Investigating Proton Pairing in ⁷⁶SE with Two-Proton Transfer onto ⁷⁴GE

The current experimental effort to detect neutrinoless double beta decay (0νββ) has encouraged significant interest in understanding the nuclei that are candidates for the observation of this process. The goal of this thesis is to contribute to the current body of work on the germanium isotopes near ⁷⁶Ge, a candidate nucleus currently being used by several large-scale searches for 0νββ. Single-nucleon transfer experiments have been very successful in determining the occupancies of the valence shells in the parent and daughter nuclei ⁷⁶Ge and ⁷⁶Se. However, understanding the ground-state pairing of neutrons in ⁷⁶Ge and protons in ⁷⁶Se is also crucial because 0νββ converts correlated neutron pairs to correlated proton pairs. Neutron pairing in ⁷⁶Ge has been found to be concentrated almost exclusively in the ground state, but studies on the tellurium isotopes have indicated that a fully neutron-paired ground state does not constrain the distribution of proton-pairing strength. This work uses the (³He,n) transfer reaction with a ⁷⁴Ge target to investigate the proton-pairing strength distribution in ⁷⁶Se. It is found that proton pairs transfer predominantly to the ground state of ⁷⁶Se. Proton-pair transfer to excited 0⁺ states in ⁷⁶Se is determined to be less than 4-8% of the ground-state pair-transfer strength.