Search for the disappearance of muon antineutrinos in the NuMI neutrino beam
(2011)
Improved search for muon-neutrino to electron-neutrino oscillations in MINOS
(2011)
Indication of electron neutrino appearance from an accelerator-produced off-axis muon neutrino beam
Physical Review Letters 107:4 (2011)
Abstract:
The T2K experiment observes indications of νμ→ν e appearance in data accumulated with 1.43×1020 protons on target. Six events pass all selection criteria at the far detector. In a three-flavor neutrino oscillation scenario with |Δm232|=2.4×10⊃- 3eV2, ⊃sin⊃ 22θ23=1 and ⊃sin⊃ 22θ13=0, the expected number of such events is 1.5±0.3(syst). Under this hypothesis, the probability to observe six or more candidate events is 7×10⊃-3, equivalent to 2.5σ significance. At 90% C.L., the data are consistent with 0.03(0.04) <⊃sin⊃ 22θ13<0.28(0.34) for δCP= 0 and a normal (inverted) hierarchy.First direct observation of muon antineutrino disappearance.
Phys Rev Lett 107:2 (2011) 021801
Abstract:
This Letter reports the first direct observation of muon antineutrino disappearance. The MINOS experiment has taken data with an accelerator beam optimized for ν(μ) production, accumulating an exposure of 1.71 × 10²⁰ protons on target. In the Far Detector, 97 charged current ν(μ) events are observed. The no-oscillation hypothesis predicts 156 events and is excluded at 6.3σ. The best fit to oscillation yields |Δm²| = [3.36(-0.40)(+0.46)(stat) ± 0.06(syst)] × 10⁻³ eV², sin²(2θ) = 0.86(-0.12)(+0.11)(stat) ± 0.01(syst). The MINOS ν(μ) and ν(μ) measurements are consistent at the 2.0% confidence level, assuming identical underlying oscillation parameters.Active to sterile neutrino mixing limits from neutral-current interactions in MINOS.
Phys Rev Lett 107:1 (2011) 011802