The charge ratio, $R_mu = N_{mu^+}/N_{mu^-}$, for cosmogenic multiple-muon events observed at an under- ground depth of 2070 mwe has been measured using the magnetized MINOS Far Detector. The multiple-muon events, recorded nearly continuously from Au
gust 2003 until April 2012, comprise two independent data sets imaged with opposite magnetic field polarities, the comparison of which allows the systematic uncertainties of the measurement to be minimized. The multiple-muon charge ratio is determined to be $R_mu = 1.104 pm 0.006 {rm ,(stat.)} ^{+0.009}_{-0.010} {rm ,(syst.)} $. This measurement complements previous determinations of single-muon and multiple-muon charge ratios at underground sites and serves to constrain models of cosmic ray interactions at TeV energies.
We report on a new analysis of neutrino oscillations in MINOS using the complete set of accelerator and atmospheric data. The analysis combines the $ u_{mu}$ disappearance and $ u_{e}$ appearance data using the three-flavor formalism. We measure $|De
lta m^{2}_{32}|=[2.28-2.46]times10^{-3}mbox{,eV}^{2}$ (68% C.L.) and $sin^{2}theta_{23}=0.35-0.65$ (90% C.L.) in the normal hierarchy, and $|Delta m^{2}_{32}|=[2.32-2.53]times10^{-3}mbox{,eV}^{2}$ (68% C.L.) and $sin^{2}theta_{23}=0.34-0.67$ (90% C.L.) in the inverted hierarchy. The data also constrain $delta_{CP}$, the $theta_{23}$ octant degeneracy and the mass hierarchy; we disfavor 36% (11%) of this three-parameter space at 68% (90%) C.L.
We report measurements of oscillation parameters from $ u_{mu}$ and $bar{ u}_{mu}$ disappearance using beam and atmospheric data from MINOS. The data comprise exposures of unit[$10.71 times 10^{20}$]{protons on target (POT)} in the $ u_{mu}$-dominate
d beam, $unit[3.36times10^{20}]{POT}}$ in the $bar{ u}_{mu}$-enhanced beam, and 37.88 kton-years of atmospheric neutrinos. Assuming identical $ u$ and $bar{ u}$ oscillation parameters, we measure mbox{$|Delta m^2}| = unit[2.41^{+0.09}_{-0.10}) times 10^{-3}]{eV^{2}}$} and $sin^{2}/!/left(2theta right) = 0.950^{+0.035}_{-0.036}$. Allowing independent $ u$ and $bar{ u}$ oscillations, we measure antineutrino parameters of $|Delta bar{m}^2| = unit[(2.50 ^{+0.23}_{-0.25}) times 10^{-3}]{eV^{2}}$ and $sin^{2}/!/left(2bar{theta} right) = 0.97^{+0.03}_{-0.08}$, with minimal change to the neutrino parameters.
This paper reports measurements of atmospheric neutrino and antineutrino interactions in the MINOS Far Detector, based on 2553 live-days (37.9 kton-years) of data. A total of 2072 candidate events are observed. These are separated into 905 contained-
vertex muons and 466 neutrino-induced rock-muons, both produced by charged-current $ u_{mu}$ and $bar{ u}_{mu}$ interactions, and 701 contained-vertex showers, composed mainly of charged-current $ u_{e}$ and $bar{ u}_{e}$ interactions and neutral-current interactions. The curvature of muon tracks in the magnetic field of the MINOS Far Detector is used to select separate samples of $ u_{mu}$ and $bar{ u}_{mu}$ events. The observed ratio of $bar{ u}_{mu}$ to $ u_{mu}$ events is compared with the Monte Carlo simulation, giving a double ratio of $R^{data}_{bar{ u}/ u}/R^{MC}_{bar{ u}/ u} = 1.03 pm 0.08 (stat.) pm 0.08 (syst.)$. The $ u_{mu}$ and $bar{ u}_{mu}$ data are separated into bins of $L/E$ resolution, based on the reconstructed energy and direction of each event, and a maximum likelihood fit to the observed $L/E$ distributions is used to determine the atmospheric neutrino oscillation parameters. This fit returns 90% confidence limits of $|Delta m^{2}| = (1.9 pm 0.4) times 10^{-3} eV^{2}$ and $sin^{2} 2theta > 0.86$. The fit is extended to incorporate separate $ u_{mu}$ and $bar{ u}_{mu}$ oscillation parameters, returning 90% confidence limits of $|Delta m^{2}|-|Delta bar{m}^{2}| = 0.6^{+2.4}_{-0.8} times 10^{-3} eV^{2}$ on the difference between the squared-mass splittings for neutrinos and antineutrinos.
