arXiv subjects

C. D. Moore

Publications and source records attributed to C. D. Moore.

At least 55 records · Page 3Linked to original sources

arXiv2013

Improved Search for $\bar ν_μ\rightarrow \bar ν_e$ Oscillations in the MiniBooNE Experiment

The MiniBooNE experiment at Fermilab reports results from an analysis of $\bar ν_e$ appearance data from $11.27 \times 10^{20}$ protons on target in antineutrino mode, an increase of approximately a factor of two over the previously reported results. An event excess of $78.4 \pm 28.5$ events ($2.8 σ$) is observed in the energy range $200<E_ν^{QE}<1250$ MeV. If interpreted in a two-neutrino oscillation model, $\barν_μ\rightarrow\barν_e$, the best oscillation fit to the excess has a probability of 66% while the background-only fit has a $χ^2$-probability of 0.5% relative to the best fit. The data are consistent with antineutrino oscillations in the $0.01 < Δm^2 < 1.0$ eV$^2$ range and have some overlap with the evidence for antineutrino oscillations from the Liquid Scintillator Neutrino Detector (LSND). All of the major backgrounds are constrained by in-situ event measurements so non-oscillation explanations would need to invoke new anomalous background processes. The neutrino mode running also shows an excess at low energy of $162.0 \pm 47.8$ events ($3.4 σ$) 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.

hep-ex↗

arXiv2013

Status of the Design of the LBNE Neutrino Beamline

The Long Baseline Neutrino Experiment (LBNE) will utilize a neutrino beamline facility located at Fermilab to carry out a compelling research program in neutrino physics. The facility will aim a beam of neutrinos toward a detector placed at the Homestake Mine in South Dakota, about 1300 km away. The neutrinos are produced as follows: First, protons extracted from the MI-10 section of the Main Injector (60-120 GeV) hit a solid target above grade and produce mesons. Then, the charged mesons are focused by a set of focusing horns into a 250 m long decay pipe, towards the far detector. Finally, the mesons that enter the decay pipe decay into neutrinos. The parameters of the facility were determined taking into account several factors including the physics goals, the modeling of the facility, spacial and radiological constraints and the experience gained by operating the NuMI facility at Fermilab. The initial beam power is expected to be ~700 kW, however some of the parameters were chosen to be able to deal with a beam power of 2.3 MW in order to enable the facility to run with an upgraded accelerator complex. We discuss here the status of the design and the associated challenges.

physics.acc-ph↗

arXiv2013

Measurement of the neutrino component of an anti-neutrino beam observed by a non-magnetized detector

Two independent methods are employed to measure the neutrino flux of the anti-neutrino-mode beam observed by the MiniBooNE detector. The first method compares data to simulated event rates in a high purity $\numu$ induced charged-current single $\pip$ (CC1$\pip$) sample while the second exploits the difference between the angular distributions of muons created in $\numu$ and $\numub$ charged-current quasi-elastic (CCQE) interactions. The results from both analyses indicate the prediction of the neutrino flux component of the pre-dominately anti-neutrino beam is over-estimated - the CC1$\pip$ analysis indicates the predicted $\numu$ flux should be scaled by $0.76 \pm 0.11$, while the CCQE angular fit yields $0.65 \pm 0.23$. 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 anti-neutrino beams observed by future non-magnetized detectors.

hep-ex↗

arXiv2013

Emittance and Phase Space Tomography for the Fermilab Linac

The Fermilab Linac delivers a variable intensity, 400-MeV beam to the The MuCool Test Area experimental hall via a beam line specifically designed to facilitate measurements of the Linac beam emittance and properties. A 10 m, dispersion-free and magnet-free straight utilizes an upstream quadrupole focusing triplet in combination with the necessary in-straight beam diagnostics to fully characterize the transverse beam properties. Since the Linac does not produce a strictly elliptical phase space, tomography must be performed on the profile data to retrieve the actual particle distribution in phase space. This is achieved by rotating the phase space distribution using different waist focusing conditions of the upstream triplet and performing a de-convolution of the profile data. Preliminary measurements using this diagnostic section are reported here.

physics.acc-ph↗

arXiv2012

Low Mass WIMP Searches with a Neutrino Experiment: A Proposal for Further MiniBooNE Running

