Speaker
Prof.
Ronai Lisboa
(UFRGN)
Description
We present relativistic mean field (RMF) calculations in
the Dirac-Hartree-Bogoliubov (DHB) formalism for hot nuclei considering
not only the self-consistent temperature and density dependence of
the relativistic interaction, but also the vapour phase to take in
account the unbound nucleon states. The temperature dependence of
the pairing gaps, nuclear deformation, radii, binding energies, entropy
and caloric curves of spherical and deformed nuclei is obtained where
the temperature is introduced in the DHB approximation by using the
Matsubara formalism. We do not include the Fock term and use a zero-range
approximation to the relativistic pairing interaction to calculate
proton--proton and neutron--neutron pairing gaps and energies. A vapor
subtraction procedure is used to account for unbound states and to
remove long range Coulomb repulsion between the hot nucleus and the
gas as well as the contribution of the external nucleon gas. We show
that n--n pairing gaps in the $^{1}S_{0}$ channel vanish for low
temperatures in the range $T_{c^p}=0.4-1.0$ MeV both for spherical
nuclei such as $^{90}$Zr and $^{140}$Ce and the deformed nuclei
$^{150}$Sm and $^{168}$Er. Thus, the nuclear superfluid phase -
at least for this channel - can only survive at very low nuclear
temperatures. For these nuclei the shell effects and nuclear deformation
disappear at slightly higher temperatures of $T_{c^s}=2.0-4.0$
MeV.
