The Neutrino Telescope of the KM3NeT Deep-Sea Research Infrastructure

Abstract

Abstract KM3NeT is a future deep-sea research infrastructure in the Mediterranean Sea that will hold a multi-cubic-kilometre neutrino telescope. Located in the northern hemisphere, KM3NeT will be able to observe point-like sources of cosmic neutrinos in a region of the sky that includes the Galactic Centre. The KM3NeT neutrino telescope will employ a number of innovative technologies that are the main subject of this article. It is planned to install optical modules of 17 inch diameter that will contain 31 photomultiplier tubes each. Triggered data will be digitised o_-shore. The optical modules will be installed on horizontal bar structures of about 6m length. Twenty of these structures will be stacked to form a vertical tower, interconnected by ropes at 40m distances. Fundamental to achieving the required pointing position for neutrino astronomy is the knowledge of the relative positions of the photomultiplier within 20 cm. Accordingly, a time synchronisation on the nanosecond level is required to reconstruct the Cherenkov cones of charged particles produced in neutrino interactions. To calibrate the complete timing in situ, LED beacons, integrated into the optical modules, and laser beacons installed on the sea floor will be used. To calibrate the positions of the optical modules on the towers, a system of acoustic transceivers at fixed positions on the sea floor and receivers along the towers will be used. Data transmission is done over a fibre optic network employing multiplexing of up to 80 wavelength over individual fibres.