Properties of highly excited nuclei

A prescription is proposed for calculating the contribution of unbound states in nuclear Hartree-Fock calculations at finite temperature. The method is based on the remark that a static Hartree-Fock calculation at finite temperature describes a hot nucleus in equilibrium with an external nucleon vapor. Properties of the hot nucleus including continuum effects are obtained by extracting the contribution of the external gas, which we calculate from a second Hartree-Fock calculation. We show that for a one-body potential this subtraction procedure yields standard formulae for partition functions in terms of phase shifts. Numerical calculations are performed in ⁵⁶Fe and ²⁰⁸Pb. The resuls indicate that continuum contributions are large beyond temperatures of the order of 4 MeV. We also find the existence of a critical temperature, of the order of 10 MeV, beyond which solutions of the equations can no longer be found.