A proposal submitted to the FNAL PAC is described to search for light sub-GeV WIMP dark matter at MiniBooNE. The possibility to steer the beam past the target and into an absorber leads to a significant reduction in neutrino background, allowing for a sensitive search for elastic scattering of WIMPs off nucleons or electrons in the detector. Dark matter models involving a vector mediator can be probed in a parameter region consistent with the required thermal relic density, and which overlaps the region in which these models can resolve the muon g-2 discrepancy. Estimates of signal significance are presented for various operational modes and parameter points. The experimental approach outlined for applying MiniBooNE to a light WIMP search may also be applicable to other neutrino facilities.

hep-ex↗

arXiv2012

Dual baseline search for muon antineutrino disappearance at 0.1 eV^2 < Δm^2 < 100 eV^2

The MiniBooNE and SciBooNE collaborations report the results of a joint search for short baseline disappearance of \bar{ν_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 datasets serves to partially constrain some of the flux and cross section uncertainties. Uncertainties in the ν_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 \bar{ν_μ} disappearance that dramatically improves upon prior limits in the Δm^2=0.1-100 eV^2 region.

hep-ex↗

arXiv2012

Letter of Intent: A new investigation of numu to nue oscillations with improved sensitivity in an enhanced MiniBooNE experiment

We propose adding 300 mg/l PPO to the existing MiniBooNE detector mineral oil to increase the scintillation response. This will allow the detection of associated neutrons and increase sensitivity to final-state nucleons in neutrino interactions. This increased capability will enable an independent test of whether the current excess seen in the MiniBooNE oscillation search is signal or background. In addition it will enable other neutrino interaction measurements to be made including a search for the strange-quark contribution to the nucleon spin Delta s and a low-energy measurement of charged-current quasielastic scattering.

hep-ex↗

arXiv2012

Overview of the LBNE Neutrino Beam

The Long Baseline Neutrino Experiment (LBNE) will utilize a neutrino beamline facility located at Fermilab. The facility is designed to aim a beam of neutrinos toward a detector placed at the Deep Underground Science and Engineering Laboratory (DUSEL) in South Dakota. The neutrinos are produced in a three-step process. First, protons from the Main Injector hit a solid target and produce mesons. Then, the charged mesons are focused by a set of focusing horns into the decay pipe, towards the far detector. Finally, the mesons that enter the decay pipe decay into neutrinos. The parameters of the facility were determined by an amalgam of the physics goals, the Monte Carlo modeling of the facility, and the experience gained by operating the NuMI facility at Fermilab. The initial beam power is expected to be ~700 kW, however some of the parameters were chosen to be able to deal with a beam power of 2.3 MW.

physics.acc-ph↗

arXiv2012

A Combined $ν_μ\to ν_e$ and $\barν_μ\to \barν_e$ Oscillation Analysis of the MiniBooNE Excesses

The MiniBooNE experiment at Fermilab reports results from an analysis of the combined $ν_e$ and $\bar ν_e$ appearance data from $6.46 \times 10^{20}$ protons on target in neutrino mode and $11.27 \times 10^{20}$ protons on target in antineutrino mode. A total excess of $240.3 \pm 34.5 \pm 52.6$ events ($3.8 σ$) is observed from combining the two data sets in the energy range $200<E_ν^{QE}<1250$ MeV. In a combined fit for CP-conserving $ν_μ\rightarrow ν_e$ and $\barν_μ\rightarrow\barν_e$ oscillations via a two-neutrino model, the background-only fit has a $χ^2$-probability of 0.03% relative to the best oscillation fit. The data are consistent with neutrino oscillations in the $0.01 < Δm^2 < 1.0$ eV$^2$ range and with the evidence for antineutrino oscillations from the Liquid Scintillator Neutrino Detector (LSND).

hep-ex↗

arXiv2012

Measurements of atmospheric neutrinos and antineutrinos in the MINOS Far Detector

