A Measurement of Neutrino Oscillations with Muon Neutrinos in the MINOS Experiment PDF Download
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Languages : en
Pages : 258
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Book Description
Experimental evidence has established that neutrino flavor states evolve over time. A neutrino of a particular flavor that travels some distance can be detected in a different neutrino flavor state. The Main Injector Neutrino Oscillation Search (MINOS) is a long-baseline experiment that is designed to study this phenomenon, called neutrino oscillations. MINOS is based at Fermilab near Chicago, IL, and consists of two detectors: the Near Detector located at Fermilab, and the Far Detector, which is located in an old iron mine in Soudan, MN. Both detectors are exposed to a beam of muon neutrinos from the NuMI beamline, and MINOS measures the fraction of muon neutrinos that disappear after traveling the 734 km between the two detectors. One can measure the atmospheric neutrino mass splitting and mixing angle by observing the energy-dependence of this muon neutrino disappearance. MINOS has made several prior measurements of these parameters. Here I describe recently-developed techniques used to enhance our sensitivity to the oscillation parameters, and I present the results obtained when they are applied to a dataset that is twice as large as has been previously analyzed. We measure the mass splitting ?m232 = (2.32-0.08+0.12) x 10-3 eV2/c4 and the mixing angle sin2(2?32) > 0.90 at 90% C.L. These results comprise the world's best measurement of the atmospheric neutrino mass splitting. Alternative disappearance models are also tested. The neutrino decay hypothesis is disfavored at 7.2? and the neutrino quantum decoherence hypothesis is disfavored at 9.0?.
Author:
Publisher:
ISBN:
Category :
Languages : en
Pages : 258
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Book Description
Experimental evidence has established that neutrino flavor states evolve over time. A neutrino of a particular flavor that travels some distance can be detected in a different neutrino flavor state. The Main Injector Neutrino Oscillation Search (MINOS) is a long-baseline experiment that is designed to study this phenomenon, called neutrino oscillations. MINOS is based at Fermilab near Chicago, IL, and consists of two detectors: the Near Detector located at Fermilab, and the Far Detector, which is located in an old iron mine in Soudan, MN. Both detectors are exposed to a beam of muon neutrinos from the NuMI beamline, and MINOS measures the fraction of muon neutrinos that disappear after traveling the 734 km between the two detectors. One can measure the atmospheric neutrino mass splitting and mixing angle by observing the energy-dependence of this muon neutrino disappearance. MINOS has made several prior measurements of these parameters. Here I describe recently-developed techniques used to enhance our sensitivity to the oscillation parameters, and I present the results obtained when they are applied to a dataset that is twice as large as has been previously analyzed. We measure the mass splitting ?m232 = (2.32-0.08+0.12) x 10-3 eV2/c4 and the mixing angle sin2(2?32) > 0.90 at 90% C.L. These results comprise the world's best measurement of the atmospheric neutrino mass splitting. Alternative disappearance models are also tested. The neutrino decay hypothesis is disfavored at 7.2? and the neutrino quantum decoherence hypothesis is disfavored at 9.0?.
Author: Stephen James Coleman
Publisher:
ISBN:
Category : Leptons (Nuclear physics)
Languages : en
Pages : 484
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Book Description
Author: Juan Pedro Ochoa-Ricoux
Publisher: Springer Science & Business Media
ISBN: 1441979492
Category : Science
Languages : en
Pages : 300
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Book Description
The centerpiece of the thesis is the search for muon neutrino to electron neutrino oscillations which would indicate a non-zero mixing angle between the first and third neutrino generations (θ13), currently the “holy grail” of neutrino physics. The optimal extraction of the electron neutrino oscillation signal is based on the novel “library event matching” (LEM) method which Ochoa developed and implemented together with colleagues at Caltech and at Cambridge, which improves MINOS’ (Main Injector Neutrino Oscillator Search) reach for establishing an oscillation signal over any other method. LEM will now be the basis for MINOS’ final results, and will likely keep MINOS at the forefront of this field until it completes its data taking in 2011. Ochoa and his colleagues also developed the successful plan to run MINOS with a beam tuned for antineutrinos, to make a sensitive test of CPT symmetry by comparing the inter-generational mass splitting for neutrinos and antineutrinos. Ochoa’s in-depth, creative approach to the solution of a variety of complex experimental problems is an outstanding example for graduate students and longtime practitioners of experimental physics alike. Some of the most exciting results in this field to emerge in the near future may find their foundations in this thesis.
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Category :
Languages : en
Pages : 238
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One of the primary goals in neutrino physics at the present moment is to make a measurement of the neutrino oscillation parameter $\theta_$. This parameter, in addition to being unknown, could potentially allow for the introduction of CP violation into the lepton sector. The MINOS long-baseline neutrino oscillation experiment has the ability to make a measurement of this parameter, by looking for the oscillation of muon neutrinos to electron neutrinos between a Near and Far Detector over a distance of 735 km. This thesis discusses the development of an analysis framework to search for this oscillation mode. Two major improvements to pre-existing analysis techniques have been implemented by the author. First, a novel particle ID technique based on strip topology, known as the Library Event Matching (LEM) method, is optimized for use in MINOS. Second, a multiple bin likelihood method is developed to fit the data. These two improvements, when combined, increase MINOS' sensitivity to $\sin^2(2\theta_)$ by 27\% over previous analyses. This thesis sees a small excess over background in the Far Detector. A Frequentist interpretation of the data rules out $\theta_=0$ at 91\%. A Bayesian interpretation of the data is also presented, placing the most stringent upper boundary on the oscillation parameter to date, at $\sin^2(2\theta_)
Author: Rustem Ospanov
Publisher:
ISBN:
Category : Muons
Languages : en
Pages : 560
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Book Description
MINOS is a long-baseline two-detector neutrino oscillation experiment that uses a high intensity muon neutrino beam to investigate the phenomena of neutrino oscillations. The neutrino beam is produced by the NuMI facility at Fermilab, Batavia, Illinois, and is observed at near and far detectors placed 734 km apart. The neutrino interactions in the near detector are used to measure the initial muon neutrino flux. The vast majority of neutrinos travel through the near detector and Earth matter without interactions. A fraction of muon neutrinos oscillate into other flavors resulting in the disappearance of muon neutrinos at the far detector. This thesis presents a measurement of the muon neutrino oscillation parameters in the framework of the two-neutrino oscillation hypothesis.
