Measuring the ¹⁸F(α,p)²¹Ne excitation function with a new ANASEN design

Several (α,p) reactions on proton-rich nuclei are among the most important nuclear reactions occurring during Type I X-ray bursts. However, large uncertainties remain in these reaction rates due to the lack of direct measurements. The Array for Nuclear Astrophysics and Structure with Exotic Nuclei (ANASEN) is a gas target and charged particle detector designed for direct measurements of (α,p) reactions. Our new approach, replacing the proportional counter with a hexagonal barrel of thin (~80 μm) silicon detectors, significantly improves the tracking resolution. The performance of this new setup was demonstrated in a measurement of the ¹⁸F(α,p)²¹Ne excitation function at TRIUMF-ISAC, which may impact asymptotic giant branch nucleosynthesis and helium burning on accreting white dwarfs. Results will be presented and plans for future measurements at TRIUMF-ISAC and FRIB will be discussed.