O compound nucleus*

The ¹³C(α, n)¹⁶O reaction is the primary source of neutrons fueling the slow neutron capture process (s-process) to produce increasingly heavier isotopes along the nuclear chart. Using both direct and indirect methods, many efforts within the nuclear astrophysics community have been made to further constrain this reaction rate. An intermediate state can be formed during the ¹³C(α, n)¹⁶O reaction, causing a resonance to appear as an excitation in the ¹⁷O compound nucleus. Further measurements are therefore required to refine the ¹⁶O total neutron cross section database, leading to a more accurate evaluation of the ¹³C(α, n)¹⁶O reaction rate. We have identified a number of narrow resonances in the ¹⁶O + n entrance channel to be studied using neutron transmission and scattering measurements. Our measurements utilize the newly-installed Fixed Angle Short Trajectory (FAST) reaction-based collimated neutron source at the Edwards Accelerator Laboratory at Ohio University. The FAST neutron station is also equipped with a newly designed time-varying voltage ramp supply, which provides a unique approach for performing narrow resonance scanning techniques. This presentation includes an explanation of the experimental apparatus, a Monte Carlo simulation design of the FAST neutron source and preliminary data from its commissioning experiments.