Hunting for Cosmic Neutrinos in the Deep Sea —The ANTARES Neutrino-Telescope
Alexander KappesPhysics InstituteUniv. Erlangen-Nuremberg
October 11, 2005Univ. Wisconsin, Madison
Introduction The ANTARES Neutrino Telescope Results from MILOM and Line0 The Future: KM3NeT
October 11, 2005 Univ. Wisconsin, Madison
2Alexander Kappes Univ. Erlangen-Nuremberg
Cosmic Radiation Discovered in 1912 by
Victor Hess during a balloon flight
At high energies predominantlyconsists of:protons and particles
satellites/balloons shower detectors
What are the sources
and
acceleration mechanisms?
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Messengers from Deep Space
Gammas (R~150 Mpc @ E=10 TeV)produced in electron or hadron acceleration
Protons E>1019 eV (R~50 Mpc)
Protons E<1019 eV
NeutrinosCosmicAccelerator
Neutrino production: Reaction of accelerated protons with interstellar medium, 3K microwave background radiation or synchrotron radiation
p + p() → + X + e + e +
) observation of prove for hadron acceleration Neutrino oscillation results in e : : ≈ 1 : 1 : 1
e : : ≈ 1 : 2 : 0
N () ≈ N ()
Magnetic fields
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Detection of Cosmic Neutrinos
A ! X
Earth used as shield against all other particles
Čerenkov light:
Čerenkov angle: 42o
wave lengths used: 350 – 500 nm
low cross section requires large detector volumes
key reaction: + N ! + X
Detector deployed in deep water / ice to reduce downgoing atmospheric muons
p
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Physics with Neutrino Telescopes
GeV TeV EeVPeV E
Low energy limit: short tracks
) only few photo sensors give signal
in sea water:40K + bioluminescence give high background
can only be lowered with a denser instrumentation of the water/ice
High energy limit: flux decreases with
E-2 … E-3
Large volumes required
. . . and also: - GZK neutrinos- supernova detection- magnetic monopoles- . . .
Dark Matter (WIMPs):direction, energy
Cosmic point Sources:direction, (energy)
Diffuse neutrino flux:energy, (direction)
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Current and Future Neutrino Telescopes
AMANDA AMANDA IceCubeIceCubeMedium: iceMedium: ice
Data since 1997 Data since 1997 under constructionunder construction
NESTORNESTORMedium: sea water;Medium: sea water;under constructionunder construction
ANTARESANTARESMedium: sea water;Medium: sea water;under constructionunder construction
BAIKALBAIKALMedium: fresh water;Medium: fresh water;
Data since 1991Data since 1991
R&D project for kmR&D project for km33 detector: NEMO (Mediterranean) detector: NEMO (Mediterranean) Future project (kmFuture project (km33): KM3NeT (Mediterranean)): KM3NeT (Mediterranean)
October 11, 2005 Univ. Wisconsin, Madison
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Why a telescope in the Mediterranean? Sky coverage complementary to AMANDA/IceCube Allows observation of the Galactic Centre
South Pole Mediterranean
Sources of VHE emissions (HESS 2005)
notnotvisiblevisible
Mkn 501Mkn 501
Mkn 421Mkn 421
CrabCrab
SS433SS433
Mkn 501Mkn 501
SS433SS433
CrabCrab
VELAVELA
GalacticGalacticCentreCentre
not visiblenot visible
RX J1713RX J1713Galactic CentreGalactic Centre
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Neutrinos from H.E.S.S. Sources?
Example: SNR RX J1713.7(shell-type supernova remnant)
W. Hofmann, ICRC 2005
Acceleration beyond 100 TeV.
Power law energy spectrum, index ~2.1–2.2.
Multi-wavelength spectrum points to hadron acceleration
) neutrino flux ~ flux Detectable in current and/or
future neutrino telescopes?!
