First proton-transfer study of 18F + p resonances relevant for novae

The 18F(p, )15O reaction is the predominant destruction mechanism in novae of the radionuclide 18F, a target of -ray observatories. Thus, its rate is important for understanding 18F production in novae. We have studied resonances in the 18F+p system by making a measurement of a protontransfer reaction 18F(d,n). We have observed 15 19Ne levels, 5 of which are below the proton threshold, including a subthreshold state, which has significant lp=0 strength. Our data provide a direct determination of the spectroscopic strength of these states and new constraints on their spins and parities, thereby resolving a controversy, which involves the 8- and 38- keV resonances. The 18F(p, )15O reaction rate is reevaluated, which takes the subthreshold resonance and other new information determined in this experiment into account.