Transcript Document

Recent Results from the
ANTARES experiment
Manuela Vecchi
on behalf of the ANTARES Collaboration
University of Roma “La Sapienza” and
INFN
ICATPP09- Como: October 6th 2009
Outline
• -astronomy: what, where, how and why?
• The ANTARES detector...
– Detection technique
– Antares facts & figures
– Detector operation
• First Physics Analysis
– Point Source Search
– Transient Source Search
– Indirect Dark Matter Search
• Multimessenger approach
• Conclusions
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Neutrino Astronomy
 quasar
Protons and photons are absorbed or deflected since they interact with matter/radiation.
Neutrinos can travel unscattered opening a new window on the far Universe.
•
Electrically neutral  not bent by the magnetic fields
•
Interacts very slightly  escape from the dense areas of the Universe
•
No absorption  observation at cosmological distances
•
Only weakly interacting particles  low interaction cross section large detection
volume is required
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Detection principle
Neutrinos can interact in the medium surrounding the telescope.
They can be detected using the visible Čerenkov radiation
produced as the high-energy charged lepton passes through the
transparent
medium.
ANTARES
12 lines MC
3D PMT
array
Cherenkov light
from 
42°
Sea bed


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A deep underwater/ice detector is
required to reduce the number of
interaction
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atmospheric μs.
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Detection principle
Neutrinos can interact in the medium surrounding the telescope.
They can be detected using the visible Čerenkov radiation
produced as the high-energy charged lepton passes through the
transparent medium.
Our GOALs:
3D PMT
array
 Search for production
sites of HE neutrinos
Understand production
mechanisms of HE
neutrinos
Cherenkov light
from 
Search for Dark Matter
(WIMPs)
42°
Exotic particles....
Sea bed


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A deep underwater/ice detector is
required to reduce the number of
interaction
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atmospheric μs.
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The ANTARES site
Institut M. Pacha
Electro-optical
Cable of
40 km
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The ANTARES detector
• 12 Lines
• 25 storeys / line
• 3 PMTs / storey
• 885 PMTs
Buoy
Floor
14.5 m
350 m
100 m
Junction
box
Electrooptical
Cable
~60-75 m
Depth : 2475 m
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Detector Milestones
~60 m
MILOM: 17th Mar 2005
Line 1: 2nd Mar 2006
Line 2: 21st Sep 2006
Line 3, 4, 5: 29th Jan 2007
Line 6, 7, 8, 9, 10: 7th Dec 2007
Line 11, 12: 30th May 2008
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Optical Background
Decay Continuous 30kHz background
Bioluminescence  30kHz background, MHz
outbursts…
40K
40K
40

