2023/08/15 by Magner, A. G., Sanzhur, A. I., Fedotkin, S. N. +3
#F.2 #FOS: Physical sciences #Nuclear Theory (nucl-th)
paper · doi:10.48550/arxiv.2308.07784
Level density ρ(E,N,Z) is calculated for the two-component close- and open-shell nuclei with a given energy E, and neutron N and proton Z numbers, taking into account pairing effects within the microscopic-macroscopic approach (MMA). These analytical calculations have been carried out by using the semiclassical statistical mean-field approximations beyond the saddle-point method of the Fermi gas model in a low excitation-energies range. The level density ρ, obtained as function of the system entropy S, depends essentially on the condensation energy E\rm cond through the excitation energy U in super-fluid nuclei. The simplest super-fluid approach, based on the BCS theory, accounts for a smooth temperature dependence of the pairing gap Δ due to particle number fluctuations. Taking into account the pairing effects in magic or semi-magic nuclei, excited below neutron resonances, one finds a notable pairing phase transition.Pairing correlations sometimes improve significantly the comparison with experimental data.