A sensor architecture for neutrino telescopes

on behalf of the KM3NeT consortium

Els de Wolf

Thank you, Claudio!Thank you, Claudio!

Buoy

OM

OM

OM

OM

OM

10 kV / 400V

~2.6 km3

300 slender strings6000 optical modules~100 MEuro

Branch cable network on the seabed Junction box

Features of the architecture

Flexible and slender string structure Optical fibre network for communication Single high pressure transition per storey Few (active) components in the deep‐sea No application specific components in the deep-sea No fault (leak)propagation from one storey to the other

or from one string to the other One wet‐mateable connections per string

(Innovative deployment: 1/~15) Minimum of material in the deep sea ‘Low’ cost

3

reliability

Analysis of DUMAND/Antares/NEMO/Nestor

Flexible string works Fibre network works Reliability can be further enhanced Costs can be reduced

4

Reliability analysis

Minimise probability of water leaks Minimise number of pressure transitions

5

1(2?) transition (1 OM)

~Same photocathodeElectronics and all other

instrumentation a single container

9 transitions (3 OMs + Hydrophone)1 transition

multi-PMT optical module

No separate electronics container Single pressure transition per storey

(optical module = storey)

6(talk Paul Kooijman)

7

Nikhef Open Day

10/10/2009

Temperature measurements in multi-PMT optical module

Sensor concept for readout&DAQ

Laser light from shore is modulated in the (optical) module with the data through reflective modulators.

Readout on heart-beat of laser pulses from shore Front-end functionality moved to shore.

8

laser

Sensor architecture concept

Unique optical connection between each module and the shore.

9

laser

(talk Jelle Hogenbirk)

Reliability of readout/DAQ

Only few non-specific active components in the deep sea

No application-specific components in the deep sea

10

Designed to our specification by telecom technical consultancy company CIP, using their off the shelf and Bellcore certified items.

Communication network

10 Gb/s bandwidth, 50 GHz channel spacing Passive Optical Network using DWDM Fibre propagation time over 100 km

measured with precision < 100 ps

Electro-optical backbone

Flexible hose Oil filled, run at equipressure Break out at each storey Wet-mateable connection to node in branch cable

12

No propagation of failure of one storey to another

(talk Eric Heine)

First reference model

Mechanics of slender string

Minimum of material in the deep sea

13

Two dyneema ropes for mechanical strength

Simple structure to support optical module

Slender string

20 storeys String master module included in

break-out-box at storey 9 Low drag Relatively easy to deploy

Single wet‐mateable connection per string

(innovative deployment: very few)

14

Buoy

OM

OM

OM

OM

OM

BOB &DWDM

BOB

Anchor

Rope

Storey

30m

570m

100m

EOC (2 fiber + 2 Cu)

DU_CON(talk Eric Heine)

Realisation speed up

Enlarge weather window for deployment Compact and light deployment structures

Increase deployment rate Many strings in a single sea operation.

Early start of construction strings Can start while on-shore electronics is still in

development

15

16

10 kV / 400V

Junction box

Sea floor: branch cables with nodes

Compact deployment of strings

Sea floor network of branch cables with nodes

node

17

Unfurling of the string

18

Connect to node in the branch cable

~2.6 km3

300 slender strings6000 optical modules~100 MEuro

Effective area

19

Simulation and reconstruction effort started late, but is ongoingPreliminary results are promising.

Claudio Kopper

130 m string distanceUpgoing tracks only

Effective area compared to Antares

20

Antares

Energy Antares Factor

100 GeV 8x10-5 m2 - 5 (?)

1 TeV 0.005 m2 0.02 m2 5

10 TeV 0.5 m2 20 m2 40

100 TeV 3m2 120 m2 40

1 PeV 20 m2 500 m2 25

Rough comparison

Summary and conclusions

Sensor architecture with slender strings is feasible Based on experience of pre-decessors Designed for high reliable Cost effective Easy to deploy

Further improvements Improvement/avoidance wet-mateable connections Reconstruction

Preparatory phase Prototype string mechanics Prototype electro-optical cable Detailing readout and DAQ Design assembly lines for OM and string Detailing seafloor network

21

Engineering effort together with industry started

(first ideas documented)

Thank you!