ANTARES: a system of underwater sensors looking

for neutrinosMiguel 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

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.

M. Ardid for ANTARES CollaborationUNWAT – SENSORCOMMValencia, 18th October 2007 Introduction

ANTARES Collaboration

IFICValencia

IFREMER,Toulon & BrestDAPNIA, SaclayIReS, StrasbourgGRPHE, MulhouseCPPM Marseille IGRAP, MarseilleCOM, Marseille

ITEPMoscow

NIKHEF, AmsterdamKVI,Groningen

Genova

BariCatania

Roma

Erlangen

LNS

Pisa Bologna

Bucharest

IGIC- UPVGandia

23 Institutions from 7 European countries

M. Ardid for ANTARES CollaborationUNWAT – SENSORCOMMValencia, 18th October 2007 Introduction

Why neutrino astronomy?

Photons: absorbed on dust and radiationProtons/nuclei: deviated by magnetic fields, reactions with radiation

1 parsec (pc) = 3.26 light years (ly)

gammas (0.01 - 1 Mpc)

protons E>1019 eV (10 Mpc)

protons E<1019 eV

neutrinos

Cosmic accelerator

M. Ardid for ANTARES CollaborationUNWAT – SENSORCOMMValencia, 18th October 2007 Introduction

Why neutrino astronomy? • Neutrinos (ν’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 ν/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, …

M. Ardid for ANTARES CollaborationUNWAT – SENSORCOMMValencia, 18th October 2007 Introduction

č

43°Sea floor

p

p,

Reconstruction of trajectory (~ ) from timing and position of PMT hits

interaction

Cherenkov light from

3D PMTarray

Detection Principle

M. Ardid for ANTARES CollaborationUNWAT – SENSORCOMMValencia, 18th October 2007

Introduction

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 (< 1 ns)

M. Ardid for ANTARES CollaborationUNWAT – SENSORCOMMValencia, 18th October 2007 Introduction

8

Toulon

40 km submarine cable

-2475m

ANTARES shore station

Site

Detector overview

~70 m~70 m

4450 m50 m

JunctionJunctionBoxBox

Interlink cablesInterlink cables

40 km to40 km toshoreshore

2500m2500m• 900 PMTs • 12 lines• 25 storeys / line• 3 PMTs / storey

9 lines + IL deployed (675 PMTs) 5 lines connected and taking data (375 PMTs)

Design

Modular detector easily expandable to larger dimensionsNearby Large Infrastructures and Scientific Laboratories

Modular detector

M. Ardid for ANTARES CollaborationUNWAT – SENSORCOMMValencia, 18th October 2007 Detector overview

Hydrophone RX

Local Control Module (in the Ti-cylinder)

Optical Beacon

for timing calibratio

n (blue LEDs)

1/4 floorsOptical Module in17” glass sphere

Storey: Basic detector element

M. Ardid for ANTARES CollaborationUNWAT – SENSORCOMMValencia, 18th October 2007 Detector overview

Optical Modules

M. Ardid for ANTARES CollaborationUNWAT – SENSORCOMMValencia, 18th October 2007 Optical Modules

Optical ModulesBlow-up of an Optical Module

Gel

PMT

-metalcage

Base

LED

Sensitive area 500 cm2

Transit time spread < 3.6 ns (FWHM)

Dark count (@ 1/3 SPE) < 10 kHz Peak/valley > 2

PMT: 10”Hamamatsu R7081-20

Main specs

The 900 PMT’s have been fully characterized

0

1

2

3

4

0 100 200 300 400 500 600 700 800 900

TT

S (

ns)

TTSSpecs: < 3.6 ns

0

1

2

3

4

0 100 200 300 400 500 600 700 800 900

P/V

P/VSpecs: > 2

Data Acquisition System

DAQ Hardware

main hardware components in the electronics module of a storey

Main processes in the DAQ system

Local Control Module

COMPASS_MB

ARS_MB

LCM_DAQ

POWER_BOX

UNIV1

Inside a Local Control Module

x 3x 4 in case of LED beacon

LCM_CLOCK

For some LCM’s, additional cards for:

LED beaconHydrophone

Front-end: ARS & MotherboardThe PMT signals (anode and dynode D12) are processed by the Analogue Ring Sampler

