Olivier Deligny

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t
Olivier Deligny for the Pierre Auger
Collaboration IPN Orsay CNRS/IN2P3 TAUP 2007,
Sendai
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A huge detector to study the Cosmic Rays at the
highest energies (EeV).
(Results and performance Plenary 6 )
We also have the capability to detect Ultra High
Energy ?
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A huge detector to study the Cosmic Rays at the
highest energies (EeV).
(Results and performance Plenary 6 )
We also have the capability to detect Ultra High
Energy ?
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Principle A shower deeply initiated by a
neutrino looks like a hadronic shower BUT at high
angle !
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All ? flavours can interact in the atmosphere
and produce an EAS, but the earth-skimming
mechanism can be used for ?
t
Lint (?) 500 km Ldecay (t) 50 km LEloss
10 km (at 1 EeV) ?gt95, Earth opaque
(µ), much larger
(e), much smaller Pierre Auger Observatory 50
x 50 km2
This channel is expected to produce more
identified neutrinos.
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Principle Build discriminative variables
sensitive to young and horizontal showers
No candidate (Jan'04 - Dec'06), while 80
identification efficiency
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Detection probability
Interactions in Earth
h parameter describing the altitude of the
shower center 10 km after the decay point, where
the shower has the largest trigger power
c
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• Conversion ? t
• Neutrino cross section
• Tau energy losses
• Tau decay

t
MC vs numerical solutions
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• Acceptance for t showers
• Depends on tau energy and altitude shower centre
• Growing detector

1 EeV
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Theoretical knowledge
All contributions
Worst/Best combination of scenarios leads to a
factor 3 difference for the flux limit
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90 CL for each flavour with the worst
systematic scenario and assuming
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• The Pierre Auger Observatory has a large
  discriminant capacity to distinguish
  earth-skimming neutrinos from standard Cosmic
  Rays.
• From Jan'04 till Dec'06 (about 1 year of a full
  Surface Detector), ZERO ? candidates have been
  found, leading to spectra dependent limit to tau
  neutrinos of E2dN/dE 210-7 GeV cm-2 s-1 sr-1.
• The Pierre Auger Observatory has its maximum
  sensitivity at the most relevant energy range (
  1 EeV) for GZK neutrinos, the expected level of
  which will be tested in about 10 years.
• The Pierre Auger Observatory is also sensitive to
  neutrinos that interact in the atmosphere. This
  channel has different systematics and depends
  differently on neutrino properties. Studies are
  ongoing

t
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0.3 EeV
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Real event, 80º
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Real event, 20º
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Sensitivity one event per year and decade of
energy with the full SD
GZK TD AGN WB
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90 CL for each flavour with the worst
systematic scenario and assuming
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