Angular correlation measurements with a segmented clover detector
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Date
2019
Authors
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Publisher
University of Zululand
Abstract
Gamma-gamma angular correlation measurements are an important tool to
determine (amongst other nuclear properties) the multipolarity and the mul-
tipole mixing ratio of a gamma-ray transition. In this work we use for the rst
time a segmented clover detector placed at close geometry to measure angular
correlation functions. Gamma-gamma angular correlation analysis was carried
out for the transitions of 133Ba and 60Co. It allowed to determine the angular
correlation coe cients, a2 and a4, and to establish the multipole mixing ratios
of several gamma-ray transitions. Codes to sort and analyze gamma-gamma
angular correlation data were developed and a technique to deduce the mix-
ing ratios was established. It was shown that the iThemba LABS segmented
clover detector has an excellent capability for gamma-gamma angular correla-
tions measurements, allowing one to determine multipole mixing ratios with
high precision. The analysis of the gamma-gamma cascades of 133Ba proved
that with this detector one can determine the M1+E2 multipole mixing ratios
for gamma-ray transitions with precision similar to that listed in the Nuclear
data tables, where the results of many di erent experiments are combined and
averaged. Note that our results were produced from 12 hours of data collec-
tion for each sources that were used namely 60Co and 133Ba. The analysis of
the 1173 �� 1332 keV cascade in 60Co showed that using the segmented clover
one can easily distinguish a stretched dipole from an unstretched quadrupole
transition. Moreover, new results on the signs of the multipole mixing ratios
for some transitions in 133Ba were obtained. In addition to measuring the
multipole mixing ratios for the transitions in 60Co and 133Ba, an analysis was
performed in order to investigate the possibility of a new 437 keV transition
in 133Ba but no evidence supporting such a transition was found.
Description
A thesis submitted for the Degree of Master of Science in Physics, in the Department of Physics, Faculty of Science and Agriculture at the University of Zululand, 2019.
Keywords
Angular correlation measurements