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 $ν_μ$ and $\barν_μ$ interactions, and 701 contained-vertex showers, composed mainly of charged-current $ν_{e}$ and $\barν_{e}$ 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 $ν_μ$ and $\barν_μ$ events. The observed ratio of $\barν_μ$ to $ν_μ$ events is compared with the Monte Carlo simulation, giving a double ratio of $R^{data}_{\barν/ν}/R^{MC}_{\barν/ν} = 1.03 \pm 0.08 (stat.) \pm 0.08 (syst.)$. The $ν_μ$ and $\barν_μ$ 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 $|Δm^{2}| = (1.9 \pm 0.4) \times 10^{-3} eV^{2}$ and $sin^{2} 2θ> 0.86$. The fit is extended to incorporate separate $ν_μ$ and $\barν_μ$ oscillation parameters, returning 90% confidence limits of $|Δm^{2}|-|Δ\bar{m}^{2}| = 0.6^{+2.4}_{-0.8} \times 10^{-3} eV^{2}$ on the difference between the squared-mass splittings for neutrinos and antineutrinos.

hep-ex↗

arXiv2012

Test of Lorentz and CPT violation with Short Baseline Neutrino Oscillation Excesses

The sidereal time dependence of MiniBooNE electron neutrino and anti-electron neutrino appearance data are analyzed to search for evidence of Lorentz and CPT violation. An unbinned Kolmogorov-Smirnov test shows both the electron neutrino and anti-electron neutrino appearance data are compatible with the null sidereal variation hypothesis to more than 5%. Using an unbinned likelihood fit with a Lorentz-violating oscillation model derived from the Standard Model Extension (SME) to describe any excess events over background, we find that the electron neutrino appearance data prefer a sidereal time-independent solution, and the anti-electron neutrino appearance data slightly prefer a sidereal time-dependent solution. Limits of order 10E-20 GeV are placed on combinations of SME coefficients. These limits give the best limits on certain SME coefficients for muon neutrino to electron neutrino and anti-muon neutrino to anti-electron neutrino oscillations. The fit values and limits of combinations of SME coefficients are provided.

hep-ex↗

arXiv2012

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.

hep-ex↗

arXiv2012

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.

hep-ex↗

arXiv2011

Dual baseline search for muon neutrino disappearance at 0.5 eV^2 < Δm^2 < 40 eV^2

The SciBooNE and MiniBooNE collaborations report the results of a ν_μdisappearance search in the Δm^2 region of 0.5-40 eV^2. The neutrino rate as measured by the SciBooNE tracking detectors is used to constrain the rate at the MiniBooNE Cherenkov detector in the first joint analysis of data from both collaborations. Two separate analyses of the combined data samples set 90% confidence level (CL) limits on ν_μdisappearance in the 0.5-40 eV^2 Δm^2 region, with an improvement over previous experimental constraints between 10 and 30 eV^2.

hep-ex↗

arXiv2011

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 |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.

hep-ex↗

arXiv2011

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 muon antineutrino production, accumulating an exposure of $1.71\times 10^{20}$ protons on target. In the Far Detector, 97 charged current muon antineutrino events are observed. The no-oscillation hypothesis predicts 156 events and is excluded at $6.3σ$. The best fit to oscillation yields $Δ\bar{m}^{2}=(3.36^{+0.46}_{-0.40}\textrm{(stat.)}\pm0.06\textrm{(syst.)})\times 10^{-3}\,\eV^{2}$, $\sin^{2}(2\barθ)=0.86^{+0.11}_{-0.12}\textrm{(stat.)}\pm0.01\textrm{(syst.)}$. The MINOS muon neutrino and muon antineutrino measurements are consistent at the 2.0% confidence level, assuming identical underlying oscillation parameters.

hep-ex↗

arXiv2011

Measurement of K+ production cross section by 8 GeV protons using high energy neutrino interactions in the SciBooNE detector

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 \times 0.76) mb/(GeV/c \times sr) 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\times0.12. 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%.

hep-ex↗

arXiv2011

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 $8.2\times10^{20}$ protons on the NuMI target at Fermilab, we find that $2\sin^2(θ_{23})\sin^2(2θ_{13})<0.12\ (0.20)$ at 90% confidence level for $δ\mathord{=}0$ and the normal (inverted) neutrino mass hierarchy, with a best fit of $2\sin^2(θ_{23})\sin^2(2θ_{13})\,\mathord{=}\,0.041^{+0.047}_{-0.031}\ (0.079^{+0.071}_{-0.053})$. The $θ_{13}\mathord{=}0$ hypothesis is disfavored by the MINOS data at the 89% confidence level.

hep-ex↗