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.Borg, Dana TamaraSubject: search.filters.subject.Geochemistry

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    THE ISOTOPIC ABUNDANCE OF CESIUM IN TRINITITE: IMPLICATIONS FOR POST-DETONATION ANALYSIS OF NUCLEAR MATERIALS
    (2013) Borg, Dana Tamara; McDonough, William F; Geology; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)
    Currently, there are few studies of post-detonation materials due to their extremely complex nature. The cesium isotopic composition of trinitite, the product of the first nuclear detonation, was determined using multi-collector inductively coupled plasma mass spectrometry (MC-ICP-MS) to evaluate the relationship between the time since the detonation of nuclear materials and their cumulative fission yields. The ratio of 137Cs/135Cs in trinitite was found on average to be 0.31±0.06, with abundances of 137Cs (t1/2=30.07a) and 135Cs (t1/2=2.3x106a) equal to 21.8±0.6pg/g and 68±12pg/g, respectively. These values result in an under-calculation of the amount of time that has passed since detonation. It is recommended that an initial 137Cs/135Cs ratio of 1.5±0.3 be used, instead of the proportion that they are produced during fission of 239Pu 0.87±0.02, due to the fractionation of 137Cs and 135Cs before their deposition in trinitite due to the approximately 200 times longer cumulative half-life of the precursors to 135Cs.