Nucleon correlations and nuclear level densities

Abstract

The high energy behaviour of two nuclear models with pairing correlations is studied. It is found that level densities very closely resemble the Fermi gas forms at all energies above the neutron binding energy. For a model with a constant pairing energy between particles in doubly occupied pair states, the moment of inertia is lower than the rigid body value up to energies considerably higher thhan the neutron binding energy. In the second model, which is an analogue of the superconducting state of a metal, the moment of inertia reeaches the limiting value below the neutron binding energy. It is suggested that for the latter model the Gorter-Casimir description of a superconductor gives a sufficient approximation to the level density.