The deployment of five new ARCA (Astroparticle Research with Cosmics in the Abyss) detection lines took place at the beginning of April in the KM3NeT research infrastructure, which houses a new generation of neutrino telescopes off the coast of Sicily: a major milestone for the KM3NeT collaboration, which brings together 300 people worldwide, including a team of engineers and researchers from SUBATECH. With the six ORCA (Oscillation Research with Cosmics in the Abyss) detection lines, the KM3NeT neutrino observatory now has a sensitivity comparable to that of its predecessor, the ANTARES telescope.
At a depth of 3,500 m on the bottom of the Mediterranean Sea, about 80 km off Capo Passero in Sicily, the ARCA telescope and its twin ORCA, located off Toulon in France, will enable scientists to identify astrophysical sources of high-energy cosmic neutrinos and to study the fundamental properties of the neutrino itself.
When completed, the KM3NeT/ARCA detector will form a network of more than 200 detection lines. Each is 700 m high and comprises 18 optical modules equipped with ultra-sensitive light sensors that record the faint flashes of light generated by particles produced after neutrinos interact in the Mediterranean seabed. A giant of a telescope!
An important step for SUBATECH
In early April, five new units were deployed, tested and connected to the seabed network. Their deployment is in addition to the first detection unit of the device, deployed in 2015. The SUBATECH team was directly involved in this latest operation: participating in starting the telescope in its new form and, in particular, in the implementation and optimisation of all the acoustic elements essential to the control of its geometry and, consequently, to its pointing accuracy.
The team was also called upon to contribute urgently to the integration of optical modules. Indeed, one of the sensors assembled in Nantes had to be sent to Catania to replace a defective module on one of the lines prepared for this deployment. The first sensor assembled at SUBATECH is now in operation at a depth of 3,500 m.
This amazing offshore operation is a milestone for KM3NeT, which is now ready to support the massive construction of the devices at both sites.
Credit: KM3NeT Collaboration and IMT Atlantique
by Pierre-Hervé VAILLANT