Feasibility study of the (α,α'γ) reaction at θlab = 0º using the K600 magnetic spectrometer

Erasmus, Wade Luke (2015-04)

Thesis (MSc)--Stellenbosch University, 2015.

Thesis

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

Please refer to this item in SUNScholar by using the following persistent URL: http://hdl.handle.net/10019.1/96955
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