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The Antares underwater neutrino telescope. Marco Anghinolfi INFN-Genova on behalf of the ANTARES Collaboration 15th Lomonosov Conference Moscow 19 August 2011. Detection Principle.

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The Antares underwater neutrino telescope

  • Marco Anghinolfi
  • INFN-Genova
  • on behalf of the ANTARES Collaboration
  • 15th Lomonosov Conference
  • Moscow 19 August 2011
detection principle
Detection Principle

Neutrinos (E > 100GeV)can be detected using the visible Cherenkov radiation produced as the high-energy charged leptons (final state of CC interactions) propagate through a transparent medium with superluminal velocity.


p, 



per year


~103 atm. 





the sky coverage of antares
The sky coverage of ANTARES
  • 42°50’ North
  • 6°10’ East

How does a muon look like?

A typical up-going event


Compaison to Monte Carlo

5-line data (May-Dec. 2007)+

9-12 line data (2008)

reconstruction BBfit v3r2,

single- and multi-line fit



1062  cand.

elevation angle 

good agreement with Monte Carlo: atmospheric neutrinos: 916 (30% syst. error)

atmospheric muons: 40 (50% syst. error)


Search for point-like n sources

Badly reconstructed

Well reconstructed

data set:

2007-2008 data

taken with

5, 9, 10, and 12

operating detector lines

uncertainties in

angle reconstruction:

median: 0.50.1O

12-line data: 0.40.1O

absolute orientation: 0.1O


The sky map in equatorial coordinates

  • 2190 selected neutrino.
  • most significant cluster (square) has p = 88% amongst background only pseudo-experiments.
  • Red circles denote the positions of the 24 sources from the candidate list.

Best Limits for the Southern sky

  • no significantsignalfound
  • limits reported for few
  • candidateneutrino sources
  • * interesting gamma/X-raysourcesforwhichmodelspredict neutrinos
  • present limits are more stringent than those obtained for the southern hemisphere by previous multi year experiments
search for a diffuse cosmic flux
Search for a diffuse cosmic  flux


Background atmospheric neutrinos have a steeply falling energy spectrum: N ~E-3.5

Many cosmic neutrino model predict much harder spectra, typically N ~E-2

→ Look for High – energy diffuse flux component


Live time: 334 days (2007-2009)

Stringent selection: 134 high energy n candidates, no atmospheric m’s

Energy estimator R: a measure of the number of delayed photons

M. Vecchi


Energy estimator

Can’t see the neutrino, only the muon when it reaches the detector

Muons above 1 TeV produce additional Cherenkov light via bremsstrahlung emission (~E)

Energy estimate R based on number of hit repetition



Results on diffuse cosmic  flux

J. Aguilar et al., Phys. Letter B 696, 16-22, 2011


On-going Physics analyses

n flux from Fermi bubbles




Two scenarios:

Su et al.: bubbles due to highly relativistic electrons emitting sincrotron radiation (GHz-WMAP)

and simultaneously produce inverse-Compton g rays.

M.Crocker & F.Aharonian: bubbles due to hadronic process : CR protons associated with long

timescale star formation in the GC and injected in the bubbles by star wind  HE neutrinos




  • If the hadronic scenario is confirmed FB
  • are possible HE neutrino sources for telescopes in the Mediteranean sea.
  • Very extended source: same analysis of diffuse neutrino flux. Need to discriminate according to energy.
  • Analysis just started: expectd
  • flux limits by the end of the year

Indirect Dark Matter searches

Neutralino search:  → +…

  • Search for neutrino signal from the Sun and from the Galactic Centre :- Analysis of data in progress
  • Studies of ANTARES sensitivity for indirect detection of DM annihilations in the Sun for various models :- Extensive scan of mSUGRA SUSY models - Study of alternative SUSY scenarios (AMSB models,…)- Study of Kaluza-Klein scenarios
  • Development of dedicated reconstruction for low energy muons :important potential gain of sensitivity for Dark Matter

Indirect Dark Matter searches

Focus point models

  • ANTARES sensitivity to DM annihilations into the Sun in mSUGRA scenarios.
  • Based on 3 years of full ANTARES data takingusing standard reconstruction
  • Background calculatedfromatmospheric neutrinos + muonsinside 3° conetowards the Sun
  • usingFeldman-Cousins approach



Searches for Neutrinos from GRB

  • Triggered search method:
  • Dedicated low level trigger after a gamma-ray satellite alert (GCN)
  • Requires Satellite trigger
  • Low backgrounds due to direction
  • and time coincidences

Searches for Neutrinos from GRB

  • Search for muons produced by neutrinos in correlation with gamma-ray bursts has been applied to the data taken during the alerts occurred in 2007:
  • candidate tracks are required to point back to
  • the GRB position to within 2° and to occur during the arrival of prompt photons, i.e. during the T90 observed by the satellite.
  • 37 GRBs in the analysis
  • No neutrino candidate muons were observed in correlation with the GRBs.
  • The limits placed on the average flux of these bursts at the 90% confidence level, for three different GRB models
  • A second search uses an alternative method to identify the shower at the neutrino-interaction vertex. This search is particularly sensitive to electron-neutrinos.

