1. Deep-sea neutrino telescopes
Prof. dr. Maarten de Jong
Nikhef / Leiden University

2. contents Neutrino astronomy Antares KM3NeT issues, ideas prototype
next generation neutrino telescope
issues, ideas

3. Neutrino astronomy n g p neutrinos Why neutrinos?
no absorption
no bending
Scientific motivation:
origin cosmic rays
creation& composition relativistic jets
mechanism cosmic particle acceleration
composition dark matter
neutrino telescope

4. Use sea water as target/detector
1960 Markov’s idea:
Use sea water as target/detector
range of muon
detect Cherenkov light
transparency of water

5. muon travels with speed of light (300,000 km/s) → ns (10 cm) @ km
How?
wavefront
neutrino
muon 1 2 3 4 5
~100 m
interaction
~few km
muon travels with speed of light (300,000 km/s) → ns (10 km

6. General layout light detection real-time event distribution 3-5 km
shore station
transmission
of (all) data
data
filter

7. prototype neutrino telescope
Antares
prototype neutrino telescope
‒ 100 persons
‒ 25 M€
1997‒2005
R&D
site explorations
measurements of water properties
2005‒2008
construction-operation
2008‒2017
operation

8. Antares
12 lines
~2.5 km
500 m
250 Atm.
~200x200 m2
25 storeys / line

9. Detection unit Optical beacon timing calibration 10” PMT
photon detection
Electronics
readout
Hydrophone
acoustic positioning
~1 m
titanium frame
mechanical support

10. Dutch industry
Gb/s transceiver
passive cooling
DC–DC converter

11. wet-matable connector (2)
deep-sea network
connector (3)
penetrator (2)
container
CPU
FPGA
PMT
e/o
100 Mb/s
5x15 m
optical fiber (21)
penetrator (3)
container
Ethernet
switch
1 Gb/s
e/o
e/o
5‒25x15 m
junction
box
container
DWDM
filter
optical fiber (4)
(40)
1 km
40 km
wet-matable connector (2)

12. data flow time CPU CPU CPU CPU CPU CPU off-shore on shore
Ethernet switch
data filter
data filter
data filter

13. data flow time CPU CPU CPU CPU CPU CPU off-shore on shore
Ethernet switch
data filter
data filter
data filter

14. data flow time CPU CPU CPU CPU CPU CPU off-shore on shore
Ethernet switch
data filter
data filter
data filter

15. Antares deep-sea infrastructure 1 km3 one main electro-optical cable
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 (l stability)
operation
10 years (some maintenance’
data transmission signal recovery by amplification

16. definitive neutrino telescope
KM3NeT
definitive neutrino telescope
‒ 300 persons
‒ 200 M€
2005‒2008
design study
2008‒2012
preparatory phase
2013‒2017
construction

17. Optical module (camera)
31 x 3” PMT
Electronics inside

18. wet-matable connector (1)
deep-sea network
optical modulator
lj+1
integrate timing system (GHz = ns)
minimise offshore electronics
penetrator (1)
receiver lj
receiver
laser
wet-matable connector (1)
DWDM
laser
DWDM
shore station

19. Needs new deployment technique
Storey
Frame
Mechanical cable storage
Data cable storage
Mechanical cable connection
Optical module
6 m
Mechanical holder
1 Digital Optical Module = Dom
2 Dom’s on 1 bar = Dom-bar
20 Dom-bar’s on 1 tower = Dom tower
Needs new deployment technique

21. Earth & Sea sciences short lived (rare) events dominate deep-sea life
permanent observatory
France
Temperature
Bioluminescence
sudden
Eddie currents
food supply
observatory
time profile

22. KM3NeT deep-sea infrastructure 10 km3 two main electro-optical cables
>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

23. Issues, ideas, etc.

24. 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)

25. 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)

26. Fiber technology data transmission Energy transmission sensor
laser/[A]PD
flexible (2 x transceiver = point-to-point link)
active feedback loop (intrinsically instable power, l)
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…