Acoustic positioning systems and passive acoustic monitoring of cetaceans with the KM3NeT underwater neutrino telescope

• Main Author: GUIDI, CARLO
• Other Authors: Guidi, Carlo, TAIUTI, MAURO GINO, ANGHINOLFI, MARCO, SANGUINETI, MATTEO, FERRANDO, RICCARDO
• Format: Doctoral or Postdoctoral Thesis
• Language: English
• Published: Università degli studi di Genova 2022
• Subjects: Acoustic; cetacean; KM3NeT; sperm whale; dolphin; passive; monitoring; neutrino; underwater; Settore FIS/01 - Fisica Sperimentale; Settore FIS/05 - Astronomia e Astrofisica; Settore FIS/07 - Fisica Applicata(Beni Culturali; Ambientali; Biol.e Medicin); Orca; Sperm whale
• Online Access: http://hdl.handle.net/11567/1062558; https://doi.org/10.15167/guidi-carlo_phd2022-01-25

KM3NeT (Cubic Kilometre Neutrino Telescope) is an underwater telescope for cosmic neutrinos detection and neutrino oscillation study. There are two detectors located in France, offshore the coast of Toulon (KM3NeT-ORCA, Oscillation Research with Cosmics in the Abyss) and in Italy, offshore Capo Passero, Sicily (KM3NeT-ARCA, Astroparticle Research with Cosmics in the Abyss). Each experimental setup detects the photons produced by the Cherenkov effect due to charged particles, which derive from the interactions of neutrinos with matter. In order to correctly reconstruct the original neutrino direction, energy and the interaction type, it is necessary to know very accurately the position of the photomultipliers. So, acoustic systems are used to monitor the flexible detector geometry. The detectors consist of several vertical structures, called Detection Units (DUs), along which 18 Digital Optical Modules (DOMs), each containing 31 photomultipliers, are positioned. During the deployment of the DUs the position of all the elements is measured with an acoustic positioning system, called Navigation and Absolute Acoustic Positioning System (NAAPS), with an accuracy of about 1 m. Subsequently, through a system of acoustic emitters and receivers (RAPS - Relative Acoustic Positioning System) the position of all the sensors is refined reaching an accuracy of 10 cm, sufficient for the reconstruction of the neutrino interaction events with the requested precision. Three autonomous emitters (called “Acoustic Beacons”), not synchronized with the master clock of telescope, are installed around the detector. On each DOM an acoustic piezo sensor is present and at the base of each line there is a hydrophone. In this PhD thesis, I have tested and improved the methods that are used to reconstruct the positions of the optical modules and line bases of the detector. This was done by using simulations of progressively more realistic configurations and subsequently applying the developed and tested RAPS methods on real data. In addition ...