dc.contributor Hardy, John C. dc.creator Park, Hyo-In dc.date.accessioned 2012-10-19T15:29:38Z dc.date.accessioned 2012-10-22T18:05:42Z dc.date.accessioned 2017-04-07T20:02:00Z dc.date.available 2012-10-19T15:29:38Z dc.date.available 2012-10-22T18:05:42Z dc.date.available 2017-04-07T20:02:00Z dc.date.created 2011-08 dc.date.issued 2012-10-19 dc.identifier.uri http://hdl.handle.net/1969.1/ETD-TAMU-2011-08-10182 dc.description.abstract As a part of our program to test the unitarity of the Cabibbo-Kobayashi-Maskawa matrix, the decay of the superallowed 0? --> 0? beta emitters ??Ca and ??V has been studied in this dissertation. For ??Ca, the half-life, 443.88(36) ms, and superallowed branching ratio, 0.7738(41), have been measured. In our half-life experiment, pure sources of ??Ca were produced and the decay positrons detected in a high-efficiency 4[pi] proportional gas counter. Since the beta? decay of ??Ca feeds ??K^m, which is itself a superallowed beta? emitter, the data were analyzed as a linked parent-daughter decay. Our result for the half-life of ??Ca, with a precision of 0.08%, is a factor of five improvement on the best previous result. The branching-ratio of ??Ca depended on beta-delayed gamma-ray intensities being measured with a high-purity germanium detector calibrated for absolute efficiency to 0.2% precision. This branching-ratio result represents our first step in bringing the ft value for the superallowed ??Ca transition into the desired range of 0.1%. With our half-life and superallowed branching ratio results for ??Ca, we obtain the Ft to be 3072(17) s, in good agreement with the conserved vector current expectation. The half-life of ??V has been measured to be 422.66(6) ms, a factor of two more precise than the best previous measurement. Our present result determines the corresponding Ft value to be 3074.5(26) s, which is consistent with the average $\overline{\mathcal{F}t}$ value of 3072.08(79) s established from the 13 best-known superallowed transitions. This demonstrates that previously accepted half-lives of ??V were correct in their contribution to a precision test of the conserved vector current hypothesis. dc.language.iso en_US dc.subject Superallowed nuclear beta decay dc.subject conserved vector current hypothesis dc.subject unitarity test of the CKM matrix dc.subject half-life dc.subject branching ratio dc.subject precision measurements dc.title High-Precision Measurements of the Superallowed Beta+ Decays of 38Ca and 46V dc.type Thesis
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