MSc Thesis Presentation: Investigation of High-Lying (alpha,gamma) Resonances in 22Ne through One-Neutron Transfer in Inverse Kinematics at TIGRESS

Date and Time


MACN 318


MSc Candidate

Beau Greaves


Our knowledge of astrophysical processes is dependent on our understanding of the nuclei involved in these reactions. By studying the structure of such nuclei, the information measured can be directly applied to reaction rate calculations, and by defining these rates, we are able to gain information on the isotopic abundances not only specific to these stellar environments, but the universe as a whole. An example of one of these key nuclei is 22Ne. Involved in both the production of 19F and as a neutron source in the s-process in both AGB and massive stars, probing the properties of the resonance states for the 18O(alpha,gamma)22Ne reaction allows for a unique opportunity to limit the uncertainty in this reaction rate, as well as the resultant isotopic abundance for the fed and competing reactions.

In November of 2018, a 165 MeV beam of 21Ne was delivered to a thin deuterated foil target (CD2) in order to study the 21Ne(d,p)22Ne reaction in the ISAC II subfacility at TRIUMF, located in Vancouver, British Colombia. This was accomplished using the high-purity, segmented germanium clover array, TIGRESS, alongside the complementary segmented silicon array for measurement of recoil particles, SHARC. From this transfer reaction, twenty four states were populated, including four of the six 18O(alpha,gamma)22Ne resonance states. The measurement of these resonance states allowed for the determination of the spin of the 9.841 MeV resonance using the gamma-coincident proton angular distribution, the main source of reaction rate uncertainty present for the 18O(alpha,gamma)22Ne reaction below 0.1 GK. Further information gained on these resonance states, as well as the methods used, are discussed in further detail throughout this work.

Examination Committee

  • Dr. Xiaorong Qin, Chair
  • Dr. Dennis Mücher, Advisor
  • Dr. Paul Garrett
  • Dr. Joanne O’Meara

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