Improvements to ATHENA for the Total Cross-Section Measurement of ¹⁵O(α,p)¹⁸F

Detecting distant novae through 511 keV γ rays from electron-positron annihilation provides a rather direct diagnostic of nova temperatures and densities as probed through nucleosynthesis. ¹⁸F is one of the important radioisotopes produced in novae since it has a half-life on the same order that novae ejecta become transparent to γ rays. The cross section of the primary destruction mechanism, ¹⁸F(p,α)¹⁵O, is still uncertain due to unknown interference between broad resonances and near- and sub-threshold resonances. The limited availability of low-energy, high-intensity ¹⁸F beams has made direct measurement difficult. However, it is feasible to measure the time-inverse reaction with a radioactive ¹⁵O beam from the TriSol facility at the University of Notre Dame with the Active Target High Efficiency detector for Nuclear Astrophysics (ATHENA). Significant improvements have been made to ATHENA to handle the beam intensity necessary to measure ¹⁵O(α,p)¹⁸F. Improvements to ATHENA, the commissioning thereof, and plans for the measurement of ¹⁵O(α,p)¹⁸F will be discussed.