Level-density parameters in superheavy nuclei

We systematically study the nuclear level densities of superheavy nuclei, including odd systems, using the single-particle energies obtained with the Woods-Saxon potential diagonalization. We applied minimization over many deformation parameters for the global minima-ground states, and the "imaginary water flow"technique on a many-deformation energy grid for the saddle points, including nonaxial shapes. The level density parameters are calculated by fitting the obtained results with the standard Fermi gas expression. The total potential energy and shell correction dependencies of the level-density parameter are analyzed at the ground state and saddle point. These parameters are compared with the results of a phenomenological approach. As shown, this expression should be modified for the saddle points, especially for small excitation energy. The ratio of the level-density parameter at the saddle point to that at the ground state is shown to be crucial for the survival probability of a heavy nucleus