ASIC full custom chip 4 x 5 mm2, 68000 transistors

200 mW under 5 V

In the same chip are gathered

Parameters adjustable via SC

A comparatorAn integratorA clockA Pulse Shape

Discriminator

GainGauge for PSDIntegration timingThresholds …

The motherboard is equipped with 3 ARS’s. By mean of a token ring, 2 of them are

activated in turn reduction of dead time 3rd one used for complementary trigger

purposes

Flash ADC (up to 1GHz sampling)

Pipe-line memoryFast output port (20 Mb/s)

M. Ardid for ANTARES CollaborationUNWAT – SENSORCOMMValencia, 18th October 2007 Data Acquisition system

DAQ Board & Data TransmissionThe main functions of the DAQ board are:

Readout and packing of the data produced by the ARS’s.

Transmission of the resulting data through the line network.

Processing of slow control messages.

Conversion to optical signals on 1 fiber (100 Mb/s)

At the level of the MLCM (i.e. sector level):

RISC-processor

Ethernet node

Bi-directional transceiver

Cf. next slide

LCM

LCM

LCM

LCM

MLCM 1

100 Mb/s link

optical bi-directional signals are merged 2 fibers (Rx and Tx) ensure the

communication with the SCM The color is different for each sector

SCM

MLCM 2

MLCM 3

MLCM 4

MLCM 5

1 Gb/s link

At the level of the SCM (i.e. line level):

colors are (de)multiplexed by DWDM’s the communication with shore is done via

two fibers per line through the Junction Box

MUX

deMUX

To shore (MEOC)

JBLine 1

Line

2

M. Ardid for ANTARES CollaborationUNWAT – SENSORCOMMValencia, 18th October 2007 Data Acquisition system

Slow control

Dedicated -controller with ADC’s and DAC’s

In combination with the acoustic positioning:

positions in space of the optical modules

Managed by the main processorMessages (requests and answers) are interleaved with ARS data (same fiber)

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

Dedicated circuit with:

Main performances:.5 to 1 for compass bearing.2 for tilt angles1 T for magnetic field

TCM2

2-D inclinometers for roll and pitch measurements

3-D magnetometers for compass bearing

reconstruction of the line shape

Main tasks:Configuration of the detector (for instance ARS’s)Supervision of the state of the detector: temperature, voltages, consumption …

Data Acquisition system

Calibration systems

• Main calibration systems are presented in other talks: – Positioning Calibration (P. Keller’s talk)

• To determine and monitor the position of optical modules

– Timing Calibration (F. Salesa’s talk)• To know the time offsets and get a good timing resolution

– Instrumentation Line + Acoustic detection (R. Lahmann’s 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

M. Ardid for ANTARES CollaborationUNWAT – SENSORCOMMValencia, 18th October 2007 Calibration systems

Construction milestones

• 1996-1999: R&D and site evaluation period.• 1999-2004: Prototype lines• 2004-2005: Final design line evaluation: Line0 (test of

mechanics) & MILOM (Mini Instrumentation Line with Optical Modules)

• February 2006-October 2007: 9 lines + IL deployed, 5 lines connected and operational, starts standard operation

• March 2008: The whole detector will be finished and ready to work at full efficiency for science operation

M. Ardid for ANTARES CollaborationUNWAT – SENSORCOMMValencia, 18th October 2007 Construction Milestones

Line 1 deployment

Construction Milestones

ROV connection of Line 1

M. Ardid for ANTARES CollaborationUNWAT – SENSORCOMMValencia, 18th October 2007 Construction Milestones

Pictures courtesy of IFREMER

Downgoing muon

Hundreds of neutrino candidates already detected

M. Ardid for ANTARES CollaborationUNWAT – SENSORCOMMValencia, 18th October 2007 Construction Milestones

Upward going muon track reconstructed (height vs. time, = 69º) during shift 07/09

Track predicted depending on orientation

Summary and conclusions

M. Ardid for ANTARES CollaborationUNWAT – SENSORCOMMValencia, 18th October 2007

• 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. Bigongiari’s talk)

Summary and conclusions

ANTARES: a system of underwater sensors looking for

neutrinos

Thank you for the attention

M. Ardid for ANTARES CollaborationUNWAT – SENSORCOMMValencia, 18th October 2007 The End