Orateur
Description
Astrophysical simulations predict that $^{22}$Na is produced in novae explosions. With its half-life of 2.6 years and its characteristic $\gamma$-ray of 1.275 MeV, it could be easily identified and measured with $\gamma$-ray space telescopes, which has not been the case yet. The amount of $^{22}$Na produced in novae depends on the rate of nuclear reactions, and in particular on the $^{22}$Na($p,\gamma)^{23}$Mg reaction rate. It has been shown that the amount of $^{22}$Na ejected from novae is directly proportional to the lifetime of the excited state at Ex=7.785 MeV in $^{23}$Mg.
We have measured this lifetime in an experiment at GANIL-France, associating the VAMOS++ magnetic spectrometer, the AGATA $\gamma$-ray tracking spectrometer and a silicon detector. The analysis of angle-integrated velocity-difference profiles allowed us to obtain a femtosecond sensitivity.
The obtained result places strong limits on the amount of $^{22}$Na produced in novae, explains its non-observation to date in $\gamma$ rays (flux $<$~2.5$\times$10$^{-4}$~ph.cm$^{-2}$s$^{-1}$), and constrains its detectability with future space-borne observatories.
Ref: https://arxiv.org/abs/2212.06302
