Joint analysis of neutrino oscillations using data from T2K and reactor experiments

Abstract

This doctoral thesis presents studies on neutrino oscillations phenomenon with the T2K experiment,located in Japan. Neutrino oscillations are a crucial phenomenon in particle physics that have been extensively studied over the past few decades, providing valuable insights into the fundamental properties of neutrinos. The work presented here includes two separate studies in the context of the T2K. The first, more physics oriented, consists in exploring the use of Daya Bay reactor neutrino experiment data as a constraint for the T2K measurements, which being an accelerator-based neutrino experiment uses a complementary technique. The Daya Bay experiment, located in China, measures the oscillation of neutrinos emitted from nuclear reactors. T2K has historically used a constraint on sin2 θ13 obtained from reactor experiments. However, this constraint has always been introduced assuming a symmetric systematic error and neglecting the sensitivity of those experiments to ∆m2 32 . The present work investigates the impact of using a two-dimensional sin2 θ13 - ∆m2 32 likelihood surface from Daya Bay as a constraint for the T2K oscillation analysis. The second study, hardware oriented, focuses on plastic scintillator ageing. This effect, being never a primary interest of researchers in neutrino experiments, have not been thoroughly explored in the past. However, plastic scintillators are extensively used in those experiments, which usually run for more than a decade. Now, in the high precision era, it is important to perfect our understanding of those components and the overall detector behavior. This thesis presents a comprehensive study of the impact of ageing on the performance of plastic scintillator detectors, and their consequences in the context of accelerator neutrino oscillation measurements.