ANTARES: a system of underwater sensors looking for neutrinos

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ANTARES a system of underwater sensors looking
for neutrinos

• Miguel Ardid
• IGIC- Universitat Politècnica de València
• on behalf of the ANTARES Collaboration
• Introduction
• Detector overview
• Optical modules
• Data acquisition system
• Calibration system
• Construction milestones schedule
• Summary and conclusions

UNWAT SENSORCOMM Valencia, 18th October 2007
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ANTARES

• ANTARES (Astronomy with a Neutrino Telescope and
  Abyss environmental RESearch) Collaboration is
  deploying a 2500 m deep 0.1 km2 underwater
  neutrino telescope in the Mediterranean Sea
• It is the largest neutrino telescope under
  construction in the northern hemisphere.
• The aim of the telescope is to detect high energy
  neutrinos, which are elusive particles expected
  from a multitude of astrophysical sources.
• ANTARES also aims to provide a research
  infrastructure for deep sea scientific
  observations.

Introduction
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ANTARES Collaboration
Erlangen
NIKHEF, Amsterdam KVI,Groningen
ITEP Moscow
Bucharest
IFREMER,Toulon Brest DAPNIA, Saclay IReS,
Strasbourg GRPHE, Mulhouse CPPM Marseille IGRAP,
Marseille COM, Marseille
Genova
Bologna
Pisa
Bari
Roma
IFIC Valencia
Catania
LNS
23 Institutions from 7 European countries
IGIC- UPV Gandia
Introduction
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Why neutrino astronomy?
Cosmic accelerator
1 parsec (pc) 3.26 light years (ly)
Photons absorbed on dust and radiation Protons/nu
clei deviated by magnetic fields, reactions with
radiation
Introduction
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Why neutrino astronomy?

• Neutrinos (?s) are elementary particles
• Extremely small mass, no electric charge, very
  small interaction difficult to detect
• Are produced in nuclear fusion (e.g. stars) or
  fission (e.g. nuclear power plants) processes
• From Sun reaching Earth 1011 ?/cm2
• Neutrinos traverse space without deflection or
  attenuation
• they point back to their sources (Search for
  astrophysical point sources)
• they allow for a view into dense environments
• they allow us to investigate the universe over
  cosmological distances (Search for Big Bang
  relics)
• Neutrinos are produced in high-energy hadronic
  processes? distinction between electron and
  proton acceleration.
• Neutrino is a good key for particle physics
  cosmology
• Magnetic monopoles, topological defects, Z
  bursts, nuclearites,

Introduction
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Detection Principle
Introduction
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Why so large? so deep? Why ?

• Why so large? Neutrino detection requires huge
  target masses due to the low probability of
  interaction ? use naturally abundant materials
  (water, ice)
• Why so deep? A large shield is needed in order to
  avoid masking from other cosmic particles ? deep
  inside the earth
• Why so many optical elements? In order to
  reconstruct the muon track, the Cherenkov light
  should be detected. Attenuation length of light
  in water 52 m.
• Why calibration systems? For the muon
  reconstruction a good accuracy of the position of
  the optical sensors is needed ( 10 cm) together
  with a good timing resolution (lt 1 ns)

Introduction
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Site
Detector overview
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Design

• 900 PMTs
• 12 lines
• 25 storeys / line
• 3 PMTs / storey

40 km to shore
9 lines IL deployed (675 PMTs) 5 lines
connected and taking data (375 PMTs)
Junction Box
Interlink cables
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Modular detector
Modular detector ? easily expandable to larger
dimensions Nearby Large Infrastructures and
Scientific Laboratories
Detector overview
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Storey Basic detector element
Optical Beacon for timing calibration (blue
LEDs) 1/4 floors
Optical Module in 17 glass sphere
Hydrophone RX
Local Control Module (in the Ti-cylinder)
Detector overview
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Optical Modules
Optical Modules
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Optical Modules
Blow-up of an Optical Module
Main specs

• Sensitive area ? 500 cm2
• Transit time spread lt 3.6 ns (FWHM)
• Dark count (_at_ 1/3 SPE) lt 10 kHz
• Peak/valley gt 2

