Search for Sterile Neutrinos Mixing with Muon Neutrinos in MINOS

We report results of a search for oscillations involving a light sterile neutrino over distances of 1.04 and 735 km in a nu(mu)-dominated beam with a peak energy of 3 GeV. The data, from an exposure of 10.56 x 10(20) protons on target, are analyzed using a phenomenological model with one sterile neutrino. We constrain the mixing parameters theta(24) and Delta m(41)(2) and set limits on parameters of the four-dimensional Pontecorvo-Maki-Nakagawa-Sakata matrix, vertical bar U-mu 4 vertical bar(2) and vertical bar U-tau 4 vertical bar(2), under the assumption that mixing between nu(e) and nu(s) is negligible (vertical bar U-e4 vertical bar(2) = 0). No evidence for nu(mu) -\u3e nu(s) transitions is found and we set a world-leading limit on theta(24) for values of Delta m(41)(2) less than or similar to 1 eV(2)

Measurement of single pi(0) production by coherent neutral-current nu Fe interactions in the MINOS Near Detector

Forward single pi(0) production by coherent neutral-current interactions, vA - \u3e vA pi(0), is investigated using a 2.8 x 10(20) protons-on-target exposure of the MINOS Near Detector. For single-shower topologies, the event distribution in production angle exhibits a clear excess above the estimated background at very forward angles for visible energy in the range 1-8 GeV. Cross sections are obtained for the detector medium comprised of 80% iron and 20% carbon nuclei with (A) = 48, the highest- \u3c A \u3e target used to date in the study of this coherent reaction. The total cross section for coherent neutral-current single pi(0) production initiated by the v(mu) flux of the NuMI low-energy beam with mean (mode) E-v of 4.9 GeV (3.0 GeV), is 77.6 +/- 5.0 (stat)(-) (+15.0)(16.8) (syst) x 10(-40) cm(2) pernucleus. The results are in good agreement with predictions of the Berger-Sehgal model

An improved measurement of muon antineutrino disappearance in MINOS

We report an improved measurement of muon anti-neutrino disappearance over a distance of 735km using the MINOS detectors and the Fermilab Main Injector neutrino beam in a muon anti-neutrino enhanced configuration. From a total exposure of 2.95e20 protons on target, of which 42% have not been previously analyzed, we make the most precise measurement of the anti-neutrino "atmospheric" delta-m squared = 2.62 +0.31/-0.28 (stat.) +/- 0.09 (syst.) and constrain the anti-neutrino atmospheric mixing angle >0.75 (90%CL). These values are in agreement with those measured for muon neutrinos, removing the tension reported previously.Comment: 5 pages, 4 figures. In submission to Phys.Rev.Let

Search for flavor-changing nonstandard neutrino interactions using nu(e) appearance in MINOS

We report new constraints on flavor-changing nonstandard neutrino interactions from the MINOS long-baseline experiment using nu(e) and (nu) over bar (e) appearance candidate events from predominantly nu(mu) and (nu) over bar (mu) beams. We used a statistical selection algorithm to separate nu(e) candidates from background events, enabling an analysis of the combined MINOS neutrino and antineutrino data. We observe no deviations from standard neutrino mixing, and thus place constraints on the nonstandard interaction matter effect, vertical bar epsilon(e tau)vertical bar, and phase, (delta(CP) + delta(e tau)), using a 30-bin likelihood fit

Active to Sterile Neutrino Mixing Limits from Neutral-Current Interactions in MINOS

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 7.07×10^(20) 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

Improved Search for Muon-Neutrino to Electron-Neutrino Oscillations in MINOS

We report the results of a search for ν_e appearance in a ν_μ beam in the MINOS long-baseline neutrino experiment. With an improved analysis and an increased exposure of 8.2×10^(20) protons on the NuMI target at Fermilab, we find 2sin^2(θ_(23))sin^2(2θ_(13))<0.12(0.20) at 90% confidence level for δ=0 and the normal (inverted) neutrino mass hierarchy, with a best-fit of 2sin^2(θ_(23))sin^2(2θ_(13))=0.041^(+0.047)_(-0.031)(0.079^(+0.071)_(-0.053). The θ_(13)= 0 hypothesis is disfavored by the MINOS data at the 89% confidence level

First Direct Observation of Muon Antineutrino Disappearance

This Letter reports the first direct observation of muon antineutrino disappearance. The MINOS experiment has taken data with an accelerator beam optimized for ν̅ _μ production, accumulating an exposure of 1.71×10^(20) protons on target. In the Far Detector, 97 charged current ν̅ _μ events are observed. The no-oscillation hypothesis predicts 156 events and is excluded at 6.3σ. The best fit to oscillation yields |Δm̅ 2|= [3.36=_(-0.40)^(+0.46)(stat)±0.06(syst)]x10^(-3)eV^2,sin^2(2θ̅)=0.86 _(-0.12)^(+0.11)(stat)±0.01(syst). The MINOS ν̅ _μ and ν̅ _μ measurements are consistent at the 2.0% confidence level, assuming identical underlying oscillation parameters

Search for the disappearance of muon antineutrinos in the NuMI neutrino beam

We report constraints on antineutrino oscillation parameters that were obtained by using the two MINOS detectors to measure the 7% muon antineutrino component of the NuMI neutrino beam. In the Far Detector, we select 130 events in the charged-current muon antineutrino sample, compared to a prediction of 136.4 ± 11.7(stat)^(+10.2)_(-8.9)(syst) events under the assumption │Δm^2│ = 2.32 X 10^(-3) eV^2, sin^2(2θ) = 1.0

Measurement of the neutrino mass splitting and flavor mixing by MINOS

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 $7.25 imes 10^{20}$ protons on target. A fit to neutrino oscillations yields values of $|Delta m^2| = (2.32^{+0.12}_{-0.08}) imes10^{-3}$,eV$^2$ for the atmospheric mass splitting and m sin^2!(2 heta) > 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