<p> The principal subject of this thesis is to experimentally determine the beta attenuation patterns in tooth enamel layers, and to examine the predictions of two theoretical models which are involved in the beta dose calculations of ESR dating. One of the models is based on empirical equations (Yokoyama, 1982) and employed by R.Grün (1986) in the DATA software of ESR dating, the other is based on the "one group" transport theory which was incorporated in the ROSY dating programme (B.J. Brennan, et al., 1997).</p> <p> The theoretical bases of Grün's approximation (i.e. the empirical approach) and the "one group" transport theory are discussed. Their predictions of beta attenuation under 2-π geometry are compared with the results of Monte Carlo simulations, and were then compared with the results of our experimental work, which show clear inclination to the predictions of "one group" theory and Monte Carlo. The previous experiment of Aitken et al.(1985) is also described and its flawed geometric arrangement is discussed.</p> <p> In this study, two sets of experiments are performed. The first set used pitchblende as the irradiator and employed the configuration of irradiator-absorber-detector, which is aimed to reassess the experiment of Aitken et al. (1985). The second set of our experiments used a pure beta source of 90Sr(90Y) and employed the innovative configuration of tooth enamel pellets in a hole of tooth enamel holder, which substantially solved the problem encountered in the first set (e.g. gamma background subtraction and non-2π geometry, etc.).</p> <p> Based on our experimental results as well as the discussion of Aitken et al.'s experiment, a conclusion is drawn that the "one group" theory is more reliable in predicting beta doses in ESR dating samples, and consequently, it challenges the ESR ages calculated by DATA software which employs the empirical approach. The comparison of ESR ages calculated by the two dating programmes is shown, and some revisions of published ESR ages based on DATA programme demonstrate the great significance of our experimental results.</p> / Thesis / Master of Science (MSc)
| Identifer | oai:union.ndltd.org:mcmaster.ca/oai:macsphere.mcmaster.ca:11375/19347 |
| Date | 08 1900 |
| Creators | Yang, Quan |
| Contributors | Rink, W. J., Schwarcz, H. P., Geology |
| Source Sets | McMaster University |
| Language | en_US |
| Detected Language | English |
| Type | Thesis |
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