Thermal and electromagnetic properties of ${}^{166}\mathrm{Er}$ and ${}^{167}\mathrm{Er}$

The primary $\gamma$-ray spectra of ${}^{166}\mathrm{Er}$ and ${}^{167}\mathrm{Er}$ are deduced from the ${(}^3\mathrm{He},\alpha \gamma )$ reaction and the ${(}^3\mathrm{He}{,}^3{\mathrm{He}}^{\prime }\gamma )$ reaction, respectively, enabling a simultaneous extraction of the level density and the $\gamma$-ray-strength function. Entropy, temperature, and heat capacity are deduced from the level density within the microcanonical and canonical ensembles, displaying signals of a phaselike transition from the pair-correlated ground state to an uncorrelated state at $T_c\sim 0.5$ MeV. The $\gamma$-ray-strength function displays a bump around $E_{\gamma }\sim 3$ MeV, interpreted as the pygmy resonance.