UC Irvine

Neutrino oscillations represent one of the most active fields of research in particle physics, yet key features of its three-flavor model remain undetermined. This dissertation presents instrumentation and calibration work carried out on two next-generation neutrino oscillation experiments, the Deep Underground Neutrino Experiment (DUNE) and the Jiangmen Underground Neutrino Observatory (JUNO), each pursuing complementary approaches to precision oscillation measurements. On DUNE, this work addresses the readout electronics of the liquid argon Near Detector (NDLAr). The integration of the DUNE Timing System endpoint into the PACMAN controller firmware is described, along with the design and validation of an optical timing testbench used to confirm nanosecond-level clock synchronization. Building on this instrumentation, a charge-scale calibration analysis is presented using cosmic-ray minimally-ionizing particles in three generations of pixelated LArTPC prototypes, extracting the most-probable dQ/dx. A dedicated simulation study further identifies and quantifies a systematic bias in the extracted electron lifetime introduced by the pixelated charge readout front-end and charge-diffusion effects, and proposes a path toward its mitigation.On JUNO, this work develops and applies a novel dual-calorimetry approach to the calibration of the experiment’s Large PMTs, exploiting the photon-counting response of the 25,600 Small PMTs to diagnose LPMT charge-level instrumental non-linearity using deployed radioactive γ sources (DCC-Gamma). This dissertation then presents the GEPRiS (Gamma-Electron Positron Response in Scintillator) framework, which combines γ-source calibration data with cosmogenic β ±-decay spectra selected from JUNO physics data to build a first-principles, Geant4-informed model of the liquid scintillator’s energy response from a global fit to multiple datasets. The resulting detector response model is propagated into an oscillation fit of JUNO’s early physics data, yielding measurements of sin2 θ12, ∆m2 21, and ∆m2 31 that are compared against JUNO’s recently published results.