Comex maritime expertise for neutrino research






14 Mar, 2019



Mar 14, 2019

What is a neutrino ?

Neutrinos are neutral elementary particles of virtually zero mass. They are produced during nuclear reactions generated by extremely violent cosmic cataclysms such as black holes, supernovae and the Big Bang.

Once produced, they move at a speed close to light speed. Because of their zero electric charge they move in a straight line without stopping, crossing the stars and planets as if they did not exist, all the way out to the borders of the Universe. The earth is crossed by trillions of neutrinos every nanosecond.

By their nature neutrinos are therefore extremely difficult to detect. Fortunately, on rare occasions, a high-energy neutrino collides with an atom. The collision disintegrates the atom nucleus and the neutrino transforms into another particle called muon.

The created muon continues its movement on a trajectory almost identical to that of the neutrino and can be identified thanks to the cone of blue light it generates, known as the Cerenkov radiation. In order to detect this tiny bit of light, it is necessary to use extremely sensitive detectors while operating under total darkness conditions.

Crédit photo : KM3NeT

Why and how to monitor neutrinos ?


Neutrinos contain information about the cataclysmic events that produced them. Scientists consider them as messengers.

The observation of high-energy neutrinos offers a new angle to look at the Universe.

A special kind of telescopes is used to detect and observe neutrinos. Since neutrinos almost hardly interact with matter and in order to be protected from cosmic radiation, such telescopes are usually buried underground in large liquid-filled caves.



ANTARES (Astronomy with a Neutrino Telescope and Abyss Environmental Research) : At the time of its design and erection, was the largest neutrino telescope in the northern hemisphere and the first built in a marine environment. In operation since 2006, it is installed deep down 2500 msw in the Mediterranean Sea, 40 kilometers offshore Toulon (France).

The main purpose of ANTARES is the search for cosmic neutrinos generated by violent phenomena of the Universe. It consists of 900 photomultipliers spread over 12 450 meter high lines, covering a surface of 0.1 km2.

The detected neutrinos are actually the few particles that collide with the matter in the vicinity of the detector, generating a muon that is detected by Cerenkov effect (blue light radiation). Unlike

optical telescopes, ANTARES looks downwards, across the Earth. The flow of particles crosses the Earth through the southern hemisphere and rises from the ocean floor up to the surface in the northern hemisphere.

KM3NeT (cubic Kilometer Neutrino Telescope) : Designed thanks to the feedback of the ANTARES detector, this second-generation telescope is being installed in the abyss of the Mediterranean sea.

A first detector, called ARCA (Astroparticle Research with Cosmics in the Abyss), installed offshore Sicily, is dedicated to the search for high-energy neutrinos coming from cataclysms in the Universe such as supernovae or the formation and evolution of black holes. A second detector, called ORCA (Oscillation Research with Cosmics in the Abyss), is under construction offshore Toulon. It will allow a determination of the mass hierarchy of neutrinos, precisely studying the flow of atmospheric neutrinos crossing the Earth.

These underwater infrastructures are also a subsea platform for multidisciplinary experimentation, hosting numerous studies in the fields of marine, terrestrial and environmental sciences as part of the EMSO seabed observatories..

This project is financed with the assistance of the PACA Region (Contract Plan State-Region), the French State (Regional Delegation to Research and Technology) and the European Union (European Regional Development Fund).

Comex maritime expertise for research


JANUS 2 surface support


General presentation

JANUS 2 is a 30-meter catamaran with dynamic positioning allowing our multidisciplinary team to use a large number of oceanographic and hydrographic equipment.

Mixed campaigns may be carried out, such as :

  • Comprehensive geophysical measurements and data gathering : Side scan Sonar, magnetometer, multibeam sonar, sediment echosounder.
  • Geotechnical measures : CPT.
  • Environmental Studies : Biology, Sediments.
  • ROV Inspections: Visual GVI/CVI, debris survey, ORUS 3D metrology, 3D submillimetre modelling.
  • Underwater work Support down to 2500 msw.
  • Shallow manned diving support vessel

The ROVs, which are constantly mobilized onboard the vessel, allow a very good combined operation of measurement tools at all times. This facilitates underwater inspection campaigns, without involving third parties and avoiding potential additional intermediate mobilizations.
JANUS 2 can operate two ROVs simultaneously, namely the 1000 msw SUPER ACHILLE ROV and the 2500 msw APACHE ROV.
Using two azimutal thrusters and two bow thrusters, JANUS 2 Dynamic Positioning system (DP) allows to carry out two different types of operations.


JANUS 2 can track one or several mobile devices equipped with transponders : Manned submarine, ROVs, AUVs etc. either in constant heading or in automatic alignment of the vessel with the target.
sur la cible.


The DP system maintains the vessel in a fixed position relative to the bottom using either the DGPS system or an acoustic beacon positioned at a fixed location on the sea bottom (transponder).

APACHE ROV main features

JANUS 2 is equipped with an APACHE Subatlantic hardwired underwater observation and light work vehicle remotely operated from the surface down to 2500msw deep. The APACHE is connected to its garage called “TMS” (Tether Management System) by a 120m+ umbilical lead.

The TMS also plays the role of relay and distribution : it carries the necessary power conversion system and data multiplexing unit between the robot and the surface.The TMS is mechanically attached to a 3000m power and optical fibre cable operated by means of a dedicated drum with multicore slipring at surface level.

The APACHE/TMS pair offers a robust and safe inspection solution throughout the water column, operated either in close vicinity of complex structures as well as in continuous systematic survey inspection up to 0.8 kts navigation speed, using the DP Navigation autofollow link.

