Observation of Atmospheric Neutrino-induced Cascades in IceCube with DeepCore

Open Access
Ha, Chang Hyon
Graduate Program:
Doctor of Philosophy
Document Type:
Date of Defense:
October 06, 2011
Committee Members:
  • Tyce De Young, Doug Cowen, Dissertation Advisor
  • Tyce De Young, Committee Chair
  • Douglas Cowen, Committee Chair
  • Peter Istvan Meszaros, Committee Member
  • Paul Sommers, Committee Member
  • neutrinos
  • cascades
  • oscillations
The recently completed IceCube neutrino observatory is composed of more than 5,000 digital optical modules attached to 86 strings and buried in the South Pole ice. The observatory includes a tightly spaced inner array in the deepest ice, called DeepCore, which allows access to low-energy neutrinos over 4π solid angle with a giant surrounding cosmic ray muon veto. Designed to be sensitive to neutrinos at energies below 1 TeV, DeepCore collects a very high flux of atmospheric neutrinos which can be used to study neutrino flavor identification and oscillation physics. Furthermore, astrophysical neutrinos from all-sky point sources and neutrinos from dark matter annihilations in the sun, earth, and center of the galaxy are potentially detectable by DeepCore. For the first time atmospheric neutrino-induced cascades are observed in Ice- Cube, using the 79-string detector with the DeepCore extension. Using 23 days of test data, a high statistics sample obtains 824 events with a cascade expectation of 312 events, and using 281 days of full data, with tighter cuts 1029 events are observed of which 59% are predicted to be cascades. The first year performance of the detector and the observation are discussed in this dissertation.