NEUTRINO FLAVOR OSCILLATIONS IN THE ICECUBE DEEPCORE ARRAY

Open Access
Author:
Giordano, Gerardo
Graduate Program:
Physics
Degree:
Doctor of Philosophy
Document Type:
Dissertation
Date of Defense:
June 23, 2011
Committee Members:
  • Irina Mocioiu, Committee Chair
  • Tyce DeYoung, Committee Member
  • Jorge Sofo, Committee Member
  • Peter Meszaros, Committee Member
  • Nitin Samarth, Committee Member
Keywords:
  • Tau
  • Neutrinos
  • DeepCore
  • IceCube
  • Neutrino Flavor Oscillations
Abstract:
A large number of experiments of different types have provided strong evidence for neutrino oscillations and thus for physics beyond the Standard Model of Particle Physics. New experiments are being built and designed to further investigate neutrino oscillations, to obtain precision measurements of dominant oscillation parameters and discover sub-dominant effects. On the other hand, neutrino telescopes, like IceCube and the IceCube DeepCore Array, are using neutrinos as a means of learning about astrophysical sources, discovering dark matter and other high energy phenomena. Atmospheric neutrinos constitute a background for these searches. This dissertation shows that the large number of atmospheric neutrinos that the IceCube DeepCore detector will accumulate can be used in order to extract useful information about neutrino oscillations. Atmospheric neutrino interactions within the IceCube DeepCore array are examined in the context of neutrino flavor oscillations. The detection of an appearance of a tau-flavored neutrino flux, not present in the original atmospheric neutrino flux is calculated and quantified using the statistical interpretation of the neutrino-induced electromagnetic and hadronic cascades within the detector. The ”track signal” of Cherenkov light created by muons created from either charged current interactions of muon-type neutrinos with detector volume nuclei or the decay of tau leptons within the detector’s instrumented volume are also examined. Using a chi-squared analysis, new precision bounds are determined for the main atmospheric neutrino oscillation parameters and shown to drastically reduce the current parameter space. The implications of these new precision measurements are discussed in the context of currently open questions in the area of neutrino flavor oscillation studies. Future work and the impact of future measurements on this analysis are also discussed. Full three-flavor neutrino oscillation transition probabilities with matter effects are calculated and employed in the study. A discussion of the calculation of the full differential cross sections for neutrino-nucleon deep inelastic scattering interactions in both the limit of a negligible mass final state lepton and in the situation of a non-negligible mass final state lepton are discussed and employed with the latter being necessary for the calculation of the tau-type neutrino charged current interaction induced cascades. Physics motivated assumptions about the systematic error present in the IceCube DeepCore detector and the effective volume of the detector are made for the analysis. In summary, it is shown that cascade measurements in the IceCube DeepCore Array can provide evidence for tau neutrino appearance in atmospheric neutrino oscillations. A statistically significant (3σ) ντ appearance signal could be obtained in only a few months of observation and is important for future ντ interaction studies. Furthermore, the very high statistics atmospheric muon neutrino data can be used to obtain precise measurements of the main oscillation parameters, significantly improving present results and aiding in the solution to open questions in the neutrino sector.