup

• CHOOZ determined each of the angles with s
  12 with 2,500 events
• Double Chooz near detector
• 160,000 events per year

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One Reactor
CHOOZ event rate (2,500) true values
q
f
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One Reactor
CHOOZ event rate (2,500) true values
q
f
Double Chooz event rate (160,000)
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Two Reactors ???
160,000 events
Single Reactor
Double Chooz 30 separation
Hypothetical setup 90 separation
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Probability Distribution Function
tilt angle w.r.t x-y plane
relative strength of the reactors, where
(assume for now )
displacement 1.9 cm
uncertainty of the displacement 20 cm
Separation angle
Central angle
For Double Chooz
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Important Points
y-axis distribution gives information on the
angular separation
x-distribution gives only information

on the center of the distribution
No distinction from a single Gauss

gt10 Mio events needed
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Important Points
y-axis distribution gives information on the
angular separation
x-distribution gives only information

on the center of the distribution
No distinction from a single Gauss

gt10 Mio events needed
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Non-Gaussianity
Good resolution
Bad resolution
No clear distinction because cosf11
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Angular Separation of 2 Sources
160,000 events Non-Gaussian behavior No
distinction from 0
Reactor 1
Separation angle
Central angle well determinded
x-distribution behaves like a single Gaussian
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7 years Double Chooz
Reactor 1
Separation angle
3 s distinction possible after 7 years
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Hypothetical 90 separation

• for 160,000 events
• Clear separation of the angles f1,f2 with
  s13.2
• central angle sc2.3
• separation angle s4.6
• Note

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Reactor Strength
Reactor strength
1 year Double Chooz 160,000 events
5 years
f145 after 1 year
True value b1b20.5
after 1 month
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Conclusions

• Separation of the two Double Chooz reactors
  challenging, because of small separation angle
  and
• 3 s separation of the two Double Chooz reactors
  after 7 years
• Separation Potential increases with increasing
  anglesgt clear distinction for 90 separation
  after 1 year
• Possible to monitor the strength of each
  individual reactor
  for 1 year Double Chooz with

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References

• M. Apollonio et al.(CHOOZ Collaboration),
  Phys.Rev.D 61 (2000) 012001 hep-ex/9906011.
• M. Apollonio et al. Eur.Phys.J. C 27 (2003) 331
  hep-ex/0301017
• F. Ardellier et al.(Double Chooz Collaboration)
  hep-ex/0606025v4 (26 October 2006).
• P. Vogel and J. F. Beacom, Phys. Rev. D 60 (1999)
  053003
• H. O. Back et al. (Borexino Collaboration),physics
  /0408032.
• P. H. Frampton and P. Vogel, Phys.Rept. 82 (1982)
  339.
• K. A. Hochmuth et al, Earth Moon Planets
  99253-264,2006 ,hep-ph/0610048.
• K. A. Hochmuth et al, Astropart.Phys.2721-29,2007
  ,hep-ph/0509136.

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Thank you!
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