[en] We report the first observation of off-axis neutrino interactions in the MiniBooNE detector from the NuMI beam line at Fermilab. The MiniBooNE detector is located 745 m from the NuMI production target, at 110 mrad angle (6.3 deg.) with respect to the NuMI beam axis. Samples of charged-current quasielastic ν_μ and ν_e interactions are analyzed and found to be in agreement with expectation. This provides a direct verification of the expected pion and kaon contributions to the neutrino flux and validates the modeling of the NuMI off-axis beam.

[en] The SciBooNE Collaboration has performed a search for charged current coherent pion production from muon neutrinos scattering on carbon, ν_μ¹²C→μ^-12Cπ⁺, with two distinct data samples. No evidence for coherent pion production is observed. We set 90% confidence level upper limits on the cross section ratio of charged current coherent pion production to the total charged current cross section at 0.67x10^-2 at mean neutrino energy 1.1 GeV and 1.36x10^-2 at mean neutrino energy 2.2 GeV.

[en] The SciBooNE Collaboration reports inclusive neutral current neutral pion production by a muon neutrino beam on a polystyrene target (C₈H₈). We obtain (7.7±0.5(stat)±0.5(sys))x10^-2 as the ratio of the neutral current neutral pion production to total charged current cross section; the mean energy of neutrinos producing detected neutral pions is 1.1 GeV. The result agrees with the Rein-Sehgal model implemented in our neutrino interaction simulation program with nuclear effects. The spectrum shape of the π⁰ momentum and angle agree with the model. We also measure the ratio of the neutral current coherent pion production to total charged current cross section to be (0.7±0.4)x10^-2.

[en] The MiniBooNE experiment at Fermilab reports results from a search for ν_μ→ν_e oscillations, using a data sample corresponding to 5.66x10²⁰ protons on target. An excess of 20.9±14.0 events is observed in the energy range 475< E_ν^QE<1250 MeV, which, when constrained by the observed ν_μ events, has a probability for consistency with the background-only hypothesis of 0.5%. On the other hand, fitting for ν_μ→ν_e oscillations, the best-fit point has a χ² probability of 8.7%. The data are consistent with ν_μ→ν_e oscillations in the 0.1 to 1.0 eV² Δm² range and with the evidence for antineutrino oscillations from the Liquid Scintillator Neutrino Detector at Los Alamos National Laboratory.

[en] Two methods are employed to measure the neutrino flux of the antineutrino-mode beam observed by the MiniBooNE detector. The first method compares data to simulated event rates in a high-purity ν_μ-induced charged-current single π⁺ (CC1π⁺) sample while the second exploits the difference between the angular distributions of muons created in ν_μ and ν_μ charged-current quasielastic (CCQE) interactions. The results from both analyses indicate the prediction of the neutrino flux component of the predominately antineutrino beam is overestimated--the CC1π⁺ analysis indicates the predicted ν_μ flux should be scaled by 0.76±0.11, while the CCQE angular fit yields 0.65±0.23. The energy spectrum of the flux prediction is checked by repeating the analyses in bins of reconstructed neutrino energy, and the results show that the spectral shape is well-modeled. These analyses are a demonstration of techniques for measuring the neutrino contamination of antineutrino beams observed by future nonmagnetized detectors.

[en] We report a measurement of inclusive charged current interactions of muon neutrinos on carbon with an average energy of 0.8 GeV using the Fermilab Booster Neutrino Beam. We compare our measurement with two neutrino interaction simulations: NEUT and NUANCE. The charged current interaction rates (product of flux and cross section) are extracted by fitting the muon kinematics, with a precision of 6%-15% for the energy dependent and 3% for the energy integrated analyses. We also extract charged current inclusive interaction cross sections from the observed rates, with a precision of 10%-30% for the energy dependent and 8% for the energy integrated analyses. This is the first measurement of the charged current inclusive cross section on carbon around 1 GeV. These results can be used to convert previous SciBooNE cross-section ratio measurements to absolute cross-section values.

[en] The SciBooNE Collaboration reports K⁺ production cross section and rate measurements using high-energy daughter muon neutrino scattering data off the SciBar polystyrene (C₈H₈) target in the SciBooNE detector. The K⁺ mesons are produced by 8 GeV protons striking a beryllium target in Fermilab Booster Neutrino Beam line (BNB). Using observed neutrino and antineutrino events in SciBooNE, we measure (d²σ/dpdΩ)=(5.34±0.76) mb/(GeV/cxsr) for p+Be→K⁺+X at mean K⁺ energy of 3.9 GeV and angle (with respect to the proton beam direction) of 3.7 degrees, corresponding to the selected K⁺ sample. Compared to Monte Carlo predictions using previous higher energy K⁺ production measurements, this measurement, which uses the NUANCE neutrino interaction generator, is consistent with a normalization factor of 0.85±0.12. This agreement is evidence that the extrapolation of the higher energy K⁺ measurements to an 8 GeV beam energy using Feynman scaling is valid. This measurement reduces the error on the K⁺ production cross section from 40% to 14%.

[en] The MiniBooNE Collaboration reports initial results from a search for ν_μ→ν_e oscillations. A signal-blind analysis was performed using a data sample corresponding to 3.39x10²⁰ protons on target. The data are consistent with background prediction across the full range of neutrino energy reconstructed assuming quasielastic scattering, 200< E_ν^QE<3000 MeV: 144 electronlike events have been observed in this energy range, compared to an expectation of 139.2±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.

[en] The SciBooNE Collaboration reports a measurement of neutral current coherent π⁰ production on carbon by a muon neutrino beam with average energy 0.8 GeV. The separation of coherent from inclusive π⁰ production has been improved by detecting recoil protons from resonant π⁰ production. We measure the ratio of the neutral current coherent π⁰ production to total charged current cross sections to be (1.16±0.24)x10^-2. The ratio of charged current coherent π⁺ to neutral current coherent π⁰ production is calculated to be 0.14_-0.28^+0.30, using our published charged current coherent pion measurement.