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Title: Measurement of the ²²Ne(ρ,γ)²³3Na reaction rate using the DRAGON facility and commissioning of the EMMA recoil mass spectrometer
Author: Williams, Matthew
Awarding Body: University of York
Current Institution: University of York
Date of Award: 2018
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The 22Ne(p,gamma)23Na reaction rate has been shown to have a significant impact on the abundances of elements produced in a variety of astrophysical environments. This thesis presents results obtained from the first inverse kinematics study of the 22Ne(p,gamma)23Na reaction, which was undertaken using the DRAGON recoil separator facility at TRIUMF. The strengths of resonances at E(c.m) = 181, 248, 458, 610, 632 and 1222 keV were measured, as well as the non-resonant contribution in the range of 282 < E(c.m.) < 511 keV. The important reference resonance at E(c.m.) = 458 keV is found to have a strength of wg = 0.467(14) eV, which is significantly lower than previously reported values. The astrophysical impact of the new 22Ne(p,gamma)23Na reaction rate was assessed, with respect to the most recent STARLIB compilations, using a variety classical nova and asymptotic giant branch (AGB) star nucleosynthesis models. The new rate results in changes of up to a factor of two in 22Ne and 23Na abundances produced in oxygen-neon and carbon-oxygen classical novae respectively, whereas no significant changes are evident for the low and intermediate mass AGB star models considered here. This thesis also documents the successful commissioning of a new recoil mass spectrometer located at the TRIUMF ISAC-II facility. The Electromagnetic Mass Analyser (EMMA) is designed to separate the products of nuclear reactions and disperse those products onto focal plane detectors in accordance with their mass/charge (m/q) ratio. EMMA's acceptances, transport efficiencies, resolution and dispersion were investigated in a series of in-beam and alpha source tests. Results from these tests compare favourably with design expectations, with the exception of apparently reduced vertical angle acceptance and larger than expected geometric aberrations at large horizontal angles; both require further investigation. In addition, EMMA was successfully able to identify the heavy products of fusion evaporation reactions induced by beams of 23Na and 24Na on a natural-Cu target. Together, the results from these commissioning tests represent important and necessary first steps toward implementing EMMA into the experimental nuclear physics program at ISAC.
Supervisor: Fulton, Brian ; Davids, Barry Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available