Atmospheric muons in ANTARES

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Atmospheric muons in ANTARES

• Claire Picq (CEA Saclay-APC)
• On behalf of the ANTARES collaboration
• Moriond 2009

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Atmospheric muons
3
?
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Muon bundle
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First Line detector results

• arxiv 0812.2095 submitted to Astroparticle
  Physics
• Data 187 hours in 2006

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Depth Intensity Relation

• Systematic errors on the data 50 mainly due to
  the PMT acceptance
• Statistical errors are negligible

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Verticalization
Sea level
?
H
?
H / cos ?

• To take into account the zenith dependence
• (? sec?) of muon flux at sea level (up to 60)

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Depth Intensity Relation

• Systematic errors on the data 50 mainly due to
  the PMT acceptance
• Statistical errors are negligible

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FIVE LINE DETECTOR RESULTS

• Data 7 months in 2007 _ Two analyses
• Low energy threshold muon flux from adjacent
  storeys
• Reconstructed muon flux
• Simulation Corsika
• with Hörandel flux (1) and QGSJet 0.1

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Low energy threshold muon flux from adjacent
storeys

• L1 two hits in OMs of the same storey
• A2 a pair of L1 on two adjacent storeys
  compatible with the muon travel time
• Taking into account correlated A2 ? the number of
  muons at depths between 2030 to 2380 m

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Low energy threshold muon flux from adjacent
stories

• Systematic errors
• OM angular acceptance 40/-30
• absolute normalization of PMT efficiency /-15
• water properties 5/-15.

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FIVE LINE DETECTOR RESULTS

• Two analyses
• Low energy threshold muon flux from adjacent
  storeys
• Reconstructed muon flux

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Measurement of the muon flux

• ltmgtMC1.19 is the simulated multiplicity (for
  every zenith angle)
• Effreco95 is the reconstruction efficiency
• Areaeff is the effective area at the trigger
  level
• ?T is the time duration of the data taking
• 17.8 days

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Effective Area at trigger level

• Effective area for muons with
• Egt20 GeV

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Systematic effect (1)
Loss in the muon flux when the angular acceptance
is changed from simulation to measurements
Angle between the optical module axis and the
photon
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Systematic effect (2)
Loss/gain in the muon flux when the absorption
length is increased/decreased by 10
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Preliminary systematics

• Charge calibration effect 10 (being estimated)
• Absorption length 25
• Angular acceptance
• -35 presented
• 20due to uncertainty of angular acceptance
  between two different OMs
• Summary from all of the above -4433

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Muon atmospheric flux at 2000 m
(1) (2)
preliminary
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Verticalization reminder
Sea level
?
H
?
H / cos ?

• To take into account the zenith dependence
• (? sec?) of muon flux at sea level (up to 60)

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Depth Intensity Relation
preliminary
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Comparison with world data
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Conclusion

• ANTARES was designed to detect up-going muons
  (OMs looking downwards, upper part of the OMs in
  black).
• The large number of downgoing muons allows a good
  understanding of our detector first estimations
  of the muon flux in ANTARES ? in agreement with
  the world data.

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Back up
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Comparison Mupage/okada
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Data

• We choose 17.8 days of data in June 2006.
• We have more that 2.3 M events.
• In muon studies, we are limited by the systematic
  errors
• With 2.3 M events, we do not have any
  significative statistical errors.

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Effect of the MC on the flux

• If number of events in the simulation increase,
  then the flux decreases

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Angular resolution
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Angular acceptance and efficiency

• A new parameterization for the angular
  acceptance (GEANT4 Genova acceptance) have been
  sent to Annarita
• The uncertainty to attribute to the a.a. is being
  presently evaluated 20

Scattering between the measurements of two Oms
cos?C