Gamma-ray spectroscopy measurements for nuclear reactions in novae
dc.contributor.advisor
Woods, Philip J.
en
dc.contributor.author
Lotay, Gavin James
en
dc.date.accessioned
2010-10-08T07:38:57Z
dc.date.available
2010-10-08T07:38:57Z
dc.date.issued
2009
dc.description.abstract
The 23Mg(pγ)24Al and 26Al(pγ)27Si astrophysical reactions are expected to be of considerable importance in the nucleosynthesis of A≥20 nuclei in classical novae. Previous studies have indicated
that both reactions are dominated by resonant capture to excited
states, above the proton-emission thresholds, in the proton-rich nuclei 24Al and 27Si, respectively. Consequently, by determining the
nuclear properties of such resonant states it is possible to estimate
the 23Mg(pγ)24Al and 26Al(pγ)27Si stellar reaction rates.
In this thesis work, excited states in 24Al and 27Si were populated
via the 10B(16O, 2n) and 12C(16O, n) heavy-ion fusion-evaporation reactions, respectively. The beams of 16O ions were produced by the
Argonne Tandem Linear Accelerator System and prompt electromagnetic radiation was detected using the GAMMASPHERE detector
array, which, in the case of the 24Al experiment, was used in coincidence with recoil selection provided by the Argonne Fragment Mass
Analyzer. The two
γray spectroscopy studies performed in this work
allowed level structure determinations below the respective proton-emission thresholds of 24Al and 27Si nuclei, with improved precision
on previous work. In addition to this, these studies also allowed
a determination of the nuclear properties of proton-unbound astrophysically important
γ decaying states, which, in turn, were used
to re-evaluate the 23Mg(pγ)24Al and 26Al(pγ)27Si stellar reaction
rates. The improved precision of the level energies and unambiguous
assignments of resonant states has reduced the relative uncertainties
in both the 23Mg(pγ)24Al and 26Al(pγ)27Si stellar reaction rates,
constraining the production of A≥20 nuclei in classical novae.
en
dc.identifier.uri
http://hdl.handle.net/1842/3893
dc.language.iso
en
dc.publisher
The University of Edinburgh
en
dc.subject
novae
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dc.subject
nucleosynthesis
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dc.subject
heavy-ion fusion-evaporation reactions
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dc.subject
γ ray spectroscopy
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dc.title
Gamma-ray spectroscopy measurements for nuclear reactions in novae
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dc.type
Thesis or Dissertation
en
dc.type.qualificationlevel
Doctoral
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dc.type.qualificationname
PhD Doctor of Philosophy
en
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