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UBC Theses and Dissertations

A positron spectrometer Brown, Charles Grant


The existing intermediate image nuclear spectrometer has been modified to count either positrons or negatrons by the addition of a helical baffle. Design considerations of the helical baffle and source requirements for the present investigation have been discussed. An investigation of the positron spectrum of ¹⁵²Eu has been completed. Kurie-plot analysis of the data has confirmed the presence of two primary positron groups with end point energies 713.5 ± 2KeV and 471 ± 5KeV, and intensities (1.0 ± 0.1) x 10⁻⁴ per decay and (0.6 ± 0.2) x 10⁻⁴ per decay respectively. It has been possible to assign error limits to these intensities for the first time. The presence of an internal pair formation positron distribution has also been confirmed. The intensity of the pair formation positrons was deduced from the data for the first time as (0.4 ± 0.05) x 10⁻⁴ per decay, in good agreement with theoretical predictions. The results are in good agreement with previous investigations, excepting the intensity of the 713.5KeV primary positron group. The disparity may be caused by effects due to source and backing thickness in previous work.

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