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Title: A study of muon neutrino disappearance with the MINOS detectors and the NuMI neutrino beam

Abstract

This thesis presents the results of an analysis of vμ disappearance with the MINOS experiment, which studies the neutrino beam produced by the NuMI facility at Fermi National Accelerator Laboratory. The rates and energy spectra of charged current vμ interactions are measured in two similar detectors, located at distances of 1 km and 735 km along the NuMI beamline. The Near Detector provides accurate measurements of the initial beam composition and energy, while the Far Detector is sensitive to the effects of neutrino oscillations. The analysis uses data collected between May 2005 and March 2007, corresponding to an exposure of 2.5 x 1020 protons on target. As part of the analysis, sophisticated software was developed to identify muon tracks in the detectors and to reconstruct muon kinematics. Events with reconstructed tracks were then analyzed using a multivariate technique to efficiently isolate a pure sample of charged current vμ events. An extrapolation method was also developed, which produces accurate predictions of the Far Detector neutrino energy spectrum, based on data collected at the Near Detector. Finally, several techniques to improve the sensitivity of an oscillation measurement were implemented, and a full study of the systematic uncertainties was performed. Extrapolating from observationsmore » at the Near Detector, 733 ± 29 Far Detector events were expected in the absence of oscillations, but only 563 events were observed. This deficit in event rate corresponds to a significance of 4.3 standard deviations. The deficit is energy dependent and clear distortion of the Far Detector energy spectrum is observed. A maximum likelihood analysis, which fully accounts for systematic uncertainties, is used to determine the allowed regions for the oscillation parameters and identifies the best fit values as Δm$$2\atop{32}$$ = 2.29$$+0.14\atop{-0.14}$$ x 10-3 eV2 and sin223 > 0.953 (68% confidence level). The models of neutrino decoherence and decay are disfavored at the 5.0σ and 3.2σ levels respectively, while the no oscillation model is excluded at the 9.4σ level.« less

Authors:
 [1]
  1. Univ. of Cambridge (United Kingdom)
Publication Date:
Research Org.:
Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States)
Sponsoring Org.:
USDOE
OSTI Identifier:
935002
Report Number(s):
FERMILAB-THESIS-2008-20
TRN: US0804038
DOE Contract Number:  
AC02-07CH11359
Resource Type:
Thesis/Dissertation
Country of Publication:
United States
Language:
English
Subject:
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS; CHARGED CURRENTS; DECAY; ENERGY SPECTRA; EXTRAPOLATION; FERMILAB ACCELERATOR; MUON NEUTRINOS; MUONS; NEUTRINO BEAMS; NEUTRINO OSCILLATION; NEUTRINOS; OSCILLATIONS; PROTONS; SENSITIVITY; Experiment-HEP

Citation Formats

Marshall, John Stuart. A study of muon neutrino disappearance with the MINOS detectors and the NuMI neutrino beam. United States: N. p., 2008. Web. doi:10.2172/935002.
Marshall, John Stuart. A study of muon neutrino disappearance with the MINOS detectors and the NuMI neutrino beam. United States. https://doi.org/10.2172/935002
Marshall, John Stuart. 2008. "A study of muon neutrino disappearance with the MINOS detectors and the NuMI neutrino beam". United States. https://doi.org/10.2172/935002. https://www.osti.gov/servlets/purl/935002.
@article{osti_935002,
title = {A study of muon neutrino disappearance with the MINOS detectors and the NuMI neutrino beam},
author = {Marshall, John Stuart},
abstractNote = {This thesis presents the results of an analysis of vμ disappearance with the MINOS experiment, which studies the neutrino beam produced by the NuMI facility at Fermi National Accelerator Laboratory. The rates and energy spectra of charged current vμ interactions are measured in two similar detectors, located at distances of 1 km and 735 km along the NuMI beamline. The Near Detector provides accurate measurements of the initial beam composition and energy, while the Far Detector is sensitive to the effects of neutrino oscillations. The analysis uses data collected between May 2005 and March 2007, corresponding to an exposure of 2.5 x 1020 protons on target. As part of the analysis, sophisticated software was developed to identify muon tracks in the detectors and to reconstruct muon kinematics. Events with reconstructed tracks were then analyzed using a multivariate technique to efficiently isolate a pure sample of charged current vμ events. An extrapolation method was also developed, which produces accurate predictions of the Far Detector neutrino energy spectrum, based on data collected at the Near Detector. Finally, several techniques to improve the sensitivity of an oscillation measurement were implemented, and a full study of the systematic uncertainties was performed. Extrapolating from observations at the Near Detector, 733 ± 29 Far Detector events were expected in the absence of oscillations, but only 563 events were observed. This deficit in event rate corresponds to a significance of 4.3 standard deviations. The deficit is energy dependent and clear distortion of the Far Detector energy spectrum is observed. A maximum likelihood analysis, which fully accounts for systematic uncertainties, is used to determine the allowed regions for the oscillation parameters and identifies the best fit values as Δm$2\atop{32}$ = 2.29$+0.14\atop{-0.14}$ x 10-3 eV2 and sin2 2θ23 > 0.953 (68% confidence level). The models of neutrino decoherence and decay are disfavored at the 5.0σ and 3.2σ levels respectively, while the no oscillation model is excluded at the 9.4σ level.},
doi = {10.2172/935002},
url = {https://www.osti.gov/biblio/935002}, journal = {},
number = ,
volume = ,
place = {United States},
year = {Sun Jun 01 00:00:00 EDT 2008},
month = {Sun Jun 01 00:00:00 EDT 2008}
}

Thesis/Dissertation:
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