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The Global ETD Search service is a free service for researchers
to find electronic theses and dissertations. This service is
provided by the
Networked Digital Library of Theses and Dissertations.
Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
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Showing 11 to 20 of 597 (0.1 seconds)| 11 |
Fission Xenon DatingTeitsma, Albert 06 1900 (has links)
<p> A new dating method has been developed which
uses fission product xenon in a manner similar to
radiogenic argon in the 40Ar - 39Ar method.
Measurable quantities of spontaneous fission xenon
accumulate with time in rocks and minerals containing
approximately 1 ppm or more of uranium as a result of
the spontaneous fission of 238u. In the past, attempts
have been made to date this type of sample by measuring
the absolute amount of fission product xenon and the
uranium content. In the new method a sample is irradiated
in a thermal neutron flux to implant xenon from
the neutron induced fission of 235u in amounts
proportional to the uranium content. After a short
cooling period (before radioactive 133xe has decayed)
the sample is placed in a high vacuum system and the
xenon is released by heating in a series of temperature
steps. For each step the isotopic composition of the
xenon is measured using a high sensitivity mass spectrameter
and the ratio of spontaneous fission xenon to
neutron fission xenon is calculated. Fission xenon ages
for all steps are then calculated from the spontaneous to neutron fission xenon ratios and the measured integrated neutron flux. </p> <p> The method has several advantages over the conventional U - Xe technique. {a) The measurement of isotope
ratios is inherently more precise than the measurement of
absolute quantities. (b) Whereas the conventional U - Xe
technique measures the sample date only once, the method
described in this thesis measures the sample date several
times. (c) If a geological disturbance has caused loss
of fission xenon a valid date can still be obtained using
the low mobility xenon released at high temperatures.
(d) In some samples disturbed dates as well as initial
formation dates can be measured. </p> <p> The method was developed and evaluated by a series
of experiments which dated four zircon samples, one sphene
sample, and a carbonatite sample. The zircon and sphene
samples had been dated in other laboratories by the conventional
u - Th - Pb and Rb - Sr methods. Fission xenon dating
of these samples provided valuable new geochronological
information. The experiments also showed that in addition
to the advantages mentioned, the new method appears to be
better able to see past metamorphic events than other
methods. </p> / Thesis / Candidate in Philosophy
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Monte Carlo Simulation Research on the Spontaneous Fission Yield of 240PuXie, Tianyou January 2015 (has links)
No description available.
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| 13 |
Range and Straggling Measurements of U-235 Fission FragmentsHallam, John William 10 1900 (has links)
The ranges and stragglings of fission fragments from the thermal neutron fission of U-235 have been measured. Particular attention was given to the preparation of very thin uranium sources, the design of a well collimated recoil system and the preparation of the fragment catcher. The ranges and range distributions in aluminum of fission products of mass numbers 95, 140, 141 and 147 have been obtained. The range values obtained agree with previous determinations within the experimental error. The refined techniques developed in this work have enabled differential range distributions to be obtained which are more precise than any previous determinations. / Thesis / Master of Science (MSc)
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| 14 |
Simulation studies of transition metal and actinide oxidesNicoll, Steven January 1995 (has links)
No description available.
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| 15 |
Characterisation of high temperature molecules by matrix isolation infrared spectroscopy and mass spectrometryDay, Trevor Neil January 1994 (has links)
No description available.
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| 16 |
The role of Ypt3p in the membrane traffic pathways of Schizosaccharomyces pombeRoberts, Theresa Helen January 1996 (has links)
No description available.
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| 17 |
Characterisation of adaption mechanisms in the intracellular signalling pathway of the Schizosaccharomyces pombe pheromone communication systemDidmon, Mark Paul January 2001 (has links)
No description available.
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| 18 |
Prompt gamma-rays from fission fragmentsAbdelrahman, Y. S. January 1988 (has links)
No description available.
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| 19 |
Fission fragment gamma-ray multiplicitiesHook, D. E. January 1987 (has links)
No description available.
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| 20 |
Voltage collapse proximity assessment for the operational planning of power systemsNavarro-Perez, Rogelio January 1993 (has links)
No description available.
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