Our paper in which we unambiguously assigned spin-parities to the sub-threshold resonances in 18F(p,α)15O has been published! These findings significantly reduce the uncertainty in the cross section, greatly improving our understanding of fluorine production in nova explosions.
Led by Dr. Federico Portillo, we used the $^{20}$Ne($^3$He,$\alpha$)$^{19}$Ne neutron pick-up reaction to probe the properties of excited stated in $^{19}$Ne. At around 6 MeV, these states strongly affect the rate at which $^{18}$F is destroyed during nova explosions through the $^{18}$F(p,$\alpha$)$^{15}$O reaction. In particular, two excited states laying below the proton threshold interfere quantum mechanically with broad resonances above the threshold. The unknown spin and parity of those states previously created large uncertainties in the reaction cross section, and thus the rate at which fluorine is burned in novae.
Our results unambiguously assigned spins and parities to the sub-threshold states in $^{19}$Ne. While the nature of interference between them and broad resonances is still unknown, these assignments significantly reduce the range of possibly cross sections. With our new results, the reaction rate uncertainty for flourine destruction in novae is reduced to a factor of two.
Reaction rate uncertainties for our new results in comparison to those presented in the literature.
