The KM3NeT-Fr infrastructure
The infrastructure of KM3NeT-Fr is part of the Mediterranean Eurocentre for Underwater Sciences and Technologies – MEUST. The KM3NeT-Fr site is located at the Mediterranean coast south of Toulon, France.
The KM3NeT-Fr deep sea installation site is located at 42°48’ N 06°02’ E about 40 km off-shore Toulon, France. It is located at a depth of about 2450 m and about 10 km west of the ANTARES neutrino telescope – the predecessor of KM3NeT. The shore station is located at the Institute Michel Pacha at La Seyne sur Mer. The location of both the ANTARES and KM3NeT-Fr (MEUST) site are visible in the picture of the map of the Mediterranean south of Toulon France.
A high-speed electro-optical network is installed on the seabed to provide power and data transmission to/from the infrastructure. The infrastructure is connected to shore via two main electro-optic cables (MEOCs). Each MEOC supplies three nodes and each node hosts eight user ports. In the baseline design, four KM3NeT detection units are daisy chained together and at least five chains are connected to each node. On each node a single user port can host earth and sea science sensors. The KM3NeT-Fr site will host the ORCA detector for particle physics.
The two MEOCs are connected to a power station at the Les Sablettes beach of La Seyne sur Mer. From there a land cable runs to the shore-station at the Institut Michel Pacha. In the shore station dedicated software running on a PC farm filters the data and applies a first selection and event reconstruction. The selected data are transmitted via a 10 GB/s link to the KM3NeT data repository at the computing centre in Lyon.
It is planned that in 2018 the shore station will be relocated to a new CNRS institute on the Ifremer campus at La Seyne sur Mer.
First phase of implementation
The first phase of the KM3NeT-Fr seabed infrastructure will comprise a single main electro-optic cable to shore, one node, seven KM3NeT/ORCA-style detection units and a single line hosting a variety of oceanographic sensors
In December 2014, the main electro-optical cable was deployed.
In April 2015, the first node of the KM3NeT-Fr deep-sea network was connected to the deep-sea end of the main cable. The node has sufficient sockets to connect at least 20 detection units, of which seven will indeed be installed in the first phase of construction of KM3NeT. Later in September 2016, the node was re-installed after the repair of the cable to shore which was damaged by a large rock at the seabed. Unfortunately, a few weeks later, the main cable faulted again; during a sea operation in November the cable was cut on board the repair ship and a new joint was made. Again bad luck: already a few days later a cable fault at a different location occurred. A new repair operation will be needed.
The foreseen next step in the implementation of the KM3NeT-Fr infrastructure is to complete the seabed network with up to six nodes for connection of the 115 detection units of the ORCA neutrino detector of KM3NeT for the determination of the relative ordering of the neutrino masses, also referred to as neutrino mass hierarchy.
Read the Memorandum of Understanding for KM3NeT-phase1 for details about the funding of the first phase of construction of KM3NeT. In the Letter of Intent for KM3NeT 2.0 the plans for the second phase of construction of KM3NeT detailed.