ANTARES performances

with the 5 line data

K. Fratinion behalf of the

ANTARES collaboration

XXth Rencontres de Blois

Outline

• 5 line data– description– calibration

• systematic studies on MC• searching for neutrinos

XXth Rencontres de Blois K.Fratini

The ANTARES detectorThe ANTARES detector

60 m60 m

1122 lines lines 2525 storeys / line storeys / line 3 PMT / storey3 PMT / storey

4450 m50 m

JunctionJunctionboxbox

Readout cablesReadout cables

40 km to40 km toshoreshore

2400m2400m

200729 jan - 4 dec

XXth Rencontres de Blois K.Fratini

x,t,Q

Single PMT rate

The detector is a grid of PMTs observing:• Cherenkov light emitted by

– – e- from decay of 40K

• Bioluminescense

“baseline” rate40K and bioluminescence

track reconstruction

“burst”

Data

Trigger rate: ~1 Hz (5 lines)

19106 detected

Date (2007)

All data active time: ~ 80%

XXth Rencontres de Blois K.Fratini

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

σ = 0.4 ns

Time difference between

the LED OB and an OMElectronics contribution less

than 0.5 nsXXth Rencontres de Blois K.Fratini

XXth Rencontres de Blois K.Fratini

25 gradients (tiltmeter&compass data from each storey)

5 position sampling points(hydrophones)

Position calibration

Measured position resolution < 10 cm

=35o

First 5 line neutrino candidate

XXth Rencontres de Blois K.Fratini

NO quality cuts

Agreement within 10%

Atmospheric muons: MC vs data

Preliminary

XXth Rencontres de Blois K.Fratini

Estimate of some systematic effects

• simulation uses in-situ measurements

• simulation was repeated with:

– abs - 10 %

abs +10 %

- 20 % reco track rate

+ 25 % reco track rate

• Physics effect: ~30-50%– hadronic model– indetermination on the primary

flux

• Other effects:?????– environmental parameters

(absorption length)– PMT properties (efficiency,

angular acceptance)

absorption length

XXth Rencontres de Blois K.Fratini

PMT efficiency

PMT total efficiency:

photocatode area

quantum efficiency

collection efficiency

mu-metal cage shadow

effect on flux - 7 %

Decrease in efficiency of 10%-15% atmospheric muon reconstructed track rate

XXth Rencontres de 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 Rencontres de Blois K.Fratini

Atmospheric neutrinos

• 5 line data• 100 active days • reconstruction

quality cut applied

Preliminary

5 line data MC true MC reco MC true MC reco

• 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

Primary all particle CR. Comparison between models

100

1000

10000

1,E+04 1,E+05 1,E+06 1,E+07 1,E+08

E, GeV

Flux*E^(2.5) [m-2s-1sr-1GeV+1.5]

HORANDEL -APP23(03),193

MUPAGE- APP25(06),1

Bugaev-Ph.Rev.D58(98)054001

KASCADE- APP24(05),1

Region of the primary CR spectrum producing 90% of the muons triggering ANTARES