Theses and Dissertations from UMD

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New submissions to the thesis/dissertation collections are added automatically as they are received from the Graduate School. Currently, the Graduate School deposits all theses and dissertations from a given semester after the official graduation date. This means that there may be up to a 4 month delay in the appearance of a give thesis/dissertation in DRUM

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Author: search.filters.author.Christy, Brian JohnSubject: search.filters.subject.IceCube

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    A Search for Relativistic Magnetic Monopoles with the IceCube 22-String Detector
    (2011) Christy, Brian John; Hoffman, Kara; Physics; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)
    Magnetic monopoles are particles which act as a source for divergent magnetic fields, equivalent to a proton's electric field. Beyond simply adding the final symmetry to Maxwell's equations, their existence would solve numerous outstanding problems in the particle physics community. However, no conclusive evidence for their existence has been found. Magnetic monopoles possess many unique characteristics that allow for detection from a variety of experimental methods. One property is the large scaling of the Cherenkov radiation (∼ 8300) compared to electrically charged particles. Magnetic monopoles are postulated to be extremely heavy (∼ 104−1017 GeV). However, they would be topologically stable and accelerated via magnetic field lines throughout the universe, potentially reaching energies ∼ 1015 GeV. Therefore, searches for relativistic magnetic monopoles incident on Earth are an important piece to the overall experimental search. The IceCube neutrino observatory, located at the South Pole, offers a novel environment to search for these particles. IceCube is a km37 GeV, E & 1011 GeV) can travel completely through the Earth while remaining relativistic. This dissertation details the first search performed for these relativistic magnetic monopoles with IceCube data. The data is from 2007, when IceCube operated as a partially completed detector with an instrumented volume of ∼0.2 km3. It considers monopoles at four discrete speeds: β = 0.76, 0.8, 0.9, 0.995, ranging from just above the Cherenkov threshold in ice to a boost factor of 10. Discrimination between a potential magnetic monopole signal and background is achieved by considering the brightness and direction of the event. After an initial search revealed deficiencies in the simulated background model, a more conservative analysis produces limits that are ∼ 10 x better than previous searches. The final limits are then transformed to be a limit on an isotropic flux at the Earth's surface, due to the dependence on direction to the overall sensitivity of the analysis.