Antineutrino Oscillations in the Atmospheric Sector

Citation

Himmel, Alexander I. (2011) Antineutrino Oscillations in the Atmospheric Sector. Dissertation (Ph.D.), California Institute of Technology. doi:10.7907/7E4S-QQ82. https://resolver.caltech.edu/CaltechTHESIS:05162011-162816431

Abstract

This thesis presents measurements of the oscillations of muon antineutrinos in the atmospheric sector, where world knowledge of antineutrino oscillations lags well behind the knowledge of neutrinos, as well as a search for ν_μ \to ν̅ _μ transitions. Differences between neutrino and antineutrino oscillations could be a sign of physics beyond the Standard Model, including non-standard matter interactions or the violation of CPT symmetry. These measurements leverage the sign-selecting capabilities of the magnetized steel-scintillator MINOS detectors to analyze antineutrinos from the NuMI beam, both when it is in FHC and when it is in RHC. Antineutrino oscillations are observed at |Δm̅²_atm| = (3.36^+0.46_-0.40(stat)±0.06(syst)) x 10^- eV² and sin²(2θ̅₂₃ = 0.860^+0.11_-0.12(stat)± 0.01(syst). The oscillation parameters measured for antineutrinos and those measured by MINOS for neutrinos differ by a large enough margin that the chance of obtaining two values as discrepant as those observed is only 2%, assuming the two measurements arise from the same underlying mechanism, with the same parameter values. No evidence is seen for neutrino-to-antineutrino transitions.

Thesis Files