Neutron transmission study of ¹⁷O resonances near the ¹³C(α,n)¹⁶O threshold

Stellar nucleosynthesis via the slow neutron-capture process (s-process) is predominantly sustained by neutrons produced through the ¹³C(α,n)¹⁶O reaction. Total and elastic scattering cross section data for ¹⁶O + n provide critical constraints on the low-energy extrapolation of the ¹³C(α,n) reaction rate. Narrow resonances at excitation energies E_x = 6.86, 6.97, and 7.52 MeV have unresolved partial widths due to limited neutron energy resolution in previous studies, motivating further investigation. We have performed new ¹⁷O total cross section measurements for the 6.97-MeV state using neutron transmission at the Fixed Angle Short Trajectory (FAST) neutron source at Ohio University. A key innovation in this measurement is the use of a sweeping DC voltage applied at the production target, which enables continuous modulation of the emitted neutron energy spectrum. This novel technique allows for precise scanning of narrow neutron resonances. We report the resonance strength at E_R = 3005.74 ± 0.24 keV to be ωΓ_n = 0.23 ± 0.09 keV. These results may inform new constraints on the ¹⁶O + n total cross section and its resonance structure relevant to s-process nucleosynthesis.