KM3NeT, a deep sea neutrino
telescope in the Mediterranean Sea
Anastasios Belias for the KM3NeT Consortium
KM3NeT objectives
The KM3NeT Design Study
Outlook
A. BELIAS, NESTOR Institute,
Pylos, Greece
TeVPA 2009, July 13-17, SLAC
1
A n-telescope in the Mediterranean sea
We need Northern n-telescope to cover the Galactic Plane
Complementarity with Ice Cube coverage
A. BELIAS, NESTOR Institute,
Pylos, Greece
TeVPA 2009, July 13-17, SLAC
2
The KM3NeT Consortium
• Consists of 40 Institutes of 10 European States
• Includes expertise from all three precursor projects,
ANTARES, NEMO, NESTOR
• Objectives
– Build and operate an extensible km3-scale water Cherenkov
neutrino telescope in the Mediterranean Sea
– Sustain a deep-sea research infrastructure for earth and marine
sciences
• KM3NeT, a multidisciplinary research infrastructure
– Synergetic with European Multidisciplinary Seafloor Observatory
(EMSO)
A. BELIAS, NESTOR Institute,
Pylos, Greece
TeVPA 2009, July 13-17, SLAC
3
KM3NeT Objectives
• Astroparticle physics with neutrinos
– “Point sources”: Galactic and extragalactic sources of
high-energy neutrinos
– The diffuse neutrino flux
– Neutrinos from Dark Matter annihilation
• Search for exotics
– Magnetic monopoles
– Nuclearites, strangelets, …
• Neutrino cross sections at high(est) energies
• The unexpected
• Earth and marine sciences
– Long-term, continuous measurements in deep-sea
– Marine biology, oceanography, geology/geophysics, …
A. BELIAS, NESTOR Institute,
Pylos, Greece
TeVPA 2009, July 13-17, SLAC
4
The KM3NeT Design Study
• Supported by the European Union in FP6 with ~9M€,
tot. value ~20M€.
• Timeline:
• Started on Feb. 1, 2006 and will end on Oct. 31, 2009
• Conceptual Design Report published, April 2008
• Technical Design Report by end of 2009
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• Detector Target Specifications:
Effective volume ≥ 1km3
0.1o angular resolution for muons (E ≥ 10TeV)
Energy threshold few 100 GeV
Field of view close to 4π for high energies
A. BELIAS, NESTOR Institute,
Pylos, Greece
TeVPA 2009, July 13-17, SLAC
5
Deep-sea n-Telescope at work
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Upward-going neutrinos
interact in rock or sea
water.
Emerging charged
particles (in particular
muons) produce
Cherenkov light in
water.
Detection by array of
photomultipliers.
Focus of scientific
interest: Neutrino
astronomy in the
energy range 1 to 100
TeV.
A. BELIAS, NESTOR Institute,
Pylos, Greece
TeVPA 2009, July 13-17, SLAC
6
Optical Module: standard...
• A standard optical
module, as used in
ANTARES, NEMO,
NESTOR
• Typically a single large
diameter (10’’) PMT
in a 17’’ glass sphere
A. BELIAS, NESTOR Institute,
Pylos, Greece
TeVPA 2009, July 13-17, SLAC
7
… or many small PMTs
• Use up to 31 small (3’’) PMTs in
a standard 17’’ glass sphere
– very high QE PMTs
• Advantages:
– increased photocathode
area
– significant improved TTS
– directionality
– improved 1-vs-2 photoelectron separation  better
sensitivity to coincidences
• Prototype tests underway
A. BELIAS, NESTOR Institute,
Pylos, Greece
TeVPA 2009, July 13-17, SLAC
8
Electronics & Data Readout Concepts
• Front-end options studies
• New improved front-end chip
in the deep-sea
– New FPGA/CPU
• Minimize active electronics in
deep-sea
– Reflective optical
modulator
– on-shore timestamp
Submarine
Telecom cable
• Both options use fibers,
Wavelength Division
Multiplexing and Point-topoint networks
• “ALL DATA TO SHORE”
Interlink cables
A. BELIAS, NESTOR Institute,
Pylos, Greece
TeVPA 2009, July 13-17, SLAC
9
Shore station real-time processing
• ALL digitized PMT data are sent to shore
• Expected rate of ~ 100Gb/s cannot be stored
• Perform time - position correlations of
photomultiplier hits
• Correlations in real-time for the whole telescope
• Data reduction factor: ~10000
A. BELIAS, NESTOR Institute,
Pylos, Greece
TeVPA 2009, July 13-17, SLAC
10
Configuration studies
• Various geometries and OM configurations have been
studied
• None is optimal for all energies and directions
• Local coincidence requirement poses important
constraints on OM pattern
A. BELIAS, NESTOR Institute,
Pylos, Greece
TeVPA 2009, July 13-17, SLAC
11
Mechanical
structures
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Flexible tower structure:
Tower deployed in compactified
“package” and unfurls thereafter
-
String structure:
Compactified string at deployment,
unfolding on sea bed
A. BELIAS, NESTOR Institute,
Pylos, Greece
TeVPA 2009, July 13-17, SLAC
12
Deployment & Sea Operations
All deployment options require ships or platforms with GPS and DP
• Deployment with ships
or dedicated platforms.
