Measurement of muon antineutrino disappearance in the T2K Experiment




Myslik, Jordan William

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The T2K ("Tokai-to-Kamioka") Experiment is a long-baseline neutrino oscillation experiment. A beam of primarily muon neutrinos (in neutrino beam mode) or antineutrinos (in antineutrino beam mode) is produced at the J-PARC ("Japan Proton Accelerator Research Complex") facility. The near detector (ND280), located 280 m from the proton beam target, measures a large event rate of neutrino interactions in the unoscillated beam, while the far detector, Super-Kamiokande, 295 km away, searches for the signatures of neutrino oscillation. This dissertation describes the analyses of data at ND280 and Super-Kamiokande leading to T2K's first results from running in antineutrino beam mode: a measurement of muon antineutrino disappearance. The measured values of the antineutrino oscillation parameters (Normal Hierarchy) are (sin²(θ̅₂₃), |Δm̅²₃₂|) = (0.450, 2.518 x 10ˉ³ eV²/c⁴), with 90% 1D confidence intervals 0.327 < sin²(θ̅₂₃) < 0.692 and 2.03 x 10ˉ³ eV²/c⁴ < |Δm̅²₃₂| < 2.92 x 10ˉ³ eV²/c⁴. These results are consistent with past measurements of these parameters by other experiments, and with T2K's past measurements of muon neutrinos.



T2K, neutrino oscillation, muon antineutrino disappearance, near detector, ND280, ND280 contribution to oscillation analysis, antineutrino beam mode, TPC, Time Projection Chamber, Gas Handling System, Super-Kamiokande