Pairing transition of nuclei at finite temperature

Pairing transition at finite temperature was investigated by the shell model and BCS calculations. The definitive signature of pairing transition is identified by a “transition temperature” <f>Tt</f> estimated from a “thermal” odd–even mass difference, while there is no sharp phase transition because of the finiteness of nucleus. It is found that <f>Tt</f> is in good agreement with predictions of critical temperature <f>Tc</f> in the BCS approximation, and the pairing correlations almost vanish at two points of the transition temperature <f>T≈2Tt</f>. The BCS calculations show that the critical temperature <f>Tc</f> increases with increasing deformation. [Copyright &y& Elsevier]