Combined three flavour oscillation analysis of the T2K neutrino beam and atmospheric neutrinos in Super-Kamiokande

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Understanding of our existence is the greatest question of humanity. The neutrino is a useful probe of our universe and our origins from the Big Bang. They are the most abundant elementary particle. However, they have no electric charge and pass almost unhindered through matter. Some are as old as the Universe itself, but we mostly observe those created in the sun, our atmosphere and nuclear reactors. More mysterious sources include supernovae and the unknown interior of our planet. The Standard Model (SM) of particle physics includes 3 types of neutrinos. The last 20 years of experiments have shown a strange behaviour of neutrinos known as oscillation, where one type transforms into another as it propagates through space. This phenomenon requires neutrinos to have mass, not included in the SM. Grand Unified Theories, attempt to explain the origin of neutrino mass in addition to unifying the fundamental forces. A theory, Leptogenesis, can link neutrino oscillation to why there is more matter than anti-matter in the universe. These theories require input from difficult experiments, and thus are the focus of intense study worldwide. The Tokai to Kamioka (T2K) experiment uses a proton accelerator for producing a neutrino beam. My work includes a proton beam monitor, critical for understanding the neutrino beam. Accelerator technology developed for particle physics is also used in the medical field for isotope production and radiotherapy, and in materials science. The neutrinos are measured at two detectors: a Canadian-led near detector and Super-Kamiokande, 295 km away. Here we attempt to complete the neutrino oscillation model and pave the way towards confirming Leptogenesis, bringing us closer to understanding our existence. Neutrino detectors can also be used for nuclear reactor monitoring, understanding nuclear processes in our sun, proton decay searches and supernovae early detection notification systems for astrophysicists and amateur astronomers.