Study of atmospheric neutrino oscillations with the deep-sea Cherenkov detector KM3NeT/ORCA and synergies with reactor neutrinos

• Main Author: Chau, Thien Nhan
• Other Authors: AstroParticule et Cosmologie (APC (UMR_7164)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité), Université Paris Cité, Antoine Kouchner
• Format: Doctoral or Postdoctoral Thesis
• Language: English
• Published: HAL CCSD 2021
• Subjects: Neutrino physics; Oscillations; Cherenkov detectors; Neutrino telescopes; KM3NeT; Physique des neutrinos; Détecteurs Cherenkov; Télescopes à neutrinos; [SDU.ASTR]Sciences of the Universe [physics]/Astrophysics [astro-ph]; Orca
• Online Access: https://theses.hal.science/tel-03999509; https://theses.hal.science/tel-03999509/document; https://theses.hal.science/tel-03999509/file/va_Chau_Thien_Nhan.pdf

KM3NeT/ORCA is a water-Cherenkov neutrino telescope being deployed in the depths of the Mediterranean Sea as part of the KM3NeT infrastructure. The detector is a tridimensional array of photomultipliers (PMTs) that detect the Cherenkov light induced by the charged particles produced when neutrinos interact with the surrounding matter. The configuration of the ORCA detector is optimized for the detection of atmospheric neutrinos with energies above 1 GeV. This thesis focuses on the study of neutrino oscillations with the KM3NeT/ORCA detector. It presents first the results of Monte Carlo simulations that allowed the study and modeling of the impact of systematic uncertainties related to the PMT quantum efficiency on the ORCA performances. The thesis then presents an updated sensitivity study of ORCAfor the neutrino mass ordering (NMO) and the oscillation parameters in the atmospheric sector: Δm²31 and θ23. A second study evaluates the gain in NMO sensitivity expected by combining the data of ORCA to those of JUNO, a next-generation reactor neutrino experiment being built in China. This gain results from the expected tension between the two experiments in the best-fit of Δm²31 when assuming the wrong ordering. Finally, the thesis also presents the first measurement of the oscillation parameters in the atmospheric sector using data taken with ORCA in its current configuration with 6 lines deployed (ORCA6). This study already excludes the hypothesis of non-oscillation at a high confidence level, and provides a constraint on Δm²31 and θ23 comparable to existing measurements from other experiments. KM3NeT/ORCA est un télescope à neutrinos déployé dans les profondeurs de la mer Méditerranée dans le cadre de l’infrastructure KM3NeT. Le détecteur est formé d’un réseau tridimensionnel de photomultiplicateurs (PMTs) qui détectent la lumière Tcherenkov induite par les particules chargées produites lors des interactions de neutrinos avec la matière environnante. La configuration du détecteur ORCA est optimisée pour la ...