Surface-layer corrections to the level-density formula for a diffuse Fermi gas

Using the Thomas-Fermi treatment and the leptodermous expansion in powers of A − 1 3 , we derive a formula for the nuclear level-density parameter a , which corrects the conventional expression for the presence of the diffuse surface region. This appears to remove the discrepancy (of about a factor of 1.7) between the empirical values of a A and those that would follow from considering the nucleus to be a simple Fermi gas at constant (bulk) density.