The sector of the Antares line to be deployed in the NEMO site Davide Piombo – INFN sez. Genova

The Goal Deploy an Antares String jointly with the NEMO phase 2 tower to take enviromental measurements of the 3500m deep site comparables with the 2500m deep enviroment of Antares detector

three storey linked by a 100 m electro mechanical optical cable (EMC). similar to the MILOM line deployed in the Antares site in no acoustics and LED beacons present Proposed configuration

Branching unit The underwater proposal in Capo Passero

Sites Differences The new site is: 1 Km deeper 100 Km far away from shore DC Power Supply Different optic fibers type in the elettro- optical main cable

Primary tasks Qualify mechanical structures for the new pressure values Adapt the string power system to the new configuration Verify that the DWDM communications can be performed using the new cable

Present Status  qualification of the Ti containers we used the hyperbaric chamber at the NEMO shore station in Catania: 24 bar + 7 full cycles bar  qualification of a new design electro optic penetrator from SEAPROOF 7 optic fibres and 7 electric conductor tested and qualified at IFREMER in Brest  acceptance tests of the 3 EMC cables 100 m long Tests performed at the facility in Brest  Ocean Design Inter Link system defined and ordered  top buoy, 6 OMs available  New BSS components available; will be assembled in our shop  electronics and DAQ hardware under test in Genova received 1 SCM +2 LCMs, clock and DWDM systems  Power board (SPM substitution) designed and under test in Genova

Tests in hyperbaric chamber at 400 bar (3300m x 1.2) of the Antares LCM containers we used the hyperbaric chamber at the NEMO shore station in Catania: 24 bar + 7 full cycles bar test was successful on 3 LCM containers

Electro Optical connector from Seaproof LCM container Opt fibres are brought from to the pressure barrier, and directly feed thru the barrier block. The electrical conductors are terminated each side in solder pots on the pressure barrier

Qualification of connectors and cable Tested using the pressure tank in 400 bar 1 loop for the optic fibres (22 x 7 = 154 m) 2 loops for the conductors measure of -electrical insulation -electrical resistence -optical attenuation

proposed solution (cost effective) 1 interlink cable New model using an interlink cable directly attached on the BSS In order to avoid that water penetration in the Titanium containers damages the string components or cause the DC/DC switch to protection mode we insert a fuse box in the underwater interconnecting cable Tasks in progress : New BSS Model

The new BSS model

The ‘fuse’ box fuse type: LIMITRON KTK3 12 Amps) diode : high power rectifier 1kV, 200 Amps from the DC/DC converter to the SPM

The splice canister containing the ‘fuse’ box

Configuration of the SPM/SCM upper cylinder: The DC/DC converter of Capo Passero directly provides 380 V DC: no additional AC/DC trasformer needed! The SPM substitution board which includes a microcontroller has been designed to: manage the power to the line filter out the noise from and to the DC/DC converter interface, via a RS485 line, the controls with the SCM. provide the same protocol specs used in the original Antares SPM sense the power dissipation and the temperature Actually the functional tests are finished and endurance test under high current load values are in progress. lower cylinder: same SCM as for Antares without acoustic boards

The SPM substitution board

1 SPM and 2 LCMs available from Pisa and Bari 1 MLCM: to be integrated in Bari The shore station computing section is realized; 2 (+1) Pentium D class workstation with 2GB RAM. available Clock and DAQ software rebuilt on this architecture Clock software has been modified to work without the GPS signal (not needed in our application) We are now testing the sofware configuration using the SCM and the same SCM Vxworks OS used in Bari to perform the integration tests. General tests on the complete system will be done before assembling at CPPM DAQ and electronics status

DWDM Communication Computed the new optical budget values Computed the chromatic dispersion value Communication test under high optical attenuation condition

Optical Budget for the DWDM System used in the Capo Passero Antares String (Sea to Shore direction) MLCM DWDM (top) to DWDM Mux connections (only 3 storey)~ -0.1dB 300 m SMF28 string cable (EMC)~ -0.1dB DWDM Mux~ -3.0dB Splice DWDM Mux to fiber~ -0.2dB Splice in SPM~ -0.1dB 200 m Cable from SCM to DC/DC converter connector~ -0.3dB Underwater connector on DC/DC converter~ -3.0dB Splice in DC/DC converter between connector and 100Km fibre~ -0.3dB 100Km fibre~ -20dB On Shore fibre splice~ -0.2dB DWDM Demux~ -3.0dB Splice DWDM Demux~ -0.2dB Total Optical Losses~ -30.5dB Nominal Laser Output Power CQF915/208~ +7dBm Nominal APD sensitivity ERM577~ -32dBm Total Optical Margin~ 39dB Optical Margin~ 8.5dB

Chromatic Dispersion In original Antares Cable: <21 ps/nm km Cable length: 50 Km In Capo Passero Cable: [ ] ps/nm km Cable length: 100 Km The new Dispersion value is less than the original antares one

Communication Tests In order to validate the computed optical margin we use variable optical attenuators to simulate the 100 Km cable attenuation

DWDM Boards and Power supply SCM Module Optical attenuators 0-30dB Clock station And control workstations Shore station and communication tests

The proposal was submitted 2 years ago when the ‘bio’ activity in the Antares site was very high the multi site solution for the km3 was not yet explored During this time some new R&D has been developed - electro optic penetrator - simplified version of the BSS - configuration of the IL some new results in detector simulations makes interesting the in situ comparison of the two different available structures..... The string will be deployed with the NEMO tower after the deployment of the Alcatel DC/DC converter (expected at the end of 2008) Conclusion