Tackling the mystery of cosmic rays by searching for cosmogenic neutrinos - transforming the ARIANNA pilot program into a discovery instrument

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Cosmic rays are the most energetic particles observed in the universe. With energies of more than 10^20 eV (~16 Joules) concentrated in a single particle, their energy is seven orders of magnitude larger than the energy achievable in the largest particle accelerators on Earth such as the large hadron collider (LHC) at CERN. The study of these ultra-high-energy cosmic rays (UHECRs) gives access to the most violent phenomena in the universe such as active galactic nuclei or gamma ray bursts which are probable sources of UHECRs.A key to the sources of ultra-high-energy cosmic rays is the measurement of cosmogenic neutrinos that are created by the interactions of cosmic rays with matter surrounding the source or with CMB photons. Neutrinos traverse the universe unimpeded and typically point back to the cosmic-ray source with sub degree accuracy, and their measurement will allow for a stringent discrimination between different astrophysical scenarios which are currently fiercely debated.The relevant neutrino energy range is 10^16.5 – 10^20.5 eV where the amount of neutrinos is so rare that current experiments (e.g. IceCube) are too small to obtain sufficient statistics in reasonable time. Sufficient sensitivity to these high-energy neutrinos can be obtained with the proposed ARIANNA high energy neutrino detector which instruments 0.5 Teratons of ice in Antarctica at low costs by measuring the radio emission created by a particle shower in ice via the Askaryan effect.The goal of this project is to transform the ARIANNA pilot program into a discovery instrument with the capability to reveal the sources of extragalactic cosmic rays for the first time. I will bring my experience with radio-based cosmic ray detection, whose signals are remarkably similar to those generated by neutrinos, to improve the precision and maturity of the reconstructed energy and angular direction of neutrino events. In addition, I will explore different methods to identify the neutrino flavor including the usage of advanced machine learning techniques and the construction of a tau-neutrino sensitive antenna array above the ice. All methods will be tested on data from the ARIANNA pilot program, which is already completed and instruments 2.7 Gigatons of ice. In the future, these methods can be applied to the full-size ARIANNA detector to efficiently search for cosmogenic neutrinos.