Atmospheric Electron Neutrinos in the MINOS Far Detector PDF Download
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Author: Speakman Benjamin Phillip
Publisher:
ISBN:
Category :
Languages : en
Pages : 450
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Author: Speakman Benjamin Phillip
Publisher:
ISBN:
Category :
Languages : en
Pages : 450
Get Book Here
Book Description
Author:
Publisher:
ISBN:
Category :
Languages : en
Pages : 220
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Neutrinos produced as a result of cosmic-ray interactions in the earth's atmosphere offer a powerful probe into the nature of this three-membered family of low-mass, weakly-interacting particles. Ten years ago, the Super-Kamiokande Experiment has confirmed earlier indications that neutrinos undergo lepton-flavor oscillations during propagation, proving that they are massive contrary to the previous Standard Model assumptions. The Soudan Underground Laboratory, located in northern Minnesota, was host to the Soudan2 Experiment, which has made important contributions to atmospheric neutrino research. This same lab has more recently been host to the MINOS far detector, a neutrino detector which serves as the downstream element of an accelerator-based long-baseline neutrino-oscillation experiment. This thesis has examined 418.5 live days of atmospheric neutrino data (fiducial exposure of 4.18 kton-years) collected in the MINOS far detector prior to the activation of the NuMI neutrino beam, with a specific emphasis on the investigation of electron-type neutrino interactions. Atmospheric neutrino interaction candidates have been selected and separated into showering or track-like events. The showering sample consists of 89 observed events, while the track-like sample consists of 112 observed events. Based on the Bartol atmospheric neutrino flux model of Barr et al. plus a Monte Carlo (MC) simulation of interactions in the MINOS detector, the expected yields of showering and track-like events in the absence of neutrino oscillations are 88.0 ± 1.0 and 149.1 ± 1.0 respectively (where the uncertainties reflect only the limited MC statistics). Major systematic uncertainties, especially those associated with the flux model, are cancelled by forming a double ratio of these observed and expected yields: R{sup data}{sub trk/shw}/R{sup MC}{sub trk/shw} = 0.74{sup +0.12}{sub -01.0}(stat.) ± 0.04 (syst.) This double ratio should be equal to unity in the absence of oscillations, and the value above disfavors null oscillation with 96.0% confidence. In addition, the showering sample can be used to measure the atmospheric neutrino flux. Based on the analysis presented in this thesis, the Bartol flux should be scaled by a factor of: S{sub atm} = 1.08 ± 0.12(stat.) ± 0.08(syst.) This is larger than, but consistent with, a measurement at the same location by the Soudan2 Experiment of S{sub atm} = 0.91 ± 0.07.
Author: Caius Leo Frederick Howcroft
Publisher:
ISBN:
Category :
Languages : en
Pages :
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Author: Aftabur Dipu Rahman
Publisher:
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Category :
Languages : en
Pages : 334
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Author: A. Blake
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Category :
Languages : en
Pages :
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Author: Juan Pedro Ochoa-Ricoux
Publisher: Springer Science & Business Media
ISBN: 1441979492
Category : Science
Languages : en
Pages : 300
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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.
Author: Bernard Raymond Becker
Publisher:
ISBN:
Category :
Languages : en
Pages : 724
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Author: Jeremy Peter Gogos
Publisher:
ISBN:
Category :
Languages : en
Pages : 384
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Author:
Publisher:
ISBN:
Category :
Languages : en
Pages : 185
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It is now widely accepted that the Standard Model assumption of massless neutrinos is wrong, due primarily to the observation of solar and atmospheric neutrino flavor oscillations by a small number of convincing experiments. The MINOS Far Detector, capable of observing both the outgoing lepton and associated showering products of a neutrino interaction, provides an excellent opportunity to independently search for an oscillation signature in atmospheric neutrinos. To this end, a MINOS data set from an 883 live day, 13.1 kt-yr exposure collected between July, 2003 and April, 2007 has been analyzed. 105 candidate charged current muon neutrino interactions were observed, with 120.5 ± 1.3 (statistical error only) expected in the absence of oscillation. A maximum likelihood analysis of the observed log(L/E) spectrum shows that the null oscillation hypothesis is excluded at over 96% confidence and that the best fit oscillation parameters are sin2 2[theta]23 = 0.95 -0.32 and [Delta]m$2\atop{23}$ = 0.93$+3.94\atop{ -0.44}$ x 10-3 eV2. This measurement of oscillation parameters is consistent with the best fit values from the Super-Kamiokande experiment at 68% confidence.
Author: J. D. Chapman
Publisher:
ISBN:
Category :
Languages : en
Pages :
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