Beta decay and rhenium cosmochronology.
dc.contributor.author | Ashktorab, Karim | en_US |
dc.contributor.advisor | Janecke, Joachim W. | en_US |
dc.date.accessioned | 2014-02-24T16:30:41Z | |
dc.date.available | 2014-02-24T16:30:41Z | |
dc.date.issued | 1992 | en_US |
dc.identifier.other | (UMI)AAI9226835 | en_US |
dc.identifier.uri | http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&res_dat=xri:pqm&rft_dat=xri:pqdiss:9226835 | en_US |
dc.identifier.uri | https://hdl.handle.net/2027.42/105839 | |
dc.description.abstract | Among the problems which limit the use of the $\sp{187}$Re/$\sp{187}$Os isobaric pair as a cosmochronometer for the age of the galaxy and the universe are the uncertainties in the partial half-lives of the continuum and bound state decays of $\sp{187}$Re. While the total half-life of the decay is well established, the partial half-life for the continuum decay is uncertain, and several measurements are not compatible. A high temperature quartz proportional counter was used in this work to remeasure the continuum $\beta\sp-$ decay of $\sp{187}$Re. The $\beta$ end-point energy for the decay of neutral $\sp{187}$Re to singly ionized $\sp{187}$Os of 2.75 $\pm$ 0.06 keV agrees with the earlier results. The corresponding half-life of (45 $\pm$ 3) $\times$ 10$\sp9$ years improves and agrees with the earlier measurement of Payne and Drever and refutes other measurements. Based on the new half-life for the continuum decay and a total half-life of (43.5 $\pm$ 1.3) $\times$ 10$\sp9$ years reported by Linder et al., the branching ratio for the bound state decay into discrete atomic states is estimated to be (3 $\pm$ 6)% in agreement with the most recent calculated theoretical branching ratio of approximately 1%. Anomalies in beta spectra reported by J. J. Simpson and others have been attributed to a 17 keV heavy-neutrino admixture. If confirmed, the implications from the existence of such a neutrino for particle and astrophysics would be significant. A multiwire "wall-less" stainless steel proportional counter has been used in the present work to investigate the spectral shape of the $\beta$ decay of $\sp{63}$Ni. No anomalies in the spectral shape were observed which could be attributed to the presence of 17 keV heavy neutrino. | en_US |
dc.format.extent | 129 p. | en_US |
dc.subject | Physics, Nuclear | en_US |
dc.title | Beta decay and rhenium cosmochronology. | en_US |
dc.type | Thesis | en_US |
dc.description.thesisdegreename | PhD | en_US |
dc.description.thesisdegreediscipline | Physics | en_US |
dc.description.thesisdegreegrantor | University of Michigan, Horace H. Rackham School of Graduate Studies | en_US |
dc.description.bitstreamurl | http://deepblue.lib.umich.edu/bitstream/2027.42/105839/1/9226835.pdf | |
dc.description.filedescription | Description of 9226835.pdf : Restricted to UM users only. | en_US |
dc.owningcollname | Dissertations and Theses (Ph.D. and Master's) |
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