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Solar Modulation of the Cosmic Ray Intensity and the Measurement of the Cerenkov Reemission in Nova’S Liquid Scintillator University of Tennessee, Knoxville TRACE: Tennessee Research and Creative Exchange Doctoral Dissertations Graduate School 12-2015 Solar Modulation of the Cosmic Ray Intensity and the Measurement of the Cerenkov Reemission in NOvA’s Liquid Scintillator Philip James Mason University of Tennessee - Knoxville, [email protected] Follow this and additional works at: https://trace.tennessee.edu/utk_graddiss Part of the Elementary Particles and Fields and String Theory Commons, Stars, Interstellar Medium and the Galaxy Commons, and the The Sun and the Solar System Commons Recommended Citation Mason, Philip James, "Solar Modulation of the Cosmic Ray Intensity and the Measurement of the Cerenkov Reemission in NOvA’s Liquid Scintillator. " PhD diss., University of Tennessee, 2015. https://trace.tennessee.edu/utk_graddiss/3595 This Dissertation is brought to you for free and open access by the Graduate School at TRACE: Tennessee Research and Creative Exchange. It has been accepted for inclusion in Doctoral Dissertations by an authorized administrator of TRACE: Tennessee Research and Creative Exchange. For more information, please contact [email protected]. To the Graduate Council: I am submitting herewith a dissertation written by Philip James Mason entitled "Solar Modulation of the Cosmic Ray Intensity and the Measurement of the Cerenkov Reemission in NOvA’s Liquid Scintillator." I have examined the final electronic copy of this dissertation for form and content and recommend that it be accepted in partial fulfillment of the equirr ements for the degree of Doctor of Philosophy, with a major in Physics. Tom Handler, Major Professor We have read this dissertation and recommend its acceptance: Yuri Kamyshkov, Yuri Efremenko, Larry Townsend Accepted for the Council: Carolyn R. Hodges Vice Provost and Dean of the Graduate School (Original signatures are on file with official studentecor r ds.) Solar Modulation of the Cosmic Ray Intensity and the Measurement of the Cerenkov Reemission in NOνA’s Liquid Scintillator A Dissertation Presented for the Doctor of Philosophy Degree The University of Tennessee, Knoxville Philip James Mason December 2015 Copyright © 2015 by Philip J Mason All rights reserved. ii ACKNOWLEDGEMENTS Thanks to Tom Handler for his guidance and supervision over the duration of this research, and to Yuri Kamyshkov for his assistance with various problems pertaining to the study of the liquid scintillator. This work would not have been possible without the resources at Fermilab or the efforts of the NOνA collaboration. iii ABSTRACT The NOνA (NuMI Off-axis electron neutrino Appearance) experiment is a long baseline neutrino oscillation experiment at Fermi National Accelerator Laboratory. Its purpose is to observe the oscillation of νµ (muon neutrino) to νe (electron neutrino) and to investigate the neutrino mass hierarchy and CP violation in the neutrino sector. Two detectors have been built for this purpose, a Near Detector 300 feet underground at Fermilab, and a Far Detector, on the surface at Ash River, Minnesota. The completion of NOνA’s Far Detector in October 2014 enabled not only the recent measurement of neutrino oscillations, but an array of other physics studies. Coronal mass ejections cause an observable effect on the cosmic ray intensity measured at and around Earth, through the enhancement of the interplanetary magnetic field. Studying this phenomenon generally entails the measurement of the change in intensity of secondary neutrons from air showers, but it is of equal interest to observe the effects on secondary muons. Presented here is the study of the intensity modulation as measured in cosmic muon data from NOνA’s Far Detector in Ash River, MN. In addition, this thesis details the study of the non-linear energy response of NOνA’s liquid scintillator through the measurement of Cerenkov reemission, providing a needed correction to NOνA’s energy calibration. iv TABLE OF CONTENTS Chapter 1. Introduction ...................................................................................................... 1 Chapter 2. Neutrino Physics and History ........................................................................... 3 2.1 Neutrino History ....................................................................................................... 3 2.2 The Solar Neutrino Problem .................................................................................... 5 2.3 Neutrino Oscillations ............................................................................................... 8 2.4 Neutrinos in the Standard Model ........................................................................... 15 2.5 Weak Interactions .................................................................................................. 17 2.6 Neutrino Mass ........................................................................................................ 24 2.7 Neutrino Interactions ............................................................................................. 26 2.7.1 Quasi-elastic Interactions ................................................................................ 28 2.7.2 Resonance Interactions ................................................................................... 37 Chapter 3. Cosmic Rays ................................................................................................... 41 3.1 Cosmic Ray Fundamentals .................................................................................. 41 3.2 Cosmic Rays at Earth ........................................................................................... 48 3.3 The Forbush Effect .............................................................................................. 52 Chapter 4. The NOvA Experiment ................................................................................... 58 4.1 Overview ................................................................................................................ 58 4.2 The NuMI Beam ................................................................................................... 60 4.3 The NOvA Detectors ............................................................................................. 62 4.4 NOvA Electronics and Data Acquisition ............................................................... 66 4.5 Near Detector on the Surface (NDOS) .................................................................. 68 4.6 Monte Carlo in NOνA ............................................................................................ 70 4.7 NOvASoft Software ................................................................................................ 73 Chapter 5. UV Cerenkov Reemission in NOvA’s Scintillator ........................................ 75 5.1 Introduction ............................................................................................................ 75 5.2 Quantities of Importance in Determining Cerenkov Reemission Efficiency ... 80 5.3 Cerenkov Re-emission Analysis ....................................................................... 91 5.4 Results ............................................................................................................... 95 Chapter 6. Forbush Effect Analysis ............................................................................... 102 6.1 Introduction .......................................................................................................... 102 6.2 Data Selection ...................................................................................................... 102 6.3 Cuts ...................................................................................................................... 104 6.4 Track Reconstruction and Analysis ..................................................................... 105 6.5 Results ................................................................................................................... 116 Chapter 7. Conclusions ................................................................................................... 125 List of References ........................................................................................................... 126 Vita .................................................................................................................................. 133 v LIST OF TABLES Table 2.1. Neutral weak vector and axial couplings. .........................................................32 Table 3.1. Relative abundances of cosmic ray nuclei at 10.6 GeV/nucleon, normalized to oxygen (= 1). ......................................................................................................................47 Table 5.1. NOνA’s mineral oil composition by percentage of alkane present ..................93 Table 6.1. The expected change in cosmic flux due to temperature and pressure ...........114 vi LIST OF FIGURES Figure 2.1 Beta decay energy spectrum ..............................................................................4 Figure 2.2 Weak interactions of the neutrino. Charged current interaction and neutral current interaction ...............................................................................................................5 Figure 1.3 Proton-Proton Chain. .........................................................................................6 Figure 2.4 Expected energy spectra for solar neutrinos. .....................................................7 Figure 2.5 Zenith angle distributions for fully
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