Transcript KM3NeT
neutrinos and the sea
Els de Wolf
NIKHEF
Ilias Meeting, Prague, February 8th 2005
KM3NeT, what is it?
Design study for a Deep Sea Facility in the
Mediterranean for Neutrino Astronomy and
Associated Sciences
Objective: develop cost-effective design of
a 1 km3 neutrino telescope (~ 200 M€)
Participants from existing collaborations:
+
+
+…
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Participating countries
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Outline
Purpose of -telescopes
-telescopes in the Mediterranean
The KM3NeT project
Active Galactic Nuclei
– History
– Why in Mediterranean Sea
– Physics Motivation
– Design Requirements
Gamma-Ray Bursts
– Design Considerations
– Challenges
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Purpose of Neutrino Telescopes
Astrophysics (-astronomy):
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Identify point sources
Composition of jets
Origin of cosmic acceleration
Diffuse fluxes
(extra) galactic -sources
Particle physics:
– Dark Matter searches:
Neutralinos
– Monopoles
– Origin of UHE-cosmic rays
Neutralino search: → +…
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Neutrino Telescopes Projects
Mediterrennean
Baikal
Antares
Dumand
NEMO
NESTOR
Amanda Icecube
km3
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Detection Principle
Neutrino reactions (key reaction is mN -> mX)
Cross sections and mechanisms known from accelerators
Extrapolation to high energy (> 100 TeV) uncertain
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ANTARES
• Flexible strings
• 10” PMTs, looking downwards
• 2500 m depth
• 40 km offshore Toulon
• 70 m between strings
• 14.5 m between storeys
• One junction box
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ANTARES deep sea data
Measurements from an ANTARES Prototype String
Rate measurements: strong fluctuation of bioluminescence
background observed
Rate (kHz)
10min
10min
time (s)
Also measured: current velocity and direction, line heading and
shape, temperature, humidity, ...
Important input for preparation and optimisation of ANTARES
operation
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NESTOR
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Rigid tower structure (titanium)
Dry mateable connectors
15” up- and downward looking PMTs
3800 m deep
Near Pylos
Tower 32 m diameter
30 m between floors
144 PMTs
First floor (reduced size) deployed and
operated in 2003
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(1/N)dN/dcos(θ)
NESTOR: atmospheric muon flux
M.C. Prediction
Data Points
Zenith Angle (degrees)
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….and comparison with others
Good agreement
confirms precise understanding of
detector response, calibration,
simulation and efficiencies
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NEMO project
3340 m deep
80 km off shore Catania
16 arms per tower
20 m arm length
Arms 40 m apart
64 PMTs per tower
Up- and down-looking PMTs
Wet mateable connectors
Hierarchy of junction boxes
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NEMO objectives
Extensive site exploration
R&D for km3: architecture, mechanical
structures, readout, electronics, …
Test installation foreseen with all critical
components
Completion expected
by 2006
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History KM3NeT
July 2002: HENAP report to PaNAGIC
“... a km3-scale detector in the Northern
hemisphere should be built to complement the
IceCube detector being constructed at the South
Pole.”
October 2003: VLVT workshop in Amsterdam
ANTARES, NEMO, NESTOR
Also industrial presentations e.g. Hamamatsu,
Photonis, ETL, Saclant, Nautilus, Seacon, Ocean
Design, …
http://www.vlvnt.nl
March 2004: KM3NeT EU FP6 Design Study
submitted
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Why in the Mediterranean Sea?
Sky view complementary to ICECUBE
Deep sites (up to ~5000m) close to shore:
– shielding against atmospheric muons
– good infrastructure
– easy to reach by boat
– short cable to shore
– repair of detector line feasible
Long scattering length
– good pointing accuracy
Experience of NESTOR, ANTARES, NEMO
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KM3NeT and IceCube
Complementary sky views*:
IceCube
KM3NeT
Mkn 421
Mkn 501
Mkn 501
SS433
Not seen
CRAB
CRAB
SS433 GX339-4 VELA
Not seen
galactic
centre
Region of sky seen in galactic coordinates assuming
100% efficiency for 2 down
(*) ANTARES location provides a sky coverage of 3.5 p sr and an instantaneous common view with
AMANDA of 0.5 p sr, and about 1.5 p sr common view per day. The Galactic centre is visible 2/3 of
the time.