90% CL Upper limits on nu fluxes from 37 GRBs


Transient sources: Flares

  • Motivation: Fermi data shows a extremely variable HE universe
  • Main goal: search for flares mainly from blazars: strong correlation between the gamma-ray and the neutrino fluxes is expected
  • Method: adapt the un-binned method used in the point-like source by adding a time PDF
  • Data: FERMI: started July
  • 2008 => used the data taken
  • with the full 12 lines
  • ANTARES detector during
  • the last four months of 2008.

Flare selection from the Fermi catalogue

Gamma-ray light curve of the blazar

3C454.3 measured by Fermi above 100 MeV for almost 2 years of data


Transient sources: Flares

  • Selection: sources located in the visible part of the sky by Antares from which the averaged one day-binned flux in the high state is greater than 20 10-8 s-1 above 300 MeV .
  • Sources: ten very bright and variable Fermi LAT blazars.
  • Most significant event: one neutrino event has been detected in time/space
  • coincidence with the gamma-ray emission from the flare 3C279
  • p-value of about 10 %, still compatible with background fluctuations
  • Perspectives: the most recent
  • measurements of Fermi in 2009-11
  • show very large flares yielding to a
  • Promising search of neutrinos

Gamma-ray light curve of the blazar

3C279. The red bar is the time of the ANTARES neutrino event



ultra high energy cosmic rays are expected to be accompanied

by gamma-rays and neutrinos from pion decays

field of view for the ANTARES telescope and

the Pierre Auger Observatory

(PAO) greatly overlap.

correlation of arrival directions

of 2190 neutrino candidate events detected by 5-12

line ANTARES neutrino telescope, and 69 UHECRs observed

by the PAO



Crosses : ANTARES neutrino

events outside of 5.2 ° bins

centered on UHECRs observed


Triangles: ANTARES neutrino

events correlating with

observed UHECRs

The most probable count for the optimized bin size of 5.2°

is 343.34 events in all 69 bins with standard deviation of 15.69 events.

After unblinding 2190 Antares neutrino candidate events,

a count of 315 events within 69 bins is obtained  NON CORRELATION found

multi messenger astronomy
Multi-Messenger astronomy

Strategy:higherdiscoverypotential by observingdifferent probes

highersignificanceby coincidencedetection

higherefficiency by relaxedcuts

MoUs for joint research




follow up:

10 s




trigger + dedicated



GRB Coord. Network:

γ satellites


An exemple:opticalfollow-up

  • Alerts sent by ANTARES
  • High energy  (nhits & amp)
  • expected ~ 2/month
  • 2  events within 3° and 15 min
  • expected ~3.5x10-3/yr
  • 27 alerts sent in 2 years (2009-2010)
  • 17 followed
  • 9 not followed
  • 1 cancelled
  • TAROT: 2 telescopes
  • Diameter: 25 cm
  • Field of view: 1.86°×1.86°
  • Magnitude limit:18-19
  • (within 1-3 min image acq.)
  • ROTSE: 4 robotic telescopes:
  • Diameter: 45 cm
  • Field of view: 1.85°×1.85°
  • Magnitude limit:
  • ~19 for 1 minute exposure

Image analysis

under development

Image to analyze

Reference Image



… and more

  • Nuclearites
  • Close to unblinding 2007-2008 data. Good prospects for limits.
  • Oscillations
  • 3 year data can exclude (3σ) the non-oscillation hypothesis. Not competitive with MINOS, but first measurement with NT.
  • Neutrinos from galactic plane
  • Will start soon
  • CR composition
  • Hit clustering algorithm selection in progress
  • Supernova detection
  • Tough due to bioluminescence. But double and triple coincidence method have sensitivity up to 4-5 kpc provided background rate is low
  • Detection of HE γ-rays
  • In progress
  • .
  • Cosmic rays anisotropies
  • Just started

… not only neutrino detection

  • The 13th line is used for the calibration of the neutrino telescope but also contains several instruments dedicated to marine and Earth sciences and to acoustic detection
  • This facility allows the continuous monitoring of the most important characteristics of the sea water at the site of the detector
  • The data are essential for a comparison to the models which describe the deep sea waters behaviour in the Mediterranean and to the R&D for future neutrino acoustic detection


  • ANTARES today:
    • Successful end of construction phase
      • Technology proven
      • Data taking ongoing
  • First physics outputs
    • Set limits on
    • Point like neutrino sources,
    • Diffuse neutrino flux
    • Analysis in pogess on
    • Indirect dark matter search
    • Neutrino flux from FB
    • Multi messenger correlations
    • Neutrino oscillations, magnetic monopoles, VHE neutrino interactions
  • …..On the road for the next step:
    • a detector at the km3 scale in the
    • Mediterranean sea