A thesis submitted to the Faculty of Science, University of the Witwatersrand, Johannesburg, in fulfilment of the requirements for the degree of Doctor of Philosophy. Johannesburg, 2016. / This study investigates the e ect of nuclear deformation on both the broad and
ne structure of the Isovector Giant Dipole Resonance (IVGDR) in the rareearth
region. The IVGDR is strongly excited at and close to zero degrees by
virtual-photon Coulomb excitation. As such, the Zero-degree Facility of the
K600 magnetic spectrometer of iThemba Laboratory for Accelerator Based
Sciences (iThemba LABS) was used with an incident proton beam energy
of 200 MeV to measure high energy-resolution (p,p0) scattering on a range
of neodymium isotopes from spherical 142
60Nd82 to the permanently deformed
150
60Nd90 and the correspondingly deformed 152
62Sm90 in the region of the IVGDR.
It is important to note that for nuclei with 88 N 92, a detailed study of
the IVGDR is of speci c interest since it is here that a transition from spherical
to permanently deformed nuclei occurs.
An extensive data analysis procedure was performed, which included cross
section extraction and conversion to equivalent photo-absorption spectra for
comparison with existing photo-absorption data and theoretical predictions. For the more deformed 150Nd and 152Sm nuclei, however,
the data from this study lack the expected double-peaked structure resulting
from the splitting of the IVGDR into K = 0 and K = 1 components, and
display a signi cant reduction in the strength of the K = 0 component of
the IVGDR in comparison to previously published photo-absorption spectra.
This reduced strength near the neutron threshold agrees very well with recent
photo-neutron experiments.
A ne structure analysis was performed on all of the measured isotopes, that
is, 142;144;146;148;150Nd and 152Sm through the use of techniques associated with
ii
the continuous wavelet transform. Characteristic energy scales for the present
high energy-resolution data are extracted using the complex Morlet motherwavelet
and compared to those obtained for the theoretically predicted B(E1)
strength functions. Finally, conclusions regarding the suitability of the model
predictions to the current data are drawn. / GR 2016
| Identifer | oai:union.ndltd.org:netd.ac.za/oai:union.ndltd.org:wits/oai:wiredspace.wits.ac.za:10539/21288 |
| Date | January 2016 |
| Creators | Donaldson, Lindsay Michelle |
| Source Sets | South African National ETD Portal |
| Language | English |
| Detected Language | English |
| Type | Thesis |
| Format | Online resource (167 leaves), application/pdf |
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