Electric monopole (E0) transitions studies in medium mass 50 ≤ A ≤ 72 nuclei
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Date
2020
Authors
Avaa, Abraham Aungwa
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Abstract
The study of electric monopole transitions between two excited 0 plus states
is important because the monopole strength carries vital information about the
nuclear structure due to its direct link with the mean-square charge radius hr2i
and quadrupole deformation parameter 2. Therefore, the measurement of internal
conversion electrons ICE or internal pair formation IPF is crucial for
E0 transition studies. Transitions between 0 plus states do not bear a change in angular
momentum. Hence, single-photon emission is forbidden, but 0+ states can
decay via conversion electrons or pair formation and two-photon emission which
is mostly negligible. To implement E0 studies at iThemba Laboratory for Accelerator
Based Sciences iThemba LABS, an electron spectrometer that uses a
solenoidal magnetic field acting as a lens and a Si Li detector has been refurbished
and characterized using calibration sources of ICE. Figures of merit have been extracted
and compared with simulations. The spectrometer coupled with an array
of LaBr3 Ce detectors and Low Energy Photon Spectrometers LEPS was successfully
implemented for in-beam experiments.
Description
A thesis submitted to the Faculty of Science, University of the Witwatersrand, in fulfillment of
the requirements for the degree of Doctor of Philosophy, 2020