Sudden stratospheric warmings seen in MINOS deep underground muon data

The rate of high energy cosmic ray muons as measured underground is shown to be strongly correlated with upper-air temperatures during short-term atmospheric (10-day) events. The effects are seen by correlating data from the MINOS underground detector and temperatures from the European Centre for Medium Range Weather Forecasts during the winter periods from 2003-2007. This effect provides an independent technique for the measurement of meteorological conditions and presents a unique opportunity to measure both short and long-term changes in this important part of the atmosphere. Citation: Osprey, S., et al. (2009), Sudden stratospheric warmings seen in MINOS deep underground muon data, Geophys. Res. Lett., 36, L05809, doi: 10.1029/2008GL036359

Measurement of the underground atmospheric muon charge ratio using the MINOS Near Detector

The magnetized MINOS Near Detector, at a depth of 225 mwe, is used to measure the atmospheric muon charge ratio. The ratio of observed positive to negative atmospheric muon rates, using 301 days of data, is measured to be 1.266 +/- 0.001(stat)(-0.014)(+0.015)(syst). This measurement is consistent with previous results from other shallow underground detectors and is 0.108 +/- 0.019(stat + syst) lower than the measurement at the functionally identical MINOS Far Detector at a depth of 2070 mwe. This increase in charge ratio as a function of depth is consistent with an increase in the fraction of muons arising from kaon decay for increasing muon surface energies

Improved Measurement of Muon Antineutrino Disappearance in MINOS

We report an improved measurement of (nu) over bar (mu) disappearance over a distance of 735 km using the MINOS detectors and the Fermilab Main Injector neutrino beam in a (nu) over bar (mu)-enhanced configuration. From a total exposure of 2.95 x 10(20) protons on target, of which 42% have not been previously analyzed, we make the most precise measurement of Delta(m) over bar (2) = [2.62(-0.28)(+0.31)(stat) +/- 0.09(syst)] x 10(-3) eV(2) and constrain the (nu) over bar (mu) mixing angle sin(2)(2 (theta) over bar) \u3e 0.75 (90% C.L.). These values are in agreement with Delta m(2) and sin(2)(2 theta) measured for nu(mu), removing the tension reported in [P. Adamson et al. (MINOS), Phys. Rev. Lett. 107, 021801 (2011).]

Search for Lorentz invariance and CPT violation with muon antineutrinos in the MINOS Near Detector

We have searched for sidereal variations in the rate of antineutrino interactions in the MINOS Near Detector. Using antineutrinos produced by the NuMI beam, we find no statistically significant sidereal modulation in the rate. When this result is placed in the context of the Standard Model Extension theory we are able to place upper limits on the coefficients defining the theory. These limits are used in combination with the results from an earlier analysis of MINOS neutrino data to further constrain the coefficients

First Measurement of Electron Neutrino Appearance in NOvA

We report results from the first search for nu(mu) -\u3e nu(e) transitions by the NOvA experiment. In an exposure equivalent to 2.74 x 10(20) protons on target in the upgraded NuMI beam at Fermilab, we observe 6 events in the Far Detector, compared to a background expectation of 0.99 +/- 0.11 (syst) events based on the Near Detector measurement. A secondary analysis observes 11 events with a background of 1.07 +/- 0.14 (syst). The 3.3 sigma excess of events observed in the primary analysis disfavors 0.1 pi \u3c delta(CP) \u3c 0.5 pi in the inverted mass hierarchy at the 90% C.L

Minimal Modification to Tri-bimaximal Mixing

We explore some ways of minimally modifying the neutrino mixing matrix from tribimaximal, characterized by introducing at most one mixing angle and a CP violating phase thus extending our earlier work. One minimal modification, motivated to some extent by group theoretic considerations, is a simple case with the elements $V_{\alpha 2}$ of the second column in the mixing matrix equal to $1/\sqrt{3}$. Modifications by keeping one of the columns or one of the rows unchanged from tri-bimaximal mixing all belong to the class of minimal modification. Some of the cases have interesting experimentally testable consequences. In particular, the T2K and MINOS collaborations have recently reported indications of a non-zero $\theta_{13}$. For the cases we consider, the new data sharply constrain the CP violating phase angle $\delta$, with $\delta$ close to 0 (in some cases) and $\pi$ disfavored.Comment: Latex 21 pages with 9 figures. Updated analysis with new combined dat

Electron Neutrino and Antineutrino Appearance in the Full MINOS Data Sample

We report on v(e) and (v) over bar (e) appearance in v(mu) and (v) over bar (mu) beams using the full MINOS data sample. The comparison of these v(e) and (v) over bar (e) appearance data at a 735 km baseline with theta(13) measurements by reactor experiments probes delta, the theta(23) octant degeneracy, and the mass hierarchy. This analysis is the first use of this technique and includes the first accelerator long-baseline search for (v) over bar (mu) -\u3e (v) over bar (e). Our data disfavor 31% (5%) of the three-parameter space defined by delta, the octant of the theta(23), and the mass hierarchy at the 68% (90%) C.L. We measure a value of 2sin(2)(2 theta(13))sin(2)(theta(23)) that is consistent with reactor experiments. DOI: 10.1103/PhysRevLett.110.17180

Observation of seasonal variation of atmospheric multiple-muon events in the MINOS Near and Far Detectors

We report the first observation of seasonal modulations in the rates of cosmic ray multiple-muon events at two underground sites, the MINOS Near Detector with an overburden of 225 mwe, and the MINOS Far Detector site at 2100 mwe. At the deeper site, multiple-muon events with muons separated by more than 8 m exhibit a seasonal rate that peaks during the summer, similar to that of single-muon events. In contrast and unexpectedly, the rate of multiple-muon events with muons separated by less than 5-8 m, and the rate of multiple-muon events in the smaller, shallower Near Detector, exhibit a seasonal rate modulation that peaks in the winter

Precision measurement of the speed of propagation of neutrinos using the MINOS detectors

We report a two-detector measurement of the propagation speed of neutrinos over a baseline of 734 km. The measurement was made with the NuMI beam at Fermilab between the near and far MINOS detectors. The fractional difference between the neutrino speed and the speed of light is determined to be (v/c - 1) = (1.0 +/- 1.1) x 10(-6), consistent with relativistic neutrinos

Measurement of the multiple-muon charge ratio in the MINOS Far Detector

The charge ratio, R-mu = N mu + / N mu-, for cosmogenic multiple-muon events observed at an underground depth of 2070 mwe has been measured using the magnetized MINOS Far Detector. The multiple-muon events, recorded nearly continuously from August 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 + / - 0.006(stat)(-0.010)( + 0.009) (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