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The ANTARES Collaboration
20 Institutes from20 Institutes from6 European countries 6 European countries
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The ANTARES Detector46
0 m
70 m
14.5
m
Str
ing
OpticalModule
JunctionBox
Buoy
Submersible
Cab
le to
Sho
re s
tatio
n
artist´s view(not to scale)
Hostile environment: pressure up to 240 bar sea water (corrosion)
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One of 12 ANTARES Strings
Buoy keeps string vertical
(horizontal displacement < 20 m)
Storey 3 optical modules (45o downwards) electronics in titanium cylinder
EMC cable copper wires + glass fibres mechanical connection between storeys
Anchor connector for cable to junction box control electronics for string dead weight acoustic release mechanism
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An ANTARES Optical ModuleGlass spheres: material: borosilicate glass (free of 40K) diameter: 43 cm; 1.5 cm thick qualified for pressures up to 650 bar
BB-screening-screening
optical moduleoptical module
Photomultipliers (PMT): Ø 10 inch (Hamamatsu) transfer time spread (TTS) = 1.3 ns quantum efficiency:
> 20% @ 1760 V (360 < < 460 nm)
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Calibration systems
Time calibration with pulsed light sources required precision: 0.5 ns (1ns = 20 cm) 1 LED in each optical module Optical emitter
- LED beacon at 4 different storeys- Laser at anchor
Acoustic positioning system required precision: < 10 cm receiver (Hydrophone) at 5 storeys 1 transceiver at anchor autonomous transceiver on sea bottom
Tiltmeter and compass at each storey
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DAQ and Online Trigger Data acquisition:
signals digitized in situ(either wave-form or integrated charge (SPE))
all data above low threshold (~0.3 SPE)sent to shore
no hardware trigger
Online trigger: computer farm at shore station (up to 100 PCs) data rate from detector ~1GB/s
(dominated by background) trigger criteria: hit amplitudes,
local coincidences, causality of hits trigger output ~1MB/s = 30 TB/year
Computer CentreComputer Centre
Control room
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Online Trigger Each PMT sends frame with hits of last 13 ms to shore all 1800 concurrent frames (2 per PMT) are combined to 1 timeslice
which is analysed by the online trigger on one PC:
Trigger logic: Level 1: coincidences at one storey (t < 20 ns)
or large individual signal (& 2.4 SPE)
Level 2: causality condition t < n / c · x
Level 3: accept if sufficiently many causally related hits exist
cos C = 1 / n
Choice of trigger parameters:discard background events to match allowed trigger output rate (~1 MB/s)
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Online TriggerImportant performance criteria: CPU time per event Scaling of trigger rate with increasing background rate Efficiency for E < 1 TeV ) Dark Matter (WIMP) search Increased sensitivity for certain directions (directional trigger)
) WIMP & point sources
EfficiencyEfficiencyBckg rate
First studies: Efficiency 100 GeV < E < 1 TeV increases by factor ~2 using directional trigger
but a lot of CPU power required
) further investigations necessary
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Optimising the Online Trigger causality relation: t < n / c · x xmin = minimum of distances of all hit pairs in an accepted
eventMuons E > 10 GeVMuons E > 10 GeV Background (100 kHz)Background (100 kHz)
Cut @ xmin < 60 m: Background suppression ≈ 97%, Efficiency loss ≈ 1.5%
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Signatures of Neutrino Reactions
Two basic light sources: Čerenkov photons from muon
track-like source Čerenkov photons from shower
hadronic or electromagnetic “point-like” source
visible in detector in all combinations
electromagn.shower
hadronicshower
muon track
hadronicshower
hadronicshower
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Position reconstruction: use timing and position information
(xi ,yi ,zi ,ti) of N hits
distance di between assumed shower position (x,y,z,t) and OMi:
subtract di in pairs ) N-1 linear equations
solve system of linear equations algebraically ) # hits ¸ 5 (on at least 3 lines)
Shower Reconstruction with ANTARES(PhD thesis B. Hartmann)
Results (no cuts): Position resolution: ~1 m shift due to elongation of shower
(Preliminary)position resolution
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Shower Reconstruction with ANTARES
Direction and energy reconstruction: prefit for direction and energy final parameters (, , E) ) Log-Likelihood fit
Ni = # photons in PMT i
# photons
parameterisationof c distribution
PMT opening angle
absorption
PMT angularefficiency
Results (no cuts): Event sample: Instrumented volume
+ 1 absorption length Angular resolution: < 13o (E > 10 TeV) but large tails in distributions Energy resolution: log(E) ¼ 0.1
(E > 100 TeV; 60 kHz bckgr per PMT,)
(Preliminary)
60 kHz bckgr per PMT
(Preliminary)
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Shower Reconstruction with ANTARESNew idea for minimization strategy:(Diploma thesis R. Auer)
common to all events: each minimum lies in broad valley
impose grid on parameter plane (, , E) and calculate likelihood for centre of tiles
take l tiles with best likelihood values and divide those into sub-tiles) compare L of sub-tiles within one tile
stop after k iterations ( k ¼ 7) and take tile with best likelihood
Likelihood in - plane
60 kHz bckgr per PMT
(Preliminary)
Results (no cuts): Event sample: fully contained
events;30 TeV < E < 50 TeV
L function: similar to previous one angular resolution: ~2.4o
no tails in distribution
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New Test-Lines: MILOM and Line0
Deployed March 2005, connected April 2005
MILOM: Mini Instrumentation Line with Optical Modules
Line0: full line without electronics(test of mechanical structure)
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MILOM setupOptical components: equipped with final electronics 3+1 optical modules at two storeys timing calibration system:
two LED beacons at two storeys Laser Beacon attached to anchor
acoustic positioning system: receiver at 1 storey transceiver (transmitter + receiver)
at anchor
allows to test all aspects of optical line
Instrumentation components: current profiler (ADCP) sound velocimeter water properties (CSTAR, CT)
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First results from MILOM (selection)
Single photon resolution (threshold 4 mV ¼ 0.1 SPE)
PMT charge spectrumpulse shape
single photon peak
Time (ADC channel)0 40 80 120
time (a.u.)
amp
litu
de
(a.u
.)
