A Search for Starting Tracks in Icecube: A New Window for Detecting Astrophysical Neutrinos

Neutrinos are a unique cosmic messenger which are in the early stages of opening a new window to the universe. Unlike their cosmic brethren, neutrinos are undeflected and unattenuated as they travel cosmic distances to reach the Earth. In recent years IceCube has pioneered the search for astrophysical neutrinos with discoveries of a diffuse astrophysical neutrino flux in two different channels of neutrino detection; upward-going muon neutrinos which use the Earth as a shield against background and neutrinos which leave a cascade-like deposit which take advantage of correlations in air showers to remove background. This thesis focuses on the underutilized detection topology of starting tracks, muon tracks from neutrinos whose interaction vertex is contained inside the detector, to access the astrophysical flux and observed new astrophysical neutrinos in archival data that would have otherwise remained unidentified. These starting tracks, when treated properly, can take advantage of a very strong effect called the direct self-veto to remove background events and open a nearly background free window for astrophysical neutrino detection in the southern sky. Newly developed methods, techniques, and simulations are vital to the success of this work and are presented along the way to the final result. ABSTRACT......Page 2 LIST OF TABLES......Page 9 LIST OF FIGURES......Page 11 Preface......Page 17 High Energy Cosmic Rays......Page 19 Physics Background......Page 25 Vetoing Atmospheric Neutrinos......Page 47 Astrophysical Neutrino Flux Measurements......Page 53 IceCube Detector......Page 80 Event Simulation......Page 106 Event Reconstruction......Page 117 Data Selection......Page 140 Analysis, Results, Outlook, and Conclusions......Page 192 Interesting Observed Events......Page 223 CORSIKA Modification For Faster Background Generation......Page 225 The pDOM DAQ......Page 231 LIST OF REFERENCES......Page 240