Empirical model for shell-corrected level densities

摘要

An empirical model for calculating level densities of closed and near- closed shell nuclei has been developed and tested. This method is based on the calculation of shell plus pairing corrections for each relevant nuclide. A new version of the ALICE code is used to extract these corrections from the Myers- Swiatecki mass formula and to apply them to the calculation of effective excitations in level densities. The corrections are applied in a backshifted fashion to assure correct threshold dependence. We compare our calculated results with experimental data for the production of 56Ni and 88Y to test shell corrections near f7/c closure and the N=50 neutron shell. We also compare our results with those using pure Fermi gas (plus pairing) level densities, and with the more computationally intensive model of Kataria and Ramamurthy.