Study for a Real-Time Alert System for Multi-Messenger Astronomy with the KM3NeT/ARCA Neutrino Telescope

The detection of a flux of high-energy neutrinos has open a new observation window on the high-energy Universe. The KM3NeT project aims to build a network of neutrino detectors in the Mediterranean Sea: ORCA, to be installed close to the Southern French coast and dedicated mainly to study the neutrino mass hierarchy; ARCA, which represents the northern counterpart of IceCube, the largest neutrino telescope presently in data taking. In the Phase-2 configuration, ARCA will be made of 230 vertical structures, called Detection Units, each hosting 18 Digital Optical Modules, and will occupy 1 cubic kilometre. Each DOM hosts 31 PMTs for detecting the Cherenkov light emitted along the path of relativistic charged particles in sea water. The sensors are continuously stressed by light sources, such as 40K beta decay and bioluminescence, in the underwater environment, requiring the use of an on-line filtering system, called TriDAS, which is also discussed. The ARCA detector is suited to be part of a global network of observatories that perform multi-messenger astrophysical and astronomy studies. The Astrophysical Neutrino Trigger System, ANTS, presented and described in this thesis, aims to perform a very fast on-line track reconstruction to drive follow-up observations by other observatories in a multi-messenger context, for neutrino induced muons in the the energy range 10 TeV < E < 10 PeV. The capabilities of ANTS, in terms of reconstruction efficiency, purity of the reconstructed sample, angular resolution, and processing speed, are discussed.