Critical temperature for quenching of pair correlations

The level density at low spin in the ${}^{161,162}\mathrm{Dy}$ and ${}^{171,172}\mathrm{Yb}$ nuclei has been extracted from primary γ rays. The nuclear heat capacity is deduced within the framework of the canonical ensemble. The heat capacity exhibits an S-formed shape as a function of temperature, which is interpreted as a fingerprint of the phase transition from a strongly correlated to an uncorrelated phase. The critical temperature for the quenching of pair correlations is found at $T_c=0.50\mathrm{}\pm 0.04\left(\mathrm{stat}\right)\pm 0.08\left(\mathrm{syst}\right)\hspace{0.5em}\mathrm{MeV}.$