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XX th Rencontres de Blois. ANTARES performances with the 5 line data. K. Fratini on behalf of the ANTARES collaboration. Outline. 5 line data description calibration systematic studies on MC searching for neutrinos. XX th Rencontres de Blois K.Fratini. The ANTARES detector.
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XXth Rencontres de Blois ANTARES performances with the 5 line data K. Fratini on behalf of the ANTARES collaboration
Outline • 5 line data • description • calibration • systematic studies on MC • searching for neutrinos XXth Rencontresde Blois K.Fratini
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
Single PMT rate “burst” The detector is a grid of PMTs observing: • Cherenkov light emitted by • • e- from decay of 40K • Bioluminescense “baseline” rate 40K and bioluminescence x,t,Q track reconstruction XXth Rencontresde Blois K.Fratini
Data All data active time: ~ 80% Trigger rate: ~1 Hz (5 lines) 19106 detected m Date (2007) XXth Rencontresde Blois K.Fratini
σ = 0.4 ns 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 < 0.5 ns Time difference between the LED OB and an OM Electronics contribution less than 0.5 ns XXth Rencontresde Blois K.Fratini
Position calibration 5 position sampling points (hydrophones) 25 gradients (tiltmeter&compass data from each storey) Measured position resolution < 10 cm XXth Rencontresde Blois K.Fratini
=35o First 5 line neutrino candidate XXth Rencontresde Blois K.Fratini
Atmospheric muons: MC vs data NO quality cuts Agreement within 10% Preliminary XXth Rencontresde Blois K.Fratini
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 Rencontresde Blois K.Fratini
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 % XXth Rencontresde Blois K.Fratini
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 XXth Rencontresde Blois K.Fratini
5 line data MC true MC reco MC true MC reco Preliminary Atmospheric neutrinos • 5 line data • 100 active days • reconstruction quality cut applied • neutrino candidate: 78 XXth Rencontresde Blois K.Fratini
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 Rencontresde Blois K.Fratini
Primary all particle CR. Comparison between models Region of the primary CR spectrum producing 90% of the muons triggering ANTARES