First Measurement of Monoenergetic Muon Neutrino Charged Current Interactions

We report the first measurement of monoenergetic muon neutrino charged current interactions. MiniBooNE has isolated 236 MeV muon neutrino events originating from charged kaon decay at rest ($K^+ \rightarrow \mu^+ \nu_\mu$) at the NuMI beamline absorber. These signal $\nu_\mu$-carbon events are distinguished from primarily pion decay in flight $\nu_\mu$ and $\overline{\nu}_\mu$ backgrounds produced at the target station and decay pipe using their arrival time and reconstructed muon energy. The significance of the signal observation is at the 3.9$\sigma$ level. The muon kinetic energy, neutrino-nucleus energy transfer ($\omega=E_\nu-E_\mu$), and total cross section for these events is extracted. This result is the first known-energy, weak-interaction-only probe of the nucleus to yield a measurement of $\omega$ using neutrinos, a quantity thus far only accessible through electron scattering.Comment: 6 pages, 4 figure

Neutral currents and tests of three-neutrino unitarity in long-baseline experiments

We examine a strategy for using neutral current measurements in long-baseline neutrino oscillation experiments to put limits on the existence of more than three light, active neutrinos. We determine the relative contributions of statistics, cross section uncertainties, event misidentification and other systematic errors to the overall uncertainty of these measurements. As specific case studies, we make simulations of beams and detectors that are like the K2K, T2K, and MINOS experiments. We find that the neutral current cross section uncertainty and contamination of the neutral current signal by charge current events allow a sensitivity for determining the presence of sterile neutinos at the 0.10--0.15 level in probablility.Comment: 24 pages, Latex2e, uses graphicx.sty, 2 postscript figures. Submitted to the Neutrino Focus Issue of New Journal Physics at http://www.njp.or

A Search for Electron Antineutrino Appearance at the Δm2∼\Delta m^2 \sim 1 eV2\mathrm{eV}^{2} Scale

The MiniBooNE Collaboration reports initial results from a search for $\bar{\nu}_{\mu}\to\bar{\nu}_e$ oscillations. A signal-blind analysis was performed using a data sample corresponding to $3.39 \times 10^{20}$ protons on target. The data are consistent with background prediction across the full range of neutrino energy reconstructed assuming quasielastic scattering, $200 < E_{\nu}^{QE} < 3000$ MeV: 144 electron-like events have been observed in this energy range, compared to an expectation of $139.2 \pm 17.6$ events. No significant excess of events has been observed, both at low energy, 200-475 MeV, and at high energy, 475-1250 MeV. The data are inconclusive with respect to antineutrino oscillations suggested by data from the Liquid Scintillator Neutrino Detector at Los Alamos National Laboratory.Comment: 5 pages, 3 figures, 2 table

A search for muon neutrino and antineutrino disappearance in MiniBooNE

The MiniBooNE Collaboration reports a search for \numu and \numubar disappearance in the \dmsq region of a few \evsq. These measurements are important for constraining models with extra types of neutrinos, extra dimensions an d CPT violation. Fits to the shape of the \numu and \numubar energy spectra reveal no evidence for disappearance at 90% confidence level (CL) in either mode. This is the first test of \numubar disappearance between \dmsq=0.1-10\evsq.Comment: 10 pages, 3 figures, submitted to PR

The MiniBooNE Detector

The MiniBooNE neutrino detector was designed and built to look for muon-neutrino to electron-neutrino oscillations in the mixing parameter space region where the LSND experiment reported a signal. The MiniBooNE experiment used a beam energy and baseline that were an order of magnitude larger than those of LSND so that the backgrounds and systematic errors would be completely different. This paper provides a detailed description of the design, function, and performance of the MiniBooNE detector.Comment: 46 pages, 21 figure

Improved Search for ν̅ [subscript μ]→ν̅ [subscript e] Oscillations in the MiniBooNE Experiment