Our APACHE ROV is compact, lightweight and very agile in manoeuvring. Specific equipment and tools can be installed on request (extra electrical and hydraulic power supply available.) he APACHE can be considered as a multi-instrumented platform able to meet the specific needs of missions such as: Underwater works assistance and support, photogrammetry/submillimetre 3D metrology, debris survey, CVI/GVI, TSS, SSS/SBP etc.

Main Features :

Dimensions H x W x W (mm): 820 x 900 x 700
Weight in Air/ Water (kg): 140/ Neutral
Power (kVA): 7.6 kVA/ 440 VAC, 50/60 Hz, 3 phases + neutral
Maximum operating depth (msw): 2800
Maximum operating depth (msw): 2800
Length of electric cable (msw): 2700

Propulsion :

4 thrusters
Longitudinal thrusters FW (kg): 50 / RV (kg): 40
1 Lateral thruster (kg): 30
1 vertical thruster (kg): 30

Payload (kg) : 30

Communication : FO single mode

Sensors and accessories :

1 KONGSBERG colour camera with tilting support
1 BOWTECH wide angle camera
1 BOWTECH mini camera
1 HD Camera
4 DEEPSEA POWER&LIGHT 250 W projectors
1 TRITECH Panoramic Seaprince 675 kHz sonar
1 PA500 altimeter
1 pressure sensor
1 Hydraulic Skid with 2 HYDROLEK 5-axis manipulators.
1 jetting pump
1 fluxgate gyroscope
1 ISA 500 Inertial Movement Unit MRU+altimeter (optional)(optionnel)

Automatic modes :

• Auto Heading
• Auto Altitude

At the ANTARES site

In 2012, Comex Marine Department joined the project and carried out the connection of a line of photosensitive sensors using the ROV APACHE at -2500 msw depth.

This was the first connection operation at -2500 msw carried out by means of an observation class ROV.
To meet the ANTARES work specifications, modifications had to be made to the ROV (addition of two hydraulic arms, three video channels, one optical connector cleaning system).

COMEX and the CNRS – CPPM have worked together to produce an adapted tool which was developed at the CPPM as part of the MEUST NUMerEnv KM3NeT project.

MEUST NUMerEnv Line base Design – 2500 m


Following the ANTARES programme, the Centre de Physique des Particules de Marseille (CPPM, AMU-CNRS/IN2P3) launched the MEUST NUMerEnv/ KM3NeT programme.

In 2014, as part of this project, COMEX was commissioned to design the supporting platform for the photomultiplier line. This bracket was deployed at a depth of -2500 msw in order to keep the line in position, ensure its stability and allow the underwater connection through a connecting cable to the junction box.
This platform supports the “Wet matable” connection system developed at the CPPM

In collaboration with the Foselev Marine CASTOR 2 support vessel, COMEX participated in the deployment and connection of the first KM3NeT/ORCA line as well as in the implementation of an instrumented module for environmental purposes.

The conditioned line was lowered from CASTOR 2 over a 2500 msw deep seabed. Operated from JANUS 2, the COMEX APACHE ROV witnessed the positioning of the line at 25 meter distance of the Node at the depth of 2500 msw. It then unrolled the connecting cable and connected the ODI electro-optical connectors to the main onshore-connected node. The compacted line was finally released by the ROV.

Crédit photo : CNRS Image
Crédit photo : IFREMER
Crédit phot : CPPM
Crédit photo : km3NeT

System Architecture


The architecture of the system as designed by COMEX is the result of the feedback and know-how acquired in recent years as part of its work carried out on behalf of the CPPM (Centre de Physique des Particules de Marseille) at ANTARES and NUMerEnv/ KM3NeTt offshore installations.

The infrastructure consists of 5 “nodes” distributed around the detector. Each node has a junction box connected to 2 lines (6 groups of 4 lines). The lines are spaced 20 m apart in the dense configuration (ORCA), thus requiring high precision in laying and connection operations. Lines are interconnected and connected to the junction box via an ODI type wet matable connector.

Consequently, once the Line base is laid on the bottom, the ROV recovers the connector with the connection cable wrapped onto the structure, unfolds the cable, takes the connector to the junction box and connects it using the specific tooling developed by the CPPM.

In agreement with the CPPM, COMEX wishes to keep this architecture based on a comprehensive field feedback, in order to meet the requirements of this contract and to ensure optimal maintainability of the subsea site while limiting operational costs.




These two installations were erected at a depth of 2500 msw. After nearly 20 years of operation, ANTARES is still operational and the renewed technical choices on the NUMerEnv/ KM3NeT project have benefited from the whole of this operational feedback.

Accordingly, and referring to these multiple references and experiences, COMEX demonstrates its ability to manage maintenance projects under operational conditions for facilities such as TREMAIL(hydrophone network).

COMEX as shown a marine engineering capability for the mechanical design of structures supporting hydrophones (DGA – TMF) or lines of photosensitive sensors (MEUST NUMerEnv). Its Design Department generated the necessary tools for each operation and drafted their detailed implementation procedures.

Based on its experience and feedback gained in projects similar to the one covered by this type of operations, COMEX acquired the ability to design a system architecture that meets the needs of DGA by specifying the different sub-assemblies, managing the supply, integration, implementation of interfaces and installation at subsea site.

Through its participation in sensitive Defense activities such as the design, construction, supply and installation of a high-speed visualization system for integration on the nuclear submarines launching devices of the French Marine Nationale in 2015, COMEX has demonstrated its capacity to cope with high quality standards and to address the requirements specific to such projects.

Similarly, COMEX organization showed its ability to meet the demanding requirements of secrecy and confidentiality.


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