On the basis of the improved level scheme of ${}_{}{}^{176}{}_{}{}^{}\mathrm{Lu}$ it is demonstrated that the stellar s-process production as well as the stellar beta decay rate of that nucleus depend strongly on temperature. This behavior results from the completely different half-lives of the ground state and the isomer; since these states are coupled by induced transitions in the hot stellar photon bath, the effective half-life of ${}_{}{}^{176}{}_{}{}^{}\mathrm{Lu}$ is drastically reduced. The $5^{\mathrm{-}}$ state at 838.64 keV was identified as the most efficient mediating level. Consequently, ${}_{}{}^{176}{}_{}{}^{}\mathrm{Lu}$ can no longer be considered as a chronometer for the age of the s process; instead, it can be interpreted as an s-process thermometer yielding a temperature range between 2.4×${10}^8$ to 3.6×${10}^8$ K.

• Received 27 September 1990

DOI:https://doi.org/10.1103/PhysRevC.44.2839