Pairing interactions and vanishing pairing correlations in hot nuclei

Finite temperature Hartree-Fock-Bogoliubov calculations are performed in Sn isotopes using Skyrme and zero-range, density-dependent pairing interactions. For both stable and very neutron-rich nuclei the critical temperature at which pairing correlations vanish is independent of the volume/surface nature of the pairing interaction. The value of the critical temperature follows approximatively the empirical rule T-c similar or equal to 0.5 Delta(T=0) for all the calculated isotopes, showing that the critical temperature could be deduced from the pairing gap at zero temperature. On the other hand, the pairing gap at temperatures,just below T-c is strongly sensitive to the volume/surface nature of the pairing interaction. (c) 2007 Elsevier B.V. All rights reserved.