How can we tell the transition from the superconducting to the normal phase?

The importance of the pairing correlation in rapidly rotating nuclei is reviewed by making use of the theoretical method which takes higher order correlations into account. The characteristic difference of the properties of the pairing correlation in the "static" and "dynamic" pairing regimes, which are distinguished by the dominance of the mean-field contributions, is emphasized. Through the investigation of the relative energy spectra the concept of the pairing phase transition is re-examined. Interesting phenomena related to the pair transfer reactions are also mentioned briefly.