The KM3NeT Research Infrastructure will consist of a network of deep-sea neutrino detectors in the Mediterranean Sea with user ports for Earth and Sea sciences.
The KM3NeT neutrino detectors employ the same technology and neutrino detection principle, namely a three-dimensional array of photosensors that is used to detect Cherenkov light produced by relativistic particles emerging from neutrino interactions. From the arrival time of the Cherenkov photons (~nanosecond precision) and the position of the sensors (~10cm precision), the energy and direction of the incoming neutrino, as well as other parameters of the neutrino interaction, can be reconstructed. The main difference between different detector designs are the density of photosensors, which is optimised for the study of neutrinos in the few-GeV (ORCA) and TeV-PeV energy range (ARCA), respectively.
The KM3NeT neutrino detectors employ the same technology and neutrino detection principle, namely a three-dimensional array of photosensors that is used to detect Cherenkov light produced by relativistic particles emerging from neutrino interactions. From the arrival time of the Cherenkov photons (~nanosecond precision) and the position of the sensors (~10cm precision), the energy and direction of the incoming neutrino, as well as other parameters of the neutrino interaction, can be reconstructed. The main difference between different detector designs are the density of photosensors, which is optimised for the study of neutrinos in the few-GeV (ORCA) and TeV-PeV energy range (ARCA), respectively.
A key technology of the KM3NeT detectors is the Digital Optical Module (DOM), a pressure-resistant glass sphere housing 31 small 3-inch photo-multiplier tubes (PMTs), their associated electronics and calibration devices. The segmented photo-cathode of the multi-PMT design allows for uniform angular coverage, single-photon counting capabilities and directional information on the photon arrival direction. The DOMs are distributed in space along flexible strings, one end of which is fixed to the sea floor and the other end is held close to vertical by a submerged buoy. Each string comprises 18 DOMs. The strings are connected to junction boxes that provide connections for power and data transmission.
A collection of 115 strings forms a single KM3NeT building block. The modular design allows building blocks with different spacings between strings/DOMs, in order to target different neutrino energies. In the KM3NeT Phase-2.0, three building blocks are foreseen: two KM3NeT/ARCA blocks, with a large spacing to target astrophysical neutrinos at TeV energies and above; and one KM3NeT/ORCA block, to target atmospheric neutrinos in the few-GeV range.
The ARCA (Astroparticle Research with Cosmics in the Abyss) detector is being installed at the KM3NeT-It site, 80km offshore the Sicilian coast offshore to Capo Passero (Italy) at a sea bottom depth of about 3450m. About 1 km^3 of seawater will be instrumented with ∼130,000PMTs. The ORCA (Oscillation Research with Cosmics in the Abyss) detector is being installed at the KM3NeT-Fr site, 40km offshore Toulon (France) at a sea bottom depth of about 2450m. A volume of about 8 Mton is instrumented with ∼65,000PMTs.
The ARCA (Astroparticle Research with Cosmics in the Abyss) detector is being installed at the KM3NeT-It site, 80km offshore the Sicilian coast offshore to Capo Passero (Italy) at a sea bottom depth of about 3450m. About 1 km^3 of seawater will be instrumented with ∼130000PMTs. The ORCA (Oscillation Research with Cosmics in the Abyss) detector is being installed at the KM3NeT-Fr site, 40km offshore Toulon (France) at a sea bottom depth of about 2450m. A volume of about 8 Mton is instrumented with ∼65000PMTs.
Technical details on the detector design are given in [1].
