String mechanics and

production

P.Kooijman,NIKHEF/UU

Pylos, april 2007

How do we get signals out of sphere

• For readout to work need single optical channel connection between shore and OM

• Cable with 1 or 2 fibres per OM

• 2 copper per OM

• Need breakout at each OM

Solution being investigated

• Seacon equipresure “hose-cable”• Routinely used• Pressure insensitive fiber!!• Connectors and feedthroughs relatively cheap

Design is flexible (more ways)

• Only small area where pressure needs to be held

• Cable is a tube filled with oil and whatever you want (gets bigger with more content)

duct-hose

optical/electrical contact block

(vulcanized rubber)

fibrecopper

twisted pair inert oilany combination

So how do we use it

Thin structures filled with oil

Hose with 2 fibers and two coppers

Small hose connector

Pressure resistant connectorAnd bulkhead

hoseconnectors

Hose with many fibers

cable

What else?

• At bottom of line we need container for DWDM• After that can continue again with just 2 fibers• Much cheaper (less expensive solution) at

junction box

Wet mateable copper only (2)

Wet mateable fiber only (2)

Splitter equipressure

Hose connectors

Pressure feedthrough connector many fibers

DWDMJB

100mToOM

1km

Price?

• Dont know yet – but estimates come in at around k€ 11 for a floor with OM with 38 PMs including cable

• Only one end of interlink is wet mateable – no non-destructive recovery

• Split fiber and copper in wet mateable – lose very expensive connectors

• Sofar saving of about factor 2 per unit looks feasible

So how do we build 500 strings in 5 years?

• 5 sites

• 500 strings

• 5 years

20 strings/site/year (1/fortnight)20 strings/site/year (1/fortnight)

400 OMs/site/year (10/week)400 OMs/site/year (10/week)

16000 PMTs/site/year (400/week)16000 PMTs/site/year (400/week)

Delivery

• 2000 glass spheres per year

• 80000 PMTs per year

• 100 500m cables with connectors fibres etc per year

Delivery of tested entities

test report

PMT

PMTassembly

characterizestorage /transport

assembledPMT-base

OM assembly

characterize

connector

mechanics

central electronics

STRINGassembly

characterize

test report

test report

storage /transport

storage /transport

cable

mechanics

assembledbottom

instrumentation instrumentationinstrumentation

Assembly line

And of course

• Transport to the site

• Deployment at the site at rate of 2/week• Deploy in containers

• Maybe more “daisy-chained” together (6?? With just 1 underwater connection)

Conclusions

• Cable with breakout and connector to sphere – OM can be separately built and tested – complete system test because of single connection from shore to OM

• Cable looks to be possible with OM supports and breakouts

• First look at production looks tough but never say never

• Needs significant organisation and delivery streamlining

PS

500 strings = 200 M € = 40 Antares = 2km3

Where did we save/lose money

• 38 pmt (8kEuro) vs 4 10” (6kEuro) X20• 1sphere(0.5kEuro) vs 4spheres (2kEuro) X20• Modulator + SER+DES (2kEuro) vs (0) X20• No (0 kEuro) vs 1 Ti cylinder (10kEuro) X20• Connectors (1kEuro) vs (5kEuro) X20• No connection at stringbottom (15kEuro)X1• Connectors to JB (5kEuro) vs (15kEuro) X1