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First results from MILOM (selection)Time calibration with LED beacons: Determination of the relative time offset of 3 optical modules
at same storey Usage of large light pulses ) TTS of PMTs small
Time difference between optical modules
Contribution of electronics to time resolution ca. 0.5 ns
t OM1 – OM0 t OM2 – OM0
=0.75ns =0.68ns
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First results from MILOM
MILOM is a success:
Data readout (waveforms + SPE) is working as expectedand yields ns timing precision
In situ timing calibration reaches required precision for target angular resolution (< 0.3o für E & 10 TeV)
All environmental sensors are working well
Continuous data from Slow Control (monitoring of various detector components)
Lots of environmental and PMT data are available andare currently analysed
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Line0 deployed to test mechanical structure equipped with autonomous recording devices
water-leakage sensors sensors to measure attenuation in
electrical and optical fibres recovered in May 2005
Results: no water leaks optical transmission losses at entry/exit of cables into/out of
electronics containers Effect caused by static water pressure;
Reason understood and reproduced in pressure tests Solutions available; detector installation not significantly delayed
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ANTARES: further schedule
Assembly of first complete string (Line 1) started last week
Deployment and connection ca. January 2006
Completion of the full detector until 2007
From 2006 on: physics data!
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The future: km3 detectors in the Mediterranean
HENAP Report to PaNAGIC, July 2002:
“The observation of cosmic neutrinos above 100 GeV is of great scientific importance. ...“
“... a km3-scale detector in the Northern hemisphere should be built to complement the IceCube detector being constructed at the South Pole.”
“The detector should be of km3-scale, the construction of which is considered technically feasible.”
October 11, 2005 Univ. Wisconsin, Madison
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Towards a km3 scale detector
scale up
new designthin out
Existing telescopes “times 50“:• to expensive• to complicated:
production/installation takes forever,maintenance impossible
• not scalable (band width, power supply, ...)
R&D required:• cost effective solutions: reduction
price/volume by factor & 2• Stability
Aim: maintenance free detector• fast installation
time for assembly & deployment shorter than lifetime of detector
• improved components
Large volume with same number of PMTs:• PMT distance:
given by absorption length in water (~60 m) and PMT characteristics) efficiency losses for larger distances
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The future: KM3NeT
Start of the initiative Sept. 2002; intensive discussions andcoordination meetings since beginning of 2003
VLVnT Workshop, Amsterdam, Oct. 2003! second workshop 8.-11. Nov. 2005 in Catania
ApPEC review, Nov 2003. Proposal submission to EU 4. March 2004 EU offer about 9 M€, July 2005 (total budget ~20 M€); Start of the Design Study beginning of 2006;
Goal: Technical Design Report after 36 months Start of construction shortly afterwards
EU FP6: Design-Studie for a “Deep-Sea Facility in the Mediterranean for
Neutrino Astronomy and Associated Sciences”
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The future: KM3NeT
Germany: Univ. Erlangen, Univ. Kiel France: CEA/Saclay, CNRS/IN2P3 (CPP Marseille,
IreS Strasbourg, APC Paris), UHA Mulhouse, IFREMER Italy: CNR/ISMAR, INFN (Univ. Bari, Bologna, LNS Catania,
Genova, Naples, Pisa, Rom-1, LNS Catania, LNF Frascati), INGV, Tecnomare SpA
Greece: HCMR, Hellenic Open Univ., NCSR Democritos, NOA/Nestor, Univ. Athens
Netherlands: FOM (NIKHEF, Univ. Amsterdam, Univ. Utrecht, KVI Groningen)
Spain: IFIC/CSIC Valencia, Univ. Valencia, UP Valencia UK: Univ. Aberdeen, Univ. Leeds, Univ. Liverpool, Univ. Sheffield Cyprus: Univ. Cyprus
Particle/Astroparticle institutes (16) – Sea science/technology institutes (6) – Coordinator
Partners in the Design Study:(contains ANTARES, NEMO, NESTOR projects)
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Detector studies at Erlangen (S. Kuch)
The future: KM3NeT
Example (NIKHEF):
Advantages:• higher quantum efficiency• better timing resolution• directional information• almost 4 sensitivity• less penetrators
First studies running since a few months
inhomogeneous km3 detector
102 103 104 105 106 107
neutrino energy
ef
fect
ive
area 102
102
10-4
10-2
10-6
1
homogeneouskm3 detector
with same # cylinders
factor ~3 better for E < 1 TeV
Example:
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Conclusions ANTARES:
Compelling physics arguments for ANTARES Shower reconstruction very important;
algorithms with good performance available MILOM: data readout is working as expected;
in situ timing calibration sufficient to reach angular resolution < 0.3o for E > 10 TeV
Line0: mechanical structure water tight and pressure resistant;losses in optical fibres at interface ) solutions available
Installation of first complete string about Jan. 2006;Completion of the whole detector until 2007
Well prepared for physics date to come in 2006
KM3NeT: future km3-scale -telescope in the Mediterranean km3-scale telescope on the Northern Hemisphere complementary
to IceCube at the South Pole 3 year EU funded Design Study (~20 M€): expected start beginning 2006