Nuclear level density and the effective nucleon mass

Novel results were obtained for the spin dispersion parameter, which demonstrate the influence of the nucleon pairing correlations and shell effects in nuclei. The volume and Surface parameters of the level density parameter, as well as the shell-damping factor, were determined as a(upsilon) = 0.076 +/- 0.009 MeV-1 a(s) = 0.180 +/- 0.047 MeV-1, and gamma(0) = 0.47 +/- 0.04 MeV-1, respectively. The effective nucleon mass at the Fermi surface is found to be enhanced and its value is m*/m = 1.09 +/- 0.13. These findings are in excellent agreement with the theoretical estimates of Shlomo and Natowitz. [S0031-9007(98)07627-3].