Toward Understanding the $^{15}$O($\alpha,\gamma$)$^{19}$Ne Reaction Rate: $\alpha$-Transfer Reactions on $^{15}$N

The $^{15}$O($\alpha,\gamma$)$^{19}$Ne reaction is well known to be an important breakout from the hot CNO cycle into the thermonuclear runaway that drives Type I X-Ray Bursts. This reaction rate is dominated by resonant $\alpha$ capture into a state at $E_x=4.033$ MeV in $^{19}$Ne. While there have been a variety of experimental studies aimed at determining this reaction rate, the $\alpha$ width of this resonance remains the dominant uncertainty. Currently, $^{15}$O beams of sufficient intensity to study this reaction directly are not available and indirect techniques must be used in order to study the 4.033-MeV state in $^{19}$Ne. Measurements of the ($^6$Li,$d$) and ($^7$Li,$t$) $\alpha$-particle transfer reactions on beams of $^{15}$N have been performed at the Argonne Tandem LINAC Accelerator System facility at Argonne National Laboratory using the HELIcal Orbit Spectrometer (HELIOS) in order to study the mirror to the 4.033-MeV state, located at 3.908 MeV in $^{19}$F. Preliminary results will be shown and implications for the $^{15}$O($\alpha,\gamma$)$^{19}$Ne reaction rate discussed.