A $\gamma$-ray spectroscopy study of excited states in ${}^{26}\mathrm{Si}$ has been performed by using the ${}^{24}\mathrm{Mg}{(}^3\mathrm{He},n)$ reaction at a beam energy of 10 MeV. In particular, states have been studied above the proton threshold relevant for burning in the ${}^{25}\mathrm{Al}(p,\gamma ){}^{26}\mathrm{Si}$ reaction in novae. This reaction influences the amount of ${}^{26}\mathrm{Al}$ injected into the interstellar medium by novae, which contributes to the overall flux of cosmic $\gamma$-ray emission from ${}^{26}\mathrm{Al}$ observed in satellite missions. The present results point strongly to the existence of a $0^{+}$ state at an excitation energy of 5890 keV lying within the Gamow burning window, which raises questions about the existence and properties of another, higher-lying state reported in previous experimental work. The existence of two such states within this excitation energy region cannot be understood within the framework of $sd$-shell-model calculations.

• Received 8 July 2015

DOI:https://doi.org/10.1103/PhysRevC.92.035808