Thesis (MSc)--Stellenbosch University, 2015. / ENGLISH ABSTRACT: The coincident measurement of gamma-rays originating from nuclei excited in
light-ion reactions and scattered alpha-particles presents interesting opportunities
to characterize the decay path for low multi-polarity nuclear excitations.
This coincident measurement at θlab = 0◦ was shown to be a powerful tool for
the spectroscopy of isoscalar E1 transitions, being selective to distinct modes
of bulk nuclear motions. Aided with the high resolution capabilities provided
by the HPGe Clover detectors as well as the K600 magnetic spectrometer for
both γ and charged particle detection, these experiments are motivated by
the need to investigate E1 strength in stable nuclei around the particle emission
threshold, more commonly referred to as the Pygmy Dipole Resonance
(PDR). However, due to our detector configuration we find that higher effi-
ciency detectors offer a better overall functionality in these α − γ coincidence
measurements which specifically suffer from low statistics.
The feasibility of the (α, α
0γ) reaction using high resolution Clover detectors
and the high efficiency HAGAR detector is characterized through their effi-
ciency to detect γ rays in coincidence with the K600 magnetic spectrometer
at θlab = 0◦
. Through the construction of Eγ − EX coincidence matrices, decay transitions of closely lying nuclear excitations can be studied on a stateby-state
basis. The result is a quantified representation of γ yield, of which
optimization is the key focus in order to extract meaningful nuclear structure
information. / AFRIKAANSE OPSOMMING: Die samevallende meting van gammastrale van kerne opgewek in die lig-ion
reaksies en verspreide alfa-deeljties, bied interessante geleenthede aan om die
verval pad vir lae multi-polariteit kern opwekkings te karakteriseer. Hierdie
samevallende meting by θlab = 0◦ was getoon om ‘n kragtige instrument vir die
spektroskopie van isoscalar E1 oorgange te wees, as gevolg van die vermoë om
selektief te onderskei tussen modes van kollektiewe kern ossillasies. Aangehelp
met die hoë resolusie moontlikhede wat deur die HPGe Clover detektors asook
die K600 magnetiese spektrometer vir beide γ en gelaaide deeltjie opsporing,
hierdie eksperimente is gemotiveer deur die behoefte om E1 krag te ondersoek
in stabiele kerne rondom die deeltjie emissie drumpel, meer algemeen na verwys
as die Pygmy Dipool Resonansie (PDR). Maar as gevolg van die detektor
opset, vind ons dat ’n hoër doeltreffendheid detector ’n beter algehele funksionaliteit
aanbied wat in hierdie samevallende metings veral belangrik is weens
lae statistiek.
Die haalbaarheid van die reaksie wat gebruik maak van hoë resolusie Clover
detektors en die hoë doeltreffendheid HAGAR detektor word gekenmerk
deur hul doeltreffendheid om gammastrale optespoor in toeval met die K600
magnetiese spektrometer by θlab = 0◦
. Deur die konstruksie van toeval Eγ −
EX matrikse, verval oorgange van kern opwekkings kan op ’n staat-by-staat
basis bestudeer word. Die resultaat is ’n gekwantifiseerde verteenwoordiging
van γ opbrengs, waarvan optimalisering die sleutel fokus is om betekenisvolle
kernstruktuur inligting te kan onttrek
| Identifer | oai:union.ndltd.org:netd.ac.za/oai:union.ndltd.org:sun/oai:scholar.sun.ac.za:10019.1/96955 |
| Date | 04 1900 |
| Creators | Erasmus, Wade Luke |
| Contributors | Papka, Paul, Stellenbosch University. Faculty of Science. Dept. of Physics. |
| Publisher | Stellenbosch : Stellenbosch University |
| Source Sets | South African National ETD Portal |
| Language | en_ZA |
| Detected Language | English |
| Type | Thesis |
| Format | xii, 77 pages : colour illustrations |
| Rights | Stellenbosch University |
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