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Scientific motivation
HESS supernova remnant RXJ1713.7-3946
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KM3NeT Design Requirements
Effective volume: 1 km3, expandable
Angular resolution: close to intrinsic resolution (< 0.1° for muons
with Em > 10 TeV)
Maximal angular acceptance for all possible detectable neutrino
signals including down-going neutrinos at VHE
Lower energy threshold of a few 100 GeV for upward going
neutrinos with the possibility to go lower for from known point
sources
Energy reconstruction within a factor of 2 for muon events
For all neutrino flavors
Field of view: close to 4
Source tracking
→ from satellites:
Duty cycle close to 100%
Operational lifetime ≥ 10 years
Cost effectiveness ~ 200 M€ per km3
All parameters need optimisation
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Associated Sciences
KM3Net Infrastructure will cooperate with the
European Sea Floor
Observatory Network
Long term and continuous
monitoring of ocean
environment around
Europe:
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Environment and Security
Geohazards
Global change
Biodiversity
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Design Considerations
Detector architecture
Photo detection
Calibration
Mechanics
Readout and Data Transfer
Deployment and Sea operations
Power distribution
Cost (~ 200 M€)
Highly
interconnected
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Detector Architecture
Homogenous strings?
Towers?
D. Zaborov at VLVT
200 m
20 x 60 m = 1200 m
40 m
200 m
250 m
m m
m=
x 40
16 50
= 1000
m640
x 20
20 x 60 m = 1200 m
20 m
x 60 m =Top
1200
m
Top
view
view
250
50 floors
20 m step
16 floors
with 4 PMTs each
40 m floor step 25 towers, each consists of 7 strings
homogeneous lattice 20 x 20 x 20 downward-looking
PMTs are directed downwards
10 “ photomultiplier tubes
64 NEMO - towers
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Detector Architecture
Homogenous strings?
D. Zaborov at VLVT
20 x 60 m = 1200 m
20 x 60 m = 1200 m
20 x 60 m = 1200 m
homogeneous lattice 20 x 20 x 20 downward-looking
10 “ photomultiplier tubes
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Detector Architecture
Towers?
D. Zaborov at VLVT
Top view
250 m
50 x 20 m = 1000 m
250 m
50 floors
20 m step
25 towers, each consists of 7 strings
PMTs are directed downwards
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Detector Architecture
D. Zaborov at VLVT
Towers?
200 m
40 m
16 x 40 m = 640 m
200 m
Top view
16 floors
with 4 PMTs each
40 m floor step
64 NEMO - towers
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Sea Operations
Rigid towers or flexible strings?
Connection in air (no ROVs) or
wet mateable connectors?
Deployment from platform
or boat?
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Photo Detection
Glass pressure vessel < 17”
Hamamatsu 15” used by NESTOR
Requirements for photo detection:
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High QE
Large photocathode areas
Wide angular coverage
Good single photon
resolution
– High dynamic range
Example of a device discussed:
Hamamatsu HY0010 HPD
Excellent np.e. resolution
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Photo Detection Options
Large segmented photocathode
area with arrays of small PMTs
packed into pressure housings low cost!
Determine the photon direction
via, e.g.
– Multi-anodic PMTs plus a matrix of
Winston cones
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Readout and Data Transfer
The data rate from a KM3
detector will be high estimated at 2.5-10 Gb/s
Questions to be addressed:
– Optimal data transfer to shore
(many fibres + few colours,
few fibres + many colours,
etc.)
– How much processing to be
done at the optical module
– Analogue vs. digital OMs implies differing approaches to
design of front end electronics
– Data filtering will play an
important role
– Distribution of (raw?) data to
data analysis centres
One possible data
distribution concept
Application of current PP
GRID technologies to
some of these open
questions?
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KM3NeT Challenges
Design:
– Simplify off-shore electronics (‘all-data-to-shore’)
– Separate detection and calibration functionalities?
Production model:
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Start construction at end of design study (TDR)
Multiple production and assembly lines or structures
Pressure and shallow water tests at production sites
Transport and deployment ‘as is’
Site selection:
– France, Italy or Greece
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KM3NeT Production Model?
Estimated size of the production:
– 10.000 optical modules
– 400 detector units (“lines”)
– 40 calibration units
15 / day
12 / month
1.5 / month
Start of data taking: 2012
– Start design study: 2006
– Start of production: 2009
Production time
of 3 years
5 – 6 production sites are needed
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Site Selection
Final choice will depend on
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Depth
Accessibility
Distance from shore
Bioluminescence
rate
Sedimentation
Sea current
Access to high speed networks on shore
……
?
– Socio-political/regional considerations
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Summary
Compelling scientific argument for complementing
IceCube with a km3 scale detector in the Northern
Hemisphere
The Mediterranean projects NESTOR, ANTARES and
NEMO provide knowledge and experience for deep sea
telescopes
The FP6 KM3NeT Design Study has been accepted
Foreseen start of the DS early 2006
Objective of the DS: TDR end 2008
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