Studies of orbital electron capture by scintillation counter methods

Joshi, Bala R (1961) Studies of orbital electron capture by scintillation counter methods. PhD thesis, University of Glasgow.

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Considerable theoretical interest lies in the measurements of the L/K capture and K/beta+ branching ratios, but in most cases, particularly for the middle and high atomic number elements, the experimental accuracies are far from being satisfactory enough to be compared profitably with the relevant theory. This arises from the technical difficulties associated in the detection and analysis of the soft X-rays and Auger electrons which accompany capture transitions. Chapter I contains a brief account of the general theory of beta-decay and a discussion of the theory of L/K capture, and K/beta+ branching ratio. The interpretation of the Pierz interference term, in the light of recent development of beta-decay theory, which can be derived from the K/beta+ measurements, is presented. The results of the theory which have a direct bearing on the present work and a review of the more reliable experimental results on the subjects are also given. A description of the new well-type technique developed for the measurement of the L/K capture ratios for the middle and high atomic number elements is given in Chapter II. This technique eliminates the need Tor the surface escape corrections. The next three chapters respectively deal with the experimental measurements on the L/K capture ratios for the allowed transitions Cs131 and Ba131, and for the "unique" first forbidden transition Ti204. The determination of the Fierz interference term from the K/beta+ ratio in pure Gamow-Teller interaction of Co58 is presented in Chapter VI. The beta- spectral branch in Ti204 has also been reinvestigated and the results extended down to 10 KeV. There were no previous measurements on the L/K ratios for Cs131, Ba131 and Ti204 and the present experimental results provide a critical examination of the validity of the theory. The measurement on Co58 is of sufficient accuracy to enable a closer limit to be put on the Fierz interference term. Suggestions regarding the future applications of the technique particularly for the study of higher order processes in the electron capture transitions are presented in chapter VII.

Item Type: Thesis (PhD)
Qualification Level: Doctoral
Additional Information: Adviser: G M Lewis
Keywords: Atomic physics, High energy physics
Date of Award: 1961
Depositing User: Enlighten Team
Unique ID: glathesis:1961-73581
Copyright: Copyright of this thesis is held by the author.
Date Deposited: 14 Jun 2019 08:56
Last Modified: 14 Jun 2019 08:56

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