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ISBN:
Category :
Languages : en
Pages : 191
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Book Description
MINOS is a long baseline neutrino oscillation experiment. It measures the flux from the predominately muon neutrino NuMI beam first 1 km from beam start and then again 735 km later using a pair of steel scintillator tracking calorimeters. The comparison of measured neutrino energy spectra at our Far Detector with the prediction based on our Near Detector measurement allows for a measurement of the parameters which define neutrino oscillations. This thesis will describe the most recent measurement of muon neutrino disappearance in the NuMI muon neutrino beam using the MINOS experiment.
Author: Ashley Michael Timmons
Publisher: Springer
ISBN: 331963769X
Category : Science
Languages : en
Pages : 177
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This thesis highlights data from MINOS, a long-baseline accelerator neutrino experiment, and details one of the most sensitive searches for the sterile neutrino ever made. Further, it presents a new analysis paradigm to enable this measurement and a comprehensive study of the myriad systematic uncertainties involved in a search for a few-percent effect, while also rigorously investigating the statistical interpretation of the findings in the context of a sterile neutrino model. Among the scientific community, this analysis was quickly recognized as a foundational measurement in light of which all previous evidence for the sterile neutrino must now be (re)interpreted. The existence of sterile neutrinos has long been one of the key questions in the field. Not only are they a central component in many theories of new physics, but a number of past experiments have yielded results consistent with their existence. Nonetheless, they remain controversial: the interpretation of the data showing evidence for these sterile neutrinos is hotly debated.
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Category :
Languages : en
Pages : 5
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The MINOS experiment utilizes the NuMI beam of muon neutrinos to study the phenomenon of neutrino oscillations. Neutrinos are sent over a baseline of 735 km, with a detector near the production point at Fermilab and one at the Soudan underground laboratory in northern Minnesota. By measuring the disappearance characteristic of oscillations, MINOS has made the best measurement of the atmospheric neutrino mass splitting to date. By looking for electron neutrino appearance, a limit has been placed on the the mixing angle sin2(2[theta]13) of
Author:
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Category :
Languages : en
Pages : 4
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Book Description
The MINOS experiment utilizes the NuMI neutrino beam to study the phenomenon of neutrino oscillations. Muon neutrinos are sent over a baseline of 735 km, with a detector near the production point at Fermilab and one at the Soudan underground laboratory in northern Minnesota. By observing the?{sub {mu}} disappearance characteristic of oscillations, MINOS can measure the oscillation parameters. MINOS has previously made the best measurement of the atmospheric-regime mass splitting to date. New results are presented in which the data-set is doubled. Further analysis improvements, and the inclusion of additional event samples, further improve the sensitivity to the oscillation parameters. The mixing angle?13 is currently not measured to differ from zero. By searching for?{sub e} appearance in the?{sub {mu}} beam, MINOS is able to set new limits on the value of?13. An observation of the neutral current interaction rate at the far detector allows limits to be placed on the existence of sterile neutrinos. From September 2009 to March 2010, MINOS has taken data with a dedicated {bar {nu}}{sub {mu}} beam, allowing the first direct precision measurement of the antineutrino oscillation parameters in the atmospheric regime.
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Category :
Languages : en
Pages : 242
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Book Description
MINOS is a long baseline neutrino oscillation experiment. A manmade beam of predominantly muon neutrinos is detected both 1 km and 735 km from the production point by two functionally identical detectors. A comparison of the energy spectra measured by the two detectors shows the energy-dependent disappearance of muon neutrinos characteristic of oscillations and allows a measurement of the parameters governing the oscillations. This thesis presents work leading to measurements of disappearance in the 6% {bar {nu}}{sub {mu}} background in that beam. A calibration is developed to correct for time-dependent changes in the responses of both detectors, reducing the corresponding uncertainty on hadronic energy measurements from 1.8% to 0.4% in the near detector and from 0.8% to 0.4% in the far detector. A method of selecting charged current {bar {nu}}{sub {mu}} events is developed, with purities (efficiencies) of 96.5% (74.4%) at the near detector, and 98.8% (70.9%) at the far detector in the region below 10 GeV reconstructed antineutrino energy. A method of using the measured near detector neutrino energy spectrum to predict that expected at the far detector is discussed, and developed for use in the {bar {nu}}{sub {mu}} analysis. Sources of systematic uncertainty contributing to the oscillation measurements are discussed. In the far detector, 32 charged current {bar {nu}}{sub {mu}} events are observed below a reconstructed energy of 30 GeV, compared to an expectation of 47.8 for [Delta]{bar m}{sub atm}2 = [Delta]m{sub atm}2, sin2(2{bar [theta]}23) = sin2(2{theta}23). This deficit, in such a low-statistics sample, makes the result difficult to interpret in the context of an oscillation parameter measurement. Possible sources for the discrepancy are discussed, concluding that considerably more data are required for a definitive solution. Running MINOS with a dedicated {bar {nu}}{sub {mu}} beam would be the ideal continuation of this work.
