1. The electro-optical cabling system for the NEMO Phase-2 tower Antonio D’Amico INFN - LNS

2. Antonio D’Amico INFN - LNS VLVnT 08 Talk layout Design criteria Detector structure Interfaces Cabling structure Serviced “Users”

3. Antonio D’Amico INFN - LNS VLVnT 08 Design criteria Fault tolerance Connectors can be Single point failures Prefer penetrators Reduce number of interfaces Modularity Adopt easy to upgrade layouts Simplicity Small number of interfaces Ease of assembly Prefer connectors Prefer light weight cables Ease of management Adopt easy to repair layouts Adopt easy to test layouts Costs Less connectors (especially optical connectors) Prefer penetrators Use standard cables

4. Antonio D’Amico INFN - LNS VLVnT 08 Modular structure  Beams (storeys) to host the instrumentation and Optical Module  Retention ropes to configure the tower in the correct geometry  Buoy to pull up the beams and keep the tower full opened Detector structure The ropes can support the backbone cabling The backbone:  is not exposed to stresses  should be light in seawater  should be flexible The floor cabling can be laid inside the beams The floor cabling  is protected by the beam  should be flexible Standard cables are suitable for this detector

5. Antonio D’Amico INFN - LNS VLVnT 08 Breakdown Structure - Interfaces Tower cabling Base cabling Backbone cabling Floor cabling JBox Jumper Acoustic Beacon Optical Modules Instruments Hydrophones JOINT JOINT

6. Antonio D’Amico INFN - LNS VLVnT 08 Design Optimization  Full Tower Backbone needs to be MODULAR in order to SIMPLIFY THE INTEGRATION PROCEDURES and to attain EASE OF HANDLING  BREAKOUT Re-Design  New BREAKOUTS designed like submarine JOINTS  ADD&DROP DWDM OPTICAL FILTERS relocated into the floor pressure vessel  ELECTRO-OPTICAL CONNECTORS REMOVED (->cost reduction and increased reliability)  Only ELECTRIC CONNECTORS at user’s interfaces P P 1 C 4 3 C P P P P 2 C C LC P Tower base module P F base 1 2 3 4 Prototype TOWER

7. Antonio D’Amico INFN - LNS VLVnT 08 Backbone - Modular Layout POD 15 BJ... POD 14 BJ POD 0 BJ  MODULARITY obtained by means of field mountable JOINTS  No optical connectors along the optical path from detector base to floor Laser into the POD  JOINTS on each floor are protected inside the storey beams o OM BASE POD BJ

8. Antonio D’Amico INFN - LNS VLVnT 08 Backbone - Electro-Optical JOINTS PP Field mountable submarine JOINT Functions:  HOST the FIBRE FUSION SPLICES  HOST the ELECTRICAL JOINTS Interfaces:  PENETRATORS (P) to interface the JOINT with the BACKBONE CABLE  EASE OF MANAGEMENT during TESTING (connectorized fibers)  EASE OF OPTICAL TESTING after FINAL INTEGRATION (fusion splices replacing the connectors) 350 bar 1 bar Pressure Vessel POD upper floor link lower floor link JOINT

9. Antonio D’Amico INFN - LNS VLVnT 08 Backbone and Floor Pressure Vessel F F BJ upper floor link lower floor link 350 bar 1 bar 350 bar Pressure Vessel P P PP main features FEEDTROUGH (F) on plastic vessel wall ELECTRICAL CONNECTOR (C) to route electrical link separately OPTICAL PENETRATORS (P) on Pressure Vessel Plastic Vessel POD C C

10. Antonio D’Amico INFN - LNS VLVnT 08 Floor Cabling - POD F F  backbone P P 2 C F OM2 OM1 H1 C DC/DC BJ OM Pressur e Vessel Plastic Vessel Instrument Hydrophones upper floor lower floor F F F F F F P P main features  point to point connection from Pressure Vessel to Users (OM, hydrophones and instruments) -> ease of maintainance and increased realiability  FEEDTROUGH (F) on plastic vessel wall  ELECTRICAL CONNECTOR (C) on pressure vessel cap and on users side (OM, hydrophones and instruments)  OPTICAL PENETRATORS (P) on pressure vessel cap for backbone fibers input/output 350 bar 1 bar 350 bar C C C C C C C C C

11. Antonio D’Amico INFN - LNS VLVnT 08 Conclusions In order to have an ease to assemble system:  Position connectors at sub-systems interfaces  it allows to have few connectors  it reduces costs.  Use light weight cables  Position connectors at users interfaces In order to minimize the Insertion Loss and Back Reflection:  few connectors  it reduces costs. Sub-systems must be testable in pressure tank:  Prefer penetrators for an easy interface with pressure tank cap or flanges.  Prefer penetrators on the backbone cable in order to have no optical “breaks” along the path  OTDR testing can be more accurate and repeatable.