Search for Na in novae supported by a novel method for measuring femtosecond nuclear lifetimes.

Classical novae are thermonuclear explosions in stellar binary systems, and important sources of Al and Na. While γ rays from the decay of the former radioisotope have been observed throughout the Galaxy, Na remains untraceable. Its half-life (2.6 yr) would allow the observation of its 1.275 MeV γ-ray line from a cosmic source. However, the prediction of such an observation requires good knowledge of its nucleosynthesis. The Na(p, γ)Mg reaction remains the only source of large uncertainty about the amount of Na ejected. Its rate is dominated by a single resonance on the short-lived state at 7785.0(7) keV in Mg. Here, we propose a combined analysis of particle-particle correlations and velocity-difference profiles to measure femtosecond nuclear lifetimes. The application of this method to the study of the Mg states, places strong limits on the amount of Na produced in novae and constrains its detectability with future space-borne observatories.