ANTARES performances

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XXth Rencontres de Blois

• ANTARES performances
• with the 5 line data

K. Fratini on behalf of the ANTARES
collaboration
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Outline

• 5 line data
• description
• calibration
• systematic studies on MC
• searching for neutrinos

XXth Rencontres de Blois K.Fratini
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The ANTARES detector
2400m
12 lines 25 storeys / line 3 PMT / storey
40 km to shore
450 m
Junction box
2007 29 jan - 4 dec
60 m
Readout cables
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Single PMT rate

• The detector is a grid of PMTs observing
• Cherenkov light emitted by
• ?
• e- from ? decay of 40K
• Bioluminescense

burst
baseline rate 40K and bioluminescence
x,t,Q
track reconstruction
XXth Rencontres de Blois K.Fratini
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Data
All data active time 80
Trigger rate 1 Hz (5 lines)
19?106 detected m
Date (2007)
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Time calibration

• Relative time resolution (among OMs) depends on
• Time transit spread (TTS) in PMTs ? 1.3 ns
• Sea water properties (light scattering, chromatic
  dispersion) ? 2 ns
• Electronics calibration ? lt 0.5 ns

Time difference between the LED OB and an OM
Electronics contribution less than 0.5 ns
XXth Rencontres de Blois K.Fratini
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Position calibration
5 position sampling points (hydrophones)
25 gradients (tiltmetercompass
data from each storey)
Measured position resolution lt 10 cm
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First 5 line neutrino candidate
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Atmospheric muons MC vs data

• NO quality cuts
• Agreement within 10

Preliminary
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Estimate of some systematic effects

• Other effects?????
• environmental parameters (absorption length)
• PMT properties (efficiency, angular acceptance)

• Physics effect 30-50
• hadronic model
• indetermination on the primary flux

absorption length

• simulation uses in-situ measurements
• simulation was repeated with
• labs - 10
• labs 10

• - 20 reco track rate
• ? 25 reco track rate

XXth Rencontres de Blois K.Fratini
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PMT efficiency
PMT total efficiency photocatode area quantum
efficiency collection efficiency mu-metal cage
shadow
-15 atmospheric muon reconstructed track rate
Decrease in efficiency of 10
effect on n flux ? - 7
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PMT angular acceptance
cut-off on the angle between PMT axis and
Cherenkov photon direction
uncertainty 20-25 on reconstructed track rate
mainly downward tracks
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Atmospheric neutrinos

• 5 line data
• 100 active days
• reconstruction quality cut applied

• neutrino candidate 78

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Conclusion

• Data with 5 lines were taken for almost one year.
  People are analysing them
• atmospheric muons total systematic uncertainties
  on the reconstructed track rate in MC simulation
  due to environmental and PMT parameters 35
• atmospheric neutrinos first signal!
• 10 lines in acquisition, detector completed, soon
  12 line connection!

XXth Rencontres de Blois K.Fratini
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Primary all particle CR. Comparison between models
Region of the primary CR spectrum producing 90
of the muons triggering ANTARES
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