Reevaluation of the $^{22}$Na(p,$\gamma$) reaction rate: Implications for the detection of $^{22}$Na gamma rays from novae

Abstract

Understanding the processes which create and destroy $^{22}$Na is important for diagnosing classical nova outbursts. Conventional $^{22}$Na(p,$\gamma$) studies are complicated by the need to employ radioactive targets. In contrast, we have formed the particle-unbound states of interest through the heavy-ion fusion reaction, $^{12}$C($^{12}$C,n)$^{23}$Mg and used the Gammasphere array to investigate their radiative decay branches. Detailed spectroscopy was possible and the $^{22}$Na(p,$\gamma$) reaction rate has been re-evaluated. New hydrodynamical calculations incorporating the upper and lower limits on the new rate suggest a reduction in the yield of $^{22}$Na with respect to previous estimates, implying a reduction in the maximum detectability distance for $^{22}$Na $\gamma$ rays from novae.