Through the looking glass:Reconstruction and optical studies for DUNE liquid argon detectors

Neutrinos are among the most elusive particles in the Standard Model, yet their properties provide critical insight into physics beyond it, including the origin of mass, CP violation, and the matter–antimatter asymmetry of the Universe. The Deep Underground Neutrino Experiment (DUNE) aims to address these open questions by precisely measuring neutrino flavor oscillations over a 1300 km baseline. DUNE will employ Liquid Argon Time Projection Chamber (LArTPC) detectors to achieve high-resolution, three-dimensional imaging of neutrino interactions. The first part of this thesis focuses on shower reconstruction and pion-argon cross-section measurements using 1 GeV charged-particle test-beam data from the ProtoDUNE-SP prototype at CERN. Shower reconstruction performance is evaluated using neutral pion decays, which provide an essential calibration benchmark for the electromagnetic shower energy scale. In addition, the pion-argon interaction cross section is measured for exclusive final states producing multiple pions, providing experimental data to improve the modeling of final-state interactions (FSI) in DUNE. The second part of the thesis addresses improvements to scintillation light detection in large-scale detectors. These studies include long-term stability tests of polyethylene naphthalate (PEN) in a liquid argon environment to evaluate its suitability as a structural wavelength shifter for next-generation detectors. Furthermore, this work describes the commissioning of the VULCAN optical characterization setup at Nikhef, which enables systematic optical characterization of detector materials in the vacuum-ultraviolet (VUV) regime. Collectively, these studies enhance the reconstruction precision and hardware validation necessary for DUNE to achieve its scientific goals.