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 |dm2bar|=2.32x10^-3 eV^2, snthetabar=1.0. Assuming no oscillations occur at the Near Detector baseline, a fit to the two-flavor oscillation approximation constrains |dm2bar|<3.37x10^-3 eV^2 at the 90% confidence level with snthetabar=1.0.
We report the results of a search for $ u_{e}$ appearance in a $ u_{mu}$ beam in the MINOS long-baseline neutrino experiment. With an improved analysis and an increased exposure of $8.2times10^{20}$ protons on the NuMI target at Fermilab, we find tha
t $2sin^2(theta_{23})sin^2(2theta_{13})<0.12 (0.20)$ at 90% confidence level for $deltamathord{=}0$ and the normal (inverted) neutrino mass hierarchy, with a best fit of $2sin^2(theta_{23})sin^2(2theta_{13}),mathord{=},0.041^{+0.047}_{-0.031} (0.079^{+0.071}_{-0.053})$. The $theta_{13}mathord{=}0$ hypothesis is disfavored by the MINOS data at the 89% confidence level.
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 $7.07times10^{20}$
protons on target. A total of 802 neutral-current event candidates is observed in the Far Detector, compared to an expected number of $754pm28rm{(stat.)}pm{37}rm{(syst.)}$ for oscillations among three active flavors. The fraction $f_s$ of disappearing umu that may transition to $ u_s$ is found to be less than 22% at the 90% C.L.
This letter reports the first direct observation of muon antineutrino disappearance. The MINOS experiment has taken data with an accelerator beam optimized for muon antineutrino production, accumulating an exposure of $1.71times 10^{20}$ protons on t
arget. In the Far Detector, 97 charged current muon antineutrino events are observed. The no-oscillation hypothesis predicts 156 events and is excluded at $6.3sigma$. The best fit to oscillation yields $Delta bar{m}^{2}=(3.36^{+0.46}_{-0.40}textrm{(stat.)}pm0.06textrm{(syst.)})times 10^{-3},eV^{2}$, $sin^{2}(2bar{theta})=0.86^{+0.11}_{-0.12}textrm{(stat.)}pm0.01textrm{(syst.)}$. The MINOS muon neutrino and muon antineutrino measurements are consistent at the 2.0% confidence level, assuming identical underlying oscillation parameters.
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 exposu
re of $7.25 times 10^{20}$ protons on target. A fit to neutrino oscillations yields values of $|Delta m^2| = (2.32^{+0.12}_{-0.08})times10^{-3}$,eV$^2$ for the atmospheric mass splitting and $rm sin^2!(2theta) > 0.90$ (90%,C.L.) for the mixing angle. Pure neutrino decay and quantum decoherence hypotheses are excluded at 7 and 9 standard deviations, respectively.
We searched for a sidereal modulation in the MINOS far detector neutrino rate. Such a signal would be a consequence of Lorentz and CPT violation as described by the Standard-Model Extension framework. It also would be the first detection of a perturb
ative effect to conventional neutrino mass oscillations. We found no evidence for this sidereal signature and the upper limits placed on the magnitudes of the Lorentz and CPT violating coefficients describing the theory are an improvement by factors of $20-510$ over the current best limits found using the MINOS near detector.
