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  • About
  • 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.
11

Fission Xenon Dating

Teitsma, 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
12

Monte Carlo Simulation Research on the Spontaneous Fission Yield of 240Pu

Xie, Tianyou January 2015 (has links)
No description available.
13

Range and Straggling Measurements of U-235 Fission Fragments

Hallam, 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)
14

Simulation studies of transition metal and actinide oxides

Nicoll, Steven January 1995 (has links)
No description available.
15

Characterisation of high temperature molecules by matrix isolation infrared spectroscopy and mass spectrometry

Day, Trevor Neil January 1994 (has links)
No description available.
16

The role of Ypt3p in the membrane traffic pathways of Schizosaccharomyces pombe

Roberts, Theresa Helen January 1996 (has links)
No description available.
17

Characterisation of adaption mechanisms in the intracellular signalling pathway of the Schizosaccharomyces pombe pheromone communication system

Didmon, Mark Paul January 2001 (has links)
No description available.
18

Prompt gamma-rays from fission fragments

Abdelrahman, Y. S. January 1988 (has links)
No description available.
19

Fission fragment gamma-ray multiplicities

Hook, D. E. January 1987 (has links)
No description available.
20

Voltage collapse proximity assessment for the operational planning of power systems

Navarro-Perez, Rogelio January 1993 (has links)
No description available.

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