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[en] We report the first detailed comparisons of the rates and spectra of neutral-current neutrino interactions at two widely separated locations. A depletion in the rate at the far site would indicate mixing between ν_μ and a sterile particle. No anomalous depletion in the reconstructed energy spectrum is observed. Assuming oscillations occur at a single mass-squared splitting, a fit to the neutral- and charged-current energy spectra limits the fraction of ν_μ oscillating to a sterile neutrino to be below 0.68 at 90% confidence level. A less stringent limit due to a possible contribution to the measured neutral-current event rate at the far site from ν_e appearance at the current experimental limit is also presented

[en] Results are reported from a search for active to sterile neutrino oscillations in the MINOS long-baseline experiment, based on the observation of neutral-current neutrino interactions, from an exposure to the NuMI neutrino beam of 7.07x10²⁰ protons on target. A total of 802 neutral-current event candidates is observed in the Far Detector, compared to an expected number of 754±28(stat)±37(syst) for oscillations among three active flavors. The fraction f_s of disappearing ν_μ that may transition to ν_s is found to be less than 22% at the 90% C.L.

[en] 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 1.71x10²⁰ 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)]x10^-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.

[en] This paper reports results from a search for ν_μ→ν_e transitions by the MINOS experiment based on a 7x10²⁰ protons-on-target exposure. Our observation of 54 candidate ν_e events in the far detector with a background of 49.1±7.0(stat)±2.7(syst) events predicted by the measurements in the near detector requires 2sin²(2θ₁₃)sin²θ₂₃<0.12(0.20) at the 90% C.L. for the normal (inverted) mass hierarchy at δ_CP=0. The experiment sets the tightest limits to date on the value of θ₁₃ for nearly all values of δ_CP for the normal neutrino mass hierarchy and maximal sin²(2θ₂₃).

[en] This Letter reports new results from the MINOS experiment based on a two-year exposure to muon neutrinos from the Fermilab NuMI beam. Our data are consistent with quantum-mechanical oscillations of neutrino flavor with mass splitting |Δm²|=(2.43±0.13)x10^-3 eV² (68% C.L.) and mixing angle sin²(2θ)>0.90 (90% C.L.). Our data disfavor two alternative explanations for the disappearance of neutrinos in flight: namely, neutrino decays into lighter particles and quantum decoherence of neutrinos, at the 3.7 and 5.7 standard-deviation levels, respectively

[en] The temperature of the upper atmosphere affects the height of primary cosmic ray interactions and the production of high-energy cosmic ray muons which can be detected deep underground. The MINOS far detector at Soudan, MN, has collected over 67x10⁶ cosmic ray induced muons. The underground muon rate measured over a period of five years exhibits a 4% peak-to-peak seasonal variation which is highly correlated with the temperature in the upper atmosphere. The coefficient, α_T, relating changes in the muon rate to changes in atmospheric temperature was found to be α_T=0.873±0.009(stat)±0.010(syst). Pions and kaons in the primary hadronic interactions of cosmic rays in the atmosphere contribute differently to α_T due to the different masses and lifetimes. This allows the measured value of α_T to be interpreted as a measurement of the K/π ratio for E_p > or approx. 7 TeV of 0.12_-0.05^+0.07, consistent with the expectation from collider experiments.

[en] A search for depletion of the combined flux of active neutrino species over a 735 km baseline is reported using neutral-current interaction data recorded by the MINOS detectors in the NuMI neutrino beam. Such a depletion is not expected according to conventional interpretations of neutrino oscillation data involving the three known neutrino flavors. A depletion would be a signature of oscillations or decay to postulated noninteracting sterile neutrinos, scenarios not ruled out by existing data. From an exposure of 3.18x10²⁰ protons on target in which neutrinos of energies between ∼500 MeV and 120 GeV are produced predominantly as ν_μ, the visible energy spectrum of candidate neutral-current reactions in the MINOS far detector is reconstructed. Comparison of this spectrum to that inferred from a similarly selected near-detector sample shows that of the portion of the ν_μ flux observed to disappear in charged-current interaction data, the fraction that could be converting to a sterile state is less than 52% at 90% confidence level (C.L.). The hypothesis that active neutrinos mix with a single sterile neutrino via oscillations is tested by fitting the data to various models. In the particular four-neutrino models considered, the mixing angles θ₂₄ and θ₃₄ are constrained to be less than 11 deg. and 56 deg. at 90% C.L., respectively. The possibility that active neutrinos may decay to sterile neutrinos is also investigated. Pure neutrino decay without oscillations is ruled out at 5.4 standard deviations. For the scenario in which active neutrinos decay into sterile states concurrently with neutrino oscillations, a lower limit is established for the neutrino decay lifetime τ₃/m₃>2.1x10^-12 s/eV at 90% C.L.

[en] The energy dependence of the neutrino-iron and antineutrino-iron inclusive charged-current cross sections and their ratio have been measured using a high-statistics sample with the MINOS near detector exposed to the NuMI beam from the main injector at Fermilab. Neutrino and antineutrino fluxes were determined using a low hadronic energy subsample of charged-current events. We report measurements of ν-Fe (ν-Fe) cross section in the energy range 3-50 GeV (5-50 GeV) with precision of 2%-8% (3%-9%) and their ratio which is measured with precision 2%-8%. The data set spans the region from low energy, where accurate measurements are sparse, up to the high-energy scaling region where the cross section is well understood.

[en] Measurements of neutrino oscillations using the disappearance of muon neutrinos from the Fermilab NuMI neutrino beam as observed by the two MINOS detectors are reported. New analysis methods have been applied to an enlarged data sample from an exposure of 7.25x10²⁰ protons on target. A fit to neutrino oscillations yields values of |Δm²|=(2.32_-0.08^+0.12)x10^-3 eV² for the atmospheric mass splitting and sin²(2θ)>0.90 (90% C.L.) for the mixing angle. Pure neutrino decay and quantum decoherence hypotheses are excluded at 7 and 9 standard deviations, respectively.