Isomeric Contributions to Stellar Nucleosynthesis

The rapid-proton capture process (rp-process) is a series of proton capture and beta-decay reactions that proceed up the proton rich side of the chart of nuclides. It is an important part of stellar nucleosynthesis, and responsible for the creation of many elements present in the Universe. Nuclear physics information is needed to calculate the rate of reactions involved stellar nucleosynthesis. In particular, excitation energies, spin-parities, spectroscopic factors, partial and total widths, γ-decay energies, and branching ratios of the involved nuclei are all properties extracted from nuclear physics experiments used with theoretical calculations to determine the rate of the reactions involved. In this work, we investigate the effects of long lived excited states, known as isomeric states, on the rates of reactions involved in rp-process nucleosynthesis. Specifically, we focus on the isomeric states of ²⁴Al (Eᵪ = 0.426 MeV, t₁/₂ = 130 ms) and ²⁶Al (Eᵪ = 0.228 MeV, t₁/₂ = 6.35 s), and how they contribute to their respective proton capture reactions ²⁴Al^m(p,γ)²⁵25Si and ²⁶Al^m(p,γ)²⁷Si. The rates of these reactions play a key role in the determination of final abundances of elements as well as abundances in meteorites and pre-solar grains. Radioactive beams of ²⁴Na and ²⁶Al were developed for this work and used to measure the ²⁴Na(d,p)²⁵Na reaction at the John D Fox Laboratory and the ²⁶Al(d,p)²⁷Al reaction at the ATLAS Facility at Argonne National Laboratory respectively. In both cases, a majority of the beam was in the isomeric state. Utilizing mirror symmetry, we were able to constrain the isomeric influence on the rates of the astrophysically relevant ²⁴Al^m(p,γ)²⁵Si and ²⁶Al^m(p,γ)²⁷Si reactions.