Deep-sea neutrino telescopes

Prof. dr. Maarten de JongNikhef / Leiden University

contents

Neutrino astronomy

Antares

‒ prototype

KM3NeT

‒ next generation neutrino telescope

issues, ideas

neutrinos

p

Scientific motivation:– origin cosmic rays– creation& composition relativistic jets– mechanism cosmic particle acceleration– composition dark matter neutrino telescope

Why neutrinos?– no absorption– no bending

Neutrino astronomy

1960 Markov’s idea:

range of muon

detect Cherenkov light

transparency of water

Use sea water as target/detector

How?

muon

wavefront1 2 3 4 5

~few km

~100 m

muon travels with speed of light (300,000 km/s) → ns (10 cm) @ km

neutrino

interaction

1.5deg.

θTeVE

General layout

lightdetection

transmissionof (all) data

datafilter

real-time event

distribution

shore station

3-5 km 800 m

50-100 km

1-2 km>1000 km

Antares

1997‒2005– R&D– site explorations– measurements of water properties

2005‒2008– construction-operation

2008‒2017– operation

prototype neutrino telescope ‒ 100 persons ‒ 25 M€

~2.5 km

500 m

250 Atm.

~200x200 m2

12 lines

25 storeys / line

Antares

Hydrophoneacoustic positioning

10” PMTphoton detection

Electronicsreadout

titanium framemechanical support

Optical beacontiming calibration

~1 m

Detection unit

Dutch industry

Gb/s transceiver

DC–DC converter

passive cooling

PMT100 Mb/s

e/o

Ethernetswitch

1 Gb/se/o e/o

optical fiber (21)

DWDMfilter

optical fiber (4)

40 km

5x15 m

5‒25x15 m

CPUFPGA

container

container

container

deep-sea network

penetrator (3)

connector (3)

penetrator (2)

wet-matable connector (2)

1 km

(40)

junctionbox

data filter data filter data filter

time

Ethernet switch

off-shore

on shore

CPU CPU CPU CPU CPU CPU

data flow

data filter data filter data filter

time

Ethernet switch

off-shore

on shore

CPU CPU CPU CPU CPU CPU

data flow

data filter data filter data filter

time

Ethernet switch

off-shore

on shore

CPU CPU CPU CPU CPU CPU

data flow

Antares deep-sea infrastructure

– 1 km3

• 900 PMTs, hydrophones, ADCP, seismometers, etc.• 10 kW, 1 GB/s

– one main electro-optical cable • 50 km, AC, 1 cupper conductor + sea return

‒ network• active multiplexing locally (Ethernet standard)• passive multiplexing based on DWDM technology

– low number of channels for reliability of offshore transceiver stability)

‒ operation• 10 years (some maintenance’• data transmission signal recovery by amplification

KM3NeT

2005‒2008– design study

2008‒2012– preparatory phase

2013‒2017– construction

definitive neutrino telescope ‒ 300 persons ‒ 200 M€

31 x 3” PMT

Optical module (camera)

Electronics inside

deep-sea network

j+1

j

optical modulator

laser

laser

receiver

receiver

integrate timing system (GHz = ns) minimise offshore electronics

DWDM shore station

DWDM

penetrator (1)

wet-matable connector (1)

6 m

Mechanical cable connection

Data cable storage

Mechanical cable storage

Frame

Optical module

Mechanical holder

Needs new deployment technique

Storey

1 Digital Optical Module = Dom2 Dom’s on 1 bar = Dom-bar

20 Dom-bar’s on 1 tower = Dom tower

suddenEddie currents

Temperature

Earth & Sea sciences

France

observatoryfood supply

Bioluminescence

short lived (rare) eventsdominate deep-sea life

permanent observatory

time profile

KM3NeT

deep-sea infrastructure– 10 km3

• >100,000 PMTs, hydrophones, ACDP, seismometers, etc.

• <100 kW, 100 GB/s– two main electro-optical cables

• 100 km, DC, 1 cupper conductor + sea return‒ network

‒ PON, point-to-point + amplification‒ new Ethernet standard

• Precision-Time-Protocol (”White Rabbit”)‒ operation

• 10 years without maintenance

Issues, ideas, etc.

Deep-sea infrastructure materials

– containers (glass, Ti, Al) mechanics

– drag, deployment, etc. cables

– dry versus oil-filled– little experience with vertical orientation

wet-matable connectors– expensive (combined fiber and cupper wires)– bulky (problems with handling)

penetrators– source of single-point-failures (error propagation)

data taking & processing network

– high-bandwidth & long haul• integration of data transmission & timing (PTP)

– (real-time) data distribution• monitoring• archival• offline analysis (astronomy, etc.)

– external triggers• satellites, other infrastructures

computing– (real-time) data processing

• algorithms (reduction of complexity & parallelization of problem)• implementation (state-of-the-art OO-programming)• hardware (multi-core, GPUs)

Fiber technology data transmission

– laser/[A]PD• flexible (2 x transceiver = point-to-point link)• active feedback loop (intrinsically instable power, )• non-negligible electrical power consumption

– modulators• wavelength, phase, intensity, polarization• very low power• reliable

– amplification• long-haul communication

Energy transmission– ?

sensor– e.g. Bragg reflectrometer as deep-sea hydrophones

• sensitivity low weight…