Cao, Peng2019-06-052019-06-052018http://udspace.udel.edu/handle/19716/24226The Antarctic Impulsive Transient Antenna (ANITA) is a balloon-based experiment designed to search for ultra-high energy(UHE) neutrinos and cosmic rays in Antarctica. A successful detection would be an important step in understanding the most energetic cosmic accelerators in the universe. The fourth flight of ANITA (ANITA-IV) funded by NASA took place in December 2016. It uses a radio antenna array designed to detect Askaryan radiation from UHE neutrino-induced showers in ice and geomagnetic radiation from Extensive Air Showers (EAS) induced by cosmic rays. ☐ In this dissertation, I present my analysis of the ANITA-IV flight data with the objective to search for ultra-high energy neutrino and cosmic ray events. The data analysis includes six major aspects: instrument calibrations, event direction reconstruction, event quality cuts, thermal events cut, anthropogenic events cut (clustering), and background estimation. Twenty-four cosmic ray candidates and one neutrino candidate events were found each with an estimated background of 0.34 event. Although the signal significance for a single neutrino event is consistent with background, it still leads to the world's best limit on the ultra-high energy neutrino flux for energy above $4 \times 10^{19}$ eV.Thesis1103606011https://doi.org/10.58088/rxj0-sa082019-02-14en