PMT 10 Hamamatsu R7081-20
The 900 PMTs have been fully characterized
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Data Acquisition System
Main processes in the DAQ system
DAQ Hardware
main hardware components in the electronics
module of a storey
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Local Control Module
Inside a Local Control Module
x 3
x 4 in case of LED beacon
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Front-end ARS Motherboard
The PMT signals (anode and dynode D12) are
processed by the Analogue Ring Sampler
In the same chip are gathered
ASIC full custom chip 4 x 5 mm2, 68000
transistors 200 mW under 5 V

• A comparator
• An integrator
• A clock
• A Pulse Shape Discriminator

• Flash ADC (up to 1GHz sampling)
• Pipe-line memory
• Fast output port (20 Mb/s)

Parameters adjustable via SC

• Gain
• Gauge for PSD
• Integration timing
• Thresholds

The motherboard is equipped with 3 ARSs.

• By mean of a token ring, 2 of them are activated
  in turn

reduction of dead time

• 3rd one used for complementary trigger purposes

Data Acquisition system
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DAQ Board Data Transmission
The main functions of the DAQ board are

• Readout and packing of the data produced by the
  ARSs.
• Transmission of the resulting data through the
  line network.
• Processing of slow control messages.
• Conversion to optical signals on 1 fiber (100
  Mb/s)

RISC m-processor

• ? Ethernet node

Cf. next slide
Bi-directional transceiver
100 Mb/s link
To shore (MEOC)
SCM
1 Gb/s link
MUX
Line 1
JB
Line 2
deMUX
At the level of the MLCM (i.e. sector level)
At the level of the SCM (i.e. line level)

• optical bi-directional signals are merged
• 2 fibers (Rx and Tx) ensure the communication
  with the SCM
• The color is different for each sector

• colors are (de)multiplexed by DWDMs
• the communication with shore is done via two
  fibers per line through the Junction Box

Data Acquisition system
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Slow control
Managed by the main processor
Messages (requests and answers) are interleaved
with ARS data (same fiber)
Main tasks

• Configuration of the detector (for instance
  ARSs)
• Supervision of the state of the detector
  temperature, voltages, consumption

Dedicated m-controller with ADCs and DACs

• to measure temperatures and humidity
• to command/monitor high voltages on PMT
• formatting of data
• an interface with compass/inclinometers

TCM2
Dedicated circuit with

• 2-D inclinometers for roll and pitch measurements
• 3-D magnetometers for compass bearing

Main performances

• .5? to 1? for compass bearing
• .2? for tilt angles
• 1 mT for magnetic field

In combination with the acoustic positioning
reconstruction of the line shape
Data Acquisition system
positions in space of the optical modules
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Calibration systems

• Main calibration systems are presented in other
  talks
• Positioning Calibration (P. Kellers talk)
• To determine and monitor the position of optical
  modules
• Timing Calibration (F. Salesas talk)
• To know the time offsets and get a good timing
  resolution
• Instrumentation Line Acoustic detection (R.
  Lahmanns talk)
• Monitor environmental and physical variables that
  could play a role in any system of the telescope
• Equipment for marine science research
• Study the viability of the acoustic detection of
  neutrinos

Calibration systems
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Construction milestones
Construction Milestones
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Line 1 deployment
Construction Milestones
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ROV connection of Line 1
Pictures courtesy of IFREMER
Construction Milestones
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Hundreds of neutrino candidates already detected
Downgoing muon
Construction Milestones
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Summary and conclusions

• ANTARES Collaboration pursued the challenge of
  building an undersea neutrino telescope as a
  sophisticated and precise system of underwater
  sensors in a hostile environment
• The design, construction and first results have
  been shown
• After a hard job, there is now almost half
  neutrino telescope operational and working within
  specifications, and will be completed early next
  year.
• For the first time, an undersea neutrino detector
  (ANTARES) sees neutrinos (most likely
  atmospherics)
• New challenge KM3NeT, a cubic kilometre undersea
  neutrino telescope (see C. Bigongiaris talk)

Summary and conclusions
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ANTARES a system of underwater sensors looking
for neutrinosThank you for the attention
The End