K

Ca

e


20
e
40
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Counting rate for 2 PMTs on line 1, as a function of time
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Muon flux at the detector
The data sample is dominated by the flux of atmospheric muons
propa- gating downward through the detector. Atmospheric
neutrinos contribute providing a flux that is 4-5 orders of
magnitude less abundant than that of atmospheric muons.
103 atmospheric
per year*
108 atmospheric
per year*
Atmosphere
Sea
Earth
cosmic 
* Reconstructed tracks in 12 line detector
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Track reconstruction
Track reconstructed as upgoing through the detector, as seen in the
online event display. Each box correnspond to 1 detection line.
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Track reconstruction
Depth
Track reconstructed as upgoing through the detector, as seen in the online
event display. Each box correnspond to 1 detection line.
Time
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5-lines data (2007)
2007 data - 19 •106  triggers
Total: 245 days
Selected: 168 days
Up 
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Down 
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Detected event are mainly
due to downgoing
atmospheric muons
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5-lines data (2007)
 candidate
events
Neutrino candidate events:
Data: 168 observed
MC: 1643(stat)33(theor) 16 (syst)
2007 data - 19 •106  triggers
Total: 245 days
Selected: 168 days
Up 
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Down 
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Atmospheric muons studies
Azimuth angle
distribution
Zenith Angle Distribution
data
CORSIKA (QGSJET01)
+ NSU model
MC uncert.
data
CORSIKA (QGSJET01)
+ NSU model
MC uncert.
5 lines data
Systematic uncertainty due to
uncertainties in the primary CR flux
and hadronic models.
No quality cut (QC) applied.
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data
MUPAGE
CORSIKA (QGSJET01)
+ NSU model
CORSIKA (QGSJET01)
+ Horandel model
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Point source search - 2007data
• Stringent cuts to ensure low background and
good resolution.
• Search applied to 25 selected sources.
• All-sky search has also been performed.
• Blinding policy followed
Two independent statistical methods
used: BINNED and UNBINNED
Selected sources for 2007 point source
search
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Point source search - 2007data
• Stringent cuts to ensure low background and
good resolution.
• Search applied to 25 selected sources.
• All-sky search has also been performed.
ANTARES 2007 skymap
• Blinding policy followed
Two independent statistical methods
used: BINNED and UNBINNED
5 line data
- 94
candidate neutrino events
selected in 168 active
days. No significant excess
has been found.
arXiv:0909.1262v1
Selected sources for 2007 point source
search
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Point source search - Results
Upper limits (90% c.l.), as a function of the declination, for the
selected point-like sources.
arXiv:0909.1262v1
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Search for  candidates
in correlation with GRB
alerts from satellites.
Whenever an alert is received, a
dedicated data-taking is performed.
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The satellite triggered data
taking efficiency during all
alert message broadcasts
from the GCN
arXiv:0908.0818v1
Search for transient sources
The response time of the satellite triggered
data taking in Antares to a satellite alert
message.
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Indirect dark matter search
Cold Dark Matter Candidate:
decays of neutralinos
(WIMPs) gravitationally
trapped in massive objects,
i.e. the Sun, can produce HE
s detectable by ANTARES.
arXiv:0905.2316v3
A search for s from
neutralino annihilation in the
Sun has been performed on
2007 data.
Data sample 68.4 effective days
No discovery  90% C.l. Upper limit
mSugra model predictions
green : WMAP favoured relic density
red : > WMAP favoured relic density
blue : < WMAP favoured relic density
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2007-2008 data
2007 (5 lines) :
168 d.  19 •106  triggers
2008 ( 9 lines):
173 d.  65 •106  triggers
TOTAL 341 days lifetime.
Up 
Down 
Single & multi-line
fit events are
shown.
•  MC error band (theoretical + systematic)
30%
•  MC error band (theoretical + systematic)
50%
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2007-2008 data
2007 (5 lines) :
168 d.  19 •106  triggers
2008 ( 9 lines):
173 d.  65 •106  triggers
TOTAL 341 days lifetime.
Up 
Down 
 candidate
events
All 2007/2008 silver runs ~ 1000 s
•  MC error band (theoretical + systematic)
30%
•  MC error band (theoretical + systematic)
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2007-2008 skymap
750 multilines neutrino candidates from 2007 and
2008, for 341 days of detector lifetime.
ANTARES 2007-2008 skymap (scrambled data)
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Multimessenger approach
Agreement with TAROT*:
•
optical telescope at
La Silla (CL)
•
FOV: 1.86° x 1.86°
•
Fast (~10s) re-positioning
•
Optical follow-up of
transient sources
arXiv:0908.0804v2
triggered by the ANTARES detector
The trigger is satisfied when: 1 evt with E > few TeV or 2 evts detected within  = 3° x
* Télescopes à3°.
Action Rapide pour les Objets Transitoires
Joint searches between gravitational-wave
interferometers and ANTARES.
•Possible common sources (GRBs from core-collapse
SN or from BH/NS binary merger; SGR; powerful
magnetars; hidden sources)
• Sky regions in common
www.gwhen-2009.org
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arXiv:0908.2454v1
• Expected low signals, coincidences increase chances
of detection
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Conclusions
• The ANTARES experiment is complete and taking
data.
• First analyses on 2007 data show that the detector
perfomance is well within expectactions.
• First upper limits to the flux of neutrinos from point-like
sources have been set.
• First flux limits from ‘hard’ and ‘soft’ neutralino
annihilation in the Sun have been set.
• Analysis of 2008 data is under way.
• Multimessenger approach is strongly pursued.
…detected 1000 neutrino candidates, a lot more science to
come.......
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Backup slides
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2007 data
Results of 2 independent analysis
Observed: 168 events
Observed: 185 events
MC: 1643(stat)33(theor) 16 (syst)
MC: 2184(stat)41(theor) +3-42
(syst)
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The trigger
Front end chip digitizes charge and time of a light signal
“ALL DATA TO SHORE” SCHEME:
All data transmitted through multiplexed Gigabit links
• the whole data flow can not be written to disk

Computer farm running a software trigger:
• look in all directions for light signals
compatible with a muon track
• when found, write a Physics Event
Other triggers exist:
cluster of storeys,GRBs, Galactic Center, …
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Expected performance
Effective area
Ndet=Aeff × Time × Flux
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Indirect DM search (2)
ANTARES 2007 data
Upper limit to the flux of  + anti
from neutralino annihilation in the Sun,
compared to other experiments, as a
function of neutralino mass.
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ANTARES FULL DETECTOR
Predicted measured flux of  +
anti
from neutralino annihilation in the
Sun, for the full ANTARES detector,
after 5 years.
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