Transition from the superfluid phase to the normal phase in nuclei far from stability

The contributions of thermal quasiparticle correlations and of continuum coupling upon the superfluid properties of neutron-rich Ni isotopes are studied within the modified BCS approximation at finite temperature. The effect of thermal quasiparticle correlations is included using a secondary Bogolyubov-type canonical transformation explicitly involving the quasiparticle occupation numbers. The effect of continuum coupling is taken into account via the finite widths of the resonant 1 states. It is shown that the combined effects of thermal quasiparticle correlations and of continuum coupling wash out the sharp superfluidnormal phase transition given by the standard BCS calculations. PACS numbers: 21.60.-n, 21.30.Fe, 24.10.Pa, Typeset using REVTEX 2