Measurement of the atmospheric muon neutrino flux with the KM3NeT/ORCA6 detector

• Main Authors: Stavropoulos, Dimitrios, Σταυρόπουλος, Δημήτριος
• Format: Doctoral or Postdoctoral Thesis
• Language: English
• Published: National Technical University of Athens (NTUA) 2024
• Subjects: Ατμοσφαιρικά Νετρίνα; Κοσμικές ακτίνες; Σωματιδιακή φυσική; Αστροσωματιδιακή φυσική; KM3NeT; Cherenkov detector; Atmospheric neutrinos; Neutrinos; Cosmic rays; Astroparticle physics; Particle physics; Φυσική; Φυσικές Επιστήμες; Σωματιδιακή φυσική και Φυσική πεδίων; Physical Sciences; Natural Sciences; Particles and fields physics; Orca
• Online Access: http://hdl.handle.net/10442/hedi/57393; https://doi.org/10.12681/eadd/57393

Atmospheric neutrinos originate from Cosmic Rays, the origin of which is an open question. They are produced in the Cosmic Ray interactions with nuclei in the atmosphere, with the properties of the specific hadronic decay channels to be loosely constrained. The lower part of their energy range is suitable to study neutrino oscillations, and to test several extensions of the Standard Model. Finally, the study of neutrinos from astrophysical sources largely profits from constraining the atmospheric neutrino flux.Despite the plethora of research topics related with atmospheric neutrinos, there is limited experimental information on their flux below the energy of 100 GeV. The aim of this work is to demonstrate that KM3NeT/ORCA is able to performa measurement of the atmospheric neutrino flux even with a preliminary detector configuration, providing the only existing up-to-date measurement of atmospheric ν µ + ν̄ µ flux after Super-Kamiokande. This thesis consists of three parts. In the first part, in Chapter 1 a brief reference on the basic concepts of neutrino physics is performed, while in Chapter 2 the flux of atmospheric neutrinos is described. In the second part, the ARCA and ORCA detectors of KM3NeT are introduced in Chapter 3, along with a description of the main detector components, the detection principle and calibration procedures. In Chapter 4, the algorithms used to simulate KM3NeT/ORCA data aredescribed, along with the detector triggers and their simulation, as well as the main event reconstruction algorithms.The part of the analysis consists of four Chapters. In Chapter 5, a neutrino event selection with high-purity is obtained from data collected with the KM3NeT/ORCA6 configuration. An overview of the ORCA6 detector configuration, of the data collected, as well as on the event simulation is given. After a description of the event preselection criteria, the final event classification, obtained using a Machine Learning Boosted Decision Tree (BDT) algorithm, is presented. A short overview of ...