The contribution of the slow neutron capture process ($s$ process) to the solar ${}^{180}\mathrm{Ta}^m$ abundance has been investigated on the basis of new experimental information. Measured neutron capture cross sections of ${}^{180}\mathrm{Ta}^m$ and the corresponding Maxwellian averaged $\left(n,\gamma \right)$ rates were important for defining the $s$ abundance of ${}^{180}\mathrm{Ta}^m$, and the result of a recent photoactivation experiment was providing an estimate of its half-life at the temperatures of the $s$-process site. Following the $s$-process network with stellar evolutionary models from the premain sequence through the asymptotic giant branch phase, it was found that the produced ${}^{180}\mathrm{Ta}^m$ survives the high temperatures during He shell flashes because of the fast convective mixing, which provides an efficient means for transporting freshly synthesized matter into cooler, outer zones. Accordingly, ${}^{180}\mathrm{Ta}^m$ appears to be predominantly of $s$-process origin.

• Received 17 February 2003

DOI:https://doi.org/10.1103/PhysRevC.69.055802