Speaker
Description
Elemental abundances are excellent probes of classical novae (CN). Sensitivity studies show that $^{38}$K($p$,$\gamma$)$^{39}$Ca reaction-rate uncertainties modify the abundance of calcium by a factor of 60 in CN ejecta. Existing direct and indirect measurements are in contradiction concerning the energies and strengths of important resonances in the $^{38}$K($p$,$\gamma$)$^{39}$Ca reaction. Direct measurements of the lowest three known $\ell = 0$ resonances at $E_\mathrm{r} = 386, 515, \text{ and } 679\,\mathrm{keV}$ have greatly reduced the uncertainties on the reaction rate for this reaction. A subsequent $^{40}$Ca($^{3}$He,$^4$He)$^{39}$Ca experiment using the SplitPole at TUNL concluded that one of the resonances ($E_\mathrm{r}$ = 701.3 or $E_\mathrm{r}$ = 679 keV depending on the source of the nuclear data) may have been misplaced in the DRAGON target during the direct measurement and that tentative new states at $E_\mathrm{x} = 5908, 6001, \text{ and } 6083\,\mathrm{keV}$ ($E_\mathrm{r} = 137, 230, \text{ and } 312\,\mathrm{keV}$) could correspond to important resonances in $^{38}$K($p$,$\gamma$)$^{39}$Ca. To resolve these, $^{39}$Ca was studied using the $^{40}$Ca($p,d$)$^{39}$Ca reaction at forward angles with a proton beam energy of $66\,\mathrm{MeV}$ using the K600 magnetic spectrometer. These measurements are aimed at verifying the properties of levels in the region where discrepancies between various experiments persist. Preliminary results will be presented.
