Impact of the Experimentally Constrained ⁹³Sr(n,γ)⁹⁴Sr Reaction for the Astrophysical i-Process

Neutron-capture cross sections play a vital role in our understanding of heavy element nucleosynthesis. In astrophysical processes such as the intermediate neutron-capture process, or i-process, element formation occurs in neutron-rich environments and involves short-lived isotopes for which capture cross sections cannot be measured via direct techniques. Instead reaction rates in these regions rely on calculations that have uncertainties up to a few orders of magnitude. Recent measurements of the β-decay of ⁹⁴Rb, which compared the neutron-to gamma-ray-branching ratio of state decays above the neutron separation energy in ⁹⁴Sr, suggest an enhanced γ-ray branch which would in turn lead to an unexpectedly large ⁹³Sr(n,γ) cross section. If confirmed, such an enhancement could have a strong impact on our understanding of i-process nucleosynthesis involving nuclei in this region. In order to investigate this potential enhancement of the ⁹³Sr(n,γ) cross section and its impact on the i-process, an experiment was performed at TRIUMF using an 8 MeV/u ⁹³Sr beam impinging on a CD₂ target. The (d,pγ) coincidence data was measured using the SHARC and TIGRESS arrays. Experimental details from the measurement of ⁹³Sr(d,pγ)⁹⁴Sr and interpretation of the ⁹³Sr(n,γ)⁹⁴Sr cross section using the Surrogate Reaction Method will be presented along with preliminary i-process calculations.