• Ships:
Buy, charter or use
ships of opportunity.
• Platform:
Delta-Berenike, under
construction in Greece
• Deep-sea submersibles
– Remotely operated
vehicles (ROVs)
– Autonomous Undersea
Vehicles (AUVs) under study
A. BELIAS, NESTOR Institute,
Pylos, Greece
Delta-Berenike: triangular
platform, central well with crane,
water jet propulsion
TeVPA 2009, July 13-17, SLAC
13
Earth and Marine Sciences
•
Associated science
devices will be
installed at various
distances around
neutrino telescope
•
Issues addressed:
– operation without
mutual interference
– interfaces
– stability of operation
and data sharing
A. BELIAS, NESTOR Institute,
Pylos, Greece
TeVPA 2009, July 13-17, SLAC
14
•
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The candidate sites
Important Criteria
Bioluminescence rate
Biofouling
Sedimentation
Sea Currents
Absorption length
Depth
Distance from Shore
Access to shore facilities
• Long-term site
measurements
performed and ongoing
• Site decision requires
scientific, technological
and political input
A. BELIAS, NESTOR Institute,
Pylos, Greece
TeVPA 2009, July 13-17, SLAC
15
Site characterisation: Example
NESTOR 4.5
36OD31.336’
Site N / 21O 25.635’ E
Transmission length
vs
wavelength
A. BELIAS, NESTOR Institute,
Pylos, Greece
TeVPA 2009, July 13-17, SLAC
16
KM3NeT Roadmap
• Design study Feb. 1, 2006 – Oct. 31, 2009
– Produced Conceptual Design Report
– Will produce Technical Design Report (by end. 2009)
• “Preparatory Phase” EU funded ~5M€, tot. ~10M€
3/2008 – 2/2011
– Initiate political process towards convergence and legal
structure
– Prepare operation organisation & user communities
– System prototypes
– Commitment of funding agencies
• Site selection around 2010 ?
• Construction Phase 2011+
– Start on extendable km3–scale neutrino telescope
A. BELIAS, NESTOR Institute,
Pylos, Greece
TeVPA 2009, July 13-17, SLAC
17
KM3NeT Technical Design Report
will address key issues
• Maximize physics output for given budget:
• Which architecture and structure to use?
– String vs Tower concept
• How to get the data to shore?
– Electronics off-shore or on-shore
• How to calibrate the detector?
– Separate calibration and detection units
• Design of photo-detection units?
– Large vs several small PMTs
• Deployment technology?
– Dry vs wet ROV/AUV vs hybrid
A. BELIAS, NESTOR Institute,
Pylos, Greece
TeVPA 2009, July 13-17, SLAC
18
Outlook
• Joint efforts of ANTARES, NEMO, NESTOR to build a
km3-scale neutrino telescope in the Mediterranean
Sea
• The Technical Design Report will be ready by end
2009
• The Preparatory Phase started
• Towards construction to start in 2011+
• The km3-scale neutrino telescope in the
Mediterranean Sea will complement IceCube in
its field of view
A. BELIAS, NESTOR Institute,
Pylos, Greece
TeVPA 2009, July 13-17, SLAC
19
A. BELIAS, NESTOR Institute,
Pylos, Greece
TeVPA 2009, July 13-17, SLAC
20
Backup slides
A. BELIAS, NESTOR Institute,
Pylos, Greece
TeVPA 2009, July 13-17, SLAC
21
Simulations of reference detector
• Sensitivity studies with a common detector layout
• Geometry:
– 15 x 15 vertical detection units
on rectangular grid,
horizontal distances 95 m
– each carries 37 OMs,
vertical distances 15.5 m
– each OM with
21 3’’ PMTs
Effective area
of reference
detector
This is NOT
the final
KM3NeT design!
A. BELIAS, NESTOR Institute,
Pylos, Greece
TeVPA 2009, July 13-17, SLAC
22
Point source sensitivity
• Based on muon
detection
• Why factor ~3 more
sensitive than
IceCube?
– larger photocathode area
– better direction
resolution
• Study still needs
refinements
A. BELIAS, NESTOR Institute,
Pylos, Greece
TeVPA 2009, July 13-17, SLAC
23
Diffuse fluxes
• Assuming E-2
neutrino energy
spectrum
• Only muons
studied
• Energy
reconstruction not
yet included
A. BELIAS, NESTOR Institute,
Pylos, Greece
TeVPA 2009, July 13-17, SLAC
24