Nuclear level density and thermal properties of $$^{115}\hbox {Sn}$$ 115 Sn from neutron evaporation

The nuclear level density of $$^{115}\\hbox {Sn}$$\n has been measured in an excitation energy range of $$\\sim 2$$\n –9 MeV using the experimental neutron evaporation spectra from the $$^{115}\\hbox {In}$$\n (p, n)\n $$^{115}\\hbox {Sn}$$\n reaction. The experimental level densities were compared with the microscopic Hartree–Fock BCS (HFBCS), Hartree–Fock–Bogoliubov plus combinatorial (HFB + C), and an exact pairing plus independent particle model (EP + IPM) calculations. It is observed that the EP + IPM provides the best description of the experimental data among the three. The thermal properties (entropy and temperature) of $$^{115}\\hbox {Sn}$$\n have been investigated from the measured level densities. The experimental temperature profile as well as the calculated heat capacity show distinct signatures of a transition from the strongly-paired nucleonic phase to the weakly paired one in this nucleus.