Photoexcitation of Astrophysically Important States in $^{26}$Mg

The $^{22}$Ne($\alpha$,n)$^{25}$Mg reaction is an important source of neutrons for the s-process in massive stars and Asymptotic Giant Branch (AGB) stars. Spin-parity ambiguities of levels in the $^{26}$Mg compound nucleus result in large uncertainties in the reaction rates at temperatures relevant to these environments. We report the results of a nuclear resonance fluorescence experiment at the High Intensity $\gamma$-ray Source (HI$\gamma$S) that used a linearly polarised photon beam to populate levels in $^{26}$Mg at astrophysically important excitation energies. High precision excitation energies, branching ratios, and unambiguous spin-parities were assigned to five levels between $E_{x}=10.5$ and $11.2$\ MeV. We will discuss the $E_{r}=630$\ keV resonance, which, contrary to previous findings, has been found to have unnatural parity, and thus does not contribute to the $^{22}$Ne$+\alpha$ rates. In addition, two natural parity states, located below the neutron threshold, are expected to reduce rate uncertainties for the competing $^{22}$Ne($\alpha$,$\gamma$)$^{26}$Mg reaction significantly.