The MiniBooNE experiment at Fermilab reports results from an analysis of ν̅ [subscript e] appearance data from 11.27×10[superscript 20] protons on target in the antineutrino mode, an increase of approximately a factor of 2 over the previously reported results. An event excess of 78.4±28.5 events (2.8σ) is observed in the energy range 200<E[subscript ν][superscript QE]<1250  MeV. If interpreted in a two-neutrino oscillation model, ν̅ [subscript μ]→ν̅ [subscript e] , the best oscillation fit to the excess has a probability of 66% while the background-only fit has a χ[superscript 2] probability of 0.5% relative to the best fit. The data are consistent with antineutrino oscillations in the 0.01<Δm[superscript 2]<1.0  eV[superscript 2] range and have some overlap with the evidence for antineutrino oscillations from the Liquid Scintillator Neutrino Detector. All of the major backgrounds are constrained by in situ event measurements so nonoscillation explanations would need to invoke new anomalous background processes. The neutrino mode running also shows an excess at low energy of 162.0±47.8 events (3.4σ) but the energy distribution of the excess is marginally compatible with a simple two neutrino oscillation formalism. Expanded models with several sterile neutrinos can reduce the incompatibility by allowing for CP violating effects between neutrino and antineutrino oscillations. © 2013 American Physical SocietyUnited States. Dept. of EnergyNational Science Foundation (U.S.)Fermi National Accelerator Laborator

First Measurement of Monoenergetic Muon Neutrino Charged Current Interactions

We report the first measurement of monoenergetic muon neutrino charged current interactions. MiniBooNE has isolated 236 MeV muon neutrino events originating from charged kaon decay at rest (K+→μ+νμ) at the NuMI beamline absorber. These signal νμ-carbon events are distinguished from primarily pion decay in flight νμ and ¯νμ backgrounds produced at the target station and decay pipe using their arrival time and reconstructed muon energy. The significance of the signal observation is at the 3.9σ level. The muon kinetic energy, neutrino-nucleus energy transfer (ω=Eν−Eμ), and total cross section for these events are extracted. This result is the first known-energy, weak-interaction-only probe of the nucleus to yield a measurement of ω using neutrinos, a quantity thus far only accessible through electron scattering

Dual baseline search for muon antineutrino disappearance at 0.1 eV² &lt; &lt;{\Delta}m² &lt; 100 eV²

The MiniBooNE and SciBooNE collaborations report the results of a joint search for short baseline disappearance of ν̅[subscript μ] at Fermilab’s Booster Neutrino Beamline. The MiniBooNE Cherenkov detector and the SciBooNE tracking detector observe antineutrinos from the same beam, therefore the combined analysis of their data sets serves to partially constrain some of the flux and cross section uncertainties. Uncertainties in the ν[subscript μ] background were constrained by neutrino flux and cross section measurements performed in both detectors. A likelihood ratio method was used to set a 90% confidence level upper limit on ν̅[subscript μ] disappearance that dramatically improves upon prior limits in the Δm[superscript 2]=0.1–100  eV[superscript 2] region

The Neutrino Flux prediction at MiniBooNE

The Booster Neutrino Experiment (MiniBooNE) searches for numu-to-nue oscillations using the O(1 GeV) neutrino beam produced by the Booster synchrotron at the Fermi National Accelerator Laboratory (FNAL). The Booster delivers protons with 8 GeV kinetic energy (8.89 GeV/c momentum) to a beryllium target, producing neutrinos from the decay of secondary particles in the beam line. We describe the Monte Carlo simulation methods used to estimate the flux of neutrinos from the beamline incident on the MiniBooNE detector for both polarities of the focussing horn. The simulation uses the Geant4 framework for propagating particles, accounting for electromagnetic processes and hadronic interactions in the beamline materials, as well as the decay of particles. The absolute double differential cross sections of pion and kaon production in the simulation have been tuned to match external measurements, as have the hadronic cross sections for nucleons and pions. The statistical precision of the flux predictions is enhanced through reweighting and resampling techniques. Systematic errors in the flux estimation have been determined by varying parameters within their uncertainties, accounting for correlations where appropriate