Interference effects due to sub-threshold resonances in the ¹⁸F destruction reaction ¹⁸F(p,α)¹⁵O at nova temperatures

The discrepancy between observed and predicted ¹⁸F abundances in classical nova explosions is still one of the main problems studied in nuclear astrophysics. This mismatch is mainly caused by uncertainties in the cross sections used in the input of nova computational models, especially in the ¹⁸F main destruction reaction ¹⁸F(p,α) ¹⁵O at low energies, hence placing a poor constraint on the ¹⁸F abundances predicted by those models. The main source of these uncertainties is the incomplete knowledge of interference effects between broad resonances (e.g. E_CM = 665 keV and E_CM = 1380 keV) and those near the proton-threshold region. Accurately determining the energies, spin-parities (J^π), and ANC (widths) of sub-threshold (unbound) states is crucial to study these interference effects. In this talk we will show the results of a ²⁰Ne( ³He,α)¹⁹Ne neutron pickup reaction performed at the Triangle Universities Nuclear Laboratory using its high resolution Enge split-pole magnetic spectrograph. We will present new values and a new compilation for energies of excited states in ¹⁹Ne ranging from 1 to 8 MeV. We will also show the results obtained for the J^π of the proton sub-threshold states in ¹⁹Ne at 6.290 MeV state (E_CM = -120 keV) and at 6.132 MeV state (E_CM = -278 keV). Finally, we will provide new reaction rates for the ¹⁸F(p,α)¹⁵O reaction that include these interference effects at nova temperatures.